[Significance of microproteinuria for early detection of hypertension-induced end organ damage].

To investigate the clinical importance of microproteinuria, we examined the prevalence of microproteinuria and its relation to cardiac structural adaptation in 80 male, middle-aged patients with essential hypertension. Patients with secondary causes of hypertension were ruled out. 14 out of 80 hypertensives (18 percent) were found to have microproteinuria defined as "negative" for urinary protein excretion in the conventional test, but "positive" (above the upper normal limit) in the 24-hour urine samples. Patients with microproteinuria had a similar age and body weight, but a higher systolic and diastolic pressure (161 +/- 14/104 +/- 12 vs 148 +/- 14/97 +/- 9 mmHg, p less than 0.02) and greater creatinine clearance (163 +/- 36 vs 136 +/- 33 ml/min, p less than 0.01) than those with normal protein excretion. Also, hypertensives with microproteinuria had a greater left ventricular mass (241 +/- 57 vs 207 +/- 45 g, p less than 0.05) and greater cross sectional area (22.2 +/- 2.8 vs 20.5 +/- 2.9 cm2, p less than 0.05) evaluated by 2-D guided M-mode echocardiography than the control group. A positive Sokolow-index was more prevalent in patients with microproteinuria than in those without (x2 = 6.2, p less than 0.02). Patients with essential hypertension and microproteinuria (prevalence 21 per cent) were characterized by a higher arterial pressure, by a higher degree of echocardiographic and electrographic evidence of left ventricular hypertrophy. Thus, microproteinuria might serve as a marker for early target organ damage in essential hypertension.