Your doctor can use a myoglobin test to detect the amount of the protein myoglobin in your urine. Your doctor might order this test for several reasons. They may order it if they think your muscle tissues have been damaged. It can help them determine your risk of kidney damage from muscle injury. If you experience sudden kidney failure, it can also help them understand why because myoglobin can cause significant damage to your kidneys.
What is myoglobin?
Myoglobin is a type of protein in your body. It’s naturally present in your heart and skeletal muscle. Skeletal muscle is what we traditionally think of as muscle throughout the body. It’s essential for the proper functioning of your musculoskeletal system and body movements.
All of your muscles require oxygen to perform normal body movements, such as sitting, standing, walking, or performing numerous daily activities. Your muscles also require oxygen for more demanding activities, including exercise. Myoglobin is a protein that binds to oxygen recruiting it into your muscle fibers from the blood stream. This helps make oxygen available for your heart and skeletal muscles to carry out their essential functions.
If you’re healthy, myoglobin will remain within your muscle. If your muscle is damaged, it will release myoglobin into your bloodstream. When it’s released into your bloodstream, your kidneys filter it out and excrete it from your body through your urine.
A urine myoglobin test requires a urine sample. The test doesn’t carry any risk. It shouldn’t cause any amount of pain.
You may need to take some steps to prepare beforehand. If you’re a man, your doctor will probably ask you to wipe the head of your penis before providing your urine sample. If you’re a woman, your doctor will probably ask you to wash your genital area with warm, soapy water, making sure to rinse the area thoroughly afterward. You probably won’t need to fast or stop taking medications before providing your sample.
After that, you simply need to catch a small amount of urine in a container provided by your doctor. A midstream sample is often preferable. This means you should urinate a small amount before you start collecting your urine in the container.
After you place the lid on the container, wash your hands thoroughly. Your doctor will send it to a laboratory for testing.
The lab will analyze your sample to determine whether your urine contains myoglobin. If it does contain myoglobin, the lab will determine the concentration.
No significant amount of myoglobin should be present in your urine. If there’s no myoglobin in your urine, it’s considered a normal result. It’s also sometimes known as a negative result.
Possible causes of abnormal results
If a measurable amount of myoglobin is in your urine sample, it’s considered an abnormal result. Abnormal results have a number of possible causes:
For example, myoglobin may appear in your urine if any of the following occur:
- Your skeletal muscles have been damaged, for instance, by accidents or surgery. Drug use, alcohol use, seizures, prolonged vigorous exercise, and low phosphate levels can also damage your skeletal muscles.
- You have muscular dystrophy or another type of disease or disorder that causes muscle damage.
- You’ve had a heart attack. A heart attack damages or destroys your cardiac muscle, which results in the release of myoglobin.
Malignant hyperthermia is an extremely rare condition that can cause muscle contracture or rigidity and myoglobin in the urine. A serious adverse reaction to certain anesthesia medications causes it. Most people who develop this condition have a genetic mutation that makes them susceptible to getting it.
What to expect
If myoglobin is in your urine, your doctor may order additional tests to determine the underlying cause and prescribe an appropriate treatment plan. The treatment for a heart attack will clearly be different than that for extensive trauma to your skeletal muscles.
Your doctor will probably monitor your kidney function closely since myoglobin can damage your kidneys. They’ll use additional tests to do this, such as the test for blood urea nitrogen, the creatinine test, or urinalysis.
Ideally, your doctor will be able to treat your underlying condition and prevent any lasting damage to your kidneys. Ask your doctor for more information about your specific diagnosis, treatment plan, and long-term outlook.