The Curious Clinicians 109 - The HITs Keep Coming
May 28, 2025
This discussion delves into the complexities of heparin-induced thrombocytopenia (HIT) and why it affects only some patients. The journey of heparin from discovery to clinical use highlights its unique properties. Surprising links between spontaneous HIT and knee surgeries reveal intricate molecular dynamics. The ongoing exploration of heparin's role in the body ties in evolutionary history and modern sourcing challenges. Insights into antibody formation and the body’s management of heparin levels deepen the understanding of this rare condition.
AI Snips
Chapters
Transcript
Episode notes
Endogenous Heparin Levels Prevent HIT
- Our bodies produce endogenous heparin but at very low concentrations compared to therapeutic doses.
- This explains why spontaneous heparin-induced thrombocytopenia (HIT) is rare despite our own heparin production.
Knee Surgery Triggers Spontaneous HIT
- Spontaneous HIT occurs mainly after total knee arthroplasty without heparin exposure.
- Negatively charged molecules from the knee likely mimic heparin and bind PF4, triggering HIT-like reactions.
Glycosaminoglycans Mimic Heparin
- Glycosaminoglycans like chondroitin and hyaluronic acid are negatively charged molecules in the knee.
- They may bind platelet factor 4 similarly to heparin, explaining spontaneous HIT after knee surgery.