This document is intended as a guideline only and should not replace sound clinical judgment
Please refer providers to the HIT Powerplan for questions regarding HIT and HIT antibodies as it will walk the provider through the 4T scoring and HIT treatment options.
Also, the Anticoagulation Pharmacist can serve as a resource and should be notified of potential HIT patients via Quantifi and/or a phone call.
Evaluation of HIT
Patients should be evaluated via the Warkentin’s (modified) 4T’s scoring system1
platelet count fall >50%
platelet count fall 30-50%
platelet count fall <30%
CLEAR onset on days 5-10
platelet fall <1 day with prior heparin exposure <30 days
UNCLEAR onset on days 5-10, OR > 10days
Platelet fall < 1day with prior heparin exposure 30-100 days
new confirmed thrombosis
skin necrosis at heparin injection sites acute systemic reaction following heparin administration
non-necrotizing skin lesions at heparin injection sites
Once 2 consecutive aPTTs in range, change to qam aPTT
Labs: daily CBC, chem7
Titration of dose:
Increase rate by 20%
New rate= current rate x 1.2
(1.5-2.5x mean normal)
AT GOAL= NO CHANGE
Hold infusion for 1 hour then restart at 50% less than previous rate
New rate= current rate x 0.5
Warfarin should not be Initiated until platelets recover to baseline or after platelets are >150,000
Recommended treatment duration (not based on strong evidence, usually recommended by Hematology)
If no thrombotic event: 1-3 months
If thrombotic event: 3-6 months
Collaborative practice with Hematology
Hematology should write at least 1 clinical note delineating duration and appropriateness of therapy
Thereafter, they may choose to sign off and turn dosing of medications over the anticoagulation service.
Please direct providers to use the HIT Powerplan in Powerchart. Educational inservice may be required.
Document originated by: Pree Sarangarm, PharmD
Reviewed by: David Garcia, MD; Richard D’Angio, PharmD; Allison Burnett, PharmD
Lo GK, Juhl D, Warkentin TE, Sigouin CS, Eichler P, Greinacher A. Evaluation of pretest clinical score (4 T’s) for the diagnosis of heparin-induced thrombocytopenia in two clinical settings. J Thromb Haemost 2006; 4: 759–65.
Lillo-Le Louët A, Boutouyrie P, Alhenc-Gelas M, Le Beller C, Gautier I, Aiach M, Lasne D. Diagnostic score for heparin-induced thrombocytopenia after cardiopulmonary bypass. J Thromb Haemost 2004; 2: 1882–8.
Cuker A, Arepally G, Crowther MA, Rice L, Datko F, Hook K, Propert KJ, Kuter DJ, Ortel TL, Konkle BA, Cines DB. The HIT Expert Probability (HEP): Score: a novel pre-test probability model for heparin-induced thrombocytopenia based on broad expert opinion. J Thromb Haemost 2010; 8:2642-50.