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Update in Hematology
- Geraldine P. Schechter, MD;
- Harish P.G. Dave, MD; and
- Barbara M. Alving, MD
- From Veterans Affairs Medical Center and George Washington University, Washington, D.C.; and National Institutes of Health, Bethesda, Maryland.
2000-2001 Series: Update Sessions from ACP-ASIM's 2000 Annual Session
Margaret Ring Gillock, Editor; David Cramer, MD, Co-Editor; and Paul T. Kefalides, MD, Co-Editor
In selecting the articles for this Update, we found that the topics that generated the most attention in the past year were the newer concepts in anticoagulation, thrombosis, hemostasis, transfusion therapy, hemochromatosis, and novel therapies for hematologic malignancy. In each of these areas, new findings have provided better ways to treat patients.
Anticoagulation
Clinical research in anticoagulant therapy has left many questions unanswered. The articles we have chosen suggest answers to such questions as, What is the correct daily dose of warfarin? How long should a patient continue to receive anticoagulants? Which patients should undergo prophylactic anticoagulation? The answers help to make the practice of hematology more effective and predictable.
Warfarin Dose Requirement Is Influenced by the Genes
Variations in the rate of response to a given dose of warfarin have been problematic. Effective daily doses can range from as low as 0.5 mg to higher than 60 mg. In an effort to make sense of the puzzle, Aithal and colleagues conducted a case–control study to determine whether genetic differences in the cytochrome P450 system influence the individual variability in dose requirements for warfarin. An asymmetric carbon in warfarin (C9) produces the enantiomers R-warfarin and S-warfarin, which are metabolized by different enzymes. S-warfarin, which is three times more potent than R-warfarin, is metabolized by the cytochrome P450 CYP2C9. The authors used polymerase chain reaction to evaluate the two allelic forms of CYP2C9 that have only 5% and 12% of the activity of the wild-type enzyme in patients with low-dose warfarin requirements (≤ 1.5 mg/d; n = 36), those with normal dose requirements who were being treated in an anticoagulation clinic (clinic controls; n = 52), and normal persons (n = 100).
The odds ratio for having one or more …
This 100-word excerpt has been provided in the absence of an abstract.
