A 4-year-old boy presents with frequent falls and bruising, along with difficulty in running and climbing. Which laboratory result would be inconsistent with the most likely diagnosis?

A 4-year-old boy presents with frequent falls and bruising, along with difficulty in running and climbing. Which laboratory result would be inconsistent with the most likely diagnosis?

• A. Moderately elevated AST
• B. Moderately elevated ALP
• C. Moderately elevated LD
• D. Markedly elevated CK

Answer: (B)

When a young boy has proximal muscle weakness with frequent falls, the pattern of enzyme elevations helps distinguish muscle disease from bone or liver conditions. In muscular dystrophy like Duchenne, there is extensive muscle membrane damage, so muscle enzymes leak into the blood and CK is markedly elevated; LD and AST can also be raised because they come from muscle. Alkaline phosphatase, however, mainly reflects bone turnover and liver biliary activity, not muscle injury, so it stays normal in this muscular dystrophy picture. Seeing a moderately elevated alkaline phosphatase would not fit the muscle-disease pattern and would suggest a bone- or liver-related process instead.

When a young boy has proximal muscle weakness with frequent falls, the pattern of enzyme elevations helps distinguish muscle disease from bone or liver conditions. In muscular dystrophy like Duchenne, there is extensive muscle membrane damage, so muscle enzymes leak into the blood and CK is markedly elevated; LD and AST can also be raised because they come from muscle. Alkaline phosphatase, however, mainly reflects bone turnover and liver biliary activity, not muscle injury, so it stays normal in this muscular dystrophy picture. Seeing a moderately elevated alkaline phosphatase would not fit the muscle-disease pattern and would suggest a bone- or liver-related process instead.