Diabetic and proteinuric nephropathy

What it is

Diabetic nephropathy is one of the causes of nephrotic syndrome that act through secondary podocyte damage, along with amyloid light-chain (AL) amyloidosis, light chain deposition disease and lupus nephritis. It is the leading cause of ESRD in high-income countries. Protein in the urine is what it shows first, but protein in the urine is not by itself disease: benign causes are the most common etiology in children, so a positive result has to be confirmed before more tests are done.

On the table that divides glomerular disease it sits on the nephrotic side, the side of proteinuria and oedema, with minimal change disease, membranous GN, focal segmental glomerulosclerosis and amyloidosis. The nephritic side, that of haematuria and hypertension, holds rapidly progressive GN, IgA nephropathy and Alport syndrome. Between the two sit diffuse proliferative GN, membranoproliferative GN and post-streptococcal GN, which belong to both.

Causes and risk

Diabetes mellitus with hypertension is the setting in which nephropathy is looked for, and microalbuminuria marks an early stage of it. Not every protein result means kidney disease: functional (exercise/stress-induced) and orthostatic proteinuria are common types of proteinuria and are transient.