Serum myoglobin

Alternative names 
Myoglobin - serum

Definition

This is a test that measures the amount of myoglobin in the blood.

Myoglobin is a protein in heart and skeletal muscles. When a muscle is exercised, it uses up available oxygen. Myoglobin has oxygen bound to it, thus providing an extra reserve of oxygen so that the muscle can maintain a high level of activity for a longer period of time.

When muscle is damaged, myoglobin is released into the bloodstream. Ultimately, it is excreted in the urine (see Urine myoglobin).

How the test is performed

Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band or blood pressure cuff is placed around the upper arm to cause veins to distend (fill with blood).

A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

For infants or young children:
The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.

How to prepare for the test
There is no special preparation.

For infants or young children:
The preparation a parent can provide for this or any test or procedure depends on the child’s age, interests, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child’s age:

How the test will feel
When the needle is inserted to draw blood, some people may feel moderate pain, while others may feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed
Myoglobin levels may be obtained to confirm suspected muscle damage, including heart and skeletal muscle damage.

Normal Values

The normal range is 0 to 85 ng/ml (sometimes a normal result is reported as “negative”).

Note: ng/ml = nanograms per milliliter

What abnormal results mean

Greater-than-normal levels (a “positive” result) may indicate:

     
  • skeletal muscle ischemia (blood deficiency)  
  • skeletal muscle trauma  
  • skeletal muscle inflammation (myositis)  
  • Heart attack  
  • Muscular Dystrophy  
  • rhabdomyolysis  
  • malignant hyperthermia (very rare)

What the risks are

     
  • excessive bleeding  
  • fainting or feeling light-headed  
  • hematoma (blood accumulating under the skin)  
  • infection (a slight risk any time the skin is broken)  
  • multiple punctures to locate veins

Special considerations

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Johns Hopkins patient information

Last revised: December 8, 2012
by Brenda A. Kuper, M.D.

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