Microalbuminuria Predicts Renal Disease in Hypertension

The level of a protein found in urine samples, when compared to the amount of creatinine excreted, is a powerful predictor of long-term development of chronic renal insufficiency (CRI).

Increased urinary albumin is a risk factor for cardiovascular events and clinical nephropathy in patients with diabetes. The urinary albumin to creatinine ratio (ACR) is used to assess the increased probability of clinical nephropathy.

In a study, conducted by Italian scientists, 917 patients who did not have diabetes but had hypertension were enrolled in the investigation and followed-up for 11.7 years. Their urine was assayed for albumin (microalbuminuria) and creatinine and the ratio calculated. Microalbuminuria occurs when the kidney leaks small amounts of albumin into the urine, in other words, when there is an abnormally high permeability for albumin in the renal glomerulus. Microalbuminuria was defined as ACR ≥ 22 mg/g in men and ACR as ≥ 31 mg/g in women.

The follow-up revealed that baseline microalbuminuria was associated with an increased risk for developing CRI; cardiovascular events, both fatal and nonfatal cardiac and cerebrovascular events; and cardiorenal events. Microalbuminuria remained significantly related to CRI and cardiorenal events even after adjustment for several baseline covariates.

The senior author on the study, Roberto Pontremoli, M.D., Ph.D., from the University of Genoa (Genoa, Italy) said. "Our findings emphasize the usefulness of a more widespread evaluation of microalbuminuria in an effort to guide the management of hypertension.” Microalbuminuria is an independent predictor of renal and cardiovascular complications in patients without diabetes and with primary hypertension.

The scientists conclude that patients with microalbuminuria should be aggressively targeted for renal and cardiovascular risk factor reduction, although further investigation is warranted to determine whether specific treatment would help to improve outcomes, as already reported for patients with diabetes. The study was reported online in April 2010 in the Clinical Journal of the American Society of Nephrology (CJASN).

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