A 10-year-old with suspected skeletal muscle disease; the best confirmatory tests would be which pair?

• A. Creatine kinase and isocitrate dehydrogenase
• B. Gamma-glutamyl transferase and alkaline phosphatase
• C. Aldolase and creatine kinase
• D. Lactate dehydrogenase and malate dehydrogenase

Answer: (C)

Muscle injury releases enzymes that are most informative when measured in the blood. Creatine kinase, especially the CK-MM isoform found predominantly in skeletal muscle, is the most sensitive early indicator of muscle damage in children. Aldolase is another enzyme that tends to rise with skeletal muscle disease, and measuring it alongside CK adds confirmation by providing a second, muscle-specific signal. Together, elevated CK and aldolase strongly point to skeletal muscle involvement.

The other enzyme pairs are less helpful for confirming a primary muscle problem because their sources are not specific to muscle. Gamma-glutamyl transferase and alkaline phosphatase are more related to liver and bone processes, while lactate dehydrogenase and malate dehydrogenase are broad, tissue-nonspecific markers that can rise in many conditions.