Comparative Ultrafiltration of Calcium and Strontium in Serum.

Abstract
Serum was ultrafiltered through cellpphane to determine relative filterability of Sr and Ca, using Sr85 and Ca45, In every case, Sr filtered more completely, values at 37.5[degree] averaging close to 60% for Sr and 40% for Ca calculated on basis of total serum filtered. None of several variables tested affected relative filterability. Neither addition of stable Sr nor slight changes in pH produced significant changes. There appeared to be a slight negative temperature effect, values of both isotopes being lower at 37.5 than at 23[degree] C. Results indicate that Ca is more completely bound to protein than is Sr.