Abstract
Background: AVS Adrenal vein sampling (AVS) is the gold standard for localizing the lesion in primary hyperaldosteronism. This case illustrates the limitations of AVS in cortisol co-secreting adenomas and highlights features of co-secreting adrenal adenomas. CASE: A 65 yr old man with hypertension and hypokalemia was diagnosed with primary hyperaldosteronism in the setting of low renin (0.41 ng/ml/h (0.25-5.82), elevated aldosterone level (39 ng/dl) and an elevated aldosterone-renin ratio (ARR) of 95. CT abdomen showed a 4.4 cm left adrenal mass with pre-contrast attenuation of negative 5 houndsfield units and 60 % post contrast washout. The patient also had elevated 24- hour urine free cortisol levels of 72.5 mcg/24hr (4.0-50.0) and an elevated morning cortisol of 10 ug/dl(<1.8) after 1mg dexamethasone. Although he had no clinical evidence of Cushings syndrome on examination, his laboratory results were consistent with cortisol hypersecretion. An initial adrenocorticotrophic hormone (ACTH) stimulated AVS was done while on spironolactone, with potassium of 3.6 mEq/L. The selectivity index was > 3.0 indicating appropriate catheter placement, however results failed to demonstrate a unilateral process (lateralization index ___ at 15 minutes). AVS was repeated off of spironolactone and the lateralization index was ___ at 15 minutes post ACTH. the pt underwent left adrenalectomy for growth of the adenoma and mild hypercortisolism. Pathology confirmed an adrenocortical adenoma. Despite 2 AVS that suggested a bilateral process, post-operatively potassium and blood pressure normalized and aldosterone level reduced to <1ng/dl with renin levels of 2.35 ng/ml/h (ARR- 0.42). This case highlights the pitfalls of using AVS in co-secreting adenoma. The lateralization index is calculated by aldosterone/cortisol ratio of dominant to non- dominant side. The higher levels of cortisol on the side of the adenoma can falsely reduce the ratio of the affected side, falsely lowering the lateralization index. Conclusion: AVS can be misleading in an adenoma that is co-secreting aldosterone and cortisol and results in false negative results. References: Rossi, Gian Paolo. "New concepts in adrenal vein sampling for aldosterone in the diagnosis of primary aldosteronism." Current hypertension reports 9.2 (2007): 90-97. Späth, Martin, et al. "Aldosterone and cortisol co-secreting adrenal tumors-the lost subtype of primary aldosteronism." European Journal of Endocrinology (2011): EJE-10.