Introduction

CPK stands for Creatine Phosphokinase. A CPK test determines the CPK level in the body. CPK is an enzyme that brings out the chemical reactions in our body. The heart, brain, and skeletal muscles are the main sites of CPK. CPK has types such as CPK-1, CPK-2, and CPK-3, with type 1 present in the brain, type 2 in the heart, and type 3 in skeletal muscles. However, CPK is not exclusive to these sites and is also present in other body parts.

CPK levels are higher when the sites of the CPK enzyme suffer a loss of oxygen supply. It releases CPK into the bloodstream. In such cases, higher levels of CPK are found in the blood.

Why CPK test

CPK levels are tested in labs to determine elevated levels of this enzyme in our bodies. 

• Heart Attack – The CPK test is run in the case of a heart attack as it helps determine if there is a chance of another heart attack. 
• Muscle Inflammation – CPK is often at high levels during the inflammation of muscles. Any exercise or strenuous physical activity can cause muscle inflammation. In that case, the doctor can prescribe the test again to re-check the levels of CPK after a period of a cool down from activity. It is mainly to determine diseases like muscular atrophy that elevate CPK levels.
• Other causes – CPK is elevated in the blood when an injury occurs. Brain injury, stroke, lung damage, and heart muscle inflammation can cause higher CPK levels.

Procedure and precautions for the CPK test 

A blood sample is required for the CPK test. The blood is drawn from veins and tested. Below are things that should be avoided before the CPK test to get accurate results.

• Drugs and alcohol – Substances like alcohol or drugs are not allowed before 24 hours of testing. 
• Medications – Certain medications that control cholesterol in the body or anti-fungal medicines are not allowed.
• Activity level – Intense exercise or prolonged intervals of inactivity are best avoided.
• Injections – Intramuscular injections, catheterization, or anesthetics should be discontinued before the CPK test.
• Surgery – In the case of surgery, the test is postponed.

Other than the above points, your doctor will inform you about other precautions as required.

Range of CPK test

When we talk about a range of CPK tests, the levels are different for men and women. Men have a higher range than women. It is because of the higher muscle mass in men.

• Men’s Normal Range of CPK is from 39 to 306 units per liter.
• Women’s normal range of CPK is from 26 to 192 units per liter.

Besides gender, the range is different after activity and injury, and there is a cool-off period when the CPK range returns to normal.

The time for the onset of an increase is 4-5 hours after injury, activity, or heart attack. It remains in the elevated zone for the next 12 hours approximately. The concentration of CPK is highest during this 12-hour window. The CPK level comes down after 2- 3 days of onset.

As mentioned, the classification of CPK is done into CPK-1, CPK-2, and CPK-3. These types determine the type of disease or the body part affected.

• An elevation in CPK -1 is a sign of distress for the brain. It indicates stroke, seizure, pulmonary infraction, etc. In some cases, brain tumors can cause elevated levels of CPK-1.
• For CPK type 2, which is related to the heart, the higher levels indicate a heart attack. Other heart conditions include heart injury due to an accident, electrical shock, or myocarditis. 
• Similarly, for type 3, CPK levels can tell about muscle injuries and long periods of inactivity (like bed-ridden cases). Substance abuse like alcohol or recreational drugs can cause an increase in CPK-3.

What if the CPK test range is above normal?

When the CPK test range is above average, lifestyle changes are adopted.

• Consult the Doctor – The Doctor will inform you about the cause and precautions for an increase in CPK. The doctor may prescribe medications if required and also explain lifestyle changes or changes in food habits.
• Get active – If you have a sedentary lifestyle, the Doctor may tell you to follow a proactive routine. On the contrary, if high levels are because of too much physical activity, the Doctor will advise resting.

Conclusion

The CPK test can determine various health issues. If there is a requirement, the doctor may prescribe more tests. In some cases, levels of CPK are affected by the thyroid. A lab test should be under a Doctor’s order. When the results are out, controlling the condition is possible through proper treatment.