Proteinuria

Excerpt

Proteinuria is a broad term used to describe protein in the urine. It is a general term for the presence of proteins, including albumin, globulin, Bence-Jones protein, and mucoprotein in the urine. Almost half of the protein lost in normal urine is derived from the distal tubule, known as Tamm-Horsfall glycoprotein (THG). Persistent proteinuria is a marker of kidney damage. It also helps with the diagnosis, prognosis, and therapy.

The primary etiology of proteinuria is the disturbance in the kidney filter. In addition to its association with early renal disease, it is also seen in benign conditions. Proteinuria has now also been used along with the estimated glomerular filtration rate (eGFR) in the classification of chronic kidney disease (CKD). Proteinuria can serve as an indicator of early renal disease. It marks an increased risk of renal damage secondary to hypertension and cardiovascular disease. The degree of proteinuria correlates with disease progression.

According to the UK chronic kidney disease guidelines, proteinuria is defined as a urine protein creatinine ratio (UPCR) of more than 45 mg/mmol, but this does not warrant further evaluation in the absence of hematuria unless the UPCR is more than 100 mg/mmol.

According to the NICE guidelines, proteinuria is defined as a UPCR of more than 50 mg/mmol or a urine albumin creatinine ratio (UACR) of more than 30 mg/mmol.