# Rapidly Progressive Disseminated Intravascular Coagulation (DIC) in Severe Fatal Heatstroke: A Diagnostic Challenge Despite Normal Initial Coagulation Tests

## TL;DR

A man with schizophrenia and heatstroke developed fatal DIC rapidly, despite normal initial blood tests, highlighting the need for early detection and better monitoring.

## Contribution

This case highlights the diagnostic challenge of DIC in heatstroke with initially normal coagulation tests.

## Key findings

- DIC developed rapidly in a heatstroke patient despite normal initial coagulation tests.
- Fibrin degradation products and fibrinogen levels were highly indicative of DIC progression.
- Aggressive treatment failed to prevent multi-organ failure and death in this case.

## Abstract

This case report describes a fatal case of rapidly progressing disseminated intravascular coagulation (DIC) in a 50-year-old male with schizophrenia following severe classic (non-exertional) heatstroke. The patient, who was receiving antipsychotic medications (risperidone and olanzapine), presented with profound hyperthermia (41.7°C) and altered consciousness. Despite initial standard coagulation tests (prothrombin time (PT), activated partial thromboplastin time (APTT), and international normalized ratio (INR)) being within the normal range, overt DIC developed within three hours. This was characterized by a sharp decline in platelet count (from 28,000 to 6,000/µL), prolonged PT (from 12.6 to 39.2 seconds) and APTT (from 23.2 to 100.6 seconds), a marked increase in fibrin degradation products (FDP) (from 4.41 to 1,282 µg/mL), and fibrinogen depletion (from 339 mg/dL to below the measurement threshold), all consistent with overt DIC. The Japanese Association for Acute Medicine (JAAM) DIC score rapidly increased from 1 to 7. This deterioration coincided with the onset of acute kidney injury and hepatic dysfunction, supporting the hypothesis that heatstroke-induced coagulopathy has systemic effects. Despite aggressive treatment, including fluid resuscitation, extracorporeal cooling, vasopressors, blood product transfusion, antithrombin administration, and continuous hemofiltration, the patient succumbed to multi-organ failure 32 hours after admission. This case highlights the need for a high index of suspicion for DIC in severe heatstroke, even when initial coagulation tests appear normal. It also emphasizes the importance of early and continuous monitoring with more sensitive biomarkers, such as FDP, fibrinogen, and point-of-care viscoelastic testing (thromboelastography (TEG)/rotational thromboelastometry (ROTEM)). Early detection, rapid pre-hospital resuscitation, and targeted interventions are crucial to preventing progression to multi-organ failure. Future research should prioritize validating early diagnostic markers of heatstroke-induced DIC and developing specific therapeutic strategies.