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Interpretation of serum creatine kinase in suspected myocardial infarction
Insights
Serum creatine kinase (CK) levels vary daily in healthy individuals, influenced by exercise. Intramuscular injections can also elevate CK, impacting myocardial infarction diagnosis.
Area of Science:
- Clinical Biochemistry
- Cardiology
Background:
- Serum creatine kinase (CK) is a biomarker used in diagnosing myocardial infarction.
- Understanding normal CK ranges and variations is crucial for accurate clinical interpretation.
Purpose of the Study:
- To establish normal serum CK ranges in different patient groups.
- To investigate daily variations in serum CK in healthy individuals.
- To assess the impact of intramuscular injections on serum CK levels.
Main Methods:
- Serum CK levels were measured in blood donors, patients with suspected myocardial infarction, and healthy hospital personnel.
- Daily CK variations were monitored in healthy controls.
- The effect of intramuscular pentazocine and diamorphine injections on serum CK was evaluated.
Main Results:
- Significant daily variations in serum CK were observed in healthy individuals, potentially linked to physical activity.
- Recommended upper limits for serum CK are 210 IU/L for ambulant patients and 165 IU/L for resting patients.
- An increase exceeding 85% in daily CK values is rare in healthy individuals.
- Intramuscular injections of pentazocine or diamorphine caused significant CK elevation in 6 of 25 patients.
Conclusions:
- Daily physical activity must be considered when interpreting serum CK levels.
- Normal CK ranges should be adjusted based on patient mobility.
- Clinicians should exercise caution when diagnosing myocardial infarction if patients have received recent intramuscular injections.
Abstract:
Serum creatine kinase (CK) was measured in blood donors, patients admitted to hospital with suspected myocardial infarction, and healthy hospital personnel to investigate the normal range, the daily variation in healthy people, and the effect of intramuscular injections of pentazocine or diamorphine.There was considerable daily variation in the healthy controls, apparently related to exercise. In defining both the normal range and the significance of day-to-day increases in the serum CK account should be taken of this factor. An upper limit of normal of 210 IU/1. Should apply to previously ambulant patients and of 165 IU/1. to patients previously at rest. An increase greater than 85% in successive daily values is uncommon in health.Intramuscular injections of both pentazocine and diamorphine caused a significant rise in the serum CK in six out of 25 patients. The highest rise observed was from 64 IU/1. to 395 IU/1. Caution is therefore urged in the diagnosis of myocardial infarction from the serum CK values when these intramuscular injections have been given.