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

A. Hemolytic anemia
B. Thrombocytopenia
C. Microangiopathic hemolytic anemia
D. Acute renal failure

**Correct Answer:** **Option A: Hemolytic anemia**

In thrombotic thrombocytopenic purpura (TTP), the key features involve microangiopathic hemolytic anemia (C), thrombocytopenia (B), and acute renal failure (D). While hemolytic anemia (A) is a common feature in TTP, it is not unique to this condition among the given options.

**Core Concept:**
Thrombotic thrombocytopenic purpura (TTP) is a rare, life-threatening disorder caused by deficiency or ineffectiveness of a plasma enzyme called ADAMTS13 (A Disintegrin and Metalloproteinase with a thrombospondin type 1 motif, member 13). ADAMTS13 is responsible for cleaving a blood protein called von Willebrand factor (vWF), which is essential for maintaining the structural integrity of blood vessels.

**Why the Correct Answer is Right:**
In TTP, the deficiency or ineffectiveness of ADAMTS13 results in uncontrolled cleavage of vWF, leading to the formation of large multimers of vWF. These large vWF multimers accumulate in the blood vessels, causing platelet aggregation and thrombosis. The platelet aggregation and thrombosis lead to microangiopathic hemolytic anemia, characterized by fragmented red blood cells (schistocytes) on blood smear examination. Thrombocytopenia is due to platelet destruction in the microvasculature, while acute renal failure is a consequence of the widespread thrombosis in the microvasculature of the kidneys.

**Why Each Wrong Option is Incorrect:**

**Option B: Thrombocytopenia**
Thrombocytopenia is a common feature in TTP but is not unique, as it can be seen in other conditions as well, such as:

1. Sickle cell anemia
2. Chronic hemolysis (e.g., in hemolytic uremic syndrome)
3. Splenomegaly

**Option C: Microangiopathic hemolytic anemia**
Microangiopathic hemolytic anemia (option C) is a specific feature of TTP. It is characterized by the presence of fragmented red blood cells (schistocytes) on a blood smear. However, this option is not unique to TTP, as other conditions such as:

1. Hemolytic uremic syndrome (HUS)
2. Hemolytic anemia related to severe bleeding disorders
3. Hemolytic anemia due to toxin-induced damage

**Option D: Acute renal failure**
Acute renal failure (option D) is a common feature in TTP, but is not unique, as it can be seen in:

1. Acute tubular necrosis (ATN)
2. Acute glomerulonephritis
3. Acute interstitial