**Question:** All are features of haemolytic uremic syndrome, except-

A. Thrombocytopenia
B. Acute renal failure
C. Diarrhoea
D. Hypotension

**Core Concept:** Haemolytic Uremic Syndrome (HUS) is a rare but potentially life-threatening condition characterized by the triad of thrombocytopenia, acute renal failure, and microangiopathic haemolytic anaemia. These features are caused by a microvascular thrombosis involving the kidneys, brain, and other organs due to an underlying cause.

**Why the Correct Answer is Right:** Option D, Hypotension, is not a feature of HUS as it primarily affects the kidneys, causing acute renal failure, rather than the cardiovascular system. The condition primarily results in vasoconstriction and decreased cardiac output, not hypotension.

**Why Each Wrong Option is Incorrect:**

A. Thrombocytopenia (Option A) is a hallmark feature of HUS, due to platelet consumption and destruction in the microvasculature.

B. Acute renal failure (Option B) is a significant component of HUS, caused by microvascular thrombosis and subsequent renal injury.

C. Diarrhoea (Option C) is a common initial symptom, often precedes the development of HUS, but is not exclusive to this condition.

**Clinical Pearl:** Haemolytic Uremic Syndrome is usually a complication of Shiga toxin-producing Escherichia coli (STEC) infection, particularly E. coli O157:H7. Early recognition and management of HUS is crucial, as it can progress rapidly to severe organ dysfunction and death. Treatment focuses on supportive care, with the primary goal being to maintain organ perfusion and prevent complications. In severe cases, extracorporeal membrane oxygenation (ECMO) may be considered as a life-saving measure.

**Correct Answer:** D - Hypotension