Association of Adrenal Steroids With Hypertension and the Metabolic Syndrome in Blacks

Abstract

Abstract-Blacks have a high prevalence of hypertension and adrenal cortical adenomas/hyperplasia. We evaluated the hypothesis that adrenal steroids are associated with hypertension and the metabolic syndrome in blacks. Ambulatory blood pressures, anthropometric measurements, and measurements of plasma renin activity (PRA), aldosterone, fasting lipids, glucose, and insulin were obtained in 397 subjects (46% hypertensive and 50% female) after discontinuing antihypertensive and lipid-lowering medications. Hypertension was defined as average ambulatory blood pressure Ͼ130/85 mm Hg. Late-night and early morning salivary cortisol, 24-hour urine-free cortisol, and cortisone excretion were measured in a consecutive subsample of 97 subjects (40% hypertensive and 52% female). Compared with normotensive subjects, hypertensive subjects had greater waist circumference and unfavorable lipid profiles, were more insulin resistant, and had lower PRA and higher plasma aldosterone and both late-night and early morning salivary cortisol concentrations. Twenty-four-hour urine-free cortisol and cortisone did not differ. Overall, ambulatory blood pressure was positively correlated with plasma aldosterone (rϭ0.22; PϽ0.0001) and late-night salivary cortisol (rϭ0.23; Pϭ0.03) and inversely correlated with PRA (rϭϪ0.21; PϽ0.001). Plasma aldosterone correlated significantly with waist circumference, total cholesterol, triglycerides, insulin, and the insulin-resistance index. Based on Adult Treatment Panel III criteria, 17% of all of the subjects were classified as having the metabolic syndrome. Plasma aldosterone levels, but not PRA, were elevated in subjects with the metabolic syndrome (Pϭ0.0002). The association of aldosterone with blood pressure, waist circumference, and insulin resistance suggests that aldosterone may contribute to obesity-related hypertension in blacks. In addition, we speculate that relatively high aldosterone and low PRA in these hypertensive individuals may reflect a mild variant of primary aldosteronism. Key Words: aldosterone Ⅲ cortisol Ⅲ hypertension Ⅲ metabolic syndrome Ⅲ insulin resistance Ⅲ plasma renin activity T he prevalence of hypertension in African-Americans is among the highest in the world. In the United States, compared with whites, hypertension is 50% more frequent in blacks. 1,2 Blacks develop hypertension at a young age and have higher rates of hypertension-related deaths and cardiovascular complications including stroke, heart disease, and end-stage renal disease. 2 In both black and white populations, hypertension is frequently associated with centripetal obesity, insulin resistance, and dyslipidemia. [3][4][5] This constellation of risk factors has been termed the metabolic syndrome and is associated with increased cardiovascular disease morbidity and mortality. 6,7 Based on an earlier study of the records of 35 000 consecutive autopsies, an increased prevalence of adrenal cortical adenomas and hyperplasia has been observed in association with essential hypertension, particularly in younger and ...

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