|Elevated urinary albumin excretion does not imply inexorably progressive nephropathy, say investigators.
Researchers with the Joslin Study of the Natural History of Microalbuminuria in Boston, Massachusetts, United States, report that modification of factors that lead to elevated urinary excretion can reduce those levels back to normal.
Lead investigator Dr. Bruce A. Perkins of the Joslin Diabetes Center and colleagues studied 386 patients with type 1 diabetes and persistent microalbuminuria with urinary albumin excretion rates ranging from 30 micrograms/min to 299 micrograms/min over a 6-year period. Excretion rates were grouped into 2-year intervals during follow-up.
Regression of microalbuminuria occurred frequently during the study period, with a 6-year cumulative incidence of 58%. Only 19% went on to develop overt proteinuria.
Regression of microalbuminuria was associated with glycosylated haemoglobin levels below 8%, systolic blood pressure below 115 mmHg, cholesterol levels below 198 mg/dL and triglyceride levels below 145 mg/dL.
Dr. Perkins notes that "our study results indicate that microalbuminuria is more likely to subside to normal levels than to progress to overt proteinuria" with modification of risk factors.
He adds that "although our findings support a new model of early diabetic nephropathy, the contributing variables are not known with precision. Clinical trials that assess the optimal target level of albumin excretion - in terms of the regression of microalbuminuria - as well as the optimal levels of other factors are warranted."