Microalbuminuria Is an Early Marker of Target Organ Damage in Essential Hypertension

Microal buminuria has been associated with a cluster of metabolic and nonmetabolic risk factors, suggesting that it might indicate the presence of generalized microvascular damage in patients with essential hypertension. To explore whether microalbuminuria is associated with early target organ damage, two groups of essential hypertensive patients, with (n = 17) (HtAlb+) and without (n = 16) (HtAlb−) microalbuminuria, and a control group (C) of healthy normotensive subjects (n = 20) were studied. The study groups, selected among participants of a large epidemiologic trial, were carefully matched for several potentially confounding variables such as gender, age, duration of hypertension, and body mass index. Albumin excretion rate was evaluated by radioimmunoassay in three nonconsecutive timed overnight collections after 3 weeks of pharmacologic wash-out. Left ventricular mass was assessed by M-B-mode echocardiography, carotid wall thickness by a high resolution ultrasound scan, and renal vascular impedance by Doppler scan. Office as well as 24-h ambulatory pressure monitoring (Takeda TM-2420) were also evaluated. There was no difference between the two hypertensive groups for office and 24-h blood pressure levels except for a lower daytime/nighttime systolic blood pressure ratio in the group with microalbuminuria. Microalbuminuric patients showed signs of early organ damage as compared to normoalbuminuric patients and normal subjects, namely greater left ventricular mass indices (LVMI 167 ± 7 g/m2 in HtAlb+; 139 ± 9 g/m2 in HtAlb−; 118 ± 5 g/m2 in C, P< .001) and increased wall thickness of common carotid arteries (intima plus media thickness 12.5 ± 0.2 mm in HtAlb+; 11.7 ± 0.3 mm in HtAlb−; 11.2 ± 0.2 mm in C, P< .001) as well as higher intrarenal vascular resistance (mean resistive index 0.62 ± 0.01 in HtAlb+; 0.59 ± 0.01 in HtAlb−; 0.59 ± 0.01 in C, P< .05). In conclusion, microalbuminuria is an early marker of diffuse target organ damage in essential hypertension and therefore can be useful to identify patients for whom more aggressive preventive strategies or additional treatment measures are advisable.