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I believe the letter writer has misinterpreted my statement on treatment of HIT. Some of that may be due to the column's major focus (wound care); for example, I didn't distinguish type I and type II HIT syndromes because of space constraints. 1, 2


It's not entirely correct to say warfarin is "contraindicated in patients with acute HIT because of the initial prothrombotic effects of warfarin-induced protein C deficiency." Warfarin is contraindicated in acute HIT when it's used as monotherapy.3-5 In fact, initial treatment of HIT should involve, as Ms. Housholder-Hughes notes, the use of either argatroban or lepirudin.


The national guideline, Heparin and Low-Molecular-Weight Heparin: Mechanisms of Action, Pharmacokinetics, Dosing, Monitoring, Efficacy, and Safety, states "warfarin appears to be safe in acute [HIT] when it is given to a patient who is adequately anticoagulated with a drug that reduces thrombin generation in [HIT], such as danaparoid [Orgaran], lepirudin, or argatroban, although it may be prudent to delay starting warfarin therapy until the platelet count has risen above 100 x 109/L." 6 I didn't specifically include these direct thrombin inhibitors' names when discussing the need for heparin cessation and the "initiation of some other form of anticoagulation", perhaps adding to the confusion.




1. Chong BH, Eisbacher M. Pathophysiology and laboratory testing of heparin-induced thrombocytopenia. Semin Hematol 1998;35(4 Suppl 5):3-8; discussion 35-6. [Context Link]


2. Conley K, Letizia M. Heparin-induced thrombocytopenia (HIT). Medsurg Nurs 1999;8(6):355-7. [Context Link]


3. Warkentin TE. Heparin-induced thrombocytopenia: a ten-year retrospective. Annu Rev Med 1999;50: 129-47. [Context Link]


4. Warkentin TE. Limitations of conventional treatment options for heparin-induced thrombocytopenia. Semin Hematol 1998;35(4 Suppl 5):17-25; discussion 35-6. [Context Link]


5. Warkentin TE, Kelton JG. Temporal aspects of heparin-induced thrombocytopenia. N Engl J Med 2001;344 (17):1286-92. [Context Link]


6. Hirsh J, et al. Heparin and low-molecular-weight heparin: mechanisms of action, pharmacokinetics, dosing, monitoring, efficacy, and safety. Chest 2001;119(1 Suppl): 64S-94S. [Context Link]