Protein (urine) Laboratory research

General Information

Within the norm, urine contains a negligible amount of protein. These are plasma proteins and other proteins that have been filtered by the glomeruli and not reabsorbed through the proximal tubules.

Increasing the amount of protein in the urine is an important indicator of kidney diseases, which often develops before the clinical manifestation of the disease. The reason for the increase in protein in the urine can be diseases of other organs. There is also a physiological protein (for example, in the background of intense physical activity).

When is the survey conducted?

• Diagnosis and monitoring of kidney diseases
• Screening for monoclonal gammopathy

Preparation of the patient: Intense physical activity is not recommended before the study

Material for examination: urine

Reference limits: < 150 mg/l

Interpretation of results

An increase in the concentration of protein in the urine may be caused by various reasons:

The transition is proteinaceous

• It can be detected accidentally during research in asymptomatic patients
• Not associated with progressive kidney disease
• Functional proteinuria occurs in 10% of hospitalized cases and is associated with such conditions as: fever, congestive heart failure, arterial hypertension, stress, body cold, excessive physical exertion, palpitations.

It is a constant protein

The causes of persistent proteinuria are:

glomerular proteinuria – by releasing proteins with high molecular weight, such as: albumin, transferrin, alpha-1-antitrypsin

idiopathic

• Membranoproliferative glomerulonephritis
• Membranous glomerulonephritis
• Focal and segmental glomerulosclerosis
• amyloidosis

secondary

• Infections (streptococcal, hepatitis B, bacterial endocarditis, malaria, infectious mononucleosis, pyelonephritis)
• Vascular diseases (thrombosis of the inferior vena cava or renal vein, sclerosis of the renal artery
• Focal and segmental glomerulosclerosis

• Autoimmune diseases (systemic lupus erythematosus, rheumatoid arthritis, dermatomyositis, polyarteritis nodosa, Goodpascher's syndrome, Henoch-Schönlein purpura, ulcerative colitis)
• malignant processes
• Medicines: anti-inflammatory non-steroids, gold salts, penicillamine, captopril, heroin
• Hereditary and metabolic disorders: polycystic kidney disease, diabetes mellitus, Fabry disease, Alport syndrome

Tubular protrinuria – With the excretion of low molecular weight proteins in the urine: alpha and beta microglobulins, free light chains, retinol transport proteins, lysozyme.

Acquired pathologies

• Interstitial nephritis
• Acute tubular nephritis
• Renal tubular acidosis
• Acute or chronic pyelonephritis
• Renal transplant removal
• Sarcoidosis
• Medications (phenacetin, aminoglycosides, cephalosporins, cyclosporins, high doses of analgesics, lithium preparations, methicillin)
• Heavy metals (lead, mercury, cadmium)

Congenital pathologies

• Fancon syndrome
• Oculo-cerebro-renal syndrome

genetic diseases

• Wilson's disease
• Sickle cell anemia
• Medullary-cystic kidney
• Oxalase
• cystinosis

Proteinuria with an increase in the amount of protein in the plasma

• Multiple myeloma
• Waldenstrom's disease
• Malignant lymphoma
• It is myoglobin
• Hemoglobinuria
• Monocytic or myelomonocytic leukemias

Common causes of moderate proteinuria (< 1g/day)

• Kimestil-Wilson syndrome
• Moderate idiopathic proteinuria
• Renal sclerosis
• Police kidney
• Medullary-cystic kidney
• Chronic obstruction of the urinary system
• chronic Interstitial nephritis

Interpretation of results

The level of protein in urine is not constant, therefore, in case of kidney diseases, the concentration of protein in different samples of the patient's urine is often different.

The protein index in the urine is influenced by the change in blood flow in the glomeruli of the kidney and, accordingly, the filtration, which is often caused by structural pathologies of the glomeruli or cardiovascular failure.

Proteinuria - an increase in the concentration of protein in the urine is not always related to kidney pathology. "Functional proteinuria" characterizes: acute infections, sepsis, injuries, leukemia, hematological diseases, pre-eclampsia, hyperthyroidism, diseases of the central nervous system, intoxications.

In a number of diseases of the urinary system, an increase in the concentration of protein in the urine may not even be observed: pyelonephritis, obstructive diseases of the urinary system, nephrolithiasis, tumors, congenital malformations of the kidney, and stenosis of the arteries.

When the urine sample is mixed with menstrual blood or prostate secretion, it is possible to detect a false increase in protein.