Extremely Elevated International Normalized Ratio of Warfarin in a Patient with CYP2C9*1/*3 and Thyrotoxicosis.
10.3346/jkms.2014.29.9.1317
- Author:
Ji Eun LEE
1
;
Duck Hyun RYU
;
Ho Jung JEONG
;
Jung Hoon KIM
;
Ji Eun JUN
;
June Soo KIM
;
Soo Youn LEE
Author Information
1. Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea. juneskim@skku.edu
- Publication Type:Case Reports
- Keywords:
Warfarin;
International Normalized Ratio;
Thyrotoxicosis;
Genotype
- MeSH:
Aged;
Anticoagulants/blood/metabolism/therapeutic use;
Aspirin/therapeutic use;
Atrial Fibrillation/*diagnosis;
Chromatography, High Pressure Liquid;
Cytochrome P-450 CYP2C9/*genetics;
Genotype;
Humans;
Male;
Polymorphism, Single Nucleotide;
Tandem Mass Spectrometry;
Thromboembolism/prevention & control;
Thyrotoxicosis/*diagnosis;
Vitamin K Epoxide Reductases/genetics;
Warfarin/*blood/metabolism/therapeutic use
- From:Journal of Korean Medical Science
2014;29(9):1317-1319
- CountryRepublic of Korea
- Language:English
-
Abstract:
A 73-yr-old Korean man with permanent atrial fibrillation visited outpatient clinic with severely increased International Normalized Ratio (INR) values after taking a usual starting dosage of warfarin to prevent thromboembolism. We found out later from his blood tests that he had hyperthyroidism at the time of treatment initiation. His genetic analysis showed CYP2C9*1/*3 and VKORC1+1173TT genotypes. We suspect that both hyperthyroidism and genetic variant would have contributed to his extremely increased INR at the beginning of warfarin therapy. From this case, we learned that pharmacogenetic and thyroid function test might be useful when deciding the starting dosage of warfarin in patients with atrial fibrillation.
