Proteiinuriaan

Proteiinuriaan is commonly referred to as proteinuria, the presence of excess protein in urine. It signals possible kidney disease or other medical conditions, but it can be transient or benign in some situations such as fever, dehydration, or intense exercise. Diagnosis typically relies on quantitative and qualitative urine tests and assessment of accompanying symptoms.

Causes and types: Glomerular proteinuria results from disruption of the glomerular filtration barrier, allowing larger amounts of protein, especially albumin, to pass into urine. Tubular proteinuria stems from tubular dysfunction, reducing reabsorption of low-molecular-weight proteins. Overflow proteinuria occurs with excess production of proteins (for example, light chains in multiple myeloma) or myoglobin after muscle injury. Orthostatic proteinuria, common in adolescents, is a positional form of proteinuria that resolves with recumbency. Nephrotic syndrome features heavy proteinuria (typically >3.5 g/day) along with edema, hypoalbuminemia, and often hyperlipidemia; nephritic syndromes involve hematuria and sometimes reduced kidney function.

Detection and evaluation: Screening begins with a urine dipstick test, which is followed by quantitative measures such as the albumin-to-creatinine ratio or protein-to-creatinine ratio on a spot sample. A 24-hour urine collection may be used for total protein assessment. Urine microscopy, serum creatinine, and electrolyte testing help assess kidney function. When a monoclonal protein is suspected, serum and urine protein electrophoresis and immunofixation are indicated. Further imaging or kidney biopsy may be needed for persistent or unexplained proteinuria.

Management and prognosis: Treatment targets the underlying cause. Blood pressure control with ACE inhibitors or ARBs reduces proteinuria; glycemic control in diabetes; diuretics for edema; lipid-lowering therapy for nephrotic syndrome. Immunosuppressive therapy is used for certain glomerulonephritides. Prognosis depends on the cause and degree of proteinuria; persistent heavy proteinuria increases the risk of progression to chronic kidney disease.