SERUM VITAMIN K1 LEVELS AS AN EARLY INDICATOR OF HYPOPROTHROMBINAEMIA ASSOCIATED WITH ANTIBIOTIC THERAPY

Abstract

The prothrombin time is an insensitive indicator of early vitamin K deficiency and serum vitamin K1 levels may correlate with liver stores. A random non-fasting range of serum vitamin K1 was established in 45 healthy adults of 150-1,530 pg/ml (mean 412 pg/ml). Nine well nourished patients, with normal serum vitamin K1 levels, (mean 546, range 310-1,350 pg/ml), maintained normal prothrombin times and factor VII clotting activity throughout 7 days therapy with cefotetan disodium, an NMTT-containing cephalosporin antibiotic. However, 11 of 20 patients with acute intra-abdominal sepsis and an initially normal prothrombin time who underwent emergency surgery, developed a raised prothrombin time (INR 1.4-3.1) associated with reduction in factor VII activity (0.74 to 0.38 iu/ml) after 3-7 days of antibiotic therapy and the presence of PIVKA II by crossed-immunoelectrophoresis. Nine of these 11 patients had clinical evidence of malnutrition by anthropometric assessment and subnormal serum vitamin K1 (mean 119, range 43-354 pg/ml) levels on admission. Seven received cefotetan but 4 were treated with other non-NMTT containing antibiotics. The 9 patients who maintained normal prothrombin times and factor VII levels had normal nutritional status and normal serum vitamin K1 levels (mean 279, range 103-915 pg/ml) at presentation. A low serum vitamin K1 level was associated with a high incidence of hypopro-thrombinaemia developing following antibiotic therapy and would appear a more sensitive indicator of reduced vitamin K stores than the prothrombin time.