Korean patients with superwarfarin intoxication and their outcome.

This observational study aimed at evaluating recent superwarfarin intoxication of Korean patients. Ten patients were diagnosed as or highly suspicious for superwarfarin intoxication. Case report forms described by attending hematologists of the patients were collected and analyzed. Bleeding symptoms were varied among the patients. Patients uniformly showed prolonged prothrombin time (PT) and activated thromboplastin time (aPTT) with decreased activity of vitamin K dependent coagulation factors. Positive serum brodifacoum test results in 4 of 5 requested patients contributed to confirmatory diagnosis. Psychiatric interview revealed an attempted ingestion in one patient. High dose vitamin K1 therapy promptly corrected prolonged PT and aPTT, but hasty discontinuation caused repeated bleeding diathesis in 6 patients. Route of intoxication was unknown or not definite among 8 of 10 patients. Three patients had a possibility of environmental exposure considering their occupations: there might be intoxication by transdermal absorption or inhalation. Therefore, high dose and prolonged use of vitamin K1 therapy is necessary for effective detoxification. Further detailed investigation on environmental exposure and efforts to improve availability of the blood level test in clinic are requested.