Impaired hemostasis and platelet function in rats fed low zinc diets based on egg white protein.

Zinc-deficient rats exhibit impaired hemostasis, a pathological sign related to defective platelet function. The original observation was made in rats fed a low zinc diet based on soy protein. The present study was designed to test the effect of feeding a low zinc, egg white-based diet on bleeding time and platelet aggregation. The reversibility of the defect and the response of washed platelets from rats fed low zinc (less than 1 mg/kg) and control (100 mg/kg) diets were also assessed. Immature male rats were fed the respective diets for 11 d, the controls being both ad libitum- and pair-fed. To test reversibility, rats depleted for 11 d were then fed the control diet for an additional 7 d. Saline bleeding time was increased, and aggregation of platelet-rich plasma (PRP) from rats of low zinc status was impaired. The rate of the secondary phase of aggregation was significantly less than that of controls, but it was not different from that of controls after 7 d of zinc repletion. Aggregation of washed platelets was also impaired by low zinc status, showing that the defect is associated with the platelet, not the plasma. Egg white as a source of protein in the low zinc diet resulted in abnormal hemostasis and platelet aggregation, including a defective response of washed platelets.