At a glance

Why get tested?

To determine if you have had a heart attack. However, this test is rarely used now; instead doctors usually request troponin.

When to get tested?

If you have chest pain and your CK levels are high.

Sample required?

A blood sample drawn from a vein in the arm.

What is being tested?

CK–MB is one of three separate forms of the enzyme creatine kinase (CK). CK–MB is found mostly in heart muscle. It rises when there is any damage to heart muscle cells.

How is the sample collected for testing?

A blood sample is taken by needle from the arm.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.

The Test

How is it used?

CK–MB levels, along with total CK, may be tested in persons who have chest pain to diagnose whether they have had a heart attack. A high total CK could indicate damage to either the heart or other muscles, but because CK-MB is specific to the heart, a high CK–MB suggests that the damage was due to heart muscle.

When is it requested?

CK-MB is rarely used now; it has been replaced by troponin. However, it may be requested with total CK, in persons with chest pain to determine whether the pain is due to a heart attack. It may also be requested in a person with a high CK to determine whether damage is to the heart or other muscles.

What does the test result mean?

Looking for reference ranges?

If CK-MB is raised, the heart is the muscle which is likely to be damaged. A high CK with a low CK-MB suggests that other muscles were damaged.

Is there anything else I should know?

If your doctor suspects injury to both heart muscle and other muscles in the body, it may be hard to detect heart injury. Then your doctor may need to request other tests (such as troponin).

Persons whose kidneys have failed can have high CK-MB levels without having had a heart attack. Rarely, long-term muscle disease, low thyroid hormone levels, and alcohol abuse can increase CK-MB, producing changes similar to those seen in a heart attack.

Common Questions

What does heart attack mean?

Heart attack means that some of the muscle in your heart has died. A medical term for this is myocardial infarction (MI). Most commonly, a heart attack starts with a kind of heavy pressure or pain in the chest, often extending into the neck or left arm. You may have trouble catching your breath, or you may feel weak and break into a cold sweat.

A heart attack usually occurs because one of the blood vessels (called coronary arteries) that bring blood to your heart muscle is blocked. This happens when a blood clot forms in a blood vessel that is already partially blocked. The partial blockage, which happens gradually over many years, is usually caused by too much fat deposited in the wall of the blood vessel (this is often called hardening of the arteries — the medical term for this is atherosclerosis).

If I have chest pain, does that mean I am having a heart attack? 

Many other problems can cause chest pain, and it is not always possible to tell just from the type of chest pain whether or not you are having a heart attack. Many people have chest pain from straining the muscles in their chest, and chest pain can occur with some lung problems. Chest pain can be a warning sign of hardening of the arteries of the heart, called coronary artery disease (CAD). Chest pain that occurs during exercise, hard work, or at times of stress, lasts for a few minutes and goes away with rest is called angina. If the pain lasts longer than just a few minutes, especially if it occurs when you are resting, seek immediate medical attention.

What are the other heart attack tests? 

Doctors often use more than one test to determine if a person who has chest pain is having a heart attack. Troponin can pick up damage to heart muscles even when there is no other evidence of a heart attack. Myoglobin and creatine kinase (CK) are also used.

What if I am not sure 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 drugs you were prescribed do not ease the pain — seek immediate medical attention.

Last Review Date: March 25, 2013