A 5-year-old is noted with dark brown urine after anesthesia; the most appropriate action is to evaluate for malignant hyperthermia.

A 5-year-old is noted with dark brown urine after anesthesia; the most appropriate action is to evaluate for malignant hyperthermia.

• A. Discharge with instructions to return if urine color does not normalize
• B. Discharge in 3 hours if no other signs or symptoms are manifested
• C. Obtain serum creatinine and blood urea nitrogen (BUN) levels and discharge if they are normal
• D. Evaluate the patient for malignant hyperthermia

Answer: (D)

Dark brown urine after anesthesia points to myoglobinuria from muscle breakdown, which can occur with malignant hyperthermia. Malignant hyperthermia is a dangerous reaction to certain anesthetics that can rapidly progress and cause rhabdomyolysis, heat production, and metabolic turmoil. When myoglobin appears in the urine, it signals possible ongoing muscle injury and potential MH, so the priority is to evaluate for this crisis rather than discharge or wait for kidney tests to change. Discharging the patient or relying on creatinine and BUN alone would miss a potentially life-threatening process that requires urgent attention. Normal renal function tests do not rule out early rhabdomyolysis or evolving MH, and they don’t address the underlying crisis. The appropriate course is to assess for malignant hyperthermia and begin immediate management if there is suspicion: stop triggering agents, provide 100% oxygen, prepare for cooling if hyperthermia is present, administer dantrolene, and monitor vitals, urine output, and electrolytes closely to mitigate complications. Early recognition and treatment markedly improve outcomes.

Dark brown urine after anesthesia points to myoglobinuria from muscle breakdown, which can occur with malignant hyperthermia. Malignant hyperthermia is a dangerous reaction to certain anesthetics that can rapidly progress and cause rhabdomyolysis, heat production, and metabolic turmoil. When myoglobin appears in the urine, it signals possible ongoing muscle injury and potential MH, so the priority is to evaluate for this crisis rather than discharge or wait for kidney tests to change.

Discharging the patient or relying on creatinine and BUN alone would miss a potentially life-threatening process that requires urgent attention. Normal renal function tests do not rule out early rhabdomyolysis or evolving MH, and they don’t address the underlying crisis. The appropriate course is to assess for malignant hyperthermia and begin immediate management if there is suspicion: stop triggering agents, provide 100% oxygen, prepare for cooling if hyperthermia is present, administer dantrolene, and monitor vitals, urine output, and electrolytes closely to mitigate complications. Early recognition and treatment markedly improve outcomes.