Serum creatine kinase after intramuscular injections.

Area of Science:

• Clinical Biochemistry
• Pharmacology
• Internal Medicine

Background:

• Serum creatine kinase (CK) elevation is a common concern in clinical practice.
• Intramuscular injections are often suspected as a cause of elevated CK levels.
• This study investigates the actual impact of common intramuscular injections on serum CK activity.

Purpose of the Study:

• To determine the frequency and magnitude of serum CK elevation following common intramuscular injections.
• To assess the contribution of different CK isoenzymes to any observed elevations.
• To challenge the clinical assumption that intramuscular injections frequently elevate CK levels.

Main Methods:

• Serum CK activity was measured in 44 hospitalized patients receiving intramuscular injections.
• Injections included diazepam, dipyrone, metoclopramide, meperidine, pentazocine, and procaine penicillin.
• CK isoenzyme analysis (MM and MB) was performed when elevations occurred.

Main Results:

• Only 7% (3 out of 44) of patients showed significant CK level increases post-injection.
• Elevations were primarily due to the MM-isoenzyme, with one case showing increased MB levels.
• The findings indicate a low incidence of CK elevation from these specific intramuscular drugs.

Conclusions:

• Intramuscular injections are not a frequent cause of significant serum CK elevation.
• Clinicians should maintain a high index of suspicion for other causes of elevated CK, especially in patients with chest pain.
• The potential impact of recent intramuscular injections on CK levels should not be overemphasized.