A case of Mc Ardle's disease
A 25-year-old man comes to your office complaining that “I feel weak when I do my exercise routine in the morning. I like to work out hard like a soldiere.” He also tells you that “sometimes my urine is red and it scares me.” After some discussion, he informs you that he takes a rest period when the weakness occurs and the symptoms resolve. But, the symptoms reappear when he resumes exercise. The man is obviously frustrated and says, “Doc, I can’t stay in shape if this keeps happening.” What is the most likely diagnosis?
Relevant Physical Examination Findings
• Burning pain, cramping, and exhaustion in legs and arms during strenuous exercise
• Normal muscle tone and strength bilaterally
• No enlargement of the liver or spleen
Relevant Lab Findings
Diagnostic anaerobic exercise test showed muscle pain, cramping, and exhaustion; increase in CPK; and no increase in blood lactate.
• Muscle biopsy showed elevated glycogen content and low phosphorylase activity.