CK, Total

Order Code

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2075

Preferred Specimen

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Collect 2 mL of serum. Allow the SST to clot upright for at least 30 minutes, then centrifuge within 2 hours of collection. Store the specimen refrigerated.

Container Type

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Serum separator tube (SST)

Alternate Specimen Requirements

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If SST is unavailable, collect 2 mL of serum in a plain red-top tube. Allow the sample to clot upright for a minimum of 60 minutes, then centrifuge and transfer the serum to a plastic transport tube within 2 hours. Clearly label the tube as serum from a plain red-top tube. Keep refrigerated.

Minimum Volume

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Adult: 0.5 mL serum

Pediatric: 0.2 mL serum (insufficient for repeat or additional testing)

Transport Temperature

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Refrigerated

Expected Turnaround Time

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1 day

Specimen Stability

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• Room Temperature: Stable for up to 5 days
• Refrigerated: Stable for up to 1 week
• Frozen: Stable for up to 1 month

Methodology

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Roche COBAS UV test

Rejection Criteria:

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Samples with moderate or greater hemolysis

Overview

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Creatine kinase (CK), also known as creatine phosphokinase (CPK), is an enzyme that facilitates the reversible transfer of inorganic phosphate from creatine phosphate to adenosine diphosphate (ADP), producing adenosine triphosphate (ATP) and creatine. This reaction plays a vital role in muscle contraction and relaxation.

CK is found primarily in skeletal muscle, brain, and heart tissue, with much lower concentrations present in other organs such as the kidneys.
Although CK testing was once a key diagnostic marker for myocardial infarction (heart attack) and cerebrovascular events, it has largely been replaced by more specific and sensitive markers like Troponin.
Nonetheless, CK measurement remains useful for the diagnosis and monitoring of skeletal muscle disorders and muscle injury.

Clinical Significance

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• Diagnosis and monitoring of muscle disease
  • CK levels are elevated in nearly all types of muscular dystrophy (MD), particularly Duchenne MD, where levels can be 20–200 times higher than normal (Rosalki, 1989).
• Monitor treatment and recovery
  • Serves as a sensitive indicator of muscle injury and can help track healing progress or therapeutic response.
• Assist in cardiac evaluation
  • May help identify acute myocardial infarction (AMI); while sensitive, CK alone is not specific.
  • CK-MB isoenzyme analysis provides greater specificity for cardiac damage.
  • After an AMI, CK levels typically rise within 4–6 hours, peak between 12–24 hours, and normalize within 48–72 hours after onset.

Additional Information

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Females:

CK consists of three isoenzymes:

• CK-MM – specific to skeletal muscle
• CK-MB – specific to the heart
• CK-BB – specific to the brain

Measuring total CK along with CK-MB quantification provides greater accuracy in diagnosing cardiac injury.
CK-MB levels can help estimate both the extent and timing of myocardial infarction.
However, Troponin I and Troponin T are now the preferred tests in cardiac evaluations.

Interpretative Information

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Increased CK/CPK Levels May Indicate:

• Muscular dystrophies (elevated even before clinical onset in Duchenne and Becker types) (Basil, 2013)
• Female carriers of Duchenne MD (X-linked)
• Muscle strain, trauma, or intense exercise
• Myositis, polymyositis, or dermatomyositis
• Rhabdomyolysis, including that caused by cocaine toxicity
• Postictal state following a recent tonic-clonic seizure
• Acute myocardial infarction
• Myocarditis
• Hypothyroidism
• Advanced malignancy
• Ruptured ectopic pregnancy (Cartwright, 2009)

Decreased CK/CPK Levels May Indicate:

• Reduced muscle mass
• Metastatic cancer
• Connective tissue disorders
• (Note: Normal CK levels do not exclude myositis in these cases)
• Alcoholic liver disease (possibly due to low muscle mass) (Rosalki, 1998)
• Rheumatoid arthritis
• Cushing’s disease (Rosalki, 1998)
• Prolonged steroid therapy

Limitations

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• Exercise, contact sports, intramuscular injections, and trauma may cause temporary increases in CK levels.
• Elevated CK cannot distinguish between cardiac and skeletal muscle injury; isoenzyme testing or specific markers (e.g., Troponin) are required.
• Multiple cardioversion shocks can release CK-MB and may lead to a false-positive indication of myocardial infarction.

References

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Diagnostic Role

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CK was once routinely used to diagnose myocardial infarction (MI), typically requiring a twofold increase for confirmation.
Due to limited specificity and the availability of more reliable cardiac markers (such as Troponins), CK testing is no longer recommended as the primary diagnostic tool for MI.
Today, CK testing remains valuable for detecting and monitoring muscle diseases and injuries, including early stages of Duchenne and Becker muscular dystrophy (Basil, 2013).

Alias

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Creatine Phosphokinase (CPK)

Test Setup Days

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Monday through Friday PM shift

CPT

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82550 LOINC: 2157-6

Reference Range

MALE:
AGE 0-5 YEARS: 0-180 U/L
6-11 YEARS: 150-499 U/L
12-17 YEARS: 94-499 U/L
>=18 YEARS: 31-336 U/L
FEMALE:
AGE 0-5 YEARS: 0-150 U/L
6-7 YEARS: 134-391 U/L
8-14 YEARS: 91-391 U/L
15-17 YEARS: 53-269 U/L
>=18 YEARS: 28-176 U/L

UNIT CODE	UNIT CODE NAME	ANALYTE	GENDER	AGE	REFERENCE RANGE	Units of Measure
2075	CPK	CPK	NOT SPECIFIED	0Y	28-336	U/L
2075	CPK	CPK	NOT SPECIFIED	6Y	<=180	U/L
2075	CPK	CPK	NOT SPECIFIED	7Y	134-499	U/L
2075	CPK	CPK	NOT SPECIFIED	14Y	91-499	U/L
2075	CPK	CPK	NOT SPECIFIED	17Y	53-499	U/L
2075	CPK	CPK	NOT SPECIFIED	150Y	28-336	U/L
2075	CPK	CPK	MALE	0Y	31-336	U/L
2075	CPK	CPK	MALE	6Y	<=180	U/L
2075	CPK	CPK	MALE	11Y	150-499	U/L
2075	CPK	CPK	MALE	17Y	94-499	U/L
2075	CPK	CPK	MALE	150Y	31-336	U/L
2075	CPK	CPK	FEMALE	0Y	28-176	U/L
2075	CPK	CPK	FEMALE	5Y	<=150	U/L
2075	CPK	CPK	FEMALE	7Y	134-391	U/L
2075	CPK	CPK	FEMALE	14Y	91-391	U/L
2075	CPK	CPK	FEMALE	17Y	53-269	U/L
2075	CPK	CPK	FEMALE	150Y	28-176	U/L