This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pediatrics
A 8 yr old boy presents with petechie, azotemic oligurea altered sensorium in casualty. There is history of diarrhoea for the past 5 days. The clinical diagnosis is - 
Select and explain. 
A. Acute prophyria, B. Idiopathic thrombocytopenic purpura, C. H.S. purpura, D. H.U.S.
A: Acute prophyria
Answer: A: Acute prophyria 
Explanation: Ans. is 'a' i.e., Hemolytic uremic syndrome The boys is suffering from hemolytic uremic syndrome. Hemolytic uremic syndrome HUS is characterized by the triad of - 1) Anemia (microangiopathic hemolytic anemia) 2) Renal failure (microangiopathy of kidney involving glomerular capillaries and aerioles). 3) Thrombocytopenia (due to platelet destruction) o HUS is common in children under 2 years of age. (But may also occur in older children). o It usually follows an episode of acute gastroenteritis. o The prodrome is usually of abdominal pain, diarrhoea and vomiting. Sholy thereafter, signs and symptoms of acute hemolytic anemia, thrombocytopenia and acute renal failure ensue. o Sometimes neurological findings also occur (But usually absent and differentiates HUS from TTP).