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, and 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.