All of the following feature may be seen in thrombotic thrombocytopenic purpura, except :
**Thrombotic Thrombocytopenic Purpura (TTP) Core Concept**
Thrombotic thrombocytopenic purpura (TTP) is a rare blood disorder characterized by the formation of blood clots (thrombi) in small blood vessels throughout the body. This leads to a decrease in platelet count (thrombocytopenia) and the presence of microangiopathic hemolytic anemia, which is a condition where red blood cells are destroyed due to mechanical damage.
**Why the Correct Answer is Right**
TTP is caused by a deficiency of the enzyme ADAMTS13, which is responsible for cleaving von Willebrand factor (vWF). In its uncleaved form, vWF promotes platelet adhesion and aggregation, leading to the formation of microthrombi. The clinical manifestations of TTP include thrombocytopenia, microangiopathic hemolytic anemia, renal failure, fever, and neurological symptoms. The diagnosis is often made by laboratory tests, including a low ADAMTS13 activity level and the presence of schistocytes (fragmented red blood cells) on a blood smear.
**Why Each Wrong Option is Incorrect**
**Option A:** Hemolytic uremic syndrome (HUS) is a similar condition to TTP, but it typically occurs in children and is caused by Shiga toxin-producing E. coli. While HUS shares some clinical features with TTP, it is not a characteristic feature of the disease.
**Option B:** Renal failure is a common complication of TTP, as the microthrombi can cause damage to the kidneys. Therefore, this option is not correct.
**Option C:** Fever is a common symptom of TTP, so this option is also not correct.
**Clinical Pearl / High-Yield Fact**
TTP is often associated with other conditions, such as pregnancy, autoimmune disorders, and malignancies. Patients with TTP may also have a history of previous episodes or family members with a similar condition.
**Correct Answer: A. HUS is a condition that is similar to TTP but is typically caused by Shiga toxin-producing E. coli and occurs in children.**