Endocrine Abstracts

Introduction: In patients with primary hyperaldosteronism, distinguishing between unilateral and bilateral adrenal hypersecretion is critical in assessing treatment options. Adrenal venous sampling (AVS) has been advocated by some to be the gold standard for localization of the responsible lesion however is invasive, technically challenging, and difficult to interpret. Adrenal computed tomographic scanning (TC) is mandatory before AVS but more studies are warranted to identify its sensitivity and specificity for subtype differentiation.

Objectives: To study the utility of the MVS in the diagnosis of subtype of PAH and its concordance with the CT.

Methods: A retrospective study of 51 patients with a biochemical diagnosis of primary hyperaldosteronism who all underwent CT scan and AVS before and after ACTH stimulation. The aldosterone-to-cortisol ratio (AC) was computed for each sample to correct for varying capture and dilution of adrenal venous effluent. Patients that demonstrated unilateral hypersecretion of aldosterone were referred for an adrenalectomy. Diagnosis of a unilateral hyperfunctioning adrenal gland was made if the AC ratio on one side was at least four times greater than on the contralateral side and the peripheral samples. An AC ratio that was lower than periphery on the unaffected side (<0.5) especially after stimulation suggested a suppressed gland and therefore a unilateral hyperfunctioning gland on the contralateral side. Diagnosis of bilateral hyperplasia was made if the AC ratio on both sides was elevated and the response to stimulation was similar with no gradient observed between the two sites.

Results: Of 26 patients that had a unilateral abnormality on CT scan, four patients lateralized to the contralateral side by AVS, and seven patients had AVS consistent with bilateral hyperplasia. Therefore, 11 patients (21%) would have had either an unnecessary adrenalectomy or adrenalectomy of the nonfunctioning adrenal gland if AVS was not performed. In 12 patients that showed bilateral disease on CT scan, AVS lateralized to one side in eight patients and was concordant with the CT scan in 4 patients. In 13 patients that had no abnormality on CT scan, seven lateralized with AVS. 15 patiens (29.5%) would have been deprived of a curative suprarenalectomy. Of the group of 51 patients, 25 patients (50%) would have been inappropriately managed based on CT scan findings alone.

Conclusions: Because 50% of patients would have been inappropriately managed based on CT scan findings, patients with biochemical evidence of primary hyperaldosteronism and considering adrenalectomy should have AVS.