DETERMINATION OF RED-CELL VOLUME WITH A NONRADIOACTIVE MARKER (SODIUMFLUORESCEIN) IN HUMANS USING FLOW-CYTOMETRY

Objective: To evaluate a method to measure red-cell volume (RCV) using a nonradioactive marker (sodium fluorescein) and flow cytometry. Desi gn: Study of reproducibility and feasibility of the method in healthy volunteers, Setting: Laboratory of an intensive care unit at a univers ity hospital, Participants: Five healthy male and 10 healthy female su bjects. Interventions: A total of 28 RCV determinations was carried ou t in the 5 male subjects to establish the reproducibility of the metho d, Twenty of the RCV determinations were performed as duplicate measur ements (interval: 1 h), The longest period between two subsequent meas urements was 112 days. In the 10 female subjects a total of 20 RCV det erminations was carried out (two measurements per subject with a 1-hou r interval, Results: The variation coefficient (mean +/- standard devi ation) in male subjects was 3.1 +/- 1.4%, The mean differences (+/- SD ) between the measurements carried out on different days and those car ried out as duplicate measurements on the same day did not differ (0.0 +/- 3.8% versus 0.6 +/- 4.7%), RCV in relation to body weight and bod y surface area, respectively, was 29.1 +/- 2.7 ml/kg and 1,108 +/- 90 ml/m(2) in males and 24.0 +/- 1.5 ml/kg and 848 +/- 56 ml/m(2) in fema les. Conclusions: We conclude that sodium fluorescein is a suitable no nradioactive marker for RCV determination and that RCV is constant ove r long periods of time.