Determination of total urine protein is used to evaluate patients with kidney disease and as a screening test to investigate monoclonal gammopathies.
More information
The general urine test includes the semi-quantitative determination of protein in a random urine sample. A small amount of protein in the urine is considered normal and consists of albumin and low-molecular-weight plasma proteins (β2 microglobulin, globulins, haptoglobin, light chains, and Tamm-Horsfall glycoprotein). Protein in the urine is a key indicator of renal impairment.
Urine albumin quantification is necessary when a random urine sample tests positive for more than 'trace' albumin. Typically, only low molecular weight proteins are small enough to pass through the glomerular membrane to the glomerular filtrate, and most of them are resorbed by the renal tubes. Proteinuria is a significant indicator of renal impairment and may result from glomerular leakage, tubular dysfunction, renal tissue damage, or excessive low molecular weight protein concentrations. Transient proteinuria can result from non-pathological conditions such as physical or emotional stress and body position. The various protein substances are excreted at different rates and at other times over 24 hours. Thus, timed 24-hour urinalysis for albumin provides a more accurate picture of kidney function.
Possible Interpretations of Pathological Values
- Non-renal diseases: Abdominal tumor, aging, severe anemia, ascites, bacterial toxins (acute streptococcal, diphtheria, pneumonia, scarlet fever, typhoid fever), heart disease, central nervous system damage, convulsions, fever, liver disease (jaundice), hypersensitivity reaction, hyperthyroidism, infection (acute), ingestion or overexposure to certain substances (arsenic, carbon tetrachloride, ether, lead, mercury, mustard, opiates, phenol, propylene glycol, sulfosalicylic acid, turpentine), intestinal obstruction, leukemia (chronic lymphocytic), subacute bacterial endocarditis, toxemia, trauma.
- Transient proteinuria: Dehydration, diet (excess protein intake), emotional stress, exposure to cold, strenuous exercise, fever, orthostatic hypotension, metahemorrhagic proteinuria, sodium depletion. Drugs: Epinephrine, levarterenol.
- Pre-renal diseases: Amyloidosis, Bence Jones proteinuria associated with myeloma, congestive heart failure, seizures, exercise, leukemia (myelocytic), orthostatic hypotension, proteinuria, Waldenstrom's macroglobulinemia.
- Renal diseases: Collagen diseases, cryoglobulinemia, Henoch-Schonlein, hypertension (malignant, nephrovascular), thrombotic thrombocytopenic purpura.
- Glomerular diseases: Amyloidosis, diabetic glomerulosclerosis and nephropathy, glomerulonephritis, Goodpasture syndrome, high molecular weight proteinuria, membranous nephropathy, polycystic disease, pyelonephritis (chronic), renal vein thrombosis, systemic lupus erythematosus.
Intermediate diseases. Bacterial pyelonephritis, calcium or uric acid deposition, idiosyncratic pharmacological reactions to the following drugs: methicillin, phenytoin, phenindione, sulfonamides. - Tubular diseases: Acute tubular necrosis, Bartter syndrome, beta-microglobulinemia, Bright disease, Butler-Albright syndrome, Fanconi syndrome, galactosemia, heavy metal poisoning (cadmium, lead, mercury), Kimmelstiel-Wilson syndrome, nephrotic syndrome, renal tubular acidosis.
- Post-renal disease: Cystitis (severe), bone tumor metastases, tumors (bladder, renal pelvis). Drugs that cause proteinuria include amikacin, amphotericin B, aurothioglucose, bacitracin, gentamicin sulfate, gold, netilmicin sulfate, neomycin sulfate, penicillins, phenylbutazone, polymyxin B, streptomycin sulfate, sulfonamides, trimethadione.
Important Note
Laboratory test results are the most critical parameter for diagnosing and monitoring all pathological conditions. Between 70 to 80% of diagnostic decisions are based on laboratory tests. Correctly interpreting laboratory results allows a doctor to distinguish "healthy" from "diseased."
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be analyzed based on each case and family history, clinical findings, and the results of other laboratory tests and information. Your physician should explain the importance of your test results.
At Diagnostiki Athinon, we answer any questions you may have about the test you perform in our laboratory and contact your doctor to ensure you receive the best possible medical care.
