There is a narrow line between the benefits and risks of anticoagulant ther
apy. Many factors influence a patient's response to warfarin, and careful m
onitoring is required to ensure that the therapeutic level of anticoagulati
on is achieved. The purpose of this retrospective review was to examine the
relationship between the postoperative response to warfarin and the preope
rative level of haemoglobin. The results showed that lower preoperative lev
els of haemoglobin are associated with an increased response to warfarin (p
= 0.01).