DIAGNOSING VASCULAR CAUSES OF RENAL-FAILURE

The incidence of renal failure due to vascular diseases is increasing. Two reasons for this are the epidemic of atherosclerotic vascular dis ease in the aging population and the widespread use of vasoactive drug s that can adversely affect renal function. These vascular causes of r enal failure include vasomotor disorders such as that associated with nonsteroidal anti-inflammatory drugs, small-vessel diseases such as ch olesterol crystal embolization, and large-vessel diseases such as rena l artery stenosis. These causes of azotemia are less familiar to physi cians than more classic causes, such as acute tubular necrosis, and ar e less likely to be recognized in their early stages. This article des cribes the various vascular diseases that impair renal function and ou tlines the steps necessary to identify them. Although some of these co nditions, such as renal artery stenosis, can gradually impair function , the vascular causes of acute renal failure are emphasized in this ar ticle. Because the vasculitides primarily cause renal failure through secondary glomerulonephritis, they are mentioned only briefly. Extensi ve testing is rarely necessary because the cause is usually suspected through syndrome recognition. The diagnosis can then be confirmed by t he results of one or two additional tests or by improved renal functio n after treatment.