[Iodo-methyl norcholesterol scintigraphy in the localization of primary hyperaldosteronism]

The aim of the study was to investigate the accuracy of iodomethyl norcholesterol, a new adrenal isotopic scanning agent, in the strategy of aldosteronism localization. Among 1499 patients examined in the clinic in 1987, 49 presented with primary aldosteronism. Nine were explored by adrenal scintigraphy (SCI). Mean age was 50 +/- 10 ans, blood pressure was 188 +/- 26/110 +/- 17 mmHg. Initial serum kalemia was 3.2 +/- 0.4 mMol/l, urinary potassium 67 +/- 39 mMol/d; standing plasma active renin was 9.9 +/- 5.0 pg/ml (20 less than N less than 50), supine plasma aldosterone was 316 +/- 200 pg/ml (50 less than N less than 150) and aldosterone excretion rate was 49 +/- 27 microgr/day (N less than 17). Adrenal CT-scan correctly predicted unilateral adenoma in 7 patients (size from 5 to 15 mm). CT-scan was negative twice. Adrenal vein aldosterone sampling and phlebography confirmed adenoma in the 8th patient. 7 patients underwent surgery, with pathological confirmation of the diagnosis. The diagnosis of adrenal hyperplasia (AH) was made in the 9th patient. (table; see text) When compared to CT-scan, SCI is unuseful if a tumor (greater than or equal to 10 mm) is detected on CT-scan (2 SCI false-negative/5 CT-scan tumors). At the opposite, when CT-scan is negative, SCI localizes 2 tumors in 4 patients (2 adenomas).

SCI should not be used as first step diagnosis procedure in the localization of primary aldosteronism.