Venous Sampling Test Research Articles

7764 A Case of Primary Hyperaldosteronism With Negative Imaging Findings -Diagnostic Approach and Outcome in a Decade

Abstract Disclosure: U.D. Gupta: None. M. Al-Ghuraibawi: None. R. Abdulhussein: None. K. Panigrahi: None. Z. Deribe: None. Distinguishing between the various subtypes of primary hyperaldosteronism (PHA) poses a clinical challenge. Nevertheless, it is notable that primary hyperaldosteronism is a prominent contributor to secondary hypertension, accounting for less than 1% of cases. The triad of hypertension, hypokalemia, and metabolic alkalosis demands screening for PHA. While bilateral adrenal hyperplasia and aldosterone-producing adenomas (APA) are common, rarer forms like unilateral adrenal hyperplasia and glucocorticoid-responsive aldosteronism can also occur. In our case, a 61-year-old patient has been diagnosed and treated for primary hyperaldosteronism for last 10-years. Presently, the patient is undergoing management for blood pressure with a medication regimen comprising Amiloride, Nifedipine, Minoxidil, Atenolol, and Eplerenone over the past decade. No abnormal findings were observed in the computed tomography or magnetic resonance imaging of the adrenal gland, and adrenal venous sampling test results were non-conclusive. The patient has exhibited favorable outcomes with medications, also subsequent imaging has not revealed the presence of an adrenal mass. This case is presented as unique due to its atypical presentation, characterized by the absence of anatomical lesions in the adrenal gland and non-conclusive sampling test results. Nevertheless, the patient responded positively to treatment, supported by the diagnostic significance of preliminary lab tests for primary hyperaldosteronism (aldosterone level: 20.5; plasma renin activity: 0.19, initially aldosterone levels were 17 and 7 before and after saline infusion). Notably, literature acknowledges that the aldosterone-producing adenomas (APAs) can be very small, sometimes <3 mm in diameter, and lesions <1 cm may be overlooked on CT scans. The limitation of adrenal venous sampling (AVS) is the challenge in obtaining good sample due to technical difficulties and variations in local expertise, success rates in AVS may vary. This case exemplifies the diagnostic complexities encountered in primary hyperaldosteronism cases, where imaging and adrenal venous sampling, though frequently recommended, may pose challenges. In conclusion, we share insights from this case and its treatment outcome. Clinically, a thorough assessment of symptoms, along with laboratory results, is crucial for diagnosis and treatment and further categorization may be challenging without imaging and adrenal venous sampling. Presentation: 6/3/2024

Selective Intra-Arterial Calcium Stimulation Venous Sampling Test for Preoperative Localization of Occult Neuroendocrine Tumors: Recall for an Old Technique

Abstract Background Surgical resection is the curative treatment for neuroendocrine tumors (NETs). Noninvasive imaging is unreliable in localizing NETs measuring less than 2 cm. This study investigates the safety and efficacy of the selective intra-arterial calcium stimulation venous sampling test (SACST) for preoperative localization of functional NETs within the pancreas. Methods This retrospective analysis of the patients referred for localization of radiologically occult functional NETs from 2004 to 2019 was performed at a single institution. The technical success, diagnostic accuracy, and complications of the test were evaluated. Results Twenty-three patients underwent SACST. The SACST was technically successful in 100% of the patients. Lesions were successfully localized in 19 (83%) patients. Tumor blush was seen in one patient. The mean ± standard deviation of maximal dimension of the resected tumor was 2.0 ± 1.9 cm. Sensitivity, specificity, positive predictive value, and negative predictive value of the SACST for localization of all lesions were 1.0, 0.57, 0.84, and 1.0, as well as 1.0, 0.57, 0.80, and 1.0 for insulinomas, respectively. Conclusion SACST is a feasible, safe, well-tolerated, and effective procedure to preoperatively localize radiologically occult NETs within the pancreas.

Diverse pathological lesions of primary aldosteronism and their clinical significance

Primary aldosteronism (PA) is mainly clinically classified as unilateral aldosterone-producing adenoma (APA) or bilateral idiopathic hyperaldosteronism. Immunohistochemistry for aldosterone synthase reveals a diverse PA pathology, including pathological APA and aldosterone-producing cell clusters. The relationship between PA pathology and adrenalectomy outcomes was examined herein. Data from 219 unilaterally adrenalectomized PA cases were analyzed. Pathological analyses revealed diverse putative aldosterone-producing lesions. Postoperative biochemical outcomes in 114 cases (test cohort) were classified as complete success (n = 85), partial success (n = 19), and absent success (n = 10). Outcomes in the large and small PA lesion groups, rather than between PA lesion types, were compared at five threshold values for PA lesion sizes (2–6 mm with 1-mm increments) to streamline the results. The proportion of complete success was significantly higher in the large PA lesion group than in the small PA lesion group at the 5-mm threshold only. The proportion of absent success was significantly higher in the small PA lesion group than in the large PA lesion group at all thresholds. Univariate and multivariate analyses of the test cohort identified serum K as an independent predictive factor for the small PA lesion group, which was confirmed in the 105-case validation cohort. Chi-squared automatic interaction detector analysis revealed that the best threshold of serum K for predicting large PA lesions was 2.82 mEq/L. These results will be beneficial for treating PA in clinical settings because patients with low serum K levels and apparent adrenal masses on CT may be subjected to adrenalectomy even if the adrenal venous sampling test is unavailable.

Are Biochemical Markers of Neuroendocrine Tumors Coreleased With Insulin Following Local Calcium Stimulation in Patients With Insulinomas?

The objective was to test whether chromogranin A (CgA), neuron-specific enolase (NSE), and pancreatic polypeptide (PP) are released from the pancreas during the selective arterial calcium stimulation and hepatic venous sampling test (ASVS) in patients with insulinomas. We determined CgA, NSE, PP, insulin, C-peptide, and proinsulin in blood samples obtained during the ASVS test in 19 patients with insulinomas. Levels following calcium injection into the arteries supplying the tumor were compared with levels following calcium stimulation of arteries supplying healthy pancreatic tissue. After calcium injection into the artery supplying the insulinoma, a significant 8-fold increase in insulin (range, 2.3-117; P < 0.001), a 3.8-fold increase in C-peptide (1.7-32.4; P < 0.001), and a 1.9-fold increase in proinsulin (0.7-5.3, P < 0.001) were detectable whereas NSE and CgA did not increase. No significant increases in insulin, C-peptide, proinsulin, CgA, and NSE concentrations were found after calcium injection into control arteries. Pancreatic polypeptide increased 1.5-fold (0.8-4.5; P = 0.017) after calcium injection into the tumor artery and 2.4-fold (0.8-7.9; P = 0.016) after injection into the control artery. Insulin, C-peptide, and proinsulin are released by insulinoma cells in response to arterial calcium stimulation, whereas CgA and NSE are not released. Also from our study it seems that PP may be released by healthy islet cells after calcium stimulation.

Arterial Stimulation and Venous Sampling (ASVS) is Useful for Recurrent Lesions of Insulinoma

We encountered a recurrent case of benign solitary insulinoma in the pancreatic tail, which may have been caused by an inadequate surgical margin in the use of an ultrasonic dissector. A 45-year-old man was referred with hypoglycemia and diagnosed solitary insulinoma in the pancreas. Laparoscopic pancreatic enucleation was performed using an ultrasonic dissector. The tumor was extracted and the surgical margins were microscopically negative. Six years later, he presented with hypoglycemia again. Multiple small well-enhanced lesions were detected by computed tomography distant from the resection stump of the first operation. He underwent resection of all visible lesions with omentum and wide excision of the soft tissue surrounding the pancreas after preoperative arterial stimulation and venous sampling test. The postoperative course of the second operation was uncomplicated and the patient presents no sign of hypoglycemia after 12 months.

Insulin determination by specific and unspecific immunoassays in patients with insulinoma evaluated by the arterial stimulation and venous sampling test

The aim of this study was to compare insulin concentrations measured by a traditional radioimmunoassay (RIA) and a more specific enzyme-linked immunosorbent assay (ELISA) in blood samples obtained during the arterial stimulation and venous sampling (ASVS) test in patients with insulinoma. Prospective case series. In 14 patients with an insulinoma undergoing an ASVS test, blood samples were obtained from the hepatic vein at baseline and 60 s after calcium injection into an artery supplying the tumour and a control artery (supplying pancreatic tissue without tumour). A selective arterial calcium stimulation was performed in five additional patients without evidence for an insulinoma. We measured insulin by a traditional RIA and a specific immunoassay. In patients with insulinoma, insulin concentrations increased between 2.3- and 24.2-fold (median 8.2-fold) when measured by RIA and between 7.3- and 59.4-fold (median 16) when measured by ELISA following calcium injection into the artery supplying the tumour. Following calcium injection into the control artery, insulin concentrations were 0.6 to 1.3 times (median 1.0) the baseline values by RIA and 0.5 to 2.5 times (median 1.1) the baseline values by ELISA. In patients without insulinoma, insulin concentrations increased following calcium stimulation between 0.7- and 2.1-fold (median 1.3-fold) when measured by RIA and between 0.6- and 4.7-fold (median 1.3-fold) when measured by ELISA. When insulin is measured by specific immunoassays, a higher cut-off (i.e. five- to sixfold increase) rather than the traditional criterion of a twofold increase should be used to localise an insulinoma during the ASVS test. The increase in insulin concentrations following calcium stimulation is significantly higher when insulin is measured by a specific assay compared with results obtained with traditional RIAs.