The effect of hypermagnesaemia on serum immunoreactive calcitonin levels in normal human subjects.

The effect of hypermagnesaemia on serum levels of immunoreactive calcitonin was studied in normal human subjects. After iv administration of magnesium sulphate over 120 min, the mean (+/- SEM) serum magnesium concentration rose from the baseline level of 0.9 +/- 0.1 to 2.6 +/- 0.3 mmol/l (P less than 0.01), and thereafter remained higher than the baseline level. The magnesium infusion caused a significant increase in serum immunoreactive calcitonin levels (P less than 0.01). The rise in serum magnesium concentration was accompanied by a significant decrease in the concentrations of corrected serum calcium and whole blood ionized calcium (P less than 0.01, P less than 0.01 respectively). Our results suggest that hypermagnesaemia causes an increase in serum immunoreactive calcitonin levels in normal human subjects despite a decrease in the concentrations of corrected serum calcium and whole blood ionized calcium.