Creatine Kinase,Total

Laboratory assay overview

Evaluation of possible myocardial damage or other cardiac diseases. See individual test descriptions for CK Isoenzymes and LD Isoenzymes.

Laboratory assay overview

MB is the myocardial fraction associated with MI and occurs in certain other states. MB can be used in estimation of infarct size. MB increases have been reported with entities which cause damage to the myocardium, such as myocarditis, some instances of cardiomyopathy, and with extensive rhabdomyolysis, Duchenne muscular dystrophy, malignant hyperthermia, polymyositis, dermatomyositis, mixed connective tissue disease, myoglobinemia, Rocky Mountain spotted fever, Reye syndrome, and rarely in rheumatoid arthritis with high titer RF.2 CK-MB does not generally abruptly rise and fall in such nonacute MI settings, as it does in acute myocardial infarct (AMI).

Laboratory assay overview

Test for acute myocardial infarct and for skeletal muscular damage; elevated in some patients with myxedema (hypothyroidism), malignant hyperthermia syndrome, and muscular dystrophy. CK is a marker for Duchenne muscular dystrophy, with elevations of 20 to 200 times normal.1 CK is increased in female carriers of this X-linked disease, and in muscular stress, in polymyositis, dermatomyositis, and with muscle trauma. Elevated in myocarditis. Documentation of postictal state (recent grand mal seizure). Extremely high values are seen in some instances of myositis and in the postictal state. CK may be elevated in a number of entities, including the eosinophilia-myalgia syndrome.2 Marked increases occur with rhabdomyolysis including that with cocaine intoxication.3 CK is sometimes increased with cerebrovascular accident. Malignancy (advanced) may show increased CK.4 Cardioversion with multiple shocks may release CK-MB and may result in a false-positive diagnosis of myocardial infarction.5 Low CK may reflect decreased muscle mass. It has been reported with a number of entities, including metastatic neoplasia, patients with steroid therapy, with alcoholic liver disease6 and with connective tissue diseases.7 Overnight bedrest may lower CK 10% to 20%.

Laboratory assay overview

This test measures creatine kinase (CK), an enzyme found primarily in striated muscle and heart tissue, and may be useful in assessing muscle damage. CK is a dimeric enzyme composed of either 2 B subunits (CK-BB), 2 M subunits (CK-MM), or an M and a B subunit (CK-MB). CK-MM is the primary isoenzyme found in the skeletal muscle and heart tissue. CK-BB is mainly found in the brain and smooth muscle of gastrointestinal tract and urinary bladder. CK-MB is mainly found in the heart with a small amount in skeletal muscle [1]. An elevated level of any isoenzyme results in an elevated total CK level. An increase in the CK level is often observed in inflammatory myopathy (eg, viral myositis, polymyositis, and immune-mediated myopathies), muscular dystrophy (eg, Duchenne sex-linked muscular dystrophy), rhabdomyolysis, or malignant hyperthermia [1]. In patients with neuromuscular disorders, an increased CK level may be the only initial manifestation [1]. Increased CK activity may also be caused by hypothyroidism, acute myocardial infarction, chronic renal failure, direct muscle trauma (eg, surgery and intramuscular injection), excessive exercise, certain medications (eg, statins, fibrates, antiretrovirals, and angiotensin II receptor antagonists), or brain damage or very low birth weight in newborns [1]. The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings. Reference 1. Panteghini M, et al. Serum enzymes. In: Rifai N, et al. eds. Tietz Textbook of Laboratory Medicine. 7th ed. Elservier Inc; 2022:4149-4299.

Quest Diagnostics population reference ranges

Quest Diagnostics calculates these statistical intervals for this specific assay and demographic group, not as universal optimal targets.

Laboratory assay overview

Diagnose myocardial infarction (MI). Three fractions normally may be found, each an isoenzyme: • MM is found in normal serum. • MB is the myocardial fraction associated with MI and occurs in certain other states. MB can be used in estimation of infarct size. MB increases have been reported with entities that cause damage to the myocardium, such as myocarditis, some instances of cardiomyopathy, and with extensive rhabdomyolysis, Duchenne muscular dystrophy, malignant hyperthermia, polymyositis, dermatomyositis, mixed connective tissue disease, myoglobinemia, Rocky Mountain spotted fever, Reye syndrome, and rarely in rheumatoid arthritis with high titer RF.2 CK-MB does not generally abruptly rise and fall in such nonacute MI settings, as it does in acute myocardial infarct (AMI). • BB is rarely present. BB has been described as a marker for adenocarcinoma of the prostate, breast, ovary, colon, adenocarcinomas of gastrointestinal tract, and for small cell anaplastic carcinoma of lung. BB has been reported with severe shock and/or hypothermia, infarction of bowel,3 brain injury, stroke, as a genetic marker in some families with malignant pyrexia, and with MB in alcoholic myopathy.

Laboratory assay overview

This test measures creatine kinase (CK), an enzyme found primarily in striated muscle and heart tissue, and may be useful in assessing muscle damage. Total CK and fractions of CK isoenzymes are reported. CK is a dimeric enzyme composed of either 2 B subunits (CK-BB), 2 M subunits (CK-MM), or an M and a B subunit (CK-MB). CK-MM is the primary isoenzyme found in the skeletal muscle and heart tissue. CK-BB is mainly found in the brain and smooth muscle of gastrointestinal tract and urinary bladder. CK-MB is mainly found in the heart with a small amount in skeletal muscle [1]. An increase in the CK level is often observed in inflammatory myopathy (eg, viral myositis, polymyositis, and immune-mediated myopathies), muscular dystrophy (eg, Duchenne sex-linked muscular dystrophy), rhabdomyolysis, or malignant hyperthermia [1]. In patients with neuromuscular disorders, an increased CK level may be the only initial manifestation [1]. Other causes of elevated CK levels include hypothyroidism, direct muscle trauma (eg, surgery and intramuscular injection), excessive exercise, and certain medications (eg, statins, fibrates, antiretrovirals, and angiotensin II receptor antagonists) [1]. The quantitation of CK-MB levels in serum was widely used to diagnose acute myocardial infarction but has been replaced by troponin I and T levels, which are more cardiac-specific [2,3]. CK-MB measurement, preferably expressed as CK-MB relative to the total CK level, is only indicated in patients with suspected acute coronary syndrome or reinfarction when troponin T and I testing are not available [2]. In individuals with chronic muscle damage/disease or chronic renal failure, CK-MB may account for the elevation of CK levels owing to the phenomenon of "fetal reversion" [1]. CK-BB levels may be increased in newborns with brain damage or very low birth weight, although healthy newborns can also have increased CK-BB levels as a result of birth-related muscle trauma [1]. The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings. References 1. Panteghini M, et al. Serum enzymes. In: Rifai N, et al. eds. Tietz Textbook of Laboratory Medicine. 7th ed. Elservier Inc; 2022:4149-4299. 2. CKMB: optimal testing recommendations. AACC. Accessed October 11, 2022. https://www.aacc.org/advocacy-and-outreach/optimal-testing-guide-to-lab-test-utilization/a-f/ckmb 3. Gulati M, et al. Circulation. 2021;144(22):e368-e454.

Laboratory assay overview

About 10-30% of patients continue with lingering symptoms four or more weeks after COVID-19 infection, including those who had mild, or no symptoms termed as post-COVID conditions. The Centers for Disease Control (CDC) provided Interim Guidance for Assessment and Testing for Evaluating and Caring for Patients with Post-COVID Conditions. The CDC recommends laboratory testing be guided by the patient history, physical examination, and clinical findings. Specialized tests might be considered if symptoms persist for 12 weeks post COVID. This panel is to be considered for persistent symptoms such as joint pains or rheumatological conditions.