A patient with heatstroke associated with consciousness disturbance secondary to hyponatremia: a case report

INTRODUCTION Little information is available on the pathogenesis of heatstroke without strenuous exercise in younger patients. Here, we report the case of a 31-year-old man who developed heatstroke secondary to hyponatremia. His condition was initially misdiagnosed as classic heatstroke. We hope the detailed description of our patient's case will provide valuable information for medical professionals faced with similar cases in the future. CASE PRESENTATION A 31-year-old Japanese man who was regularly taking anti-hypertensive agents, including a thiazide, was admitted to our hospital owing to consciousness disturbance and a high-grade fever. A thorough examination revealed mild renal dysfunction, rhabdomyolysis, a hyper-coagulable state, and severe hyponatremia (114mEq/L). Because he worked in a hot environment, an initial diagnosis of heatstroke was established. His general condition improved rapidly with supportive measures, and he was discharged on the fourth day after admission. Interestingly, he did not recognize feeling hot while working in a hot environment. These findings suggest that the consciousness disturbance, which was probably attributable to acute hyponatremia caused by the thiazide, preceded the onset of the heatstroke. CONCLUSIONS Clinicians should consider the presence of underlying diseases, especially consciousness disturbance, when younger individuals develop heatstroke in the absence of strenuous exercise.