CALCITROPIC HORMONES AND OCCUPATIONAL LEAD-EXPOSURE

The authors sought to clarify in a cross-sectional study the possible associations between homeostatic regulators of calcium and occupationa l exposure to lead. Subjects were 146 industrial male employees, 56 wi th and 90 without occupational lead exposure. The main outcome measure s were serum concentration of parathyroid hormone (PTH) and 1,25-dihyd roxyvitamin D (calcitriol). The median values of blood lead were 40.5 mu g/dl in the exposed group and 4.0 mu g/dl in the controls. There we re no differences between groups in dietary history and serum calcium levels, PTH and calcitriol levels were significantly higher in the exp osed than in the nonexposed subjects (42.0 +/- 24.2 vs. 33.6 +/- 14.9 pg/ml, p <0.05; and 83.8 +/- 27.0 vs. 67.9 +/- 17.6 pmol/liter, p <0.0 01, respectively), Multivariate analyses showed that after controlling for possible confounders, occupational lead exposure (no/yes) was ind ependently associated with PTH level (pg/ml) (beta = 7.81,95% confiden ce interval (Cl) 3.7-11.5) and with calcitriol (pmol/liter) (beta = 12 .3, 95% Cl 3.84-20.8). It is concluded that subjects occupationally ex posed to lead show a substantial compensatory increase in PTH and calc itriol activities which keep serum calcium levels within normal range. This may be of clinical significance since a sustained increase in ca lcitropic hormones in susceptible subjects may eventually increase the risk of bone disorders.