Optimizing adrenal vein sampling in primary aldosteronism subtyping through LC-MS/MS and secretion ratios of aldosterone, 18-oxocortisol, and 18-hydroxycortisol

Prevalence of unilateral hyperaldosteronism in primary aldosteronism: impact of a novel chemiluminescent immunoassay for measuring plasma aldosterone in Japan

This study aims to evaluate the prevalence of unilateral hyperaldosteronism (UHA) and its clinical characteristics in patients with primary aldosteronism (PA), diagnosed using plasma aldosterone concentration (PAC) measured by chemiluminescent enzyme immunoassay (CLEIA). We retrospectively analyzed data of 199 PA patients from the Japan Primary Aldosteronism Study II (JPAS II) dataset, including patients who underwent adrenal venous sampling (AVS) and the captopril challenge test (CCT) and/or saline infusion test (SIT), with PAC measured by CLEIA. We focused on two categories: confirmed PA, where patients exhibit clear biochemical evidence of the disorder, and borderline PA, where patients present with marginal biochemical indicators, as outlined in the Japan Endocrine Society's clinical practice guideline for the diagnosis and management of PA. In confirmed PA cases, over the half of patients was UHA, while approximately 15 to 20% of borderline cases were found to be UHA. The prevalence of hypokalemia was identified as predictor of UHA among borderline cases. Among borderline cases with no hypokalemia and adrenal nodules on CT imaging, only 6 to 8% of patients were found to have UHA. Notably, some patients exhibited UHA despite negative results on one test but confirmed result on the other, particularly those with hypokalemia or adrenal nodules on CT imaging. In conclusion, the findings validate the importance of AVS in confirmed PA cases and the need for careful assessment in borderline cases. When feasible, conducting both CCT and SIT, and interpreting their results alongside other clinical indicators, could provide a more comprehensive assessment.

Determination of three C18-oxygenated steroids in adrenal lesion segments in primary aldosteronism by super-selective adrenal venous sampling and LC/ESI-MS/MS

Super-selective adrenal venous sampling (ssAVS) can collect the adrenal tributary venous blood in the aldosterone (ALD)-hypersecreting segments in primary aldosteronism. The concentrations of the C18-oxygenated steroids, especially 18-oxocortisol (18-oxoF), in the lesion segments might be more useful indices than those in the peripheral or adrenal central veins (current candidate indexes) for the differential diagnosis of unilateral ALD-producing adenoma (APA) and bilateral adrenal hyperplasia (BAH). To verify this hypothesis, we developed a liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) method for simultaneously quantifying ALD, 18-oxoF and 18-hydroxycortisol in the adrenal tributary venous serum sample collected by ssAVS (ssAVS serum) and compared their concentrations between APA and BAH patients. Only deproteinization was required for a 10 μl sample prior to the LC/ESI-MS/MS analysis. Endogenous corticoids did not interfere with the quantifications, and the intra-assay and interassay precisions (≤ 8.3%) and accuracies (94.2-102.7%) were acceptable. The clinical study revealed that the 18-oxoF concentration was significantly higher in the ALD-producing tumor tissues (from APA patients) than in the hyperplastic tissues (from BAH patients). However, in conclusion, the 18-oxoF concentration in the ssAVS serum sample can be a rough indication but cannot be decisive for the differential diagnosis between APA and BAH owing to the significant individual difference.