The influence of high concentrations of dietary copper on vitamin K-dependent coagulation factors

It has been shown that high concentrations of some copper complexes can inhibit in vitro the vitamin K-dependent carboxylation of specific glutamic residues. The present study was conducted in order to determine whether high levels of dietary copper would affect the circulating levels of blood clotting factors. Rats fed for 7 weeks purified diets containing 10 (control), 100, 1000, or 2000 μg/g Cu had liver copper concentrations of 4, 4, 67, and 603 μg/g Cu, respectively. The severity of the toxicity of the 2000 μg/g Cu diet was evidenced by four deaths in this diet group. Despite the severity of the copper toxicity, values for one-stage prothrombin, activated partial thromboplastin, and Russell's Viper Venom times were similar for all groups. In addition, dietary copper level had no effect on the circulating levels of the specific vitamin K-dependent coagulation factors II, VII, IX, and X. These data provide evidence that an impairment in the blood clotting cascade is not a characteristic of dietary copper toxicosis.