Immunoglobulin-associated creatine kinase masquerading as macro-creatine kinase type 2 in a statin user

Area of Science:

• Clinical chemistry
• Immunology
• Biochemical diagnostics

Background:

• Macro-creatine kinase (CK) is a known cause of artifactually elevated total CK levels.
• Macro-CK type 1 is typically immunoglobulin-associated, while type 2 is polymeric mitochondrial CK.

Observation:

• An asymptomatic elderly female patient presented with elevated CK levels following statin therapy.
• CK gel electrophoresis revealed coexisting macro-CK type 1 and type 2 patterns.

Findings:

• Further immunofixation and serum mixing studies identified an IgG-associated macro-CK (type 1) mimicking the electrophoretic pattern of macro-CK type 2.
• This unusual case demonstrates a potential for misinterpreting macro-CK type 1 as type 2.

Implications:

• Accurate differentiation of macro-CK subtypes is crucial for correct clinical interpretation.
• Falsely elevated CK levels necessitate thorough laboratory investigation, even with advanced instrumentation.