Microalbuminuria is associated with salt sensitivity in hypertensive patients

We have investigated 59 patients with mild-to-moderate uncomplicated essential hypertension in order to estimate whether salt sensitivity is associated with greater urinary albumin excretion. Patients whose average mean blood pressure (BP) value on day 5 of the high-sodium regimen (300 mmol/l NaCl) exceeded 10 mm Hg or more than that on day 5 of the low-sodium regimen (40 mmol/l NaCl) were classified as salt sensitive. We have demonstrated that salt sensitive patients (n = 29) manifest greater urinary albumin excretion than salt resistant patients (51.5 +/- 15 vs 11.5 +/- 12.8 mg/24h). Hypertensive patients selected as salt sensitive had a longer duration of hypertension (87 +/- 62 vs 41.5 +/- 33.6 months); greater body mass index (BMI) (29.0 +/- 4.7 vs 24.7 +/- 3.6 kg/m2); lower urinary excretion of sodium after 3 days of sodium loading (172.1 +/- 23.3 vs 245.8 +/- 21.6 mmol/day); and slightly, but significantly higher mean BP (121.3 +/- 7.4 vs 115.3 +/- 5.3 mmHg) than salt resistant patients (n = 29). Nevertheless, there was no significant correlation between duration of hypertension and the degree of urinary albumin excretion in salt sensitive patients. On the other hand, a significant correlation was demonstrated in a group of salt resistant hypertensive patients, suggesting that salt sensitivity could be linked with an early tendency to abnormal albumin excretion, while in salt resistant patients it may depend on hypertension-related renal disfunction. Therefore, measurement of microalbuminuria in patients with essential hypertension can be a useful marker for salt sensitivity.