Enzyme Markers

What are enzyme markers?

An enzyme marker is a blood test to measure the levels of specific enzymes in your blood. Musculoskeletal diseases, organ damage and injuries can cause enzymes to leak from cells into your blood.

Your healthcare provider may refer to enzyme markers as biomarkers (biological markers). A biomarker is a measurable indicator (medical sign) of a disease.

What are enzymes?

Enzymes are proteins that aid chemical changes in your body and speed up metabolism. Your body has thousands of enzymes that perform unique functions. Enzymes play important roles in the:

• Circulatory system (blood clotting).
• Digestive system (digestion).
• Musculoskeletal system (muscles and movements).
• Nervous system (brain, spine and nerve function).
• Respiratory system (breathing).
• Urinary system (waste removal from your body).

Who needs an enzyme marker test?

Healthcare providers use enzyme marker tests for different purposes:

• Screenings: As part of a routine physical examination, an enzyme marker test can identify potential problems like organ or muscle damage or stress.
• Diagnosis: You may get an enzyme marker test to diagnose a specific disease or heart problem.
• Monitoring: Test results can show if a treatment is working or if medications are damaging organs.

What are the types of enzyme marker tests?

Healthcare providers use different enzyme marker tests to check for diseases and disease progression. Enzyme marker tests include:

• Cardiac enzyme test.
• Creatinine phosphokinase (CPK) isoenzymes or creatine kinase test, including CK-MB, CK-MM, and CK MM.
• Liver enzyme test (ALT, AST, Alkaline phosphatase, GGT, 5’-NT).

What is a cardiac enzyme test?

A cardiac enzyme test checks for signs of heart muscle damage following a heart attack or another heart problem. It can also assess heart function after surgeries like coronary artery bypass grafting (CABG) or angioplasty.

Injury or damage to the heart causes it to release protein called troponin (cTn) and creatinine phosphokinase (CPK). CPK levels rise quickly after a heart attack or injury and were once used to diagnose heart attack. Now, if you’re receiving medical care for a possible heart attack, your healthcare provider will likely use troponin tests to help confirm the diagnosis. Elevated CPK levels may also indicate coronary artery disease. This condition clogs arteries, increasing your risk of a heart attack.

The heart is the only organ that has troponin enzymes. It can take up to 12 hours for troponin levels to increase after a heart attack. Because enzyme levels change after a heart attack, you may get several cardiac enzyme tests spaced several hours apart to measure CPK and troponin levels.

Blood levels of troponin are typically low — around 0.02 nanograms per milliliter (ng/mL). Elevated cardiac enzymes indicate a heart attack. A higher number is a sign of more severe heart damage.

Your healthcare provider may order a cardiac enzyme test if you have symptoms of a heart problem like:

• Chest pain.
• Dizziness.
• Nausea.
• Profuse sweating (hyperhidrosis).
• Shortness of breath (dyspnea).

What is a CPK isoenzymes test?

A CPK isoenzymes test looks for elevated CPK levels that indicate tissue damage. Your muscles (including heart muscle), brain and lungs release CPK isoenzymes when there’s tissue damage from a disease or injury. Isoenzymes are forms of the enzyme that are specific to certain organs or tissues. The form of CK that’s specific to the heart is known as CK-MB. The form of CK that’s specific to skeletal muscle is known as CK-MM. CK when used on its own refers to the total amount of CK from all sources.

Depending on your symptoms, diagnosis or disease risk factors, your healthcare provider may order a CPK isoenzymes test to check for conditions like:

• Heart attack.
• Stroke.
• Brain cancer (brain tumor).
• Muscular dystrophy.
• Dermatomyositis.
• Inclusion body myositis.
• Polymyositis.
• Malignant hyperthermia.

What is a liver enzyme test?

Damage to your liver from diseases or an injury causes it to release different enzymes into your bloodstream. The two most common enzymes are alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Your liver primarily makes ALT. Your liver, heart, kidneys, brain and muscles make AST.