Creatine Kinase

Cleveland Heartlab C, Standard Laboratory Tests, Test

CPT Code: 82550
Order Code: C137
ABN Requirement:  No
Synonyms: CK; Total CK; Creatine Phosphokinase; CPK
Specimen: Serum
Volume: 0.5 mL
Minimum Volume: 0.2mL
Container: Gel-barrier tube (SST, Tiger Top)


  1. Collect and label sample according to standard protocols.
  2. Gently invert tube 5 times immediately after draw. Do not shake.
  3. Allow at least 30 minutes, and up to 60 minutes, from patient draw and ensure a complete clot has formed before placing the specimen in the centrifuge.
  4. Centrifuge sample for 15 minutes.

Transport: Store serum at 2°C to 8°C after collection and ship the same day per packaging instructions included with the provided shipping box.


Ambient (15-25°C): 2 days
Refrigerated (2-8°C): 7 days
Frozen (-20°C): 4 weeks

Causes for Rejection: Specimens other than serum; improper labeling; samples not stored properly; samples older than stability limits; hemolyzed specimens

Methodology: Photometric

Turn Around Time: 1 to 3 days

Reference Range:

Age Male U/L Female U/L
All Ages 20-200 20-180

Priority Values:

AgePriority 2 Values (U/L)

≤18 years≥1000
>18 years≥6000

Clinical Significance: 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 muscle1. 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 hyperthermia1. In patients with neuromuscular disorders, an increased CK level may be the only initial manifestation1. 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 newborns1.

The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings.


  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.

Limitations: Cyanokit (Hydroxocobalamin) may cause interference with results. In very rare cases gammopathy may cause unreliable results. Non-hemolyzed samples are recommended by the IFCC for testing. Highly lipemic specimens may cause unreliable results.

The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.