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Creatinine Kinase

Checked: 12-04-2024 by Rob Adams Next Review: 12-04-2026

Overview

Creatine kinase (CK) is found in cardiac and skeletal muscle and brain. Other tissues such as kidney have low levels of enzyme activity (1).

CK is usually used to investigate cardiac or skeletal muscle pathology.

Cardiac Causes - CK rises approximately 6 hours after myocardial infarction (MI) and may remain elevated for 36 - 48 hours. CK rises earlier but is less specific than Troponin T in MI and is no longer routinely used.
Skeletal Causes - CK may be elevated when any muscle trauma has occurred e.g. strenuous exercise, Intra-muscular injection, crush injury or bruising, surgery, cardioversion.
Rhabdomyolysis - Very high CK levels are seen in rhabdomyolysis.
Other Causes - CK may be elevated in hypothyroidism.

Interpretation of result

Most elevations in creatine kinase are physiological or secondary to exercise and do not require further investigation unless likely to be secondary to newly prescribed drug therapies. (3)

Persistent symptomatic changes in creatine kinase warrant investigation for underlying secondary causes including endocrine, autoimmune, and genetic disorders. (3)

Measure creatine kinase if a patient on statin therapy develops muscle pain. (3)

An algorhythm to guide clinicians in interpretation and investigation of raised CK is available via the Severn Pathology website below:

Clinical Biochemistry in Primary Care | North Bristol NHS Trust (nbt.nhs.uk)

Red Flags

CK levels greater than 5000 IU/l may be associated with Rhabdomyolysis - consider admssion and an urgent repeat level should be done together with UE and K+ (2).

Resources

(1) Creatine Kinase (CK) (gloshospitals.nhs.uk)

(2) Clinical Biochemistry in Primary Care | North Bristol NHS Trust (nbt.nhs.uk)

(3) Investigating raised creatine kinase | The BMJ - full article requires BMA member log in.

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