Clinical Scenario:
A 7-year-old boy develops repeated vomiting and progressive drowsiness several days after recovering from a febrile viral illness. On examination, he is confused and has no focal neurological signs or meningeal irritation. Investigations show:
- Blood glucose: 2.4 mmol/L
- AST/ALT: markedly elevated
- Ammonia: elevated
- Prothrombin time: prolonged
- Serum bilirubin: normal
- CSF: no evidence of infection
Which of the following is the most likely diagnosis?
A. Acute viral hepatitis
B. Acute liver failure due to Wilson disease
C. Reye syndrome
D. Urea cycle disorder
E. Viral encephalitis
Correct answer & Explanation:
Correct answer: C. Reye syndrome
Explanation
Reye syndrome is a rare but serious disorder characterized by acute encephalopathy and hepatic dysfunction, classically occurring in children recovering from a viral infection.
The combination of persistent vomiting, altered consciousness, hypoglycemia, hyperammonemia and markedly elevated transaminases with relatively normal bilirubin is highly suggestive. The absence of evidence for CNS infection further supports the diagnosis.
Reye syndrome has a strong epidemiologic association with salicylate exposure during certain viral illnesses, particularly influenza and varicella. Therefore, a history of aspirin or other salicylate use should be specifically sought.
Management is supportive and requires PICU care, with particular attention to hypoglycemia, cerebral edema, intracranial pressure, coagulation abnormalities and metabolic disturbances. There is no specific antidote for Reye syndrome.
Exam pearl:
Child + viral prodrome + persistent vomiting + encephalopathy + hypoglycemia + hyperammonemia + ↑transaminases + normal bilirubin → think Reye syndrome.
References
- Chapman J, Arnold JK. Reye Syndrome. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan.
- Victorio MC. Reye Syndrome. Merck Manual Professional Edition. Updated December 2025.
You may practice another MCQ on Chronic Diarrhea.
