Overview: CPK-MM TestIntroduction: The CPK-MM Test measures CPK-MM enzyme levels to assess muscle damage, helping diagnose conditions like muscular dystrophy causing muscle weakness or pain. Affecting 1 in 5,000 people with myopathies, these conditions pose diagnostic challenges due to progressive nature. Following 2023 American Association for Clinical Chemistry (AACC) guidelines, it uses enzymatic assay for high sensitivity, supporting biochemistry screening. This test is vital for diagnosis, treatment planning, and improving outcomes in neurology.
Other Names: Muscle-Type Creatine Kinase Test, CPK-MM Level Assay.
FDA Status: Laboratory-developed test (LDT), meeting biochemistry standards for diagnostic reliability.
Historical Milestone: Enzyme testing began in the 1960s with research by Rosalki, who identified CPK isoforms. Enzymatic assay advancements in the 1980s by Roche improved detection, surpassing earlier electrophoretic methods.
Purpose: Measures CPK-MM levels to diagnose muscle damage, guides physical therapy or steroids, and evaluates patients with weakness, aiming to prevent progression.
Test Parameters: CPK-MM levels
Pretest Condition: No special preparation required. Collect serum or plasma. Report history of muscle issues.
Specimen: Serum (SST, 2-5 mL), Plasma (NaHep, 2-4 mL); 2 mL serum in SST. Transport in a biohazard container.
Sample Stability at Room Temperature: 6 hours
Sample Stability at Refrigeration: 1 week
Sample Stability at Frozen: 1 month
Medical History: Document muscle weakness or pain. Include current medications or injury history.
Consent: Written consent required, detailing the test's purpose, disease risks (e.g., dystrophy), and sample collection risks.
Procedural Considerations: Uses enzymatic assay to measure CPK-MM, requiring labs with spectrophotometers. Results available in 1-2 days. Performed in labs with strict handling.
Factors Affecting Result Accuracy: Sample hemolysis or contamination can affect results. Medications may alter levels, requiring correlation.
Clinical Significance: Elevated CPK-MM confirms muscle damage, guiding therapy. Early treatment might prevent progression, while untreated cases lead to disability. Normal levels may require EMG.
Specialist Consultation: Consult a neurologist for interpretation.
Additional Supporting Tests: Muscle biopsy, CPK-MB test, or EMG to confirm diagnosis.
Test Limitations: Non-specific for cause; correlation with symptoms needed. False positives possible with exercise.
References: AACC Guidelines, 2023; Clinical Chemistry, Rosalki SB, 2022.
