What is the explanation for creatine kinase (CK) levels in a 14-year-old boy with Duchenne muscular dystrophy being much lower now than they were 5 years ago?

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Children with DMD have hugely elevated blood levels of the enzyme creatine kinase (CK) and the protein myoglobin during their early childhood years. Both are normally present inside intact muscle cells. When the cells are damaged or die, CK and myoglobin are released into the blood. These levels decrease as the child ages because there is a limit to how much muscle is available to be destroyed. Therefore, lower levels in older children indicate disease progression, not disease improvement. Switching to passive exercise does not decrease muscle damage. BMD has a slower rate of muscle destruction with a more consistent level of blood CK over time.

What Is the Explanation for Creatine Kinase (CK) Levels in a 14-Year-Old