Risks of HIT

Q: Which of the following patients has the highest risk of Heparin-Induced Thrombocytopenia (HIT)? - select one

A) Medical patients receiving Low Molecular Weight (LMW) heparin

B) Obstetric patients receiving Unfractionated Heparin (UFH)

C) Major surgery patients receiving LMW heparin

Answer: C

Although not written on the stone, usually patients receiving Heparin - either UF or LMW - are divided into three categories for the risk of developing HIT.

Low (less than 0.1%)

• Medical or obstetric patients receiving LMW heparin
• Minor surgery or minor trauma patients receiving LMW heparin
• Patients receiving fondaparinux or an anticoagulant not associated with the development of HIT

Intermediate (less than 0.1 to 1%)

• Medical or obstetric patients receiving UFH
• Major surgery or major trauma patients receiving LMW heparin

High (more than 1%)

• Major surgery or major trauma patients receiving UFH

- Low-risk patients do not require monitoring.

- Intermediate and high-risk patients require monitoring every 2-3 days from day 0 to day 14

Also, the risk of HIT is higher for therapeutic dose UFH than for lower doses, which include heparin flushes.

#hematology

#pharmacology

References:

1. Cuker A, Arepally GM, Chong BH, et al. American Society of Hematology 2018 guidelines for management of venous thromboembolism: heparin-induced thrombocytopenia. Blood Advances 2018; 2:3360.

2. Hogan M, Berger JS. Heparin-induced thrombocytopenia (HIT): Review of incidence, diagnosis, and management. Vasc Med. 2020 Apr;25(2):160-173. doi: 10.1177/1358863X19898253. Epub 2020 Mar 20. PMID: 32195628.