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Macro creatine kinase BB in serum, and some data on its prevalence
Clinical Chemistry
|March 1, 1979
Summary
This study identifies a rare form of macro creatine kinase (CK) in patient serum, characterized by abnormal CK-BB isoenzymes complexed with IgG. This finding highlights a potential diagnostic marker for specific clinical conditions.
Area of Science:
- Biochemistry
- Clinical Chemistry
Background:
- Creatine kinase (CK) exists as isoenzymes (CK-MM, CK-MB, CK-BB) with distinct tissue distributions and clinical significance.
- Persistently elevated serum CK activity can indicate underlying muscle or cardiac pathology, necessitating detailed isoenzyme analysis.
Observation:
- A patient presented with persistently elevated serum CK activity, with a significant fraction migrating aberrantly on electrophoresis and anion-exchange chromatography.
- Biochemical analysis revealed the abnormal CK activity was predominantly CK-BB (93% B-isomers) and complexed with immunoglobulin G (IgG).
Findings:
- The abnormal CK-BB exhibited increased molecular mass and enhanced in vitro stability compared to normal CK isoenzymes.
- Incubation of normal CK-BB with patient serum induced the formation of macro-CK-BB, suggesting a serum factor responsible for complexation.
- Screening of 310 additional sera identified five cases (1.6%) with similar electrophoretically abnormal CK isoenzymes, all of BB nature and increased molecular mass, with at least three complexed with IgG.
Implications:
- The presence of macro CK-BB, particularly when complexed with IgG, represents a distinct biochemical entity that can cause pseudohyperCKemia.
- This finding has implications for the accurate interpretation of serum CK levels in clinical diagnostics, potentially requiring specific assays for macro CK detection.
- Further research is warranted to elucidate the clinical relevance and prevalence of this macro CK-BB variant.