Factors Influencing Warfarin Requirements

We carried out a retrospective medical chart survey to clarify the effects of various patient factors on warfarin dose requirements. Age, body weight, biochemical data and daily warfarin dose were recorded for 332 outpatients stabilized on warfarin. We found that there was a negative correlation between age and therapeutic warfarin dose (r=-0.3089, p<0.01, n=332), and positive correlations between body weight and therapeutic warfarin dose (r=0.1623, p<0.05, n=213) and lactate dehydrogenase (LDH) concentration and therapeutic warfarin dose (r= 0.2071, p<0.01, n=328).The mean serum LDH levels in patients with and without valve prostheses were 561.82 ± 151.06 and 393.61 ± 113.66 IU/L, respectively (p<0.01), suggesting the release of LDH due to red cell hemolysis in patients with valve prostheses. Moreover, the correlation coefficient between LDH concentration and therapeutic warfarin dose in patients with valve prostheses was higher than that in patients without valve prostheses, such greater correlation between LDH concentration and warfarin dose also indicating warfarin-induced release of LDH from red blood cellsin patients with valve prostheses.