Albuminuria in untreated patients with primary aldosteronism or essential hypertension

The determinants and significance of urinary albumin excretion have been studied in normal subjects and in hypertensive patients; however, they are unknown in patients with primary aldosteronism.

From a population of 114 patients with documented primary aldosteronism, we selected 23 never-treated patients (12 males, 11 females; 11 tumoral, 12 non-tumoral) and compared them to patients with never-treated essential hypertension with low renin (supine plasma renin activity <1 ng/ml per h, n = 23) or normal renin (supine plasma renin activity between 1 and 4 ng/ml per h, n = 23), matched for age, body mass index, mean arterial pressure, renal function and known duration of hypertension.

The patients with primary aldosteronism had lower serum potassium and higher plasma aldosterone concentrations than those with essential hypertension. Urinary albumin and beta2-microglobulin excretion were greater in untreated patients with primary aldosteronism than in those with low- or normal-renin essential hypertension. Among the patients with essential hypertension, the renin activity was not a determinant of albuminuria.

These findings indicate that primary aldosteronism is associated with excessive urinary albumin excretion. This albuminuria could be due to impairment of proximal tubular reabsorption caused by hypokalemic nephropathy and/or by high levels of circulating aldosterone; however, it could be an indicator of target-organ damage associated with primary aldosteronism.