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Myoglobin - urine
Definition
Urine myoglobin is a test to detect the presence of myoglobin in a sample of urine.
Myoglobin is a protein in heart and skeletal muscles. When a muscle is exercised, it uses up available oxygen. Myoglobin has oxygen attached to it, which provides extra oxygen for the muscle to keep up a high level of activity for a longer period of time.
When muscle is damaged, the myoglobin in muscle cells is released into the bloodstream. The kidneys help remove myoglobin out of the body. In large amounts, myoglobin can damage the kidneys.
Alternative Names
Urine myoglobin
How the Test is Performed
A clean-catch (midstream) urine sample is needed.
Men or boys should first wipe clean the head of the penis. Women or girls need to wash the area between the lips of the vagina with soapy water and rinse well.
As you start to urinate, allow a small amount to fall into the toilet bowl (this clears the urethra of contaminants). Then, in a clean container, catch about 1 to 2 ounces of urine and remove the container from the urine stream. Give the container to the health care provider or assistant.
In infants, thoroughly wash the area where urine exits the body. Open a urine collection bag (a plastic bag with an adhesive paper on one end), and place it on your infant. For boys, place the entire penis in the bag and attach the adhesive to the skin. For girls, place the bag over the labia. Diaper as usual over the secured bag.
This procedure may take a couple of attempts -- lively infants can move the bag, causing the urine to be absorbed by the diaper. Check the infant frequently and change the bag after the infant has urinated into it. Drain the urine from the bag into the container provided by your health care provider.
Deliver it to the laboratory or your health care provider as soon as possible upon completion.
How the Test Will Feel
The test involves only normal urination, which should cause no discomfort.
Why the Test is Performed
Myoglobin levels may be taken when the health care provider suspects muscle damage, including skeletal and heart muscle damage. It may also be done when someone has acute kidney failure without an obvious cause.
Normal Results
A normal urine sample does not have myoglobin. Sometimes a normal result is reported as negative.
Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
What Abnormal Results Mean
The presence of myoglobin in the urine may indicate:
- Heart attack
- Malignant hyperthermia (very rare)
- Muscular dystrophy
- Rhabdomyolysis
- Skeletal muscle inflammation (myositis)
- Skeletal muscle ischemia (blood deficiency)
- Skeletal muscle trauma
Risks
There are no risks.
References
Amato AA, Brooke MH. Disorders of skeletal muscle. In: Bradley WG, Daroff RB, Fenichel GM, Jankovic J, eds. Neurology in Clinical Practice. 5th ed. Philadelphia, Pa: Butterworth-Heinemann Elsevier;2008:chap 83.
Barohn RJ. Muscle diseases. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 447.
O'Connor FG, Deuster PA. Rhabdomyolysis. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 114.
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
