Unilateral adrenal hyperplasia causing primary aldosteronism: limitations of I-131 norcholesterol scanning

Abstract

Primary aldosteronism is a disorder that is commonly considered in patients referred to the hypertension clinic. The ease of measuring the random aldosterone-to-renin ratio in conjunction with an elevated serum aldosterone level has led to an increased screening for this disorder. Typically, patients undergo a confirmatory test after a positive screening test. However, once primary aldosteronism is confirmed, subtype delineation is critical to decide on the optimal treatment. We report a patient with resistant hypertension and primary aldosteronism with a normal computed tomographic scan of the adrenal glands, a left-sided uptake on adrenal scintigraphy, and a right-sided lateralization of aldosterone after adrenal vein sampling. A repeat adrenal vein sampling confirmed the aldosterone lateralization to the right adrenal gland, which was then removed laparoscopically. The patient had a good clinical and biochemical response, and unilateral adrenal hyperplasia was discovered at histology. Excessive reliance on adrenal scintigraphy without adrenal vein sampling may lead to serious errors in patient management.

A Case of Primary Aldosteronism Due to Unilateral Adrenal Hyperplasia

“…In previous reports of UAH, the bilateral adrenal vein sampling method was performed in 15 cases. Of these, 3 cases (9,16,17) were performed under ACTH stimulation and the PAC in the affected side was dependent of ACTH in all cases. Our case met both criteria with a lateralized ratio of 11.4 and a contralateralized ratio of 0.7 after ACTH stimulation, strongly suggesting a unilateral autonomous lesion.…”

Localization of Aldosterone-Producing Adrenocortical Adenomas: Significance of Adrenal Venous Sampling

“…Regarding adrenal scintigraphy, adrenal iodomethyl-norcholesterol (NP-59) uptake depends primarily on the size of the APA rather than on its functional activity (12). This test might not be useful for detecting a small APA, because the tracer uptake is poor in APAs of less than 1.5 cm in diameter (13)(14)(15). In addition, PA may be associated with non-aldosterone-secreting nodules in the ipsilateral or contralateral adrenal gland (16)(17)(18).…”

Long-term Outcomes of Unilateral Adrenalectomy in Patients with Dominant-side Adrenal Hyperplasia

“…According to the new guidelines, the selectivity to confirm successful cannulation should be higher than 2.5 and higher than 4 with cosyntropin infusion. 9 The recommended lateralization ratio for the diagnosis of adenoma is now higher than 2.5.…”