Abstract
The present study was undertaken to determine the effect of chronic fluoride toxicity on calcium metabolism. Rabbits (n = 10) were orally administered an aqueous solution of 10 mg NaF/kg body wt daily for 18 months. Equal numbers (n = 10) of age-, sex- and weight-matched rabbits kept under identical laboratory conditions, but not treated, with NaF solution, served as control. The fasting plasma calcium concentrations of fluoride-treated rabbits were significantly lower (P < 0.001) than those of control animals. In contrast to the decrease in plasma calcium level, an increase in intestinal radioactive calcium (45Ca) absorption was observed (P < 0.001) in all fluoride-treated animals. However, urinary calcium excretion levels were found to be reduced (P = not significant) in fluoride-treated rabbits. It is therefore concluded that long-term fluoride poisoning alters the calcium homeostatic mechanism, thereby affecting calcium metabolism.