Anterior Pituitary Research Articles

8168 From Salt to the Sella- Discovering Empty Sella Syndrome as a Rare Cause of Severe Hyponatremia

Abstract Disclosure: P. Vemparala: None. S. Challagulla: None. Introduction: Hyponatremia is a common electrolyte disorder with potentially life-threatening consequences. Careful evaluation of hyponatremia can uncover significant underlying conditions. We present an interesting case of a patient who presented with symptoms of severe hyponatremia and a workup led us to the discovery of empty sella syndrome as the etiology. Case Presentation: A 54-year-old male with hypertension presented with 2 days of left-sided headache, blurred vision, generalized weakness, and vomiting. Pertinent medication history revealed the use of thiazide diuretic, bupropion and varenicline. Physical examination was unremarkable. Laboratory data showed severe hyponatremia with a serum sodium of 118 meq/L. Initial improvement with fluids was followed by a decline (106-112 meq/L). CT head without contrast showed a prominent empty sella turcica. Workup revealed urine osmolality and elevated urine sodium. A low AM cortisol level of 1.0 mcg/dl (reference range- AM- 7.0 - 25.0 mcg/dl), and decreased adrenocorticotropic hormone (ACTH) level of 5.2 pg/ml (reference range- 7.2 - 63.3 pg/ml) suggested secondary adrenal insufficiency. All other anterior pituitary hormones were normal. Brain magnetic resonance imaging (MRI) confirmed the diagnosis of partial empty sella. Treatment with hypertonic saline, fluid restriction, and steroids led to symptom resolution. Conclusion: Empty sella syndrome is a rare pituitary condition that can be primary- characterized by herniation of the subarachnoid space within the sella, or secondary- which occurs when the sella is empty due to damage to the pituitary gland by tumor, radiation, etc. It can cause potential hypopituitarism, be asymptomatic, or present with symptoms of raised intracranial pressure. In patients with hypopituitarism, deficiencies of ACTH and TSH are rarer and appear to be more common with a complete empty sella. This case emphasizes the need for a comprehensive hyponatremia workup, awareness of secondary adrenal insufficiency, and recognition of the life-threatening potential of even partial empty sella syndrome when untreated. Presentation: 6/1/2024

8239 Recurrent Superior Laryngeal Nerve Glucocorticoid Injections: A Likely Cause Of Secondary Adrenal Insufficiency In An Otherwise Healthy Man

Abstract Disclosure: A. Lorin: None. M.C. Pranger: None. J. Park: None. C.A. Clutter: None. Background: Secondary adrenal insufficiency is well described in the literature with various offending agents implicated. Superior laryngeal nerve (SLN) glucocorticoid injections, however, have rarely been recorded as causal agents of secondary adrenal insufficiency. We present a case of a generally healthy man with secondary adrenal insufficiency after chronic administration ofsuperior laryngeal nerve glucocorticoid injections without other identifiable etiologies. Clinical Case: A 68-year-old man with no significant medical history presented to endocrinology clinic due to persistent nausea and severe fatigue. His initial labs were notable for morning cortisol of 1.66 mcg/dL (5-25) and an undetectable ACTH (<3.2 pg/mL, 10-60) suggestive of adrenal insufficiency. FSH/LH, testosterone, FT4, and IGF-1 were otherwise normal. On initial review of his medication history, the only glucocorticoid exposure appeared to be intranasal beclomethasone, with remote courses of oral prednisone. Further history revealed that the patient was receiving superior laryngeal nerve glucocorticoid injections for chronic cough every three weeks for over a year. The injection consisted of 1:1 mixture of 1 mL of triamcinolone acetonide 200 mg/5 mL and local anesthetic, which is equivalent to triamcinolone 40 mg or hydrocortisone 200 mg. Given the volume and chronicity of the glucocorticoid injections, the patient developed secondary adrenal insufficiency as above. Since the diagnosis, the patient discontinued SLN glucocorticoid injections and was placed on physiologic hydrocortisone replacement, with gradual recovery of his HPA axis. Conclusions: Sequelae of percutaneous glucocorticoid injection into the superior laryngeal nerve for treatment of chronic cough are not well documented in terms of their effects on the HPA axis. While an effective and increasingly common treatment for chronic cough, SLN glucocorticoid injection has the potential to cause suppression of the HPA axis and cause secondary adrenal insufficiency. Excess glucocorticoid appeared to solely inhibit ACTH production, as the other anterior pituitary hormones were not affected. Understanding consequences of glucocorticoid use in any formulation is important when considering such therapies, as these may alter normal HPA function with recurrent dosing. Recovery from a disrupted HPA axis may be achieved with the use of physiologic doses of hydrocortisone replacement in the case of secondary adrenal insufficiency. Presentation: 6/3/2024

8565 Impact of Mild Blast Traumatic Brain Injury on Pituitary Hormone Secretion Trajectory in Male and Female Mice in Response to Restraint

Abstract Disclosure: H. Donaldson: None. T.J. Wu: None. Over 10 million people suffer from traumatic brain injury (TBI) annually. Mild blast TBI (mbTBI) account for about 80% of TBIs in service members. One third of people exposed to mbTBIs have prolonged neuroendocrine defects, particularly anterior pituitary dysfunction. Previous studies in our laboratory have shown that male and female mice demonstrate different neuroendocrine defects in response to mbTBI. Specifically, male mice with mbTBI have an increase (p<0.05) in corticosterone (CORT) response at 30 min after the initiation of restraint. Conversely, female mice show attenuated (p<0.05) levels of CORT at the same timepoint after the initiation of restraint. It is not known, however, what the trajectory of anterior pituitary hormone changes is in response to mbTBI. Our project aims to characterize the temporal relationship of peripheral anterior pituitary hormones in male and female mice in response to mbTBI and restraint. Male and female mice were randomly assigned to undergo sham or mbTBI injury using the Advanced Blast System (ABS). At 1 week after mbTBI, mice within each group were randomly assigned to be killed at 0-, 5-, 10-, 20-, 30-, or 90-min after the initiation of a 20-min restraint. At the appropriate timepoint, tissue was collected after the mice were euthanized. Prolactin (PRL) and adrenocorticotropin hormone (ACTH). were measured using commercially available ELISA. Analysis of the data show that the peak response to restraint was altered in mice exposed to the ABS. PRL increased (p<0.05) starting at 5 min in both males and females after the initiation of restraint and returned to baseline by 90 min. ACTH increased (p<0.05) starting at 10 min and 20 min after the initiation of restraint and returned to baseline by 90 min in males and females, respectively. Peak PRL was delayed in both males (20 min vs 5 min) and females (10 min vs 5 min) whereas peak ACTH advanced in both males (10 min vs 30 min) and females (20 min vs 30 min). Area under the curve analysis show that ABS decreased overall PRL in both males and females whereas ACTH was lower in males and higher in females. The results of the current study showed that mice of both sexes have different serum PRL and ACTH trajectories in response to restraint when exposed to mbTBI. Presentation: 6/2/2024

8110 Lymphocytic Hypophysitis secondary to a ruptured Rathke’s Cleft Cyst complicated by post surgical recurrence: A rare phenomenon

Abstract Disclosure: M.S. Maharaul: None. F. Thelmo: None. I. Ahmed: None. Introduction: Lymphocytic hypophysitis secondary to ruptured Rathke’s cleft cyst (RCC) is a rare entity. Rathke’s cleft cysts are benign fluid-filled intra-sellar cysts that originate from the remnants of Rathke’s pouch and contain mucoid material. Most are asymptomatic; some may get symptomatic during cyst expansion and rupture releasing liquid content and trigger local inflammation. Surgical resection followed by glucocorticoids is usually curative. Case: A 42-year-old female presented to the hospital with one week history of right sided frontal headache associated with blurred vision in right eye. MRI Brain showed a 15 mm complex cystic lesion in the sella with suprasellar extension associated with peripheral calcifications. On admission, endocrine laboratory investigations including pregnancy test were normal. Ophthalmic testing did not reveal any acute abnormalities. Transsphenoidal surgery was performed for tumor resection. Pathology examination revealed infiltration of massive lymphocytes, macrophages, plasma cells, and eosinophils that were diagnostic of lymphocytic hypophysitis in the anterior pituitary lobe. She was started on glucocorticoids and discharged home. Rheumatology and Infectious diseases workup were unrevealing. On follow up 3 weeks later, she had self-discontinued steroids. The following week, she presented to the emergency room again with a right sided headache and blurred vision. MRI Brain revealed a 16 mm recurrent inflammatory mass lesion in the sella. Endocrine panel demonstrated an 8 am serum cortisol level of 7.4 mcg/dl, ACTH 20 pg/ml, FSH 6.2 mIU/ml, LH 4.9 mIU/ml, free T4 1.1 ng/dl and prolactin 8 ng/ml. She underwent transsphenoidal resection of the mass again and was restarted on glucocorticoids. This time pathology examination revealed an epithelial lined cyst most compatible with Rathke’s cleft cyst. She continued to remain on a glucocorticoid taper during the follow up period. On re-evaluation, her endocrinology laboratory investigations continued to show a deficiency of gonadotropins for which she is following up with OBGYN, but the remaining pituitary hormones were all within normal limits. Conclusion: Rathke’s Cleft Cysts (RCCs) should be in the differential diagnoses for evaluation of hypophysitis. There have only been a handful of cases in the literature of hypophysitis associated with a ruptured RCC, and only one case of recurrence after surgical debulking. This case provides an insight into the clinical behavior, diagnosis, and timely management of lymphocytic hypophysitis due to a ruptured Rathke’s cleft cyst and management post-recurrence. Presentation: 6/3/2024

8184 A Case With Primary Hyperparathyroidism Caries A New Variant Of Uncertain Significance (VUS) Of The Multiple Endocrine Neoplasia Type 1 (MEN1) Gene

Abstract Disclosure: E. Caliskan Guzelce: None. E. Fieg: None. C. Pallias: None. Background: Multiple endocrine neoplasia type 1 (MEN1) is a rare, autosomal dominant disorder caused by mutations in the MEN1 tumor suppressor gene. MEN1 syndrome is classically characterized by a predisposition to tumors of the parathyroid glands, anterior pituitary, and pancreatic islet cells. However, the clinical spectrum of this disorder has been expanded: carcinoid tumors,adrenal adenomas and lipomas are more common than in the general population.We report a case whose personal and family history is highly suggestive of and consistent with a monogenic disorder such as MEN1, also found to be a carrier of a new variant of uncertain significance (VUS) of the MEN1 gene. A study performed with the French Universal Mutation Database (UMD) for the MEN1 gene showed that one-third of the missense MEN1 variants were VUSs, mainly due to the lack of clinical and segregation data. Therefore, it is very important to identify and report the subjects with VUS of the MEN1 gene. Case report: 68-year-old female with a past medical history significant for hypertension, type 2 diabetes mellitus, hyperlipidemia, CKD stage 4, and nephrolithiasis, GERD who presented with chief complaints of nausea and upper abdominal/epigastric pain and dark stools and found to have moderate hypercalcemia c/w primary hyperparathyroidism, several pancreatic cystic lesions most likely branch duct intraductal papillary mucinous neoplasms, and multinodular goiter and adrenal adenoma. Family history significant for recurrent hyperparathyroidism and nephrolithiasis; her daughter and brother had nephrolithiasis; her daughter has undergone parathyroidectomy twice. The patient's mother died at a young age because of gastric ulcer-related complications. Hyperparathyroidism-related genes were analyzed; AP2S1, CASR, CDC73, CDKN1B, GNA11, RET, MEN1, and only a Variant of Uncertain Significance, c.247_249dup (p.Leu83dup), was identified in MEN1 gene. The patient’s daughter and granddaughter are found to have the same mutation. Conclusion: This variant, c.247_249dup, results in the insertion of 1 amino acid(s) of the MEN1 protein (p. Leu83dup), but otherwise preserves the integrity of the reading frame. This variant is not present in population databases (gnomAD no frequency). The literature has not reported this variant in individuals affected with MEN1-related conditions. Presentation: 6/3/2024

8800 A Case of Hypopituitarism Due to Sheehan Syndrome

Abstract Disclosure: N. Akabogu: None. S. Dejhansathit: None. F. Marium: None. B. Stanley: None. E.M. Bazuaye: None. L.S. Krusniak: None. L.G. Kurukulasuriya: None. U.Z. Khan: None. Background: Sheehan syndrome, which is also known as postpartum pituitary infarction, refers to the necrosis of the anterior pituitary gland due to postpartum hypovolemia, hemorrhage, shock, resulting in various degrees of hypopituitarism. The pituitary gland enlarges during pregnancy due to estrogen stimulation and becomes hyper-vascular, making it prone to infarction with postpartum hemorrhage. The initial symptoms include hyponatremia, weakness, weight loss, but the most prominent specific symptoms are inability to nurse and postpartum amenorrhea. Depending on the severity of hypopituitarism, symptoms may develop within the first few days to weeks after delivery or may take months to years to develop. Case presentation: 35year-old Caucasian female with a medical history of gestational diabetes, hyperlipidemia, and hypertension, who presented to the hospital with flu-like symptoms, leg pain, abdominal pain, and proximal muscle weakness. The evaluating hospitalist observed that patient appeared sluggish and spoke with a deep coarse voice, which concerned him for hypothyroidism. Thyroid function test revealed undetectable free T4 with inappropriately normal TSH of 1.38 – consistent with secondary hypothyroidism. Additional history from patient uncovered 9 months history of constant fatigue, weight gain, dry skin, hair loss, cold intolerance, and intermittent ankle swelling. There is no history of brain irradiation or head trauma. She has 4 biological children, and her last childbirth 3years ago was complicated by severe bleeding from her incision site, requiring transfusion of 6 units of blood. She has been amenorrheic since and is neither on birth control nor had hysterectomy. Physical exam showed mildly enlarged tongue, diffuse pallor, dry scaly skin on upper arms, scanty eyebrows, and slowed speech. Further work-up for pituitary insufficiency showed secondary adrenal insufficiency, secondary hypogonadism, low prolactin, and growth hormone deficiency. There was no evidence of AVP deficiency. Other lab and clinical findings were hypoglycemia, hyperlipidemia, elevated CK, elevated Cr, pericardial effusion, and diastolic hypertension. Pituitary MRI showed markedly attenuated and flattened pituitary gland with no focal mass. Patient was given stress dose hydrocortisone and thyroid hormone replacement, initially IV then oral. Following hydrocortisone and thyroid hormone replacement, her diastolic BP, hypoglycemia, CK, and Cr improved. Further management plans include initiating estrogen (plus progesterone) for bone health. Conclusion: Although Sheehan syndrome is rare in developed countries, it does occur. This case emphasizes the importance of detailed history taking, to discover the root of patients’ presentation. Even though TSH is the screening test for thyroid disease, when pituitary etiology is suspected, it is important to also check a free T4. Presentation: 6/1/2024

8144 Hypertension in Sheehan Syndrome: A Diagnostic Challenge

Abstract Disclosure: E. Ahsan: None. F.F. Foo: None. C. Lesniak: None. M. Akula: None. K. Hu: None. R. Ong: None. K. Chalasani: None. J. Cheng: None. S. Holland: None. Introduction: Postpartum pituitary necrosis, commonly known as Sheehan syndrome (SS), is the term used to describe the necrosis of anterior pituitary gland cells that occurs after significant postpartum bleeding, hypovolemia, and shock. This typically occurs after delivery, during which the mother suffers significant blood loss. The pituitary gland fails to produce hormones due to this blood loss. Depending on the degree of tissue damage, SS can have an acute or chronic course, and patients may present with a wide range of clinical symptoms at diagnosis. Acute SS is associated with postpartum pituitary infarction, which can result in hypotension, shock, hypoglycemia, hyponatremia, headache, vision disturbances, unconsciousness, and an inability to lactate. We present a rare case of SS where the patient experienced hypertension instead of classic hypotension due to postpartum preeclampsia. Clinical Case: A 40-year-old female with no significant medical history presented to the hospital for scheduled induction of labor for polyhydramnios and underwent vacuum-assisted vaginal delivery and postpartum hysterectomy due to severe postpartum hemorrhage secondary to DIC. The postpartum course was also complicated by preeclampsia with severe features. Patients developed features like excessive fatigue, hypoglycemia, hyponatremia, hypothyroidism, polyuria, and failure of lactation, which were consistent with panhypopituitarism secondary to Sheehan syndrome. However, the patient was hypertensive to 145/91 before steroids were given. Labs were significant for serum sodium 116 mmol/L (135-145 mmol/L), FSH <0.7 mIU/mL (Follicular Phase: 2.5-10.2, Mid-cycle Peak: 3.1-17.7, Luteal Phase: 1.5-9.1, Postmenopausal: 23.0-116.3), LH <0.2 mIU/m (Follicular Phase: 1.9-12.5, Mid-Cycle Peak: 8.7-76.3, Luteal Phase: 0.5-16.9, Postmenopausal: 10.0-54.7), Prolactin: 2.4 ng/mL (Non-pregnant: 3.0-30.0, Pregnant: 10.0-209.0, Postmenopausal: 2.0-20.0), PM Cortisol on admission: 1.10 ug/dL (3.44-16.76 ug/dL), plasma ACTH 7 pg/mL( 6 - 50 pg/mL), TSH 0.430 uIU/mL (0.550 - 4.780 uIU/mL), FT4 0.59 ng/dL - 1.76 ng/dL). MRI of the brain pituitary showed- A 1.5 cm region of hypoenhancement and an additional 2 mm focus of hypoenhancement in the sella, findings represent evolving pituitary necrosis. The patient received 24 units of blood transfusion and hormone replacement therapy, followed by outpatient endocrinology follow-up. Clinical lessons: Although considerable blood loss causes hypotension in patients with SS, additional postpartum medical issues can sometimes result in atypical presentations. In our patient, postpartum preeclampsia caused hypertension. Identifying the atypical symptoms of SS is just as vital as identifying its typical features to prevent potentially fatal consequences. Presentation: 6/2/2024

8738 Unveiling Potential Therapeutic Candidates for ACTH-Silent Pituitary Neuroendocrine Tumors Through High Throughput Drug Screening

Abstract Disclosure: J.M. Marques: None. N.D. D' Alessandre: None. G.D. Guardia: None. F.L. Craveiro: None. C. Grutzmacher: None. G.O. Silva: None. B.B. Mendonca: None. L.R. Carvalho: None. F. Fattahi: None. P.A. Galante: None. R.L. Batista: None. Introduction: ACTH-silent pituitary neuroendocrine tumours (PitNETs) are a subtype of PitNETs that arise from corticotroph cells of the anterior pituitary gland. They can show positive immunoreactivity for adrenocorticotropic hormone (ACTH) but with no clinical or laboratory evidence of hypercortisolism. ACTH-silent PitNETs display notably more aggressive behavior and treatment resistance. Currently, there is no established pharmacological therapy for this specific tumor subtype. Aim: To use high throughput drug screening to identify compounds that modulate ACTH secretion and tumor progression in ACTH-silent PitNETs. Methods: WTC11 cells (GM25256) were differentiated into pituitary using E6 with SB431542 10µM, SHH 200ng/mL, FGF8 100ng/mL and FGF10 50ng/mL until day 30. Pituitary cells were passaged in 384 well plates and treated with FDA-approved compound library with 3113 drugs at 1μM for 72h (#L1300, Selleckchem). Cells were stained with ACTH and imaged on ImageXpress® HCS. ACTH intensity was normalized to total cell number, measured by DAPI, using MetaXpress Software and compounds z-score was calculated, considering -2.5 for analysis. Gene and pathway enrichment analysis were performed and PitNET RNAseq data, publicly available (GSE207937), was used to determine target drugs based on similar target pathways and gene expression. To validate hits, we collected tumor samples from a patient with an aggressive silent ACTH PitNET. PitNET was histologically confirmed and hypercortisolism was excluded clinically and laboratory. Samples were cultured on DMEN/F12 with 10% FBS and 1% antibiotic and pituitary hormones were measured at days 3, 6 and 8. Cells were treated with 1uM of Letrozole, Linsitinib and Raloxifene for 48h and sample for RNA and hormone dosage were collected. Results: We identified 8 drugs that decreased ACTH in induced pituitary cells and selected 3 of them for validation. PitNET was successfully cultured and treated with selected drugs and ACTH secretion was detected at all periods (972.1 pg/mL to 10490 pg/mL), gonadotropins were below the detected level. Letrozole significantly reduced ACTH in the PitNET culture at day 8 (600.9 ± 25.8pg/mL, p<0,001). ACTH was also decreased in Linsitinib treated cells (932 ± 12.7pg/mL, p<0.05), while Raloxifene did not change ACTH secretion (980 ± 95.1pg/mL, p=0.061). Microscopically, PitNET cells aggregate in spheres and this seems to be affected by letrozole treatment, not influencing cell viability. Conclusion: We performed a high throughput drug screen using induced pituitary cells that led to the discovery of 3 compounds that might be used as an alternative for PitNET treatment. Pathway and gene expression analysis from target drugs and PitNET RNAseq may help in the understanding of drug effect in the PitNET context and improve the understanding of tumorigenesis and pharmacological treatment. Presentation: 6/1/2024

8188 Pituitary hyperplasia resulting from primary hypothyroidism: A case report

Abstract Disclosure: M. Aziz: None. M.I. Manolas: None. V. Tabatabaie: None. L. Rincon: None. Pituitary hyperplasia resulting from primary hypothyroidism: A case report.Background: Primary hypothyroidism is a common endocrine condition seen in 4.6% of USpopulation (1). We describe an uncommon presentation of prolonged severe primaryhypothyroidism leading to significant hyperplasia of the pituitary gland resembling a pituitarymacroadenoma. Clinical Case: A 34-year male with schizophrenia and Hashimoto’s hypothyroidism diagnosedat the age of 17 presented with hallucinations, chest pain, fatigue, and dyspnea. The patient hada 15-year history of uncontrolled hypothyroidism with persistently elevated TSH with values ashigh as 2,299 (n 0.30-4.20 uU/mL) due to poor adherence to levothyroxine. Initial laboratorystudies revealed hyponatremia (Na 130, n135-145 mEq/L), elevated TSH (>100, n0.30-4.20 uU/mL), undetectable FT4 (<0.4, n0.6-1.5 ng/dL) and elevated CK (5671, n<200 U/L).Levothyroxine was restarted at dose of 150 mcg daily. Head CT performed for evaluation ofaltered mental status and hallucinations revealed hyperdensity within the pituitary gland,concerning for underlying hemorrhage and apoplexy. Neurosurgical consultation was requested,and a pituitary MRI was obtained in preparation for potential surgical intervention. MRI showeda prominent anterior pituitary gland measuring up to 14 mm with homogeneous enhancementwithout evidence of hemorrhage. In the absence of any hemorrhage or definitive mass, thepituitary enlargement was considered secondary to the long-standing history of uncontrolledprimary hypothyroidism leading to pituitary hyperplasia, and surgical intervention was deemedunnecessary. Repeat labs 1 week later showed TSH >100uU/mL, FT4 0.6 ng/dL, CK 2799 andrepeat MRI showed slight decrease in size of the pituitary gland, confirming hyperplasiasecondary to severe, prolonged hypothyroidism. Conclusion: Prolonged primary hypothyroidism can lead to pituitary hyperplasia which can bemistaken as pituitary macroadenoma, leading to unnecessary surgical intervention. Carefulreview of history and TSH trends can help elucidate this diagnosis.

5086 Approaching the Enigma: Unveiling a Pituitary Stalk Lesion with Imaging and Hormonal Patterns

Abstract Disclosure: N. Rodriguez-Morales: None. P. Guido: None. Background: Pituitary stalk lesions (PSL) pose a diagnostic dilemma for endocrinologists. Multiple studies have attempted to associate hormonal imbalances and imaging patterns to a specific etiology (1,2). However, the diagnosis remains a mystery on many occasions. We describe a case of secondary hypogonadism and central DI attributed by a PSL. Clinical Case: A 39-year-old male presented with symptoms of hypogonadism and polyuria. Initial workup was consistent with secondary hypogonadism; decreased free and total testosterone levels (1.8 pg/dL and 9 ng/dL, n>35 pg/dL, n>250 ng/dL), LH (0.2 mIU/mL, n>1.5 mIU/mL), and FSH (<0.7 mIU/mL, n>1.6 mIU/mL). The remaining anterior pituitary hormones were within normal limits. The patient was also polyuric (6.5L urine output in 24hr). HgbA1c was normal. Urine Na, urine Osm demonstrated water diuresis (13 mmol/L and 54 mOsm/kg, respectively). A water deprivation test was performed. Initial urine Osm after water restriction was 119 mOsm/kg, which more than tripled to 575 mOsm/kg after administration of desmopressin, diagnostic of central DI. Pituitary MRI showed a well-circumscribed thickening of the pituitary stalk (6x6x5mm), with uniform enhancement. Evaluation for etiology to rule out germ cell tumor, lymphoma, sarcoidosis, opportunistic infection, tuberculosis, Langerhans cell histiocytosis showed a normal serum hCG, HIV, ACE, LDH, AFP. A lumbar puncture demonstrated normal cytology and was negative for AFB. Whole body bone scintigraphy and chest X-ray were normal. Pituitary deficits were treated with hormone replacement (testosterone and desmopressin), and a repeat MRI showed a stable lesion. Conclusion: Noninvasive testing is key to the evaluation of a pituitary stalk lesion. Careful consideration of inflammatory, infectious, and neoplastic etiologies along with attention to pituitary deficits is very important. Our patient most likely has a craniopharyngioma based on data from other case series (1,2). This case serves to bring additional data to the body of literature on this complicated clinical scenario.

6529 The Risk of Hypophysitis Following Treatment With Relatlimab+Nivolumab Appears Higher Than Expected

Abstract Disclosure: N. Chamorro-Pareja: None. A.T. Faje: None. K.K. Miller: Stock Owner; Self; Bristol-Myers Squibb. Hypophysitis is a recognized complication of immune checkpoint inhibitor therapy; the risk of developing hypophysitis in patients receiving nivolumab (an anti-programmed death-ligand 1 [anti-PD-1]) is estimated to be < 1%. Relatlimab is a human monoclonal antibody targeting lymphocyte activation gene 3 (LAG-3) recently approved in combination with nivolumab for the treatment of unresectable or metastatic melanoma. The risk of hypophysitis as a complication of relatlimab therapy is not well-defined. Objective: To examine the prevalence, identify risk factors, and characterize the clinical presentation of hypophysitis in patients receiving relatlimab+nivolumab. Methods: 159 patients received relatlimab+nivolumab at the Mass General Brigham health care system between 6/2015 and 11/2023. Twenty-seven patients were excluded because they were either diagnosed with adrenal insufficiency (AI) before receiving relatlimab+nivolumab or AI was secondary to other factors, primarily exogenous glucocorticoid administration, leaving a total of 122 patients. The medical records of these patients, including provider encounters, laboratory results, medication records, and radiologic images were reviewed. Data are presented as mean ± SD. Results: Central AI was diagnosed in 10 patients (7.5% of the cohort) after relatlimab+nivolumab administration. The mean age was 64.5±13.8 vs. 67.1±14.4 in patients with AI vs. patients without AI (p= 0.58). Sixty percent of patients in the AI group were male compared to 53% of patients without AI (p= 0.68). The development of AI was not related to the cumulative dose of relatlimab+nivolumab (mean number of cycles 6.4±3.2 vs. 4.9±5.0, p=0.35). The most common presenting symptoms of AI were fatigue, anorexia, nausea, and vomiting. No patients were diagnosed with additional anterior pituitary hormone deficiencies, though not all patients were evaluated for these diagnoses; none had diabetes insipidus. Nine patients had MRIs performed after the diagnosis of central AI; 7 of these patients had pre-treatment MRIs for comparison. Diffuse pituitary enlargement was seen on MRI after initiation of relatlimab+nivolumab in 3 patients up to 8 weeks prior to the diagnosis of hypopituitarism. All patients had persistent hypopituitarism at the most recent evaluation. Conclusions: This study is the first cohort analysis of hypophysitis in patients treated with relatlimab+nivolumab. A significant portion of patients were diagnosed with central AI, presumptively due to hypophysitis given the lack of an identifiable alternative etiology. Although the clinical phenotype of these patients paralleled published studies analyzing anti-PD-1 monotherapy, combination treatment with relatlimab+nivolumab appeared to confer a significantly higher risk of developing hypophysitis. Presentation: 6/3/2024

12525 Feline Hypersomatotropism In The USA And Canada: Demographics Of 4620 Cats With Presumed Acromegaly

Abstract Disclosure: R.J. Egbert: None. R.C. Fowkes: None. S.J. Niessen: None. B.K. Petroff: None. Spontaneous models of endocrinopathies are powerful tools to understand disease etiology. Endocrine diseases in companion animals are particularly useful to study, as they share their environment with humans and typically present with clinical disease that phenocopies human symptoms. One such disease in domestic cats, hypersomatotropism (HST, feline acromegaly), is a disorder of excessive growth hormone and increased IGF-1 (Insulin like Growth Factor 1), usually caused by hyperplasia or neuroendocrine tumors of the pars distalis of the pituitary gland. This retrospective study used serum IGF-1 results to investigate population characteristics for domestic cats with HST in the United States and Canada. Laboratory records from 1Jan06 to 31Dec22 were reviewed and animals with a circulating IGF-1 hormone concentration of 190 nmol/L (1,450 ng/mL) or greater were presumed to have acromegaly. This review identified 4,620 such cats with a mean age (n=4,351) of 11.2 years (median: 11.2, range: .5-20.3yr) and mean weight (n=2,086) of 6.03 Kg (median: 5.91, range: 2.27-15.0 Kg). Males outnumbered females in the database, which included 3,048 males and 1,181 females. Domestic Short/Medium/Longhair cats were the most prevalent breed (n=3,563; 77%), followed by Maine Coon cats (n=120; 2.6%) and Siamese cats (n=111, 2.4%). Just under half of the animals (n=2,037, 44%) had a history of diabetes mellitus on the submission form. Most submissions were from the US (n=4,347, 94%) with the most hypersomatotropic cats from California (n=841, 18.2%), New York (n=604, 13.1%), Massachusetts (n=402, 8.7%), Colorado (225, 4.9%), and Texas (200, 4.3%). The mean serum IGF-1 concentration of these animals was 358 nmol/mL (median: 345, range 190-761 nmol/mL). For comparison, an age and sex matched control group of 95 animals with residual samples previously submitted for unrelated testing was selected. The mean IGF-1 concentration for the control group was 97 nmol/mL (median: 85, range 0-311 nmol/mL). In summary, HST is diagnosed most frequently in older male cats in urbanized North America, and potentially displays some breed disposition, suggesting both a genetic and environmental component to the disease etiology. Presentation: 6/2/2024

7229 A Rare Case of Igg4 Hypophysitis Presenting as Hypogonadotropic Hypogonadism

Abstract Disclosure: C. Dimech: None. G. Jaiswal: None. Hypophysitis is a rare pituitary disorder including a broad range of inflammatory processes which affect the pituitary gland and infundibulum. Previously reported as 1 per 9 million individuals, the true incidence of hypophysitis per year is largely unknown due to the increase of novel etiologies such as immunoglobulin G4 (IgG4)- related disease. IgG4-related hypophysitis (IgG4-RH) was first clinically described in 2004 and later biopsy proven in 2007. The main clinical features are elevated serum IgG4 level and IgG4-positive lymphocyte infiltration of tissues on histopathology. IgG4-RH is reported to account for 1.3% of primary hypophysitis with 3.2:1 incidence ratio of men to women, in the 6th decade of life. Here we present a case of a 68-year-old Caucasian male who presented for evaluation of hypogonadotropic hypogonadism. As fasting morning testosterone levels were significantly low, MRI pituitary was completed which revealed a homogenously enhancing pituitary gland with thickened, nodular enhancement of the pituitary infundibulum. Subsequent lab work-up revealed normal function of remaining anterior pituitary without evidence of central vasopressin deficiency. Evaluation of underlying etiologies was unremarkable except for significantly elevated IgG4 levels (472mg/dL). Based on the significantly elevated IgG-4 levels (>135 mg/dl) and the radiographic findings of the pituitary infundibulum, the diagnosis of possible IgG4-RH was made. The patient was initiated on treatment with rituximab and glucocorticoid therapy with prednisone. Following 3 months of medical therapy, MRI pituitary showed resolution of stalk inflammation, confirming diagnosis of IgG4- RH. Presentation: 6/1/2024

Subclinical Hyperthyroidism Enhances Gonadotropin-Lowering Effects of Metformin in Postmenopausal Women.

Metformin treatment decreases elevated concentrations of anterior pituitary hormones. The aim of this prospective, cohort study was to investigate whether hyperthyroidism modulates the impact of metformin on gonadotroph secretory function. The study population included 48 postmenopausal women with untreated type 2 diabetes or prediabetes, 24 of whom had coexisting grade 1 subclinical hyperthyroidism. Both groups were matched for age, insulin sensitivity, and gonadotropin levels. Over the entire study period, all participants were treated with metformin (2.55-3 g daily). Plasma glucose, insulin, thyroid-stimulating hormone (TSH), total and free thyroid hormones, follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol, prolactin, adrenocorticotropic hormone (ACTH), and insulin-like growth factor-1 (IGF-1) were assayed at entry and 6 months later. At baseline, the study groups differed in levels of TSH and thyroid hormones but not in body mass index, blood pressure, glucose homeostasis markers (fasting glucose, homeostatic model assessment 1 of insulin resistance ratio [HOMA1-IR], and glycated hemoglobin [HbA1c]), and the remaining hormones. There were no differences between both groups in the degree of reduction in plasma glucose and HbA1c in response to metformin treatment. Although metformin decreased HOMA1-IR in both groups, this effect was stronger in women with hyperthyroidism than with normal thyroid function (-50 ± 20% vs -30 ± 15%). Similar relationships were observed for FSH (-43 ± 21% vs -21 ± 12%). Only in hyperthyroid women did the drug reduce LH concentration (by 35 ± 17%). Metformin did not affect circulating levels of TSH, total and free thyroxine, total and free triiodothyronine, estradiol, prolactin, ACTH, and IGF-1. The obtained results indicate that hyperthyroidism enhances the gonadotropin-lowering effects of metformin, as well as the fact that this agent has a neutral effect on the hypothalamic-pituitary-thyroid axis in case of its overactivity.

Sex-Dependent Changes in Gonadotropin-Releasing Hormone Neuron Voltage-Gated Potassium Currents in a Mouse Model of Temporal Lobe Epilepsy.

Temporal lobe epilepsy (TLE) is the most common focal epilepsy in adults, and people with TLE exhibit higher rates of reproductive endocrine dysfunction. Hypothalamic gonadotropin-releasing hormone (GnRH) neurons regulate reproductive function in mammals by regulating gonadotropin secretion from the anterior pituitary. Previous research demonstrated GnRH neuron hyperexcitability in both sexes in the intrahippocampal kainic acid (IHKA) mouse model of TLE. Fast-inactivating A-type (I A) and delayed rectifier K-type (I K) K+ currents play critical roles in modulating neuronal excitability, including in GnRH neurons. Here, we tested the hypothesis that GnRH neuron hyperexcitability is associated with reduced I A and I K conductances. At 2 months after IHKA or control saline injection, when IHKA mice exhibit chronic epilepsy, we recorded GnRH neuron excitability, I A, and I K using whole-cell patch-clamp electrophysiology. GnRH neurons from both IHKA male and diestrus female GnRH-GFP mice exhibited hyperexcitability compared with controls. In IHKA males, although maximum I A current density was increased, I K recovery from inactivation was significantly slower, consistent with a hyperexcitability phenotype. In IHKA females, however, both I A and I K were unchanged. Sex differences were not observed in I A or I K properties in controls, but IHKA mice exhibited sex effects in I A properties. These results indicate that although the emergent phenotype of increased GnRH neuron excitability is similar in IHKA males and diestrus females, the underlying mechanisms are distinct. This study thus highlights sex-specific changes in voltage-gated K+ currents in GnRH neurons in a mouse model of TLE and suggesting potential sex differences in GnRH neuron ion channel properties.

Complete remission after glucocorticoid therapy in a patient with primary hypophysitis.

Primary hypophysitis is a rare disease that may have variable clinical presentations. The main treatment options are clinical observation, immunosuppressive drugs, and surgery. Glucocorticoids are used as first-line medical therapy; however, non-responsiveness and recurrences are the major problems. We present a 30-year-old male patient who had an excellent radiologic response to a single course of glucocorticoids. The patient presented with malaise and severe headaches of acute onset. Cranial MRI revealed a pituitary mass compressing the optic chiasm. Hormonal evaluation studies were consistent with anterior pituitary hormone dysfunction except for the growth hormone axis. There was a mild compression on the optic chiasm in the pituitary MRI. The patient was started on methylprednisolone therapy at a dose of 80 mg/day. The pituitary MRI revealed complete regression of the mass after 2 months, and there was a complete recovery of pituitary functions after 6 months. There is no consensus on the optimal dose and duration of glucocorticoid therapy for primary hypophysitis in the literature. We report that steroid therapy, even in lower doses, might be effective in mild-to-moderate cases. Primary hypophysitis is a rare disease with a varied clinical course, and hence the treatment strategies should be individualized. There is no consensus on the optimal dose and duration of glucocorticoid therapy. Glucocorticoid therapy may induce complete remission in some patients, especially with a mild-to-moderate disease course and during the acute phase of the disease.

Delayed onset arginine vasopressin deficiency after traumatic brain injury.

Delayed arginine vasopressin deficiency (AVP-D) can present in patients following traumatic brain injury (TBI) and may occur years after the trauma, presenting with nonspecific symptoms. The objective of this case is to highlight the importance of considering the delayed onset AVP-D in patients with a history of TBI. We report a case of a patient who had sustained severe traumatic brain injury 8 years before and who presented with polydipsia, behavioural disorder and frequent falls during the last 3 months. The diagnosis of AVP-D was confirmed by water restriction with a positive response to desmopressin, and pituitary MRI showed an absent spontaneous posterior hyperintensity on T1WI. Follow-up confirmed permanent diabetes insipidus as well as a suspected anterior pituitary deficiency. Pituitary dysfunction occurs following TBI and is correlated with severity. As in our case, symptoms are generally non-specific and are difficult to explore given the patient's neurologic sequelae. MRI 8 years post trauma showed changes in pituitary morphology. Some authors have proposed the need for active screening of post-TBI patients. This case highlights the need for clinicians to be aware that AVP-D can occur years after traumatic brain injury. Delayed onset post-traumatic arginine vasopressin deficiency may occur in patients with TBI and is correlated with the severity. The clinical picture is usually non-specific and diagnosis of AVP-D is challenging in non-verbal patients. An active screening for pituitary dysfunction is warranted in TBI patients and should be extended should one hormone deficit be identified.

Immune checkpoint inhibitor induced hypophysitis: a specific disease of corticotrophs?

The aim of this study was to define functional and anatomical pituitary disease at the time of presentation following immune checkpoint inhibitor (ICI) therapy and to describe any changes in pituitary function over time. We conducted a retrospective observational audit of patients on ICI therapy at our centre between January 2013 and September 2023. We reviewed all patients on ICI therapy under the care of the oncology department at University Hospital Plymouth, a 1000-bedded hospital serving a population of 500,000 people. From this group, we identified all individuals referred to the endocrinology department with a suspected diagnosis of adrenal insufficiency. Patients were established on adrenal steroid replacement and subsequently underwent formal pituitary testing. People were included if they had pituitary disease, as evidenced by low ACTH, other pituitary dysfunction and/or abnormalities on pituitary imaging. Nine hundred and fifty-four patients received ICI therapy during the study period, and 37 (a prevalence of 3.9%) developed hypothalamic-pituitary-adrenal axis dysfunction. Their mean age was 65 years, and 70% were male. About 86.5% of the total patients affected were treated for metastatic malignancies. Ten of the 37 patients died during follow-up as a direct consequence or complication of their primary cancer diagnosis. The median interval for the onset of symptoms was 4 months. Following repeated testing, there was no recovery in cortisol or ACTH levels for any individual. Other permanent anterior pituitary hormone defects were unusual. Hypophysitis associated with immunotherapy appears to specifically target the corticotrophs, with no evidence of recovery over time. There was a specific abnormality seen in MRI scans of 7 of 27 patients who had scans, which appeared to be a particular feature of immune-mediated hypophysitis. These were confined to the anterior aspect of the pituitary gland, appearing as striations, and were not visible on any of the scans performed more than 3 months after the likely onset of the disease. These data show that immune-related hypophysitis is a common complication of immune checkpoint inhibitor therapy. This may result in an imaging abnormality within the areas of the pituitary that are richest in corticotrophs. The endocrine consequence of this is a permanent defect in ACTH and, therefore, cortisol production.

Associations of the AVPR1A RS1 Microsatellite Locus with the Level of Hormones of the Anterior Pituitary Gland and Personality Traits.

The arginine vasopressin receptor gene (AVPR1A) is one of the genes affecting mental processes. The aim of this study was to search for associations of microsatellite locus RS1, which is related to the AVPR1A expression level, with the level of hormones of the anterior pituitary gland and personality traits. The study sample included Yakut men aged 18-26years (n = 121). The analysis of RS1 locus was carried out using the PCR method and sequencing of the primary nucleotide sequence. Serum hormonal levels of thyroid-stimulating hormone (TSH), follicle-stimulating hormone (FSH), luteinizing hormone (LH) and prolactin were determined by the time-resolved fluorescence immunoassay (DELFIA), plasma adrenocorticotropic hormone (ACTH) levels were determined by enzyme-linked immunosorbent assay (ELISA). In the Yakut population "short" (S) alleles of the AVPR1A RS1 locus containing ≤ 10 repeats (63%) and the corresponding SS genotypes (44.6%) were more frequent, while individuals with "long" (LL) and "heterozygous" (SL) genotypes accounted for 18.2 and 37.2%, respectively. The range of concentrations of ACTH and TSH in the group of SS genotype carriers was significantly lower than that observed in the group of LL genotype carriers (p = 0.042 and p = 0.048, respectively); the LH level was significantly higher (p = 0.029). The trend towards higher neuroticism in SS genotype carriers compared to the individuals with LL genotypes (p = 0.05) is revealed. The results obtained indicate the modulating effect of genetic variants of the AVPR1A gene on the level of anterior pituitary hormones, which could slightly affect the level of neuroticism in humans.

Estrogen-dependent oxytocin expression in the hypothalamus and estrogen-dependent vasopressin in the median eminence.

The posterior pituitary (PP) hormones oxytocin (OXT) and arginine vasopressin (AVP) are synthesized within the hypothalamic nucleus and released from the PP into systemic circulation. Hypothalamic AVP projects its axons into the external layer of median eminence (eME) and regulates anterior pituitary hormone secretion during stress responses. Although similar as PP hormones, we demonstrate distinct regulatory roles of estrogen in hypothalamic OXT and AVP dynamics. OXT dynamics in the hypothalamus exhibit sex-dependent variations and that estrogen may influence dynamic OXT level changes, as observed in OXT-mRFP1 transgenic rats. Estrogen was also observed to modulate dynamic changes in AVP levels in the axon terminals of eME in female AVP-eGFP transgenic rats. Although OXT and AVP are produced within the similar hypothalamic region, both exhibit distinct dynamics within the hypothalamus. Estrogen acts on the hypothalamus, and further effects of estrogen replacement therapy can be expected.