Renal Biopsy Detects Nondiabetic Kidney Disease in Diabetic Patients

Renal biopsy can be useful in establishing the correct diagnosis and treatment in patients with diabetes—a population with a high prevalence of nondiabetic renal disease (NDRD), according to a meta-analysis in Nephrology Dialysis Transplantation.

The researchers identified and analyzed data on the frequency of diabetic nephropathy, NDRD, and “mixed” forms of kidney disease among patients with diabetes. The analysis included data on 4876 patients undergoing renal biopsy, reported in 48 studies.

For all three diagnostic categories, prevalence varied widely: from 6.5% to 94% for diabetic nephropathy, 3.0% to 82.9% for NDRD, and 4.0% to 45.5% for mixed kidney disease. IgA nephropathy was the most common NDRD diagnosis in 16 studies, membranous nephropathy in 9, focal segmental glomerulosclerosis in 6, and acute interstitial nephritis in 4.

The positive predictive value of renal biopsy was 50.1% for diabetic nephropathy, 36.9% for NDRD, 19.7% for mixed diagnoses, and 49.2% for the combination of nondiabetic and mixed kidney disease. On metaregression, factors explaining heterogeneity for NDRD were systolic blood pressure, HbA1c, duration of diabetes, and diabetic retinopathy. In contrast, for diabetic nephropathy, serum creatinine was the only explanatory factor. Crude odds ratio for detecting diabetic nephropathy at renal biopsy was 69% higher than that for NDRD, and more than four times higher than that for mixed kidney disease.

There is ongoing controversy over the value of renal biopsy in patients with diabetes; its performance is commonly based on opinion or institutional policy. Rapidly declining kidney function or unusual clinical features in diabetic patients may lead to a “clinical diagnosis” of diabetic nephropathy. However, many such patients may have NDRD or a mixed diagnosis requiring different management.

This review and meta-analysis suggests a “seriously high” prevalence of NDRD on renal biopsy in patients with suspected diabetic nephropathy.

“Clinical judgment alone can lead to wrong diagnoses and delay the establishment of adequate therapies,” the researchers write. They highlight the need for further studies to better identify patients who can benefit from renal biopsy [Fiorentino M, et al. Renal biopsy in patients with diabetes: a pooled meta-analysis of 48 studies. Nephrol Dial Transplant 2017; 32:97–110].