Medical emergencies

• People with McArdle’s are at risk of episodes of rhabdomyolysis with possible acute renal failure and/or compartment syndrome [1].

• Episodes cannot be managed in general practice. Patients must understand when to attend the hospital. They should carry an ‘Information/ Emergency Card’ which has guidance (page 19).

• Ideally patients should show a letter from their McArdle specialist and the “At hospital” leaflet on arrival, or show their card and/or this page.

• Kidneys normally recover fully following an episode of rhabdomyolysis and myoglobinuria.

• For further information on medical emergencies see: https://www.iamgsd.org/urgent

[1] Exertional rhabdomyolysis: a clinical review with a focus on genetic influences. Landau ME, Kenney K, Deuster P, Campbell W. (2012) J Clin Neuromuscul Dis. Mar;13(3):122-36. https://doi: 10.1097/CND.

Information for the hospital doctor

Patients may present with muscle cramps, fixed contractures, myoglobinuria, oliguria or anuria or feeling very unwell (’flu like aches and fever) following activity.

Do not be concerned about McArdle’s as such, but instead:

Urgent assessment for rhabdomyolysis

• Consider urine analysis for myoglobinuria and full chemistry panel – CK (page 10), glucose, calcium and bone profile, urea and electrolytes.

Suggested management

• IV fluid bolus, then saline at 2x maintenance and (unless diabetic) consider if 10% dextrose needed to keep blood glucose >3.5 mmol/L (>61 mg/dL).

• Monitor urine output, CK and electrolyte status.

Potential complications

• Acute renal failure – prompt referral for hemodialysis.

• Increased swelling causing compartment syndrome – assess the need for urgent surgical intervention.