Superwarfarin poisoning

Abstract

Background: Superwarfarin sodium exposure or poisoning is a growing public health problem. There were 5133 reported cases of superwarfarin exposure and poisoning in 1988 and 13 423 cases in 1995. Cases may be associated with accidental exposure, suicide attempts, or Munchausen syndrome, and may be difficult to diagnose.

Patients and methods: Patients from northern Wisconsin with superwarfarin exposure or poisoning were examined at a tertiary referral center in rural Wisconsin to determine what led to their exposure and to review the clinical manifestations, diagnosis, treatment, and prevention of superwarfarin poisoning.

Results: Eleven cases satisfied the criteria for superwarfarin exposure or poisoning. All 7 children included in the study had accidentally ingested superwarfarin, 2 adults had Munchausen syndrome, and 1 teenager and 1 adult had attempted suicide using superwarfarin. Nine of the 11 cases had taken brodifacoum. The patients who had accidentally ingested superwarfarin or attempted suicide using it were easily diagnosed, while diagnosis was markedly delayed for the 2 patients with Munchausen syndrome. Full reversal of anticoagulation was quickly achieved in the cases of accidental ingestion and attempted suicide. We examined and treated the patients with Munchausen syndrome for months before establishing a diagnosis and fully reversing the anticoagulation. None of the patients in our study died of superwarfarin poisoning.

Conclusions: Superwarfarin exposure or poisoning is a growing public health problem that should be part of the differential diagnosis of patients who present with a coagulopathy consistent with vitamin K deficiency in the absence of coumadin therapy, liver disease, or the use of an inhibitor, and whose conditions do not resolve with large doses of parenteral vitamin K1 therapy.