Phosphaturic effect of I.V. Administered calcitonin in man.

Porcine calcitonin (CT) was administered intravenously to 4 patients whose kidney function and plasma Ca and P levels were normal. A significant increase in urinary P excretion with an increase in urinary cyclic AMP (cAMP) excretion was observed. Plasma P and cAMP levels which were determined simultaneously did not show any significant change. Furthermore, plasma PTH levels determined by the radioimmunoassay revealed that the increased PTH levels provoked by the CT infusion was not responsible for an increase in urinary P or cAMP excretion, since no increase in plasma PTH levels was found during the period when an increase in urinary P or cAMP excretion was observed. In addition, the CT infusion caused an increase in urinary excretion of Ca, Na and Mg as well as P. Based on these data, it can be concluded that CT administered intravenously acts directly on the kidney, resulting in an increase in urinary P excretion which could be mediated through cAMP in the kidney.