IS MICROALBUMINURIA A MARKER OF EARLY INTRARENAL VASCULAR DYSFUNCTIONIN ESSENTIAL-HYPERTENSION

The relation between basal intrarenal hemodynamics and the renal respo nse to acute inhibition of angiotensin-converting enzyme by captopril and albuminuria was assessed in 106 lean patients with essential hyper tension without detectable proteinuria. It was observed that the micro albuminuric group (24.5% of the total population) was characterized by a higher systemic arterial pressure, a lower level of high-density li poprotein cholesterol, and similar mean values of age, duration of hyp ertension, glomerular filtration rate, renal plasma flow, filtration f raction, and plasma renin activity when compared with normoalbuminuric subjects. In response to captopril, a significant renal vasodilatatio n without a change in glomerular filtration rate or a fall in filtrati on fraction was observed in normoalbuminuric patients only. In contras t, the renal vasodilator response was abolished in microalbuminuric su bjects, together with blunting of the rise in plasma renin activity as sociated with captopril. This occurred despite similar indexes of acti vity of the endogenous renin-angiotensin system. It is suggested that microalbuminuria may be a marker of early functional or fixed intraren al vascular dysfunction in never-treated lean patients with essential hypertension.