How do we diagnose diabetic nephropathy?

In today’s post our previous lesson from last week on the pathophysiology (the what goes wrong) of diabetic nephropathy will be helpful. To review – the process of waste products filtering out of the blood and being excreted via urine occurs in the kidneys. Due to the damage done to the kidneys by high blood glucose levels associated with diabetes, the structures do not filter as well. As the damage accumulates, an important protein called albumin is leaked in the urine.

Diabetic nephropathy is diagnosed by testing albumin levels in the urine. Screening for microalbuminaria should be performed yearly starting 5 years after diagnosis in type 1 diabetes and right away in patients with type 2 diabetes.

There are two stages of diabetic nephropathy, both of which refer to urinary albumin levels:

1.     Microalbuminaria – urinary albumin excretion (UAE) is between 20 micrograms and 199 micrograms per minute

2.     Macroalbuminaria – UAE is greater than 200 micrograms per minute

The first step in diagnosing diabetic nephropathy is to measure albumin in a urine sample that would be collected as the first urine after waking up or at a random time. The results are expressed as urinary albumin concentrations. Any test that returns with abnormal results must confirmed in the following 3-6 months with two out of three tests indicating albumin in the urine.

As the disease progresses, urinary albumin excretion will increase. In addition to testing for albumin, your healthcare provider may run labs looking at creatinine. Creatinine levels are an accurate measure of kidney function.

Gross, J.L., Azevedo, Silveiro, Canani, Caramori, Zelmanovitz. (January 2005). Diabetic Nephropathy: Diagnosis, Prevention, and Treatment. Diabetes Care, 28 (1) doi:10.2337/diacare.28.1.164