Why is a daily urine analysis for protein assigned, how to collect material, norm and deviations
The content of the article:
- Why is a daily urine protein test prescribed?
- How to properly collect daily urine
- Factors influencing research results
- Decoding the result: norm and deviations
Daily urine analysis for protein is prescribed for the diagnosis and monitoring of kidney disease, diabetes and infectious diseases, as well as in a number of other cases. The study allows you to distinguish physiological from pathological proteinuria. To obtain reliable results, you must follow the rules for collecting material.
Urine is a biological fluid that is formed by the kidneys and contains metabolic products intended for elimination from the body. It is formed as a result of the passage of blood through the glomerular filter of the kidney, which does not allow large molecules, including proteins, to pass through. Therefore, in a healthy person, there is no protein in the urine, or a small amount of it (traces) is determined. The content of protein in a single urine sample of more than 0.1 g / l or in the daily sample over 0.15 g / l is regarded as proteinuria.
Why is a daily urine protein test prescribed?
A short-term increase in protein in the urine may be due to physiological reasons (intake of large amounts of protein foods, heavy physical exertion, hypothermia or overheating, stress, a sharp change in body position before collecting material).
Analysis of daily urine for protein allows you to distinguish between physiological proteinuria and pathological
Pathological causes of proteinuria are diseases of the kidneys, cardiovascular and endocrine systems, including:
- nephritis;
- glomerulonephritis;
- pyelonephritis;
- diabetic nephropathy;
- arterial hypertension;
- congestive heart failure;
- gestosis;
- amyloidosis of the kidneys;
- hereditary tubulopathy;
- collagenosis.
In the presence of these diseases or suspicion of them, patients are prescribed to pass a daily urine test for protein.
Other indications for research are:
- severe infectious diseases;
- feverish conditions;
- poisoning with nephrotoxic poisons (mercuric chloride, heavy metal salts);
- overdose of nephrotoxic antibiotics (aminoglycosides, streptomycin).
In addition, the indication for the study of daily urine for protein is the detection of an increased concentration of protein in the general analysis of urine.
Since a short-term increase in protein in the urine can be caused by physiological reasons, a differential diagnosis between physiological (short-term) and pathological (permanent) proteinuria is called for the analysis of daily urine for protein. The main goal is to assess the loss of protein by the patient's body in 24 hours.
How to properly collect daily urine
In order for the results of the study to be accurate and reliable, the rules for the preparation and collection of daily urine should be carefully followed:
- the patient adheres to the usual water and food regime;
- urine collection is carried out in a previously prepared clean container with a lid of at least three liters (a special container for collecting daily urine can be purchased at the pharmacy);
- in the morning, the patient should conduct the toilet of the external genital organs and urinate into the toilet, noting the time, which will be the starting point of the time interval;
- during the day, all urine should be collected in a container, which is stored closed in a cool and dark place;
- the first morning urine is not collected for analysis; instead, the first morning urine of the next day is collected;
- on the direction to the laboratory, the patient notes the amount of urine collected per day (daily diuresis);
- the collected urine is thoroughly mixed, poured into a small container of 100-150 ml and delivered to the laboratory.
Factors influencing research results
There are a number of factors that can have a significant impact on the results of a daily urine protein test. Falsely increased results are caused by contamination of urine with feces, as well as taking the following medications:
- bicarbonate of soda;
- sulfonamides;
- penicillin;
- cephalosporins;
- X-ray contrast agents containing iodine.
Therefore, it is so important to thoroughly toilet the external genitals before collecting urine. In addition, it should be repeated after a bowel movement.
Forced diuresis, caused by the intake of diuretics, including those of plant origin, as well as drinking a large amount of liquid, leads to falsely underestimated results.
Taking this into account, it is necessary that patients during the daily urine collection adhere to the usual water regime, and also do not take medications that can affect the study result.
Decoding the result: norm and deviations
On average, a healthy person excretes 50–80 mg of protein in the urine (the upper limit of the norm is 150 mg). With significant physical exertion, protein excretion increases and can reach 250 mg / day. This phenomenon is considered physiological proteinuria, that is, it is not a sign of any disease.
Depending on the amount of protein loss per day, proteinuria is divided into three degrees:
- moderate - less than 1 g;
- medium - from 1 to 3 g;
- pronounced - from 3 g and above.
Protein loss of less than 500 mg per day usually indicates the presence of chronic pyelonephritis and a number of other kidney diseases in which the glomerular apparatus is slightly affected.
An average degree of proteinuria can be a symptom of the following diseases:
- amyloidosis of the kidneys;
- acute and chronic glomerulonephritis;
- toxic nephritis;
- diabetic nephropathy;
- severe heart failure.
Severe proteinuria is characteristic of nephrotic syndrome.
The combination of proteinuria with hematuria speaks of diffuse or focal lesions of the urinary tract, and with leukocyturia - of their infectious lesion.
The loss of protein in the urine can be associated with other reasons, for example, infectious diseases, damage to the central nervous system. During pregnancy, starting in the second half, proteinuria is often caused by the development of OPG-gestosis, or late toxicosis of pregnant women.
If protein is detected in urine, a qualitative determination of its composition is performed by electrophoresis, which increases the diagnostic value of the analysis. Thus, the detection of the Bens-Jones protein is characteristic of multiple myeloma. With increased permeability of the capillary walls of the renal glomeruli, albumin appears in the urine. The appearance of myoglobin indicates muscle damage, and hemoglobin - of intravascular hemolysis of the blood, which can be caused by various reasons (hemolytic crisis, transfusion of incompatible blood, poisoning with hemolytic poisons).
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Elena Minkina Doctor anesthesiologist-resuscitator About the author
Education: graduated from the Tashkent State Medical Institute, specializing in general medicine in 1991. Repeatedly passed refresher courses.
Work experience: anesthesiologist-resuscitator of the city maternity complex, resuscitator of the hemodialysis department.
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