A 62-year-old man who presented with gross hematuria was found to have a severe and prolonged coagulopathy. The workup involved mixing studies, which suggested an acquired factor deficiency, and specific factor assays, which demonstrated isolated defects in vitamin K—dependent factors. With vitamin K deficiency excluded, and serum warfarin levels undetectable, so-called superwarfarin ingestion was suspected. This diagnosis was subsequently proved by biochemical evidence (an increase in the serum vitamin K epoxide—vitamin K ratio) and compatible history. This case illustrates how a logical workup can lead to a diagnosis of superwarfarin ingestion, even without a history of such an ingestion. New serum assays for specific superwarfarins are also mentioned. This case report should increase clinicians' awareness of long-acting rodenticide ingestions.
(Arch Intern Med. 1992;152:410-412)