Screening for diabetic nephropathy

What it is

Nephropathy is one of the three diabetic microvascular complications, with retinopathy and neuropathy; macro is CVD and stroke. It is one of the two most common causes of chronic kidney disease, the other being hypertensive nephrosclerosis, and it is the leading cause of ESRD in high-income countries.

How it presents

The earliest renal abnormality is glomerular hyperfiltration, and the earliest sign is microalbuminuria (30-300 mg/day). The kidney itself shows GBM thickening, mesangial expansion and glomerular sclerosis, and the association is eosinophilic nodular glomerulosclerosis, the Kimmelstiel Wilson nodules.

Kidney size on ultrasound points to the cause: 1) enlarged kidneys - diabetic nephropathy, whose early stages show hypertrophy from hyperfiltration, and polycystic kidney disease (ADPKD), with massive enlargement due to numerous cysts; 2) normal size - minimal change disease, with no structural damage and normal imaging, and acute tubular necrosis, which often remains normal or mildly enlarged; 3) small kidneys - chronic kidney disease, the final common pathway of many chronic conditions, and chronic glomerulonephritis, which leads to scarring and atrophy. So enlarged kidneys in a diabetic with proteinuria mean early diabetic nephropathy, while in chronic kidney disease they are small.