Key Takeaway
Myoglobinuria and exertion-associated muscle pain were reported in this small cohort, but the retrospective design does not provide a triage rule, prevention protocol, or prediction for an individual.
Evidence Summary
Myoglobinuria and muscle pain are common in patients with limb-girdle muscular dystrophy 2I
Retrospective report of self-reported myoglobinuria and muscle pain in a 26-person FKRP-related LGMD2I cohort.
cohortPhenotypeDiagnosisFamilies
Citation: Mathews KD, Stephan CM, Laubenthal K, et al. Myoglobinuria and muscle pain are common in patients with limb-girdle muscular dystrophy 2I. Neurology. 2011;76(2):194-195.
Main findings
- Twenty-six participants with confirmed FKRP variants completed a questionnaire and interview, with medical-record review for selected history and laboratory information.
- Seven participants reported at least one episode of dark urine described as myoglobinuria, and 16 reported significant muscle pain or cramps.
- Reported episodes were commonly associated with physical activity, and most first episodes in this series occurred before age 18.
Practical relevance
- Supports including prior dark-urine episodes and muscle pain in a clinical history when discussing an FKRP-related presentation.
- Does not determine what symptoms mean in a particular event or what evaluation or emergency action is appropriate.
Limitations and cautions
- Small single-center series based substantially on participant recall and self-report.
- The paper did not prospectively verify every reported episode or establish incidence for the wider FKRP population.
- The reported associations do not establish safe activity limits, laboratory thresholds, prevention steps, or emergency instructions.
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