urinprotein

Urinprotein, or protein in urine, describes the presence of measurable protein in the urine. In healthy adults, the amount of protein in urine is very small because the glomerular filtration barrier limits protein passage. Normal daily protein excretion is typically under 150 mg.

Proteinuria can be transient or persistent. Transient proteinuria may occur after intense exercise, fever, dehydration, or acute illness and often resolves without treatment. Persistent proteinuria may indicate kidney disease or other medical conditions. It is commonly categorized by location or mechanism as glomerular (increased permeability of the glomerular filter), tubular (proximal tubule dysfunction leading to loss of low-molecular-weight proteins), or overflow (excessive production of filtered proteins such as monoclonal light chains).

Measurement and interpretation vary by method. Dipstick tests are semi-quantitative and mainly detect albumin, but they can be influenced by urine concentration. More precise assessment uses the albumin-to-creatinine ratio (ACR) in a random urine sample or a 24-hour urine collection to quantify total protein. Typical thresholds are: normal below about 30 mg/g creatinine, microalbuminuria 30–300 mg/g, and overt proteinuria above 300 mg/g. Nephrotic-range proteinuria is generally defined as more than 3.5 g/day.

Clinical significance and management. Persistent proteinuria is a marker of kidney disease and a risk factor for progression to chronic kidney disease. Evaluation includes repeat testing, urine sediment examination for red or white blood cells and casts, and assessment for underlying conditions such as diabetes or hypertension. Treatment focuses on the cause, blood pressure control, and reduction of proteinuria using agents such as ACE inhibitors or ARBs, along with lifestyle and risk-factor modification. Regular monitoring is advised to track changes over time.