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Protein in the urine
Last reviewed: 19.11.2021
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A protein in the urine, or proteinuria, is a pathological condition when the urine contains protein molecules that are normally absent in the urine or are found in extremely small amounts. Proteins are the building material for the entire human body, including muscle and bone tissue, all internal organs, hair and nails. Also, the protein takes part in a very large number of processes occurring in the human body at the cellular and molecular levels. The main function of the protein is to support the oncotic pressure, thus providing a homeostasis in the body.
The main protein that is most often found in urine is albumin. In the event of damage to the glomerulus of the kidneys, the protein begins to pass through the glomerular filter. Albuminuria - the presence of albumin in the urine. The main function of albumin in the blood is the support of oncotic pressure with the help of water retention in tissues and intercellular water.
In healthy people, the daily amount of urine contains 50-100 mg of protein.
Proteinuria - excretion of protein in the urine, exceeding 300 mg / day, is one of the most reliable signs of kidney damage .
The causes of the appearance of protein in the urine can be physiological and pathological. The glomerular proteinuria resulting from impaired permeability of the glomerulus membrane is observed most often, it is one of the most reliable signs of a lesion of the kidney parenchyma. The degree of activity of kidney damage is estimated by the expression of proteinuria.
Microalbuminuria - excretion of albumin with urine from 30 to 300 mg / day is the most sensitive marker of kidney development in essential hypertension and diabetes, when its presence reliably indicates the development of diabetic nephropathy.
Clinical evaluation of microalbuminuria in patients with diabetes mellitus
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Survey plan |
Required Activities |
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Regular Screening Elimination of the causes of transient microalbuminuria Confirmation of the persistent nature of microalbuminuria |
In patients with diabetes mellitus type 1, a duration of more than 5 years, the study is conducted every year In patients with diabetes mellitus type 2, the study is conducted when establishing a diagnosis, in the future - every year Abdominal obesity (at least once a year) Exclusion of hyperglycemia, urinary tract infections, physical exertion, essential hypertension, chronic heart failure III-IV FK (NYHA) * If microalbuminuria is detected, repeat the study for 3-6 months to confirm its persistent nature |
* NYHA (New York Heart Association) - functional classes according to the classification of the New York Heart Association.
Microalbuminuria is considered as one of the reliable signs of generalized endothelial dysfunction, which causes an unfavorable prognosis in patients with cardiovascular diseases. In this regard, the study on microalbuminuria is advisable to perform in risk groups, including the following conditions:
- essential arterial hypertension;
- diabetes mellitus type 1 and type 2;
- obesity;
- metabolic syndrome;
- chronic heart failure;
- acute coronary syndrome / acute myocardial infarction.
Beta 2- microglobulinuria (normally up to 0.4 μg / l) is observed with tubulointerstitial nephritis, pyelonephritis and congenital tubulopathies.
Myoglobinuria indicates an increase in the catabolism of tissue components, including muscle. It is observed in the syndrome of prolonged crushing (sgauy-syndrome), dermatomyositis-polyomyositis of severe course. People who abuse alcohol are also observed hemoglobinuria (in particular, with acetic acid instead of alcoholic beverages) and myoglobinuria (with traumatic and non-traumatic forms of rhabdomyolysis). Myoglobinuria and hemoglobinuria are precursors of acute hemoglobinuria and myoglobinuric nephrosis; As a result of obstruction of the tubules by these proteins, acute renal failure develops, as a rule, difficult to remove.
Increase in the excretion of light chains of immunoglobulins, as a rule, pathologically altered (paraproteins), is a reliable sign of plasma-cell dyscrasias (multiple myeloma, Waldenstrom's macroglobulinemia, lung disease). With multiple myeloma, a Bens-Jones protein is found that has a thermolability: when heated to 56 ° C this substance precipitates, to 100 ° C it dissolves again. Upon cooling to room temperature, the Bens-Jones protein again precipitates. With plasma cell dyscrasia, overflow proteinuria often appears as the first symptom of the disease, until the characteristic bone changes are detected and the corresponding pattern of peripheral blood smear is developed. In some cases, proteinuria in this group of hemoblastoses outstrips changes in cytological preparations of the sternal punctate and scallop of the ilium.
Orthostatic proteinuria is observed at the age of 13-20 years, more often in young men, while there are no other signs of kidney damage.
Proteinuria of tension in healthy individuals, including athletes, occurs after severe (especially dynamic) physical activity. Protein in urine is detected only in the first collected portion of urine.
Feverish proteinuria develops with fevers with a body temperature of 39-41 ° C, mainly in children and senile individuals. Diagnosis of febrile proteinuria involves dynamic observation of the patient's kidneys.
High values of excretion of proteins with urine, especially those resistant to treatment, tend to have unfavorable prognostic value ("Proteinuria and nephrotic syndrome").
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