Exercise-induced urticaria with muscle injury: a case report

Exercise has become an integral part of life in this modern era due to sedentary lifestyle. Although, urticaria patients are being evaluated for all the common triggering factors like food, environmental allergens and infections, an entity called exercise induced urticaria often get missed. Exertional and asymptomatic rhabdomyolysis must be kept in mind during evaluation. A 27 year male patient was diagnosed with severe exercise induced urticaria with muscle injury. Patient developed urticaria within 30 minutes of strenuous exercise. Clinical history was insignificant for any allergen exposure except for clear history of urticaria once weekly after strenuous exercise. Patient also reported need for oral analgesics on the day of strenuous exercise indicating muscle injury. Asymptomatic phase correlated with abstinence of exercise. His lesions gradually got relieved with anti-histamines. Routine blood investigations were normal except elevation of aspartate aminotransferase (AST-354U/L), Lactate dehydrogenase (LDH-619U/L) and normal alanine aminotransferase (ALT-51U/L), altered AST/ALT ratio more than 6. Creatinine kinase (CK) can increase ten folds in healthy individuals following strenuous exercise. Hence, CK was not done for this patient. Aminotransferases may remain elevated even after normalisation of CK up to 2-3 weeks.  LDH was done as an additional investigation. Simple routine investigation for altered AST and confirmation with LDH or CK for its source from muscle injury can be done. Severe exercise induced urticaria with muscle injury can be managed with moderation of exercise intensity along with short course of antihistamines owing to the benefit of exercise. This patient was followed up for 2 years and there was no episode of urticaria after stepping down the exercise intensity. Detailed history of exercise duration and intensity is required along with basic investigations for evaluating exercise induced urticaria. A sub-entity called severe exercise induced urticaria with muscle injury must be kept in mind due to the risk of asymptomatic or exertional rhabdomyolysis.