Renal Excretion of Calcium

Abstract

Calcium, like sodium, potassium and magnesium, the other biologically important cations in the group I and Ha elements of the periodic table, is not catabolized by the human body and its total content in tissues is set by the balance between that absorbed and that excreted. In the form of complexes calcium is, in general, well tolerated by tissues but tolerance to the ionized form is limited. Because ionized calcium is utilized in a wide range of cellular mechanisms, efficient excretory systems have evolved to avoid, on the one hand, the development of toxic levels and on the other, low levels injurious to normal function.