What does selective proteinuria mean?

Selective proteinuria refers to the presence of predominantly low- or medium-molecular-weight proteins in the urine, especially albumin, accompanied by a small amount of low-molecular-weight proteins. High-molecular-weight proteins, such as immunoglobulins and transferrin, are rarely present. This phenomenon indicates early damage to the glomerular filtration membrane and is more commonly seen in diseases such as minimal change nephropathy and light chain deposition disease.

Specifically, if the urine mainly contains low-molecular-weight plasma proteins, it suggests that the selectivity of the glomerular filtration barrier remains relatively intact, and this type of proteinuria is termed selective proteinuria. Conversely, if various high-molecular-weight proteins appear in the urine, it indicates poor selectivity of the glomerular filtration barrier, and this type of proteinuria is referred to as nonselective proteinuria.

By analyzing the types and molecular weight distribution of proteins in the urine, physicians can assess the extent and nature of damage to the glomerular filtration membrane. The classic condition associated with selective proteinuria is nephrotic syndrome, with semi-quantitative test results typically ranging from +++ to ++++.