Supportive and Preventive Medicine

Initiate warfarin once the Plt has recovered and is within normal limits (at least 150,000/mm3)

and after at least 5 days of therapy with an alternative parenteral anticoagulant. Alternatively,

conservative warfarin dosing may begin once the Plt is recovering. If a patient is receiving warfarin

at the time of HIT diagnosis, reversing with vitamin K is recommended.

Initiation of warfarin before Plt recovery increases the risk of thrombotic complications because

of depletion of protein C in the setting of HIT.

supporting DOACs for HIT are limited to case series and small observational cohort studies

DOACs are a recommended therapeutic option in the American Society of Hematology 2018

guidelines for VTE management in HIT.

Most of the published data for DOAC use in HIT is with rivaroxaban (Blood Adv. 2018;2(2):3360-

3392); however, DOAC selection should be based on patient- and drug-specific factors.

ii.

Varying dosing strategies have been described based on the presence of thrombosis and/or

platelet recovery

Argatroban

Bivalirudin

Fondaparinux

FDA approved for the

treatment of HIT

Yes

Yes (percutaneous coronary

intervention with HIT)

No

Mechanism of action

Direct thrombin inhibitor

Direct thrombin inhibitor

Factor Xa inhibitor

Elimination half-life

40–50 min

25 min

17–20 hr

Elimination

Hepatobiliary

80% enzymatic

20% renal

Renal

Dosing

2 mcg/kg/min

(see above for dosing in the

critically ill population)

Unlabeled dose for HIT:

0.15–0.2 mg/kg/hr

(see above for dosing in the

critically ill population)

Unlabeled dose for HIT:

< 50 kg, 5 mg SC daily;

50-100 kg, 7.5 mg SC daily;

> 100 kg, 10 mg SC daily

Monitoring

aPTT

aPTT

Anti-Xa concentration

INR elevation

Excessive

Moderate

None

aPTT = activated partial thromboplastin time; HIT = heparin-induced thrombocytopenia SC = subcutaneous(ly).