Biopsy required for accurate renal diagnosis in diabetes

By Sally Robertson, B.Sc.Aug 17 2012

People with diabetes and symptoms of nephropathy should undergo renal biopsy before a diagnosis of diabetic nephropathy (DN) is assumed, report researchers.

Renal biopsy could be particularly important for diabetes patients with presumed DN in the absence of poor glycemic control or diabetic retinopathy (DR), they say.

"Histological confirmation of renal involvement in patients with diabetes mellitus could prove essential, because DN and primary glomerulopathies require different treatment strategies," explain Yasuhiro Akai (Nara Medical University, Kashihara, Japan) and colleagues.

"However, it is generally agreed that renal biopsy would not be carried out as a routine diagnostic test in a typical clinical situation of DN."

In Akai and team's analysis of 55 patients presumptively diagnosed with DN, percutaneous renal biopsy carried out in all patients showed that just 30 (54.5%) individuals were histologically diagnosed with DN, while 25 (45.5%) were diagnosed with non-DN conditions.

The conditions that non-DN patients were diagnosed with included immunoglobulin A nephropathy, focal segmental glomerulosclerosis, membranous nephropathy, membranoproliferative glomerulonephritis, minimal change nephritic syndrome, and crescentic glomerulonephritis.

Akai and colleagues found that fasting plasma glucose and glycated hemoglobin were significantly associated with incidence of DN, whereas baseline renal function and duration of diabetes were not.

In addition, patients with DN were significantly more likely to have DR than those without DN, at an odds ratio of 11.0.

Furthermore, patients with DN also had more severe tubulo-interstitial and vascular damage than those with other renal diseases.

"Therefore… if the patients had a similar clinical profile, such as the degree of proteinuria and renal function, the patients with DN would have a worse renal prognosis than those with other renal disease," write Akai et al in the Journal of Diabetes Investigation.

The team says the findings show that renal biopsy should be considered in diabetes patients with unusual clinical presentation, even in cases with a long duration of disease.

"Furthermore, the present study showed that poor glycemic control and the existence of DR were significantly predictive markers," they add.

Therefore, renal biopsy should especially be considered in diabetes patients with presumed DN in the absence of either of these predictive factors, concludes the team.

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