A proteinuria is defined by the presence of abnormal amounts of protein about urine. It can be linked to many pathologies, in particular kidney disease.

Normally urine contains less than 50 mg / L of protein. The proteins contained in the urine are mainly albumin (the main protein in the blood), Tamm-Horsfall mucoprotein, a protein synthesized and secreted specifically in the kidney, and small proteins.

Proteinuria can be discovered with a simple urine test with a dipstick. It is also often discovered by chance during a health check-up, pregnancy follow-up or during a urine test in a medical analysis laboratory.

24-hour proteinuria measurement can be requested to refine the diagnosis or to obtain more precise values ​​for total proteinuria and the proteinuria / albuminuria ratio (to better understand the type of protein excreted).

24-hour urine collection involves removing the first urine of the morning in the toilet, then collecting all urine in the same container for 24 hours. Note the date and time of the first urine on the jar and continue collecting until the next day at the same time.

This sample is not complicated but it is long and impractical to perform (it is better to stay all day at home).

Urine should be stored in a cool place, at best in a refrigerator, and brought to the laboratory during the day (2st day, therefore).

The analysis is often combined with an assay for creatininuria 24h (excretion of creatinine in the urine).

Proteinuria is defined by the elimination in the urine of an amount of protein greater than 150 mg per 24 hours.

If the test is positive, the doctor may order other tests, such as a blood test for the levels of sodium, potassium, total protein, creatinine and urea; a cytobacteriological examination of the urine (ECBU); detection of blood in the urine (hematuria); testing for microalbuminuria; blood pressure measurement. 

Note that proteinuria is not necessarily serious. In the majority of cases, it is even benign and is sometimes seen in cases of fever, intense physical exercise, stress, exposure to cold. In these cases, proteinuria goes away quickly and is not a problem. It is often less than 1 g / L, with a predominance of albumin.

During pregnancy, proteinuria is naturally multiplied by 2 or 3: it increases during the first trimester to around 200 mg / 24 h.

In the event of protein excretion greater than 150 mg / 24 hours in the urine, outside of any pregnancy, proteinuria may be considered pathological.

It can occur in the context of kidney disease (chronic renal failure), but also in cases of:

• type I and II diabetes
• cardiovascular illnesses
• hypertension
• preeclampsia (during pregnancy)
• certain hematological diseases (multiple myeloma).