Also known as:
Name:
Related tests: Cardiac markers, CK, CK-MB, Troponin
Why measure it?
To find out whether muscle, particularly heart muscle, has been damaged.
When to measure it?
Every 2-3 hours for the first few hours after chest pain that is suspected to be a heart attack; rarely requested on its own at this stage as a cardiac marker, but requested together with troponin to better rule out a heart attack
Sample required?
A blood sample taken from a vein in the arm
What is being measured?
The blood is tested for myoglobin, a small protein found in the heart and other muscles. While haemoglobin carries oxygen around most of the body, myoglobin traps oxygen in muscle so that muscle cells can work properly. When the heart or other skeletal muscle is damaged, myoglobin is released into the blood. It is one of the first cardiac markers to rise in the blood.
How is the sample collected?
A blood sample is obtained by inserting a needle into a vein in the arm.
How is it used?
When is it requested?
Is there anything else I should know?
How is it used?
As a cardiac marker, myoglobin is used together with troponin and other tests to help rule out a heart attack. Myoglobin levels start to rise within 2-3 hours of a heart attack or other muscle damage, reach high levels at 8-12 hours and generally return to normal a day after the damage occurred. The myoglobin test is therefore used to help rule out a heart attack in the emergency department.
When is it requested?
Because of the high level of confidence in the troponin test, many doctors do not request myoglobin. When it is requested, it is requested together with troponin to assess people with chest pain who are suspected of having a heart attack. Myoglobin levels are often requested every 2-3 hours for the first few hours after a patient with chest pain arrives in the emergency department.
When myoglobin rises, there has been recent damage to the heart or other muscle tissue. If myoglobin has not risen after 5 hours, a heart attack is very unlikely unless the chest pain began more than a day earlier.
Since myoglobin is also found in other muscles, high levels usually require other tests (such as CK-MB or troponin) to tell whether the damage was to the heart or to other skeletal muscle. High levels can occur with accidents, strokes, surgery or other muscle diseases, such as muscular dystrophy.
Is there anything else I should know?
Raised myoglobin levels can occur after an intramuscular injection or physical exertion. Since the kidneys remove myoglobin from the blood, myoglobin levels may be high in people whose kidneys are damaged. Rarely, heavy alcohol abuse and some medicines can cause muscle damage and raise myoglobin.
1. What is a heart attack?
2. If I have chest pain, does it mean I am having a heart attack?
3. What other tests are there for a heart attack?
4. What if I am not sure whether I am having a heart attack?
5. Is myoglobin useful for assessing a stroke?
1. What is a heart attack?
A heart attack means that part of the muscle in your heart has died. The medical term for this is myocardial infarction. Most commonly, a heart attack starts with a feeling of heavy pressure or pain in the chest, often spreading to the neck and left arm. You may have difficulty breathing, feel weak or break out in a cold sweat.
A heart attack usually happens because a blood vessel (called a coronary artery) that carries blood to the heart muscle is blocked. This usually happens when a blood clot forms in a vessel that is already partly blocked. The partial blockage, which develops gradually over time, is usually caused by too much fat deposited in the vessel wall (this is often called hardening of the arteries; the medical term for it is arteriosclerosis).
2. If I have chest pain, does it mean I am having a heart attack?
Many other problems can cause chest pain, and it is not always possible to tell from the type of chest pain alone whether or not you are having a heart attack. Many people have chest pain from straining the chest muscles, and chest pain can occur with some lung problems. Chest pain can be a sign of hardening of the arteries of the heart (coronary artery disease, or CAD).
Chest pain that occurs during exercise, heavy work or stress, lasts a few minutes and goes away with rest is called angina. If the pain lasts longer than a few minutes, especially if it happens while you are resting, seek medical help immediately.
3. What other tests are there for a heart attack?
Doctors often use more than one test to determine whether a person with chest pain is having a heart attack. Troponin can detect damage to heart muscle even when there is no other evidence of a heart attack. Myoglobin and creatine kinase, two other proteins found in the heart and other muscles, do not usually rise in people with heart damage unless they have a heart attack. Some doctors use the term “mild heart attack” if troponin is high but one or both of the other muscle proteins are not.
4. What if I am not sure whether I am having a heart attack?
If you have prolonged chest pain, especially if it does not go away with rest, or if you have been told you have angina and the medicines prescribed for you do not relieve the pain, seek medical help immediately. Many people who have had a heart attack die without ever trying to call an ambulance or go to A&E.
5. Is myoglobin also useful for assessing a stroke?
A stroke, sometimes called a “brain attack”, occurs when part of the brain dies. Like a heart attack, it is usually due to a blockage of a vessel that carries blood to the brain. Myoglobin is found only in muscle cells, not in the brain, so it is not useful for assessing a person who may have had a stroke.