Written by Mary Marschner
Spoon Feed
For patients with low platelets, check for hemolytic anemia to catch immune thrombotic thrombocytopenic purpura (iTTP, also called TTP). Order ADAMTS13 prior to treatment to make hematology happy; treatment with high-dose steroids, plasma exchange, rituximab, and caplacizumab achieves >90% survival at 30 days.
ADAM and iTTP
iTTP remains rare (2-6 cases per million) and is caused by ADAMTS13 antibody. ADAMTS13 usually cleaves vWF and, when inactivated, causes microangiopathic hemolytic anemia. The chief complaint is variable (i.e. almost anything), and can include headache, confusion, vision changes, nausea, vomiting, or diarrhea. Identification of low platelets or hemolytic anemia (elevated LDH, elevated indirect bilirubin, high reticulocytes, low haptoglobin, negative Coombs, schistocytes on smear) is crucial to early diagnosis and treatment.
This JAMA review summarizes current understanding of iTTP pathophysiology, epidemiology, diagnosis, and treatment strategies. Combination therapy with plasma exchange, corticosteroids, and rituximab achieves over 90% 30-day survival. Adding caplacizumab accelerates platelet recovery and reduces recurrences during treatment but increases bleeding risk. Monitoring ADAMTS13 activity during remission and administering rituximab when levels fall below 20% significantly lowers relapse risk (OR 0.09; 95%CI 0.04–0.24).
How does this change my practice?
This is a nice review of iTTP, which I only see every few years. It reminded me to make order ADAMTS13 and consult hematology early to start high-dose steroids, plasma exchange, and rituximab. It also introduced me to caplacizumab, which was a new therapy for me.
Source
Immune Thrombotic Thrombocytopenic Purpura: A Review. JAMA. 2025 May 19. doi: 10.1001/jama.2025.3807. Epub ahead of print. PMID: 40388146
