What Are the Normal Serum Creatine Kinase Values for Skeletal Muscle? A Worldwide Systematic Review

Area of Science:

• Biochemistry
• Clinical Diagnostics
• Human Physiology

Background:

• Serum creatine kinase (CK) has been a diagnostic marker for neuromuscular disorders since 1959.
• Manufacturer-provided CK normative data may underestimate true values due to physiological factors like age, race, and gender.
• Establishing reliable CK normal ranges is crucial for accurate diagnosis, especially in asymptomatic patients.

Approach:

• Systematic review of observational studies with a cross-sectional, descriptive design.
• Included studies focused on healthy adults (>= 18 years) with at least 100 participants.
• Searched PubMed, Embase, and Cochrane databases for studies establishing normal CK values.

Key Points:

• CK values often show a non-Gaussian distribution.
• Black individuals exhibit significantly higher CK levels than Caucasians and Asians.
• Upper reference limits for CK vary by race and sex, with higher ranges for Black males and females compared to other groups.

Conclusions:

• Normal CK values may exceed current suggestions, particularly in certain racial groups.
• Laboratories should determine their own CK reference values based on local population data.
• Accurate CK reference ranges are essential for reliable diagnosis of neuromuscular disorders.