Liddle's syndrome, a rare cause of hypokalemic
hypertension, is characterized by a renal tubular
sodium channel defect resulting in excessive
sodium absorption and concomitant
potassium wasting. In this disorder, although the clinical manifestations resemble primary
aldosteronism, serum and urine
aldosterone are suppressed. The syndrome is transmitted in an autosomal dominant pattern. It has been reported previously in white and oriental populations but not in the black individuals. We identified four patients (two of whom are black) in our nephrology clinic, with severe hypokalemic
hypertension not correctly diagnosed for several years. All patients underwent an extensive work-up for secondary
hypertension because of persistent severe
hypertension (average blood pressure, 210/130 mm Hg) despite high-dose multi-
drug therapy. Primary
aldosteronism was excluded because of low serum
aldosterone.
Cushing's syndrome,
pheochromocytoma,
renal artery stenosis, and enzymatic deficiencies of
cortisol synthesis (
11 beta-hydroxylase,
17 alpha-hydroxylase, 5 beta-
reductase, and
11 beta-hydroxysteroid dehydrogenase) were ruled out with extensive endocrine and radiologic studies. Once the diagnosis of Liddle's syndrome was suspected, all patients were treated with either
triamterene or ameloride, with resolution of
hypokalemia and correction of
hypertension occurring within 5 to 7 days. Our findings suggest that Liddle's syndrome can occur in the black population. Although the actual incidence of this syndrome remains unknown, it may be significantly more common than we are led to believe since it is inherited in a Mendelian pattern. Whether there is a subset of low-
renin,
salt-sensitive black hypertensive patients who have the same or similar
sodium channel defect remains to be elucidated.