What Is a Myoglobin Urine Measurement?
A myoglobin urine measurement is a test used to detect the amount of the protein myoglobin in the urine. There are several reasons why this test might be ordered. It is generally done when a doctor suspects that muscle tissues have been damaged. It is useful to determine if there is a risk for kidney damage as a result of muscle injury. It is also helpful to explain a sudden kidney failure since myoglobin can cause significant damage to these vital organs.
What Is Myoglobin and Why Might It Be Present in Urine?
Myoglobin is a type of protein found in the body. It is found naturally in heart muscle as well as skeletal muscles. Skeletal muscles are found throughout the body and are essential to proper functioning of the musculoskeletal system and our body movements.
All of our muscles require oxygen to perform. This includes normal body movements such as sitting, standing, walking or performing numerous daily activities. Muscle oxygen is also required for exertional activity and exercise Myoglobin is the protein that binds to oxygen, “trapping” it within the muscles, and, therefore, making it available for heart and skeletal muscles to carry out their essential functions.
Myoglobin in Urine
In a healthy individual, myoglobin will remain within the muscle. If muscle is damaged, myoglobin will be released into the bloodstream. When the protein is released, it is filtered out of the blood by the kidneys and excreted from the body through the urine.
How a Myoglobin Urine Measurement Is Performed
A urine myoglobin test requires a urine sample. According to the National Institutes of Health, the test does not carry any risk, and it should not cause any amount of pain (NIH).
Some simple preparation will be needed prior to collecting the urine sample for testing. The test does not usually require fasting or discontinuation of medications in preparation for the test. Prior to giving the urine sample, males will be asked to wipe the head of the penis. Women will be asked to wash the genital area with warm, soapy water, making sure to rinse the area thoroughly afterward.
After that, it is simply a matter of catching a small amount of urine in the container provided. The only thing to keep in mind is that a “mid-stream” sample is preferred which means a small amount of urine is voided before you start collecting the sample in the container.
After you place the lid on the container, wash your hands thoroughly, and give the sample to the professional overseeing your test.
After our sample is received in the laboratory, it will be analyzed to determine whether your urine contains myoglobin and, if so, in what concentration.
According to the American Association for Clinical Chemistry, no significant amount of myoglobin should be present in the urine (AACC). This is considered a normal result, sometimes also known as a negative result, because there is no myoglobin in the urine.
A myoglobin urine measurement is abnormal if a measurable amount of myoglobin is detected in the sample. There can be a number of reasons for this.
Some causes of myoglobin in the urine include:
- The skeletal muscles have been damaged. Some common causes of skeletal muscle damage are accidents and surgery. Severe muscle damage is called rhabdomyolysis. Injury and trauma are two causes of muscle fiber destruction. According to the National Institutes of Health, there are several other possible causes, including drug and alcohol use, seizures, prolonged vigorous exercise, and low phosphate levels (NIH).
- The person is having a heart attack. A heart attack damages or destroys cardiac muscle, and this results in the release of myoglobin.
- The person may have muscular dystrophy or another type of disease or disorder that causes muscle damage.
- The person may have malignant hyperthermia. This is a genetic disease that is extremely rare. It is not a typical cause of myoglobin in urine.
What Will Happen After the Test?
If there is myoglobin in the urine, treatment of the underlying cause will take place. For that reason, there is no single treatment. The treatment for a heart attack will clearly be different than that for extensive trauma to the skeletal muscles.
According to the American Association for Clinical Chemistry, however, kidney function is usually closely monitored when myoglobin is found in the urine. This is done through the use of additional tests such as blood urea nitrogen (BUN), urinalysis, and creatinine (AACC).
The ideal result is that doctors will be able to treat the underlying condition and prevent any lasting damage to the kidneys.