Clinical value of microalbuminuria in hypertension

Microalbuminuria (MA) is a well recognized marker of cardiovascular complic ations in hypertension, but whether MA can predict adverse outcome in this clinical condition is still a subject for debate, The fact that in hyperten sive cohorts those patients who showed an increase in albumin excretion rat e also manifested an increased incidence of morbid events indicates that th e presence of MA in hypertension may carry an increased cardiovascular risk . However, the prognostic significance of MA remains controversial because no results of prospective studies performed in hypertensive subjects withou t diabetes mellitus are available. Several factors can affect the prevalenc e of MA in hypertension, including severity of the disease, selection proce dures, concomitant risk factors, degree of obesity, age, and sex distributi on. This accounts for the large differences in the prevalence of MA that ca n be found in the literature, with prevalence rates going from a low of 4.7 % to a high of 40%. There is still conflict over whether MA in hypertension is due to increased intraglomerular pressure or to glomerular damage. The data from the literature suggest that in subjects with mild hypertension th e main determinant of albumin excretion rate is the haemodynamic load. In s ubjects with more severe hypertension and hypertensive complications, the a ugmented urinary albumin leak is probably the consequence of a systemic mic rovascular disturbance which involves the glomeruli. In this respect, the i nsulin resistance state often associated to high blood pressure appears as one of the main pathogenetic factors. Whether management of hypertensive po pulations may be improved by monitoring of albumin excretion rate and wheth er antihypertensive drugs which are more effective in decreasing urinary al bumin can be more beneficial in patients with MA remains to be determined. J Hypertens 2000, 18:645-654 (C) Lippincott Williams & Wilkins.