227: A CASE REPORT ON HEATSTROKE ASSOCIATED WITH SIADH

Abstract

Introduction: Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is known to be associated with central nervous system disorders such as stroke, infectious diseases, trauma, and neoplastic lesions. However, its association with heat stroke has not been reported. In this report, we describe a case of heat stroke complicated with SIADH. Description: A 54-year-old man had no history of heat stroke. He was living in a non-air-conditioned room during a heat wave with temperatures exceeding 35 °C every day. He had been feeling unwell since the previous day and was confined to the toilet in his home since breakfast. A few hours later, he collapsed and had convulsions that led to a call for emergency medical assistance. When he came to the hospital, his convulsions had aborted and his vital signs were: pulse 124 times/min, blood pressure 129/77 mmHg, respiratory rate 30 times/min, SpO2 97% (room air), and rectal temperature 42.0 °C. His level of consciousness had decreased to E1V1M4/GCS. Blood tests showed a mildly elevated inflammatory response and hyponaemia of Na 110.4 mEq/L. CT and MRI scans showed no intracranial lesions. The patient’s loss of consciousness was attributed to heat stroke and hyponaemia. Aggressive cooling and fluid infusion were performed and the patient was admitted in the ICU. Physical examination revealed no dehydration. The laboratory test showed plasma osmolality 244 mOsm/kg, urine osmolality 423 mOsm/kg, urinary Na concentration 99 mEq/L, ADH 43.1 pg/ml, and cortisol 46.8 μg/dl, consistent with a diagnosis of SIADH. The patient serum Na levels recovered to 136.1 mEq/L on the 7th day. On the 11th day, his level of consciousness improved to E4V4M6/GCS, and he was transferred to the hospital for rehabilitation on the 13th day. Discussion: Heat stroke can cause central nervous system (CNS) disorders via unclear mechanisms. It can cause cerebral edema, neuroinflammation, and oxidative stress. Their mechanisms are like those of neuropathy caused by trauma and inflammation, suggesting that heat stroke can cause SIADH. In this patient, heat stroke was complicated by SIADH, rendering the patient severely hyponaemic. In this case, there was no other possible cause of SIADH other than CNS damage due to heat stroke, suggesting an association between heat stroke and SIADH.