Creatine Kinase
CardíacoÚltima revisão: 7 de abril de 2026. Abordagem de fontes: contexto padrão de interpretação laboratorial, material médico de referência e orientações clínicas ou de saúde pública quando relevantes.
O que é Creatine Kinase?
Creatine kinase (CK), also known as creatine phosphokinase (CPK), is an enzyme that catalyzes the reversible transfer of a phosphate group from phosphocreatine to ADP, regenerating ATP—the cell's primary energy currency. This reaction is critical in tissues with high and fluctuating energy demands, particularly skeletal muscle, cardiac muscle, and the brain. CK exists in three isoenzyme forms: CK-MM (predominant in skeletal muscle, accounting for ~95% of total CK in serum), CK-MB (found mainly in cardiac muscle, typically 1–3% of total CK), and CK-BB (found in the brain and smooth muscle, rarely detected in serum).
Total CK is a well-established marker of muscle damage. When muscle cells are injured—whether from exercise, trauma, ischemia, or disease—CK leaks into the bloodstream in proportion to the degree of damage. While CK-MB was historically the primary cardiac biomarker for diagnosing myocardial infarction, high-sensitivity troponin assays have largely supplanted it for this purpose. Total CK remains essential for diagnosing rhabdomyolysis, monitoring myopathies and muscular dystrophies, and detecting statin-related muscle toxicity.
Por que isso importa
CK is the most sensitive widely available marker for skeletal muscle injury. In rhabdomyolysis, CK levels can exceed 10,000–100,000 U/L or higher, and the degree of elevation correlates with the risk of acute kidney injury from myoglobin-induced tubular damage. CK monitoring is also critical for patients on statin therapy, as statins can rarely cause myopathy or rhabdomyolysis. In neuromuscular diseases such as Duchenne muscular dystrophy, CK levels are typically elevated 10–100 times normal even before clinical symptoms appear, making it useful for early detection and monitoring. CK-MB, while less used now, still plays a role in detecting reinfarction in patients who have already had a heart attack, as it rises and falls more quickly than troponin.
Faixas de referência normais
| Grupo | Faixa | Unidade |
|---|---|---|
| Adult Men | 39–308 | U/L |
| Adult Women | 26–192 | U/L |
| Children | 60–305 | U/L |
| Newborns | 68–580 | U/L |
As faixas de referência podem variar entre laboratórios. Sempre compare seus resultados com as faixas fornecidas pelo seu local de exame.
O que significam níveis altos de CK
Causas comuns
- Rhabdomyolysis (crush injury, prolonged immobilization, hyperthermia)
- Intense or prolonged exercise (especially eccentric exercise)
- Myocardial infarction (CK-MB fraction elevated)
- Muscular dystrophies (Duchenne, Becker)
- Inflammatory myopathies (polymyositis, dermatomyositis)
- Hypothyroidism-associated myopathy
- Statin or other drug-induced myopathy
- Seizures (prolonged)
- Intramuscular injections
- Malignant hyperthermia
Possíveis sintomas
- Muscle pain, tenderness, and swelling
- Muscle weakness
- Dark brown or tea-colored urine (myoglobinuria in rhabdomyolysis)
- Decreased urine output (if acute kidney injury develops)
- Chest pain with cardiac CK-MB elevation
- Fatigue and malaise
O que fazer: The clinical context dictates management. For suspected rhabdomyolysis (CK >5x normal with risk factors), aggressive intravenous fluid resuscitation is critical to prevent kidney damage. Monitor renal function, electrolytes (especially potassium and calcium), and urine output. For suspected cardiac causes, troponin is the preferred biomarker. If statin-related, hold the statin and recheck CK. For neuromuscular disease, refer for neurological evaluation and possible muscle biopsy or genetic testing.
O que significam níveis baixos de CK
Causas comuns
- Low muscle mass (sarcopenia, cachexia, or prolonged immobility)
- Connective tissue diseases (rheumatoid arthritis, lupus—some patients)
- Alcoholic liver disease (reduced muscle mass)
- Early pregnancy
Possíveis sintomas
- Low CK itself does not cause symptoms
- May reflect underlying muscle wasting or deconditioning
O que fazer: Low CK is usually not clinically concerning and often reflects low muscle mass. If accompanied by muscle weakness, consider a neurological evaluation. Ensure adequate nutrition and physical activity. No specific treatment is needed for isolated low CK.
Quando o exame de CK é recomendado?
- When rhabdomyolysis is suspected (dark urine, muscle pain after crush injury or extreme exertion)
- When monitoring patients on statin therapy who develop muscle symptoms
- In the evaluation of suspected myopathies or muscular dystrophies
- As part of the workup for suspected myocardial infarction (CK-MB, though troponin is preferred)
- When monitoring drug-related muscle toxicity (colchicine, daptomycin)
Perguntas frequentes
Biomarcadores relacionados
Referências e abordagem de revisão
As páginas do glossário de biomarcadores são explicações educativas e devem ser interpretadas junto com as faixas de referência e observações fornecidas pelo seu laboratório e pelo seu médico. Para conhecer nossos padrões editoriais e processo de revisão, veja nossa Política editorial e a nossa revisão de conteúdo.
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Enviar resultados de exames →Aviso médico: Estas informações são apenas educativas e não substituem orientação, diagnóstico ou tratamento médico profissional. As faixas de referência podem variar entre laboratórios. Sempre converse com seu profissional de saúde sobre a interpretação dos seus resultados específicos.