Which of the following is a risk factor for TTP?

• A. Chemotherapy
• B. Vitamin C deficiency
• C. Low blood pressure
• D. Excess iron

Answer: (A)

Chemotherapy can trigger thrombotic thrombocytopenic purpura by injuring the lining of small vessels and/or promoting immune changes that reduce the activity of ADAMTS13. When ADAMTS13 activity is decreased or inhibited, ultra-large von Willebrand factor multimers accumulate and drive widespread platelet clumping in small vessels. These microthrombi consume platelets and shear red blood cells, leading to the hallmark combination of thrombocytopenia and microangiopathic hemolytic anemia, with possible neurologic and renal involvement.

Other options don’t fit TTP as well: vitamin C deficiency causes scurvy with bleeding and gum issues rather than the microangiopathic process; low blood pressure and excess iron are not established risk factors for TTP.