**Question:** All of the following feature may be seen in thrombotic thrombocytopenic purpura, except -

A. Haemolytic anaemia
B. Renal impairment
C. Encephalopathy
D. Hypotension

**Correct Answer:** .

**Core Concept:**
Thrombotic thrombocytopenic purpura (TTP) is a rare, life-threatening disorder characterized by microangiopathic haemolytic anaemia, thrombocytopenia, and renal impairment due to the deficiency of a plasma enzyme called ADAMTS13. ADAMTS13 is responsible for cleaving von Willebrand factor multimers, preventing the formation of large von Willebrand factor multimers and platelet aggregates in the microvasculature. When ADAMTS13 is deficient, these large von Willebrand factor multimers cannot be cleaved, leading to platelet aggregation and microvascular thrombosis.

**Why the Correct Answer is Right:**
In TTP, the deficiency of ADAMTS13 results in the accumulation of large von Willebrand factor multimers, which promote platelet aggregation and microvascular thrombosis. This leads to the clinical manifestations seen in TTP, such as haemolytic anaemia, thrombocytopenia, and renal impairment.

**Why Each Wrong Option is Incorrect:**
A) Hypotension is not a typical clinical presentation of TTP. TTP primarily affects the microvasculature, leading to organ dysfunction, but hypotension is a more severe circulatory collapse resulting from severe vasodilation or hypovolemia.

B) Hypotension is not a typical clinical presentation of TTP. As explained earlier, TTP primarily affects the microvasculature leading to organ dysfunction, but hypotension is a more severe circulatory collapse resulting from severe vasodilation or hypovolemia.

C) Encephalopathy is a neurological manifestation of TTP, characterized by confusion, seizures, and coma. In contrast, hypotension is a circulatory manifestation and does not fit the core features of TTP.

D) Hypotension is not a typical clinical presentation of TTP. As explained earlier, TTP primarily affects the microvasculature leading to organ dysfunction, but hypotension is a more severe circulatory collapse resulting from severe vasodilation or hypovolemia.

**Clinical Pearl:**
TTP is a critical clinical diagnosis requiring a high index of suspicion, as it is often misdiagnosed as sepsis or DIC. The diagnostic criteria for TTP include the presence of microangiopathic haemolytic anaemia, thrombocytopenia, and organ dysfunction (typically kidney, liver, and CNS).

**Explanation:**

TTP is a rare but potentially life-threatening disease characterized by the accumulation of von Willebrand factor (vWF) multimers in the microvasculature. These vWF multimers cause platelet adhesion and aggregation, leading to microvascular thrombosis and organ dysfunction. The typical clinical presentation includes microangiopathic haemolytic anaemia, thrombocytopenia, and organ dysfunction (usually affecting kidney, liver, and central nervous system).

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