A Comparison of Chromium Sesquioxide and [51Cr]Chromic Chloride as Inert Markers in Calcium Balance Studies

Abstract

1. Chromium sesquioxide (Cr₂O₃; 1·5 g/day) and [⁵¹Cr]chromic chloride [³¹CrCl₃ (0·3 μCi/day)] were compared as continuously administered non-absorbed markers for the correction of faecal recoveries in 14 calcium balance studies each lasting at least 18 days. 2. The mean recoveries of each, 98·4% for Cr₂O₃ and 101·9% for ⁵¹CrCl₃, were not significantly different from 100. 3. The two markers reduced the uncertainty in a typical 3 × 6 day calcium balance study to a similar extent (sd = 1·4 mmol/day for Cr₂O₃ and sd = 1·5 mmol/day for ⁵¹CrCl₃). 4. ^5lCrCl₃ is a convenient and satisfactory alternative to Cr₂O₃ when the laboratory hazards associated with estimating the latter cannot easily be eliminated.