Question 1

How do you remember Heparin?

Accepted Answer

Heparin breaks down as HEP = hep + A-RIN = antithrombin rinse. Break heparin into HEP, A, and RIN. HEP means hep to it, fast, because heparin works in seconds. The A is antithrombin, the protein heparin activates. RIN is rinse: the activated antithrombin rinses out your blood vessels so no clot can form. Hep for fast, A for antithrombin, Rin for rinse clotting factors.

Question 2

What class of drug is Heparin?

Accepted Answer

Heparin is a Antithrombin Activator • Immediate Anticoagulant • IV.

Question 3

How is Heparin tested on the USMLE?

Accepted Answer

Heparin binds antithrombin and accelerates it, which inactivates thrombin (factor IIa) and factor X. It works by IV and is monitored with PTT, unlike warfarin, which takes days and is monitored with PT/INR.

Question 4

A 54-year-old man with a pulmonary embolism is started on IV heparin. Despite escalating doses over 24 hours, his PTT fails to rise above baseline. What underlying problem should be suspected?

Accepted Answer

A - Heparin has no direct anticoagulant activity of its own. It works by binding antithrombin and accelerating it, so a patient deficient in antithrombin will not respond no matter how much heparin is given. B describes warfarin's pathway, C is not a real clinical scenario, and D causes activated protein C resistance rather than heparin resistance.

Heparin

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