Myoglobin - urine

Alternative names:

urine myoglobin

How the test is performed:

Child or adult:
Collect a "clean-catch" ("midstream") urine sample. To obtain a clean-catch sample, men or boys should 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.

Infant:
Thoroughly wash the area around the urethra. Open a urine collection bag (a plastic bag with an adhesive paper on one end), and place it on your infant. For males, the entire penis can be placed in the bag and the adhesive attached to the skin. For females, the bag is placed over the labia. Place a diaper over the infant (bag and all). Check your baby frequently and remove the bag after the infant has urinated into it. For active infants, this procedure may take a couple of attempts--lively infants can displace the bag, causing an inability to obtain the specimen. The urine is drained into a container for transport back to the health care provider.

How to prepare for the test:

No special preparation is necessary for this test, but if the collection is being taken from an infant, a couple of extra collection bags may be necessary.

How the test will feel:

The test involves only normal urination, and there is no discomfort.

Why the test is performed:

Myoglobin levels may be obtained when muscle damage, including heart muscle damage, is suspected.

Myoglobin is an oxygen-binding protein found in cardiac and skeletal muscle. The myoglobin molecule contains iron. Exercising muscle uses up available oxygen as it metabolizes available fuel (that is, glucose and fatty acids) for energy. The presence of myoglobin in muscle provides an extra reserve of oxygen so that exercising muscle can maintain a high level of activity for a longer period of time. When skeletal muscle is damaged, the myoglobin is released into the bloodstream. It is filtered out of the bloodstream by the kidneys. Myoglobin can occlude the structures of the kidney. Myoglobin breaks down into potentially toxic compounds that can also cause kidney failure.