Microalbuminuria: prognostic implications.

Microalbuminuria is the presence of albumin above the normal but below the detectable range with the conventional urine dipstick methodology. Microalbuminuria is present in a variety of renal and non-renal diseases but only recently has its importance as a prognostic indicator been appreciated. It is an independent risk factor for renal mortality in patients with insulin-dependent diabetes mellitus and most probably for those with non-insulin-dependent diabetes mellitus. Moreover, it is associated with a four- to sixfold increase in cardiovascular mortality in diabetic subjects. Its role as a prognostic indicator in non-diabetic subjects is controversial. The available data suggest that it is not an independent risk factor in patients without diabetes, including hypertensive subjects. Moreover, in this latter group it appears to be simply a reflection of events that result in tissue injury from elevated arterial pressures rather than an initiator of injury. The converse may be true in the diabetic patient. A large body of data also exists to support the notion of early aggressive intervention to attenuate the rise of microalbuminuria with blood glucose control. In addition, agents such as angiotensin-converting enzyme inhibitors attenuate both the rise in microalbuminuria and progression of insulin-dependent diabetes mellitus nephropathy. Fewer but similar findings have been reported for subjects with non-insulin-dependent diabetes mellitus nephropathy. Thus, microalbuminuria should be assessed annually in all diabetic subjects. Routine screening for microalbuminuria in hypertensive non-diabetic subjects is not recommended at this time.