A single dose of lithium carbonate acutely elevates intact parathyroid hormone levels in humans

Hyperparathyroidism has been reported in patients receiving lithium therapy, and lithium alters calcium-regulated PTH release in vitro. Previous studies in vivo have used assays which measure fragments of PTH as well as the intact hormone. To determine if lithium acutely elevates intact PTH levels, we studied 9 subjects who received a single oral dose of lithium carbonate (600 mg). Serum levels of intact PTH, ionized calcium, and lithium were measured before, 2 and 14 h after the dose of lithium. PTH levels rose significantly 2 h following the dose of lithium (before 22 +/- 5.0, post 32 +/- 7.3 ng/l, p less than 0.02). PTH levels had returned to baseline at 14 h (22 +/- 3.8 ng/l). There were no significant changes in ionized calcium levels. Therefore, a single oral dose of lithium carbonate acutely elevates intact PTH values in human subjects.