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Creatine-Kinase

Cardiac profile Biomarker

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Collection Type: Blood

Body System

Related System: Cardiac profile

Overview

Creatine kinase (CK) is an enzyme mainly found in heart, skeletal muscle and brain that helps regenerate cellular energy by converting creatine and ATP. The CK test measures total CK activity in blood; higher levels indicate damage to muscle cells releasing CK into circulation. It is used in cardiac profiles (historically with CK-MB isoenzyme) to help detect myocardial injury, but troponin is now preferred for heart attack diagnosis. Elevated CK can signal heart attack, myocarditis, rhabdomyolysis, muscular dystrophy or other muscle injury. Symptoms prompting testing include chest pain, shortness of breath, muscle pain or weakness, dark urine or recent trauma/excessive exercise. CK levels vary by age, sex (higher in men), race, muscle mass and recent exercise.

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Test Preparation

No special preparation is required

Why Do I Need This Test

Profile: Cardiac profile (often measured with cardiac isoenzymes when evaluating chest pain) - Symptoms: chest pain, palpitations, unexplained muscle pain/weakness, dark urine, recent trauma or seizures - Conditions: myocardial infarction (historically), myocarditis, rhabdomyolysis, myositis, muscular dystrophy - Causes of abnormal levels: muscle cell injury, strenuous exercise, trauma, intramuscular injections, seizures, medications (e.g., statins), hypothyroidism - Biological meaning: elevated CK = muscle membrane disruption and enzyme release - Lifestyle/family: recent intense exercise, alcohol or drug use; family history of inherited muscle disease increases need for testing

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Understanding Test Results

Values up to the stated upper limits are considered normal for adults.
Mild elevations (≈1–3× upper limit; e.g., up to ~350–500 U/L) commonly reflect recent exercise, minor muscle injury, intramuscular injection or chronic muscle disease.
Moderate elevations (≈5× upper limit; e.g., ~500–1,000 U/L) suggest more significant muscle injury or inflammatory myopathy.
Marked elevations (>1,000 U/L and especially >5,000 U/L) indicate severe muscle breakdown/rhabdomyolysis and carry a high risk of complications such as acute kidney injury urgent treatment is needed.
In suspected myocardial infarction, CK-MB fraction (or preferentially troponin) and timing matter: CK rises ~4–6 hours after injury, peaks near 24 hours and falls over 48–72 hours.
Low values generally have no clinical concern but may occur with low muscle mass or advanced age.
Always interpret CK with clinical context and consider repeat testing or isoenzyme/troponin measurement.

Normal Range

Male: 38-174 U/L OR Female: 26-140 U/L

FAQs

Q: What does it mean when creatine kinase is high?

A: High creatine kinase (CK) means muscle cells are damaged or more permeable, releasing CK into the blood. Causes range from intense exercise, trauma, seizures or injections to muscle diseases, statin use, heart attack or rhabdomyolysis. Clinicians interpret total CK and isoforms, repeat testing, review symptoms/medications and order targeted tests (e.g., troponin, kidney function) to find and treat the cause.

Q: What is the function of creatine kinase?

A: Creatine kinase (CK) is an enzyme that catalyzes the reversible transfer of a phosphate group between ATP and creatine to form phosphocreatine and ADP. This reaction stores and rapidly regenerates ATP in high‑energy tissues (muscle, brain, heart), buffering cellular energy during contraction and stress. CK isoenzymes are also measured clinically as biomarkers of muscle injury and myocardial damage.

Q: How do I get my CK levels down?

A: Lowering creatine kinase (CK) involves treating the cause: rest and avoid strenuous exercise, stay well hydrated, stop or switch offending drugs (e.g. statins) only with your doctor, and treat underlying conditions (thyroid disease, infections). Repeat blood tests as recommended. Seek urgent care for severe muscle pain, weakness, or dark urine possible rhabdomyolysis requiring immediate treatment.

Q: What medications cause high creatine kinase?

A: Medications commonly causing raised creatine kinase include statins (especially with fibrates or interacting drugs), fibrates (gemfibrozil), daptomycin, certain antipsychotics (risk of neuroleptic malignant syndrome), some antivirals (e.g., zidovudine), colchicine, and antimalarials (chloroquine/hydroxychloroquine). Rarely, fluoroquinolone antibiotics or overdoses can trigger rhabdomyolysis with large CK rises. Monitor CK if symptoms occur.

Q: What is the treatment for high creatine kinase?

A: Treatment for high creatine kinase depends on the cause. Key steps: stop or change offending drugs (e.g., statins), rest and avoid strenuous activity, provide aggressive IV fluids and urine alkalinization for rhabdomyolysis, monitor and correct electrolytes and kidney function, treat underlying conditions (infections, hypothyroidism), offer supportive care and physical therapy, and hospitalize or initiate dialysis if severe.

Q: Can dehydration cause high CK levels?

A: Yes. Dehydration can contribute to elevated creatine kinase (CK) by reducing muscle perfusion and increasing risk of muscle breakdown or rhabdomyolysis—especially with heat, intense exercise, or certain medications. Mild dehydration alone usually won’t cause large CK rises, but severe dehydration or combined factors can. Rehydration and prompt medical evaluation are advised if you have muscle pain, weakness, or dark urine.