NONTUMOROUS PRIMARY HYPERALDOSTERONISM - AN UNDERRECOGNIZED CAUSE OF HYPERTENSION - REPORT OF 8 CASES

Nontumorous primary hyperaldosteronism (NTPHA), in which no adrenal ad enoma is detectable, is an underrecognized, treatable cause of arteria l hypertension. Eight cases of NTPHA were diagnosed among the 137 hype rtensive patients admitted to an internal medicine department between July 1992 and December 1993. There were seven women and one man. Mean age was 53 years (range, 41-72). The mean time interval between onset of hypertension and diagnosis of NTPHA was 9.5 years (range, 2-19). An tihypertensive treatments given before the diagnosis of NTPHA (calcium channel antagonists, angiotensin-converting enzyme inhibitors, betabl ockers) failed to provide adequate blood pressure control, and mean bl ood pressure at admission (under treatment) was 176/100. NTPHA was sus pected when tests showed moderate hypokalemia (mean 3.48 -mmol/L; rang e, 3.1-4.1) with normal urinary excretion of potassium. Plasma renin a ctivity was low and plasma aldosterone levels were moderately elevated (21.6 ng/dl; range, 9-33) in the supine position (n=5-10) and high (4 4.7 ng/dl; range, 22-60) in the standing position (n=15-25). Computed tomography showed that the adrenal glands were normal in 6 cases and h yperplastic in 2. Iodine-labeled nor-cholesterol scintigraphy found no evidence of an adenoma. Spironolactone was consistently effective in lowering blood pressure and restoring normal serum potassium levels. S tudies are needed to determine the prevalence of NTPHA, which is proba bly grossly underestimated in the literature, and to evaluate potentia l links of NTPHA with type II diabetes mellitus (present in 5 of our 8 patients) and low-renin hypertension.