Effects of hyperparathyroidism on blood lead concentrations in man

To investigate whether hyperparathyroidism has an effect on blood lead (Pb) concentrations and whether parathyroidectomy will alter blood Pb concentrations, we studied 15 subjects with primary hyperparathyroidism (HPTH) and 7 control subjects with thyroid nodules (TC). Blood Pb concentrations were determined several weeks prior to surgery and then again 4 months later. A reference group (REF) of nonsurgical lab/office workers was examined over the same periods of time. Initial mean blood Pb concentrations were 6.6 +/- 2.8, 6.0 +/- 2.9, and 5.0 +/- 1.7 micrograms/dl for the HPTH, TC, and REF groups (not significantly different), respectively. The mean percentage changes in blood Pb (before vs after) were -13.9, -4.9, and -6.1%. While the paired changes in blood Pb concentrations within the HPTH group were significant (P < 0.05), the percentage changes compared to either of the TC or REF groups were not significantly different. The percentage change in blood Pb correlated with the percentage change in serum calcium across all subjects (r = 0.5176, P = 0.0024, n = 24), although this correlation was not significant within any group alone. The HPTH group demonstrated expected changes in serum calcium, parathyroid hormone, and alkaline phosphatase concentrations. Three of the HPTH subjects received a CaNa2 EDTA chelation challenge (1 g intramuscularly) before and 4 months after surgery. Chelated amounts of Pb (microgram/24 hr before vs after) were 52 vs 38, 42 vs 47, and 60 vs 34. These data indicate that in the high bone turnover state of hyperparathyroidism that Pb concentrations in the blood-soft tissue compartment, and probably Pb mass, are not likely to be different from other individuals. Also parathyroidectomy results in a lowering of blood Pb concentrations possibly due to parallel movements of calcium.