What improves first in TTP in response to successful treatment with plasma exchange?

• A. Renal function
• B. Platelet count
• C. Hemolysis
• D. Neurological symptoms

Answer: (D)

The fastest change you’d expect after successful plasma exchange for TTP is a rise in the platelet count. Plasma exchange removes the autoantibodies against ADAMTS13 and replenishes the enzyme, which quickly halts the formation of ultra-large von Willebrand factor–mediated platelet aggregates. As these microthrombi form fewer platelets are consumed, so the platelet count rebounds promptly—often within days.

Hemolysis markers and schistocytes start to improve as the microangiopathy resolves, and renal function or neurological symptoms may take longer to normalize. In fact, neurological symptoms can persist even after platelets have recovered, depending on the extent and duration of microvascular injury. Hence, the earliest sign of improvement is the platelet count rising.