Myoglobin is a protein found in striated muscles, including the heart muscle, and is responsible for binding oxygen and storing it until needed, such as during physical activity, for example. However, in the presence of any situation that compromises the muscles, myoglobin and other proteins may be released into the circulation.
Thus, the myoglobin test is done to identify the amount of this protein in the blood, being useful in the diagnosis of muscle and heart injuries, whether due to a sports injury or a heart attack, in which the levels of this protein begin to increase in the blood 1 to 3 hours after the infarction, it peaks between 6 and 7 hours and returns to normal after 24 hours.
What is the exam for
The myoglobin test serves mainly to assess the functioning of striated muscles, as the presence of this protein in the circulation is indicative of muscle damage, including cardiac damage. Thus, the measurement of myoglobin in the blood is requested when there is suspicion of a muscle injury caused by:
- Muscular dystrophy;
- Severe blow to muscles;
- Muscle inflammation;
Although it can be used when there is a suspicion of infarction, the test most used today to confirm the diagnosis is the troponin test, which measures the presence of another protein that is only present in the heart and is not influenced by other muscle injuries. Learn more about the troponin test.
In addition, if the presence of myoglobin in the blood is confirmed and it is in very high values, a urine test can still be performed to assess renal health, as very high levels of myoglobin can damage the kidneys, impairing their functioning .
How is the exam taken
The main way to get myoglobin tested is to take a blood sample, however, in many cases, your doctor may also order a urine sample as myoglobin is filtered and eliminated by the kidneys. For any of the exams, it is not necessary to make any type of preparation, such as fasting.
what does the result mean
The normal result of the myoglobin test must be equal to or less than 0.15 mcg/dL, since in normal situations myoglobin is not found in the blood, only in the muscles.
However, when values above 0.15 mcg/dL are verified, it is indicated in the exam that myoglobin is high, being normally indicative of a problem in the heart or other muscles of the body and, therefore, the doctor may order more tests such as electrocardiograms or cardiac markers to arrive at a more specific diagnosis.
Elevated myoglobin levels can also be a sign of other problems not related to the muscles, such as excessive alcohol consumption or kidney problems, and therefore the result should always be evaluated with the doctor based on each person’s history.