Comparative Passage of Calcium and Strontium from Plasma into Cerebrospinal Fluid in Man. ∗

Abstract

Summary

Comparative rates of passage of strontium and calcium from plasma into cerebrospinal fluid have been studied in man following intravenous injection of Sr⁸⁵ and Ca⁴⁵. Cerebrospinal fluid to plasma ratios of Sr⁸⁵ and Ca⁴⁵ were approximately the same except in one patient who showed a greater ratio for Ca⁴⁵. As a greater proportion of Sr⁸⁵ than of Ca⁴⁵ is unbound to protein, differential passage into the cerebrospinal fluid in favor of Ca⁴⁵ appears to take place. The data indicate that cerebrospinal fluid may be formed by secretion rather than ultrafiltration. Rate of formation of fluid has been calculated to be approximately 0.03 to 0.04 ml/hr/kg of body weight.