The measurement of myoglobin in the urine is used to confirm muscle damage caused by any cause.
Myoglobin is a protein similar to hemoglobin, it contains a heme molecule, binds oxygen and is found exclusively in the straight and smooth muscle fibers as well as the heart muscle. It acts as a short-term oxygen storage. It is released into the intercellular fluid, with elevated serum levels being detected 30-60 minutes after myocardial infarction or damage to any muscle tissue. Serum myoglobin is generally detected earlier than classical cardiac enzymes (total creatine kinase [CPK] or cardiac creatinine kinase isoenzyme [CK-MB]). As myoglobin is present in both skeletal and cardiac muscle, it is not used alone to diagnose myocardial infarction. Tests used in combination with myoglobin for this purpose include troponin and CK-MB. Measurement of serum myoglobin is not completely specific for the diagnosis of myocardial infarction.
Elevated levels of myoglobin are also observed following angina, chest trauma, cocaine use, electric shock accidents, post-exercise, intramuscular injection, muscle injury of any type and renal failure. Within 8 hours of the onset of symptoms, the specificity is 98% myoglobin for acute myocardial infarction, in contrast to CK-MB which has 100% specificity.
Pathologies associated with myoglobinuria include:
- Hereditary myoglobinuria
- Sporadic myoglobinuria
- Phosphorylase deficiency
- Myoglobinuria of progressive muscle disease
- Myocardial infarction
- Catastrophic syndrome
Possible Interpretations of Pathological Values
- Increase: Acute alcohol intoxication with scrapie, after cardiac arrest (probable increase), after open heart surgery, angina (probable increase), burns (severe), congestive heart failure (probable increase), dermatitis, glycogen and lipid storage diseases, hyperthermia, hypothermia, muscular dystrophy, myocardial infarction (elevated levels are detected 2-3 hours after infarction, peak at 6-9 hours and return to baseline within 36 hours), polymy deficiency, rhabdomyolysis, shock, skeletal muscle injury or extreme muscle training, surgery, systemic lupus erythematosus (SLE), trauma, viral or bacterial infection. Medications: ethyl alcohol (ethanol), statins, theophylline.
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. Correct interpretation of 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 interpreted in relation to each individual case and family history, clinical findings and the results of other laboratory tests and information. Your personal 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 we contact your doctor to get the best possible medical care.