Urinary Metanephrines Research Articles

Reference intervals for deconjugated urine metanephrines by Bhattacharya analysis.

Urine metanephrines are used to screen for phaeochromocytoma or paraganglioma (PPGL). Current reference intervals (RI) derived in healthy individuals are not age or sex-stratified, and lower than in hypertensive patients, leading to high false positive rates. This study aims to determine age and sex-stratified RI from a contingent screening population. Patients with 24-h deconjugated urine metanephrines from 3/6/2010 to 27/8/2022 were included (2936 males, 5285 females), initially by liquid chromatography-electrochemical detection (LC-ECD) then liquid chromatography-tandem mass spectrometry (LC-MS/MS). Bhattacharya analysis was used after log transformation to determine age and sex-stratified RI for metanephrine excretion, normetanephrine excretion, metanephrine/creatinine and normetanephrine/creatinine ratios. Normetanephrine excretion increases with age (RI: males: 18-<30years: <3.4µmol/24h, 30-<40years: <3.7µmol/24h, 40+ years: <5.3µmol/24h; females: 18-<30years: <2.7µmol/24h, 30-<40years: <3.1µmol/24h, 40+ years: <3.7µmol/24h), while metanephrine excretion was consistent across adulthood (RI: males: 18+ years: <1.8µmol/24h; females: 18+ years: <1.2µmol/24h). However, normetanephrine/creatinine and metanephrine/creatinine increase steadily with age after early adulthood, likely due to a decrease in muscle mass, with females having higher normetanephrine/creatinine and metanephrine/creatinine ratios. Age and sex-stratified RI were derived for metanephrine excretion, normetanephrine excretion, metanephrine/creatinine and normetanephrine/creatinine ratios. This is expected to reduce false positives while flagging most PPGL.

An Unusual Cause of Bilateral Adrenal Incidentaloma: A Case Report of Primary Adrenal Lymphoma

Primary adrenal lymphoma (PAL) is an extremely rare among the causes of adrenal incidentaloma. Most were diagnosed with adrenal insufficiency and B symptoms (unexplained weight loss, night sweats, fever). This article presented a 57-year-old woman who was investigated for bilateral adrenal masses found incidentally on computed tomography (CT). Physical examination and laboratory tests revealed no evidence of adrenal insufficiency or B symptoms. Only 24-hour urinary metanephrine and normetanephrine excretion were increased. Tumour F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET/CT) scan showed the greatest dimension was 14 cm in the left adrenal mass and the maximum standardized uptake value (SUV max) was 26.1 (relative to mean SUV in the normal liver parenchyma, which was 2). An adrenal biopsy was performed after taking adequate precautions against the possibility of a catecholamine crisis. Histopathology revealed high-grade B-cell lymphoma. Bone marrow involvement and brain metastasis were not observed. She received the R-EPOCH (rituximab, etoposide, prednisone, vincristine, cyclophosphamide, and doxorubicin) regimen and intrathecal methotrexate therapy as central nervous system prophylaxis. The patient responded well to treatment, and close clinical follow-up continues. PAL should always be considered when a bilateral adrenal mass is detected.

Comparison of the effectiveness of various methods for determining the level of metanephrines in the diagnosis of pheochromocytomas

Pheochromocytoma (PHEO) is a tumor from the chromaffin tissue of the adrenal medulla, capable of hyperproduction of catecholamines. The increased production of hormones by the tumor leads to catecholamine crises, which have a pathological effect on all organs and systems. In the primary diagnosis of pheochromocytomas, it is important to determine the level of the metabolite of catecholamines - metanephrines. Currently, in clinical practice, various methods are used to determine the level of this metabolite: in blood plasma or in urine, total or only free form, fractionated analysis or unfractionated. Comparison of the effectiveness of various methods for determining the level of metanephrines for the diagnosis of pheochromocytomas. A retrospective single-center cohort study was conducted on a sample of patients who were initially operated on for adrenal neoplasm at the Pirogov St. Petersburg State University High Medical Technology Clinic from November 2007 to December 2022 and who passed analysis to determine the level of blood or urine metanephrins before surgical treatment. The results of tests for metanephrine and tumor size were evaluated. 1088 patients with adrenal neoplasms who underwent surgical treatment were examined, of which 348 had histologically confirmed the presence of pheochromocytoma. Four types of metanephrine assays were compared: free fractionated plasma metanephrines (232 patients), unfractionated daily urine metanephrines (431 patients), fractionated total daily urine metanephrines (427 patients) and fractionated free daily urine metanephrines (178 patients). The greatest sensitivity was demonstrated by the analysis of free fractionated plasma methanephrines (95.4%). Unlike others, the sensitivity of this analysis did not decrease in the group of patients with small pheochromocytomas (3 cm or less). The greatest specificity was demonstrated by the analysis of unfractionated metanephrines in daily urine (97.8%), with the lowest sensitivity among all tests (67.6%). The study of fractionated total daily urine metanephrins showed good results of sensitivity and specificity, only slightly inferior to the best indicators, and the analysis of free daily urine metanephrins demonstrated unexpectedly low efficiency. There is a positive correlation between the level of metanephrine in the blood and the size of the tumor. Based on the data obtained, the preferred assays for the primary diagnosis of pheochromocytoma can be considered the determination of fractionated free plasma metanephrines and fractionated total daily urine metanephrines, which is consistent with relevant clinical recommendations. It was found that the size of the tumor correlates with the severity of an increase in the level of metanephrins determined by any of the described methods.

FRI217 False Negative Plasma Metanephrines In A Patient With A Bladder Paraganglioma

Abstract Disclosure: T.F. King: None. G. Sng: None. T. Puar: None. Introduction: Both plasma free metanephrines and urinary metanephrines have high (&amp;gt;90%) sensitivity to detect phaeochromocytoma and paragangliomas (PPGL). False positive urine metanephrines are seen in many conditions including obstructive sleep apnoea (OSA), and plasma metanephrines have been proposed to be a useful diagnostic tool in this patient population. Clinical Case: A 53 year old female was recruited into a study evaluating the utility of plasma and urine metanephrines in the diagnosis of PPGL in patients with OSA. She had a 6 year history of hypertension that was well controlled with amlodipine 5mg daily. She had no headache, palpitations or paroxysmal symptoms. She had 3 previous uneventful pregnancies and there was no significant family history of note. She was overweight (BMI 28.3 Kg/m2) and blood pressure was 130/80 mmHg. Sleep studies revealed severe OSA. Screening plasma and 24 hour urine metanephrines were performed at baseline and again after 6 months (Table 1). 24 hr Urinary normetanephrine, mcg/day (Upper Reference interval 423): Baseline 437, Visit 2 (Six Months later) 535, Post-operative 235. Table 1. Serial measurements of urine and plasma metanephrines. In view of the persistently elevated urinary normetaneprine, a CT abdomen and pelvis was performed. This revealed normal adrenal glands, but an avidly enhancing 2cm focal nodular lesion was seen at the left lateral posterior wall of the urinary bladder. Transurethral biopsy revealed a tumour with immunohistochemistry positive for synaptophysin and GATA3, consistent with a paraganglioma. A CT/PET Ga68 dotatpeptide scan showed intense uptake in the same area with no evidence of lymphadenopathy or distant disease. Amlodipine was changed to terazosin pre-operatively and the patient went on to have an uneventful robot assisted excision and partial cystectomy. Histology was consistent with a bladder paraganglioma with clear tumour margins. Genetic analysis for hereditary PPGL was negative for mutations in SDHx, VHL, RET, NF1, but there was a variant of uncertain significance in the MUTYH gene, namely c.767C&amp;gt;T (p.Thr245Ile). At two months post-operative review, the patient remained well and home blood pressure readings were all &amp;gt;120/80mmHg on 5mg amlodipine. Repeat urine and plasma metanephrines were normal. Conclusions: Plasma metanephrines may not be sensitive enough to detect small asymptomatic bladder paragangliomas. Further studies are warranted to elucidate the optimal diagnostic tests in patients with sleep apnoea and suspected PPGL. Interval measurements of metanephrines may be useful in the diagnosis of small PPGL that may manifest with time. Presentation: Friday, June 16, 2023

FRI200 Severe Cushing Syndrome Due To An ACTH-producing Pheochromocytoma

Abstract Disclosure: G.A. Stamatiades: None. A. Bikas: None. H.J. Shah: None. K. Wong: None. A. Vaidya: None. M. Nehs: None. S.S. Basaria: None. Background: Pheochromocytomas are rare catecholamine-secreting tumors that arise from sympathetic adrenomedullary chromaffin tissue. Rarely, pheochromocytomas co-secrete ACTH and patients present with Cushing syndrome. Due to its rarity, clinicians may not consider this etiology of Cushing syndrome. We report a case of a man with ACTH-producing pheochromocytoma in whom methodic systematic approach led to its diagnosis and successful treatment. Clinical Case: A 48-year-old man presented with altered mental status. His family confirmed depressed mood, paucity of thought, and occasional blank stares. The patient was diagnosed with type-2 diabetes mellitus and hypertension 3 months ago, which were not controlled despite being on multiple anti-hypertensives and anti-diabetic agents. His EEG, head CT, and brain MRI were normal. On admission, his laboratory tests were notable for hypokalemia (3.0 mmol/L, n&amp;lt;5.3 mmol/L) and metabolic alkalosis (HCO3 33 mmol/L, n&amp;lt;32 mmol/L). Physical examination showed facial plethora, multiple ecchymoses and profound proximal muscle weakness. CT scan of the abdomen showed a 3.4 cm left adrenal nodule with a density of 33 Hounsfield units and a 73% absolute washout. The right adrenal gland was hyperplastic. Plasma and urinary metanephrines were significantly elevated (plasma metanephrines 1.6 nmol/l, n &amp;lt; 0.50 nmol/l, urinary metanephrines 1,685 mcg/24h, n &amp;lt;646 mcg/24h). Midnight salivary cortisol was 11,500 ng/dl (n&amp;lt;100 ng/dl) and 24h urinary free cortisol was 13,099 mcg/24h (n &amp;lt; 45 mcg/24h). ACTH was 450 pg/ml (n&amp;lt;63pg/ml) with a serum cortisol of 93 ug/dl (n&amp;lt;18.4 ug/dl). His serum cortisol after 8 mg Dexamethasone Suppression test was 100 ug/dl. DOTATATE PET CT scan showed uptake in the left adrenal nodule. The workup was suggestive of left-sided pheochromocytoma producing ectopic ACTH. The patient underwent laparoscopic left adrenalectomy. Postoperative ACTH was undetectable, indicating surgical cure. His blood pressure and plasma glucose gradually improved and remained normal after discontinuation of all medications. Surgical pathology was consistent with pheochromocytoma with positive staining for ACTH, confirming the diagnosis of ACTH-producing pheochromocytoma. He was discharged home after successful rehabilitation. Clinical Lessons: Pheochromocytomas are a rare cause of ectopic ACTH production, resulting in clinical Cushing syndrome. Imaging of the contralateral adrenal gland provides a valuable clue in making the diagnosis of ectopic ACTH production (as the gland is enlarged rather than atrophic). Reference: (1) Elliott PF, Berhane T, Ragnarsson O, Falhammar H. Ectopic ACTH- and/or CRH-Producing Pheochromocytomas. J Clin Endocrinol Metab. 2021 Jan 23;106(2):598-608. doi: 10.1210/clinem/dgaa488. PMID: 32710791. Presentation: Friday, June 16, 2023

SAT342 Stress-induced Cardiomyopathy And Pheochromocytoma

Abstract Disclosure: C.G. Rivas Pajuelo: None. Introduction Pheochromocytoma (PCC) can be associated with certain genetic syndromes such as Neurofibromatosis type 1(NF1). About 5-7% of patients with NF1 will develop PCC/PGL in their lifetime. Typically, PCC presents with hypertension, and rarely, as stress-induced cardiomyopathy. Herein we present a case of a patient with NF1, and stress-induced cardiomyopathy due to Pheochromocytoma. Case presentation: A 63-year-old woman with medical history of NF1 presented to the hospital for acute hypoxemic respiratory failure and hypertensive emergency. On admission, had troponin level 27 ng/L, pro-BNP 2446 pg/ml; had a transthoracic echocardiogram (TTE) that showed EF of 30%, with global hypokinesis, anteroseptal and inferoseptal akinesis. Given NF1 history and hypertension, a CT chest/abdomen/pelvis was ordered and showed bilateral adrenal adenomas; a 2.6 cm left adrenal adenoma HFU 3, and a right adrenal mass 4.0 x 3.7 cm HFU 45 with indeterminate density. Biochemically, had markedly elevated plasma catecholamines (epinephrine 352 pg/mL, Norepinephrine 1904 pg/mL) and urinary metanephrines (2155 mcg/24 h). She markedly improved after IV diuresis, and prior to discharge was started on alpha-blockade with prazosin. This was titrated as outpatient, with addition of metoprolol 1 week later. MIBG showed intense tracer uptake in the right adrenal gland suggestive of pheochromocytoma, the left adrenal nodule was lipid rich. A repeat TTE 2 months later showed improved EF to 60% and had left heart catheterization revealing normal coronary arteries. She underwent right laparoscopic adrenalectomy, with final pathology report of 4.8 cm pheochromocytoma with negative margins. Discussion: Stress-induced cardiomyopathy is a life-threatening complication that can be the initial presentation in patients with PCC. Hypersecretion of catecholamines specifically norepinephrine and epinephrine, are thought to play a role in combination with PCC tumor cells, to act synergistically and induce direct cardiotoxic effect. Treatment with medical management followed by surgical excision of the PCC will reverse cardiomyopathy as in our patient. Ultimately, because patients with NF1 are at increased risk for PCC, it is recommended they undergo screening with plasma metanephrines and catecholamines or urinary metanephrines at least every 1-2 years especially if hypertension or tachycardia are present. Presentation: Saturday, June 17, 2023

FRI224 A Rare Case Of Recurrent Paraganglioma Presented With Liver Metastasis

Abstract Disclosure: E. Gupta: None. M. Al Mushref: None. Malignant Paragangliomas (PGLs) and Pheochromocytomas (PCC) are extremely rare. Approximately 10% of PCCs and 25% of PGLs are metastatic. Metastatic PGLs typically occur in patients with predisposing genetic mutations. We present a case of recurrent metastatic PGL in a young female with no known genetic predisposition to metastatic disease occurring after surgical resection. Our patient is a 28-year-old female with a history of PGL status post left adrenalectomy and nephrectomy two and a half years prior who presented to the ED for abdominal pain. She was first diagnosed after being admitted for hypertensive emergency. During time of diagnosis, plasma and urinary metanephrines were significantly elevated at 1.13 nmol/L and 907 ug/gCr respectively and plasma and urinary normetanephrines were elevated at 80.2 nmol/L and 52043 ug/gCr respectively. MRI showed a 16 cm left retroperitoneal mass and MIBG scan showed increased uptake in the mass however no evidence of metastatic disease was noted then. The patient had immigrated from Haiti. Her mother had passed away at age 20 of unknown cause and her father has no known history. Genetic testing was negative for hereditary gene mutations including multiple SDHDs, VHL, NF1, MEN1 and MAX. Surgical exploration showed a giant left retroperitoneal neoplasm involving the left kidney and left adrenal and both organs were resected. Pathology revealed PGL, focally extending to peripheral specimen margin and benign retroperitoneal lymph nodes and soft tissues. Post-resection meta- and normetanephrines levels were normal. Unfortunately, the patient was lost to follow up after surgery. On this admission, she endorsed right lower quadrant abdominal pain. Plasma normetanephrine was 1.72 nmol/L, metanephrine was normal, and chromogranin A level was elevated at 545 ng/mL. CT scan revealed multiple hepatic lesions and MIBG scan further showed new increased uptake suggesting metastasis. The patient was asymptomatic and blood pressure remained normal during her hospitalization. Due to concerns of recurrent PGL with metastasis, she established care with Oncology for initiation of treatment. PGL is an extremely rare neuroendocrine tumor and is closely related to PCC. Sympathetic PGLs cause catecholamine surge symptoms but low volume disease may remain asymptomatic. Genetic predisposition is common in malignant PGL particularly succinate dehydrogenase mutation subunit B. Patients should be closely followed up to screen for recurrence and genetic testing should also be done. In our patient’s case, despite surgical resection and negative genetic testing, she developed recurrence of the PGL with new metastasis emphasizing the importance of close surveillance in the case of PGL to monitor for recurrence. Presentation: Friday, June 16, 2023

FRI227 Functional Transformation Of An Initially Non-functional Paraganglioma In A Patient With Cyanotic Congenital Heart Disease

Abstract Disclosure: M. McConnell: None. M. Kanin: None. M.S. Auerbach: None. R. Yu: None. Background: Most pheochromocytomas and about half of paragangliomas (P-PGLs) are functional in that they produce catecholamines. Transformation of non-functional to functional P-PGLs is exceedingly rare. We present a case of such transformation in a young male with cyanotic congenital heart disease (CCHD), resulting in catecholamine-induced cardiomyopathy. Clinical Case: A 27-year-old male with CCHD presented to the hospital with tachycardia, hypertension, and hypoxia. He had a newly depressed ejection fraction of &amp;lt;20% and was in florid heart failure. Despite intervention, he decompensated rapidly, requiring extracorporeal membrane oxygenation (ECMO). Five years prior to this presentation, he had had normal 24-hour urine fractionated metanephrines, vanillylmandelic acid (VMA), and homovanillic acid (HVA) levels; on imaging, he had been incidentally found to harbor a 3.3 x 1.6 x 2.5-cm nodule in the upper aortocaval space which could represent a paraganglioma. Subsequent imaging showed slow growth of this mass. Given this pertinent history, urine and plasma free metanephrine studies were repeated during the hospitalization while he was not on vasopressors. 24-hour urine normetanephrines were elevated at 2,644 mcg/d (81-667 mcg/d), metanephrines at 405 mcg/d (55-320 mcg/d) while plasma free metanephrines were elevated at 0.92 nmol/L (0-0.49 nmol/L) and normetanephrines at 11.85 nmol/L (0-0.89 nmol/L). DOTATATE PET/CT revealed a soft tissue mass measuring 4.3 x 3.1 x 4.9 cm with intense DOTATATE activity in the right paravertebral space between the aorta and cava. He was treated with alpha-adrenergic blockade with improvement in blood pressure. Two months later, he underwent resection of the mass with pathology confirming a 4.9 cm paraganglioma. Conclusion: It is very rare for a paraganglioma to undergo transformation from non-functional to functional status although it is reported in the literature. This scenario is supported by our patient’s normal 24-hour urine metanephrines, VMA, and HVA results on initial presentation followed by marked elevation in urine and plasma metanephrines 5 years later when he presented with heart failure. The functional transformation in this patient was accompanied by significant growth of the paraganglioma. We surmise that alterations in gene expression during tumor growth may be responsible for the functional transformation. It is crucial to reassess the functionality of a paraganglioma if the clinical condition suggests catecholamine excess. Presentation: Friday, June 16, 2023

FRI194 Pheochromocytoma Presenting As Catecholamine-Induced Cardiomyopathy: A Case Report

Abstract Disclosure: M. Tsikala Vafea: None. D. Lee: None. Introduction: Pheochromocytoma (PCC) is a rare catecholamine-secreting neuroendocrine tumor presenting with the classic triad of episodic headache, sweating and tachycardia. Catecholamine-induced cardiomyopathy (CICMP) can occur as a complication of PCC in 7-11% of patients. It presents more commonly as dilated cardiomyopathy and inverted Takotsubo cardiomyopathy but also as hypertrophic or unspecified cardiomyopathy. Following appropriate pharmacologic treatment and resection of PCC, these cardiac complications usually resolve. Case report: 36 year old man with history of hypertension presented to the hospital with worsening orthopnea and cough. Following antibiotic treatment failure for suspected pneumonia, he was re-admitted with hemoptysis, tachycardia, hypoxia, and hypertensive emergency. Troponin and brain natriuretic peptide were found to be elevated. CT chest and abdomen showed pulmonary nodules and a large left adrenal mass measuring 9.6x9.3x9.4 cm, concerning for metastatic PCC. He was subsequently started on doxazosin. Transthoracic echo showed bi-atrial enlargement, diffuse severe left ventricle hypokinesis, reduced ejection fraction 25% and diastolic dysfunction. Stress cardiac MRI showed non-ischemic cardiomyopathy, corroborating the diagnosis of CICMP. After achieving adequate alpha-adrenergic blockade, he was started on goal-direct medical therapy consisting of valsartan, metoprolol and empagliflozin. His pulmonary nodular opacities improved on repeat imaging, congruent with pulmonary edema rather than metastases. Plasma and 24-hour urine metanephrines (2,964 pg/mL and 23,310 mcg/24 hr, respectively) and normetanephrines (9,266 pg/mL and 33,927 mcg/24 hr, respectively), as well as dopamine (493 pg/mL), epinephrine (3,205 pg/mL) and norepinephrine (above reportable range of 4,800 pg/mL) eventually came back significantly elevated, confirming his diagnosis of PCC. A month after presentation, he underwent left adrenalectomy, which revealed an 11 cm composite PCC ganglioneuroma. One-month postoperatively, urine metanephrines and normetanephrines were normal but his ejection fraction remained unchanged. Discussion: CICMP should be considered in patients presenting with acute heart failure and an incidental adrenal mass to avoid delays in treatment. Acute pulmonary edema may resemble pulmonary nodules on CT, so interpretation of these findings should correlate with the clinical presentation. Timely initiation of alpha-adrenergic blockade upon suspicion of PCC is crucial as it can significantly improve hemodynamics, and biochemical markers take time to result. 96% of CICMP cases improve after resection of PCC within a variable time frame ranging from one week to several months. Our patient’s CICMP had not improved one month after his adrenalectomy, but it remains to be seen whether he eventually recovers his cardiac function. Presentation: Friday, June 16, 2023

SAT337 Maternal Cell free DNA Testing Reveals Incidental Finding Of Adrenocortical Carcinoma

Abstract Disclosure: F. Akanbi: None. S. Raja: None. T. Else: None. Maternal Cell-free DNA Testing Reveals Incidental Adrenocortical Carcinoma IntroductionAdrenocortical carcinoma (ACC) is rare; with 1 to 2 cases per million. It is unclear if ACC in pregnancy represents a specific association though 150 cases have been reported. We report a case of ACC detected during fetal sex determination using cell free DNA (cfDNA). Case Report: A 30 year old G1P0 woman presented at GA of 25 weeks with results of non-invasive prenatal screening (NIPS) done for fetal sex determination, which noted atypical findings concerning for possible maternal neoplasm. Pregnancy had been uncomplicated; she had no significant past medical history or features of hypercortisolism. Family history was positive for lung and prostate cancer. Physical examination revealed healthy looking female with no Cushingoid facies, abdomen matched stated GA. Full body MRI revealed 5.5 cm right adrenal mass with lymph nodes metastases. CT-guided retroperitoneal lymph node biopsy showed ACC.She was asymptomatic with significantly elevated urine free cortisol 3648 (3.5-45 mcg/24 hour), serum cortisol 67.5 (5-25 ug/dl), 11-deoxycortisol 3910 (10-79 ng/dl), and suppressed ACTH &amp;lt;5 (5-52 pg/ml). Electrolytes were normal, DHEAS 342 (35-430 ug/dl), aldosterone &amp;lt; 3 (4-31 ng/dl), renin mass 5 (4-44pg/ml), urinary free normetanephrine 0.23 (&amp;lt; 0.9 nmol/l), urinary free metanephrine &amp;lt; 0.2 (&amp;lt; 0.5 nmol/l). MRI of the chest and brain did not show metastases. She developed at GA 29 weeks, hypertension, proteinuria, and transaminitis. Cesarean section was done at GA 30 weeks followed the next day by right adrenalectomy, IVC repair and retroperitoneal lymph node resection. Pathology showed high-grade adrenal cortical carcinoma (12 cm size) with negative margins, vascular invasion and lymph node involvement (T3, N1, M0), no caval involvement, stage III ACC. During chemotherapy planning, metastases were noted, mitotane and pembrolizumab were initiated, but discontinued after 2 cycles on account of generalized rash and elevated liver enzymes. The tumor progressed on etoposide, doxorubicin and cisplatin (EDP), and second line therapy (gemcitabine and capecitabine) was initiated. Conclusion: Physiologic changes of pregnancy mimic clinical features of ACC and pregnancy associated changes in the HPA axis also make ACC diagnosis challenging. Short fragments of DNA (cfDNA) released into the maternal bloodstream can be detected after 7 weeks of gestation. Approximately 2-20% of total cfDNA is placental, it is used for sex determination and detection of congenital genetic abnormalities, cfDNA can also originate from maternal neoplasms and has been shown to detect lung, breast and colon while case series in patients with ACC showed detection of only 1 out of 3 cases. Surgery remains first line therapy for ACC, but adjuvant therapy, surveillance and hormone replacement are also vital in ACC management. Presentation: Saturday, June 17, 2023

FRI165 BIUXX

Abstract Disclosure: A. Haider: None. M. Sadiq: None. J. Shakesprere: None. G.K. Sidhu: None. Background: Syndrome of inappropriate anti-diuretic hormone (ADH) secretion (SIADH) is characterized by inappropriate ADH secretion causing hyponatremia due to free water retention. Plasma volume expansion leads to renin inhibition by the renal juxtaglomerular complex, resulting in decreased aldosterone secretion with inappropriate natriuresis. However, when autonomous renin-independent aldosterone production is present, natriuresis can be suppressed, causing normal sodium levels despite inappropriately high ADH. Case: 58-year-old male with history of resistant hypertension &amp; bipolar disorder on Oxcarbazepine presented with dizziness, lightheadedness, and severe hypokalemia (2.7 mmol/L, n 3.5-5.0 mmol/L). CT Adrenals revealed an incidental 1.2 cm left-sided adrenal adenoma [HU 6, 40% washout]. Serum aldosterone and plasma renin activity (PRA) were obtained in the supine position via LC/MS/MS assay; concurrent serum K+ was 3.4 mmol/L. Spironolactone was started and titrated to 50 mg BID for blood pressure control due to high suspicion of hyperaldosteronism. The patient was continued on Oxcarbazepine 900 mg BID. A 3 mg Dexamethasone suppression test showed suppressed morning cortisol (1.0 μg/dL, n &amp;lt;1.8 μg/dL). Urine catecholamines and metanephrines were obtained and normal. 3-4 days after starting Spironolactone, the patient developed severe subacute hyponatremia (119 mmol/L, n 135-145 mmol/L) from an admission level of 137 mmol/L. No active renal or GI losses, diuretic use, or untreated hypothyroidism were documented. Serum osmolality was low (262 mOsm/kg, n 275-295 mOsm/kg) with urine osmolality of 357 mOsm/kg (n 50-1200 mOsm/kg) and urine sodium of 92 mEq/L (n &amp;gt;20 mEq/L). Serum aldosterone and PRA levels returned with normal aldosterone (7 ng/dL, n 2-9 ng/dL) but suppressed PRA (0.07 ng/mL/hr, n 0.7-3.3 ng/mL/hr) and elevated aldosterone-renin ratio (100 ng/dL per ng/mL/hr, n ≤ 30 ng/dL per ng/mL/hr). As renin was very low despite mild hypokalemia and active Losartan use at the time of testing, these findings were suggestive of primary aldosteronism. In-hospital 24-hour urine aldosterone collection showed urine aldosterone of 29.3 mcg/24 h (n 5-19 mcg/24 h) with urine sodium of 93 mmol/ 24 h (n 40-220 mmol/24 h). Oxcarbazepine was subsequently tapered off; Spironolactone was intermittently held until complete discontinuation. Fluid restriction and oral salt repletion were started and the patient’s sodium ultimately normalized. Outpatient saline suppression testing and adrenal vein sampling were scheduled. Conclusion: Oxcarbazepine was likely causing high ADH release but co-occurring untreated hyperaldosteronism inhibited natriuresis. Use of Spironolactone unmasked natriuresis by blocking aldosterone activity on the intercalated cells of the renal nephron. Stopping Oxcarbazepine ultimately resulted in hyponatremia resolution. Presentation Date: Friday, June 16, 2023

FRI197 Patient Suffering From Resistant HTN For 15 Years With Negative CT Diagnosed With Hyperaldosteronism Due To Adrenal Cortical Adenoma

Abstract Disclosure: J. Seidenberg: None. M.J. Ansari: None. Background: Resistant HTN, blood pressure remaining above goal despite concurrent use of three antihypertensives of different classes at maximum doses is a common presentation in both endocrinology and primary care settings. Patients can often be prescribed multiple max-dosed antihypertensives with varying results and adverse effects and still spend years with uncontrolled HTN leading to long term health concerns. Hyperaldosteronism is diagnosed for resistant HTN in 4% of primary care patients and 10% endocrinology-referred patients. Adrenal adenomas account for 40% of all cases characterized by high aldosterone/renin activity ratio, hypokalemia, mild hypernatremia and hypomagnesemia commonly diagnosed with a mass found in the adrenals on CT. Clinical Case: Patient is a 39 year old Female who presented to the endocrinology office due to elevated urine metanephrine levels, BP 159/100. Patient had resistant HTN since her early 20s treated currently with labetalol and nifedipine, and hypokalemia treated with potassium supplements. Lab results revealed potassium 3.4 mmol/L (3.6 -5.2 mmol/L), normetanephrines 787 mcg/g (0-145 mcg/g) , aldosterone 11 ng/dL (2-9 ng/dL) , renin 0.2 ng/mL/h (0.7- 3.3 ng/mg/hr), aldosterone/renin activity ratio 55 (&amp;lt;25) . Renal US showed no renal artery stenosis. The patient was suspected of having hyperaldosteronism using cutoff ratios aldosterone renin ratio &amp;gt;30, and 15 years of potassium levels between 3.0 and 3.5. CT of the adrenals revealed no masses. Patient underwent IR guided venous sampling which indicated R adrenal gland producing 45x more aldosterone than the L adrenal gland. Patient underwent R sided adrenalectomy for definitive management of primary hyperaldosteronism. Pathology showed cortical adenoma. Patient was continued on chlorthalidone, losartan and nifedipine, and within 3 months her BP averaged 120/70 mmHg, with potassium within normal limits, Aldosterone 13 ng/dL, renin 1.25 ng/mL. Conclusion: Concurrent hyperaldosteronism with essential HTN is an uncommon but potential cause of resistant HTN. Patients with resistant HTN, prescribed multiple max-dosage antihypertensive medications while also having negative renal artery US result should undergo aldosterone and renin lab work. CT scans can have low sensitivity for adrenal adenoma. Concerning lab work should be followed up by IR-guided venous sampling for evaluation of an adrenal cortical adenoma, which can be treated surgically. Underlying essential HTN will still require treatment, but at significantly decreased medication dosages. Patients with resistant HTN should be evaluated for hyperaldosteronism early in their disease course regardless of a negative CT to prevent sequelae of untreated hyperaldosteronism including cardiac hypertrophy, arrhythmias, nephrogenic diabetes insipidus and neuromuscular symptoms. Presentation: Friday, June 16, 2023

THU615 Rhabdomyolysis: A Rare Presentation Of Extra-adrenal Neuroendocrine Tumor

Abstract Disclosure: M. Saleem: None. S.M. Harman: None. J. Targovnik: None. Introduction:Paraganglioma is a rare neuroendocrine tumor (NET) arising from neural crest progenitors located outside of the adrenal gland and predominantly produce norepinephrine if functional. Here, we present a case of epinephrine producing extra-adrenal sympathetic neuroendocrine tumor. Case: A 66-year-old male with history of resistant hypertension (on amlodipine, lisinopril &amp; metoprolol), hyperlipidemia &amp; obesity presented for evaluation of possible pheochromocytoma/paraganglioma. He reported paroxysmal episodes of muscle spasm &amp; paresthesia accompanied by hypertension (up to 200 mm Hg), palpitation, sweating &amp; tremor lasting about 30-60 minutes. His CPK was elevated up to 428 U/L (NR 30-170 U/L) during those episodes. He reported 7 "major episodes" beginning ∼15 years prior to diagnosis, of which 3 occurred after major surgery with "small episodes" occurring monthly, exacerbated by sun &amp; heat. Family history was remarkable for sister with recurrent rhabdomyolysis. Labs showed elevated epinephrine 181 pg/ml (normal &amp;lt;57), Dopamin 67 pg/ml (normal &amp;lt;10) and normal norepinephrine, significantly elevated 24h urine metanephrine 855 mcg/24h (normal 90-315), normal normetanephrine &amp; dopamine levels. CT showed a 2.2 x 2.2 x 2.1 cm retroperitoneal mass with 84% absolute concerning for possible paraganglioma. FDG-PET and DOTATATE showed hypermetabolic activity (SUV max 6.63) and DOTATATE avid left retroperitoneal mass respectively. After discontinuing beta blocker and optimizing alpha blockage with doxazosin, the patient was referred to endocrine surgery and had a successful resection of this mass and left adrenalectomy. Pathology was consistent with chromaffin cell neoplasm and normal left adrenal gland. Patient had clinical and biochemical resolution of his symptoms post-op. Genetic counseling was done with pending results. Discussion: Pheochromocytomas &amp; paragangliomas (PPGLs) are rare NET arising from chromaffin cells of the adrenal medulla or neural crest progenitors located outside of the adrenal gland, and predominantly produce epinephrine and norepinephrine respectively. Adrenal medullary tissue secretes epinephrine due to the activity of PNMT, induced by high local levels of cortisol from the adrenal cortex, which attaches a methyl radical to the catechol amino group. Extramedullary sympathetic secretory cells normally lack this enzyme and secrete norepinephrine. Thus, it is likely that the neoplasm we report had ectopic expression of this enzyme. PPGLs have variable signs and symptoms which mainly reflect the hemodynamic and metabolic actions of the catecholamines produced and secreted by the tumors with hypertension being the most common sign. Rhabdomyolysis is an unusual manifestation. This case is unique in that it presented as an extra-adrenal NET predominantly produced epinephrine and presented with rhabdomyolysis. Presentation: Thursday, June 15, 2023

FRI601 Unique Considerations For Workup And Management Of An 11 Year Old Male With Concern For A Neuroendocrine Tumor

Abstract Disclosure: N.C. Gunaratne: None. D. Deplewski: None. Background: Pheochromocytoma/paragangliomas are very rare in children. In patients who are undergoing work up for paragangliomas and pheochromocytomas, special considerations need to be made to distinguish neuroendocrine tumor findings from medication and other symptoms. Clinical Case: An 11 yo male with past medical history of migraines presented with new onset seizure, hypertension and tachycardia. Initial exam was remarkable for severe lower back pain, which eventually progressed to generalized pain. His tachycardia and hypertension were initially thought to be related to his pain, but were not improved with escalating pain and intermittent anti-hypertensive medications – leading to admission to the intensive care unit. He was started on lisinopril and metoprolol, but continued to have persistent tachycardia and hypertension.Initial work up included an echocardiogram revealing concentric left ventricular hypertrophy suggesting long-standing hypertension, MRI brain significant for Posterior Reversible Encephalopathy Syndrome, MRI abdomen and spine with no significant findings, and elevated urine metanephrines. Urine and serum catecholamines and serum metanephrines were also elevated, but not at levels typical of neuroendocrine tumors. Due to concern for possible pheochromocytoma/paraganglioma, patient was started on alpha-blocker phenoxybenzamine, and had marked improvement in hypertension. Patient was also started on scheduled gabapentin one day after initiation of phenoxybenzamine and noted to have some improvement in pain – making cause of acute improvement in blood pressure less clear. Patient underwent Ga-68 DOTATATE imaging that was significant for “mild to moderately increased activity within the left adrenal gland,” but no distinct lesion was appreciated on scan. After discussion with endocrine surgery, plan was made to monitor the patient in outpatient setting with serial plasma free metanephrines and chromogranin A while continuing phenoxybenzamine. Conclusion: Pheochromocytoma/paragangliomas are very rare in children. In patients who are undergoing work up for paragangliomas and pheochromocytomas, special considerations need to be made when patient has concomitant pain or is on beta-blockers. Ability to interpret urine/plasma metanephrines and catecholamine levels while on beta-blockers and other pharmacologic agents is difficult due to known iatrogenic alterations of these levels. Management for patients with elevated metanephrines without a localized neuroendocrine tumor can consist of pharmacologic intervention with alpha-blockers and close monitoring with serial labs. Presentation: Friday, June 16, 2023

THU514 Atypical Presentation Of Birt-Hogg-Dubé Syndrome With Poorly Differentiated Follicular Thyroid Cancer And Paraganglioma

Abstract Disclosure: K. Lertdetkajorn: None. J. Haw: None. J.E. Paysour: None. Background: Birt-Hogg-Dubé syndrome (BHDS) is a rare genetic disorder typically presenting with skin hamartomas, renal tumors, and lung cysts. BHD is caused by germline mutations of the folliculin (FLCN) gene. We present the case of a patient with follicular thyroid cancer and paraganglioma diagnosed with BHDS. Case: A 64-year-old female was noted to have progressive enlargement of a neck mass over six months following admission for a hypertensive emergency. CT neck demonstrated a heterogeneous mass centered within the left thyroid lobe measuring 10.4 x 8.6 x 7.6 cm with internal calcifications. TSH was normal. FNA of this mass was suspicious for follicular neoplasm, and she underwent a total thyroidectomy. The pathology reported poorly differentiated adenocarcinoma of the thyroid gland, follicular variant, pT3aN0M0 with positive margins, and lymph-vascular space invasion (LVI). FDG-PET/CT scan showed postsurgical changes of a total thyroidectomy with ill-defined FDG uptake along the left thyroid bed, 3 x 2.8 cm portacaval lymph node (SUV of 9.6) and focal soft tissue FDG avid rectal abnormality. MRI abdomen demonstrated a 4.0 x 4.1 x 3.2 cm soft tissue mass characterized by arterial hyperenhancement and washout in the portacaval region broadly interfacing with the IVC, main portal vein, and left renal vein. EGD was unremarkable, but an EUS demonstrated 3.7 x 3.5 hypoechoic, well-circumscribed, mild-vascular hypoechoic portocaval mass. FNA of this mass was consistent with paraganglioma. Laboratory results supported the diagnosis of paraganglioma with urine metanephrine 9661 mcg/24 h (224 - 832 mcg/24 h) and urine normetanephrine 9457 mcg/24 h (122 - 676 mcg/24 h). The patient was referred for genetic testing to investigate whether the co-existence of follicular thyroid cancer and paraganglioma was secondary to a genetic disorder. The germline genetic testing revealed the pathogenic variant, c.1436dup (p.Thr481Hisfs*5), identified in the FLCN gene with no detections of VHL or SDH complex variants, confirming the diagnosis of BHDS. The patient later underwent a colonoscopy and was found to have stage I colon cancer. Some early reports have shown an association between BHDS and colon tumors. The patient decided not to have any surgery at this time. She continues to follow up in the clinic and takes levothyroxine for suppressive goals. Octreotide LAR, along with blood pressure medications including phenoxybenzamine, was started to treat her paraganglioma. Conclusion: Patients with BHDS may present with atypical clinical manifestations. Genetic testing will aid in diagnosing a germline mutation in the FLCN gene. The association between thyroid cancer and BHDS has been reported previously; however, paraganglioma as a spectrum of BHDS has not been published. Further reported cases and research may provide additional data to investigate the relationship between BHDS and paraganglioma. Presentation: Thursday, June 15, 2023

FRI214 Adrenal Adenoma With Biochemical Findings Suggestive Of Cushing's Disease

Abstract Disclosure: A. Calimag: None. U. Tarabichi: None. M. Ahmad: None. M. Kazi: None. Introduction: We are presenting a case of a young female with prior history of multiple endocrinopathies presenting with a left adrenal adenoma with biochemical findings suggestive of Cushing's disease. Case Presentation: A 22-year-old female with a history of Type 1 Diabetes Mellitus was found to have a left adrenal adenoma 2.8 cm on CT. Absolute washout of 85 % and a relative washout of 63%, having 12 Hounsfield units (HU) on the non-contrast phase, findings suggestive of a benign adenoma. Further work up including 1 mg Dexamethasone suppression test (DST) showed unsuppressed plasma ACTH 17 pg/ml and total cortisol 9.4 mcg/dL. 8 mg DST showed ACTH 12 pg/ml, AM cortisol 8.8 mcg/dL, and Dexamethasone 991 ng/dl. Late night salivary cortisol 0.07 ug/dl, and 0.09 ug/dl, 24 hr urine cortisol 40.7. Other labs showed Aldosterone level was normal at 6.7, Renin level was also normal at 1.1. 24 hr urine catecholamines were Norepinephrine 35 mcg/24 hr, Epinephrine 3.9 mcg/24 hr, while urine Metanephrine level was &amp;lt;0.24, and normetanephrine level at 0.34. TSH 1.2mcU/ml. One day prior to surgery ACTH level was suppressed at 2.1 pg/ml drawn from a different lab. MRI of the Pituitary showed a slightly enlarged pituitary gland with uniform contrast enhancement and no definite lesion. The patient underwent a laparoscopic left adrenalectomy. Pathology showed an adrenal cortical neoplasm consistent with adrenal cortical adenoma, with no significant cytologic atypia, mitotic activity, or necrosis. Immunoperoxidase stain, the tumor is positive for inhibin and negative for PAX8. Post-op she developed adrenal insufficiency which was treated with hydrocortisone. The follow-up cortisol level was 11.3 mcg/dL when the patient was off hydrocortisone. Discussion: In this case, the biochemical exam showed elevated cortisol with ACTH not fully suppressed at both 1 mg and 8 mg DST which was done twice, and normal 24-hour urine cortisol. Determining whether this is adrenal vs pituitary mediated was one of the clinical dilemmas of this case. Initially, the patient’s ACTH was unsuppressed however the day before surgery ACTH was suppressed and the patient’s cortisol level normalized after the left adrenalectomy. Immunoassays for ACTH levels may occasionally be susceptible to analytical errors. (1-2) There are several case series and studies mentioning assay interference when using Immulite Assay versus Cobas ACTH assay. (1-2) Therefore, it is important to analyze clinical findings and biochemical testing and if lab tests are discordant, recheck using a different analytical platform in a different lab or an alternate ACTH assay to confirm ACTH levels. (1-2)

FRI264 A Case Of Composite Pheochromocytoma And Ganglioneuroma

Abstract Disclosure: D. He: None. J. Pullman: None. S. Stefan: None. B.Y. Wong: None. Background: Pheochromocytomas are catecholamine-secreting tumors that arise from chromaffin cells in the adrenal medulla or paraganglia. Representing 1-9% of pheochromocytomas, composite pheochromocytomas are rare tumors composed of pheochromocytoma and neural tumor components such as neuroblastoma, ganglioneuroblastoma, ganglioneuroma or peripheral nerve sheath tumor1. We present a case of composite pheochromocytoma and ganglioneuroma. Clinical Case: A 69-year-old man presented with recurrent dyspnea at rest, diaphoresis and tachycardia. He was diagnosed with heart failure with reduced ejection fraction and management included metoprolol 50 mg daily. On work-up, he was incidentally found to have a 1.2 cm left upper lobe lung lesion and an indeterminate 2.4 cm right adrenal mass on CTA chest. PET/CT scan showed an intensely avid left upper lobe lung nodule and a right adrenal mass with mild FDG uptake (SUV max 3.8). MRI abdomen demonstrated a 3.1 cm right adrenal lesion with a mildly thickened enhancing rim and a central enhancing nodular component suspicious for pheochromocytoma, metastases, schwannoma or ganglioneuroma. He then had a stroke with mild residual right-sided weakness. Oncological work-up of his lung and adrenal lesions eventually directed tissue sampling to biopsy of the adrenal lesion and pathology was consistent with pheochromocytoma. Subsequent biochemical evaluation revealed elevated plasma metanephrines of 194 pg/mL (&amp;lt;= 57 pg/mL), plasma normetanephrines of 474 pg/mL (&amp;lt;= 148 pg/mL), 24-hour urine metanephrines of 389 mcg (90-315 mcg) and 24-hour urine normetanephrines of 428 mcg (122-676 mcg). Pre-operatively, he was placed on phenoxybenazmine 10 mg twice daily and metoprolol 62.5 mg every 8 hours. The patient then underwent right adrenalectomy. The tumor nodule was adherent to and dissected off the inferior vena cava. Pathology showed composite pheochromocytoma with a small component of ganglioneuroma. Conclusion: This rare case of a composite pheochromocytoma with ganglioneuroma was diagnosed through histopathology as composite pheochromocytomas are clinically and radiographically indistinguishable from pheochromocytomas1. Management of composite pheochromocytomas with ganglioneuroma is similar to the management of pheochromocytomas, and surgical resection remains the first line treatment. Combined alpha and beta-adrenergic blockade is recommended to prevent intraoperative hypertensive crisis. However, more studies are needed to further understand these rare composite pheochromocytomas.

THU529 Challenges In The Management Of Biochemically Silent Paraganglioma

Abstract Disclosure: S. Dewan: None. A. Farooqi: None. J. Jun: None. Biochemically silent Pheochromocytoma and Paraganglioma (PPGL) are rare neuro-endocrine tumors because of which there is low quality evidence and insufficient guidelines for their management. 74-year-old Female was referred to our Endocrine clinic for incidentally discovered Retroperitoneal mass on MRI. On evaluation patient reported having concerns of escalating anxiety, difficult to control HTN and episodic flushing after physical activity in the last one year. A CT abdomen and pelvis with contrast was ordered which showed 1.7 x 1.8 cm mass anterior to the L5 vertebral body just caudal to the aortic bifurcation. The biochemical work up including 24-hour urine Metanephrines (104 ug/24 hr; n 52-341), Normetanephrines (479 ug/24 hr; n 88-444), Total Metanephrines (583 ug/24 hr; n 88-444), 3 Methoxytyramine (166 mcg/24 hr; n &amp;lt;242) was inconclusive. For further evaluation PET CT DOTATATE scan was ordered which showed the lesion to be DOTATAE somatostatin analogue avid, consistent with somatostatin receptor positive neuroendocrine tumor. Patient was scheduled for surgery in 2 weeks and was started on Terazosin in addition to her anti HTN medications Amlodipine, Losartan and HCTZ. The surgery had to be rescheduled due to inadequate blood pressure control. Her amlodipine and Terazosin dosage were gradually increased while the procedure was rescheduled. Eventually she underwent Laparotomy exploration and resection of the lesion. Patient tolerated the procedure well and had no major intra or post operative fluctuations in her blood pressure, heart rate or blood glucose. According to the Endocrine Surgery team, the tumor could not be sufficiently removed since it was immovable during surgery and could not be delineated from the spine. The post-operative CT scan showed nodular lesion at aortic bifurcation slightly increased in soft tissue component from prior CT scan. After discussions with surgery and oncology team, patient opted for imaging surveillance for now and will consider genetic counseling and/or radiation therapy if the tumor increases in size. Untreated PPGL carries a high risk of cardiovascular morbidity and mortality, and some may also be malignant with a propensity to cause mass effects and metastasis. Currently, there are scarce evidence-based studies comparing treatment options in biochemically silent PPGL, and there is no consensus for the most appropriate peri-operative management of biochemically silent PPGL. This case adds to the literature on how a combination of calcium channel blocker and alpha blocker can be used to achieve peri-operative blood pressure and heart rate control with no major side effects. It also demonstrates the importance of functional imaging, especially in clinically or radiologically suspected PPGL, even with a normal biochemical work up. We suggest multi-disciplinary evaluation and individualized management to ensure positive outcomes. Presentation: Thursday, June 15, 2023

Plasma Metanephrines Yield Fewer False-Positive Results Than Urine Metanephrines in Patients With Obstructive Sleep Apnea.

Obstructive sleep apnea (OSA) is associated with increased nocturnal sympathetic activity. In OSA patients, elevations in metanephrines may lead to false-positive tests when evaluating for pheochromocytoma or paraganglioma (PPGL). To evaluate whether morning plasma metanephrines would lead to fewer false-positive results than 24-hour urinary metanephrines in OSA patients. Patients undergoing polysomnography for suspected OSA were recruited. Plasma free and 24-hour urinary metanephrines were measured by HPLC-MS/MS. Patients with elevated levels had repeat measurements, abdominal imaging, and follow-up to diagnose or exclude a PPGL. Seventy-six patients completed polysomnography and biochemical testing; 68 (89.5%) patients had OSA, of whom 19 (27.9%) had elevated plasma and/or urinary metanephrines. On follow-up, one patient had a bladder paraganglioma, while PPGL was excluded in the remaining patients. OSA patients had more false-positive urinary metanephrines (17 of 67, 25.4%) than plasma metanephrines (2 of 67, 3.0%), P < .01, and this was more common in severe OSA (13 of 34, 38.2%), compared to moderate/mild OSA (4 of 33, 12.1%), P < .01. Both plasma and urinary metanephrines decreased after treatment with continuous positive airway pressure. On multivariable analysis, severe OSA, obesity, and family history of hypertension were positive predictors for false-positive urinary metanephrines in patients with suspected OSA. In OSA patients, plasma metanephrines are less likely to yield false-positive results for the diagnosis of PPGL than 24-hour urinary metanephrines. In patients with suspected OSA, obesity, or a family history of hypertension, plasma metanephrines may be the preferred first-line test to avoid unnecessary anxiety or follow-up.

The Role of Chromogranin A Assay in the Diagnosis of Pheochromocytomas

Background: Pheochromocytomas (Pheo) are rare neuroendocrine tumors with a suggestive clinical picture, characterized by hypersecretion of catecholamines and other neuroendocrine biomarkers. Methods: The purpose of the study was to analyze the diagnostic features of Pheo and investigate the role played by different neuroendocrine and hormonal markers in diagnosing Pheo.The retrospective study involved a group of 69 patients diagnosed and treated with Pheo, who had both urinary and plasma catecholamines and neuroendocrine markers measured pre- and postoperatively. Results: After comparing pre- and postoperative hormonal parameters and neuroendocrine biomarker changes, numerous statistically significant findings were found. The analysis of the relationships between chromogranin A (CgA) levels, plasma and urine metanephrines, and normetanephrine and Pheo tumor size was included in the study. Additionally, we evaluated Cg A's diagnostic efficacy in comparison to plasma metanephrines, normetanephrine, and neuron-specific enolase (NSE) for Pheo. Conclusions: We obtained statistically significant data on pre- and postoperative differences for plasma and urinary catecholamines, CgA and NSE. Pheo tumor size is interdependent with serum levels of Cg A, plasma and urinary metanephrines, and normetanephrine. The best diagnostic power for Pheo was plasma normetanephrine, followed by plasma metanephrines and CgA.