A 35-year-old woman presents with sudden severe thrombocytopenia, microangiopathic haemolytic anaemia, neurological symptoms, renal impairment, and fever. ADAMTS13 activity is <10%. This is thrombotic thrombocytopenic purpura (TTP). ADAMTS13 deficiency leads to accumulation of which substrate?

• A Fibrin degradation products causing DIC-like coagulopathy
• B Ultra-large von Willebrand factor (ULVWF) multimers causing platelet agglutination ✓
• C Factor VIII–VWF complexes inhibiting primary haemostasis
• D Complement fragments causing endothelial activation and thrombosis

Explanation

ADAMTS13 is a metalloprotease that cleaves ultra-large VWF (ULVWF) multimers released from endothelial Weibel-Palade bodies. Deficiency (congenital in Upshaw-Schulman, or acquired via IgG inhibitor) allows ULVWF to accumulate, which spontaneously captures platelets and causes widespread platelet-rich microthrombi — the hallmark of TTP. This leads to the pentad: MAHA, thrombocytopenia, neurological symptoms, renal failure, and fever.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.