skip to main content

HIT — RACP Adult Medicine MCQ

Instant feedback + full explanation. One question, done properly.

ModerateHaematologyHITRACP Adult Medicine

A 60-year-old man develops thrombocytopenia (platelets 45 × 10⁹/L from baseline 250) on day 8 of unfractionated heparin for DVT. He develops a new PE despite anticoagulation. 4Ts score is 7 (high probability). Anti-PF4/heparin antibodies are positive with positive serotonin release assay. What is the most likely diagnosis?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: A — Heparin-induced thrombocytopenia

Thrombocytopenia developing 5–10 days after heparin initiation with paradoxical thrombosis (new PE), high 4Ts score, and positive anti-PF4/heparin antibodies with confirmatory SRA is diagnostic of HIT type II. All heparin must be ceased immediately and a non-heparin anticoagulant (argatroban or fondaparinux) commenced. Warfarin should not be started until platelets recover.

Reference: ASH – 2018 – HIT Guidelines; eTG Haematology 2024