Heat Illness- Running

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HISTORY: A 14 year-old highly competitive runner presented to our sports medicine clinics one week after collapsing during his first 10 km race in a hot and humid climate. His goal was to achieve a time similar to adult elite runners. He felt dizzy but did not want to slow down. At 8 km he was seen disoriented and stumbling and soon after collapsed. He was taken unconscious to a local ER, where IV hydration was given. After ~25 min he regained consciousness but was disoriented and irrational. He did not remember having collapsed or transport to the ER. After ~two hours he was alert and felt better, and was discharged. Upon arrival to his home he showered with cold water. He reported a mild sore throat the day before and leg pain after the race. PHYSICAL EXAMINATION: Normal vital signs (BP: 116/68; HR: 68 bpm), alert, does not remember details of race. Normal cardiovascular, pulmonary, musculoskeletal and neurological exam. DIFFERENTIAL DIAGNOSIS: 1. Syncope associated to dehydration 2. Syncope associated to hypoglycemia 3. Rhabdomyolysis 4. Syncope associated to exertional heat stroke TEST AND RESULTS: In ER: According to the athlete’s parents: his blood pressure was low, body temperature was not measured nor any blood analysis performed. He was discharged with a diagnosis of “dehydration”. Two days after discharge from ER his primary care physician ordered urinalysis and CBC: Blood and protein trace in urine; Blood glucose=84 mg/dL; Creatinine=0.94 mg/dL; Na+= 142 and K+= 4.7 mmol/L; AST: 1,923 and ALT: 1,996 U/L. CK was not ordered. At 9 days: AST: 100 and ALT: 424 U/L; CK ordered but not done. At 16 days: AST: 55 and ALT: 170 U/L; CK=151 U/L Five weeks after discharge from ER: Heat Tolerance Test (running outdoors @ 12.8 to 13.8 km/hr in 32°C, 75% RH). Test stopped at 40 min when Tc= 39.3°C. HR=145-173 bpm. Sweat rate=1.8 L/h; Fluid replaced=16% Dehydration=1.9%; Rating of hot/overheated= 8 and thirst= 8 (0-10 scale). FINAL /WORKING DIAGNOSIS: Exertional heat stroke related to inadequate heat acclimatization. TREATMENT AND OUTCOMES: 1. Allowed to swim and run in cool environment after 2 weeks at reduced pace but no running in the heat for 5 weeks. 2. Recommendations about proper hydration and gradual heat exposure to acclimatize to heat. 3. Referred to sports psychologist. 4. Repeat heat tolerance test for clearance to compete in the heat.