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Cardiac Enzyme Studies

How It Feels

The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.

Risks

There is very little chance of a problem from having a blood sample taken from a vein.

  • You may get a small bruise at the site. You can lower the chance of bruising by keeping pressure on the site for several minutes.
  • In rare cases, the vein may become swollen after the blood sample is taken. This problem is called phlebitis. A warm compress can be used several times a day to treat this.
  • Ongoing bleeding can be a problem for people with bleeding disorders. Aspirin, warfarin (Coumadin) and other blood-thinning medicines can make bleeding more likely. If you have bleeding or clotting problems, or if you take blood-thinning medicine, tell your doctor before your blood sample is taken.

Results

Cardiac enzyme studies measure the levels of the enzymes creatine phosphokinase (CPK) and creatine kinase (CK), and the proteins troponin I (TnI) and troponin T (TnT) in the blood.

Values and units for reporting the results of cardiac enzyme tests vary considerably. The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.

Troponin normal values:1

Total CPK (creatine phosphokinase) normal values:1

  • 0–120 micrograms per liter (mcg/L)

CK-MB (creatine kinase) normal values:1

  • 0–3 micrograms per liter (mcg/L)

What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

What To Think About

  • CPK-MB, which is found in large amounts in damaged heart muscle is a more specific way to estimate the amount of heart muscle damage than total CPK. The total CPK enzyme level can be elevated from vigorous exercise, intramuscular injections, crush injuries to muscles, muscular dystrophy, or muscle inflammation.
  • Another protein, myoglobin, may be tested along with cardiac enzymes to diagnose a heart attack.

WebMD Medical Reference from Healthwise

Last Updated: August 05, 2011
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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