RED-CELL VOLUME DETERMINATION USING A STABLE-ISOTOPE OF CHROMIUM

OBJECTIVE: To validate and improve a method of red cell volume determi nation by use of a stable isotope of chromium. METHODS: Twelve subject s were sequentially injected with red blood cells labeled with a stabl e isotope of chromium (Cr-53) and red blood cells labeled with radiois otopic chromium (Cr-51). Measurement of Cr-53 dilution was by gas chro matography/mass spectrometry. Measurement of Cr-51 dilution was by gam ma counter. RESULTS: Comparison of the two methods led to results that differed on average by 34.5 +/- 45.0 mL (1.8 +/- 2.2%), 0.3 to 3.2%, 95% confidence interval. CONCLUSION: Measurement of red cell volume by use of a stable isotope of chromium is accurate, with potential appli cations including measurement is pregnant women and children or other groups in whom exposure to radioisotopes is undesirable. Copyright (C) 1997 by the Society for Gynecologic Investigation.