Historically, most studies with neonates have reported spun hematocrits, thus forming the basis for the standard in most nurseries. Recently, automated whole-blood analyzers, which measure hemoglobin concentration are used for most laboratory determinations. A finding of a consistent and close relationship between hemoglobin and spun hematocrit would permit elimination of the latter, thus saving time, money, and blood draws. Methods and Results: 156 paired determinations of hemoglobins (Ciba Corning [Chiron] 865) and spun hematocrits were measured on NICU inpatients. The instrument calculates hematocrit (%) by multiplying measured hemoglobin (g/dl) by 2.941. Values were compared by the Bland-Altman technique (Lancet, 1:307, 1986). The mean difference between values was 0.3, with ±2 SD of the values falling within 2.7 hematocrit units, which is clinically acceptable and close to the 95% CI reproducibility error for our laboratory for spun hematocrits(2.0 units). Conclusion: Neonatal hematocrits can accurately be calculated from measured hemoglobin (g/dl) × 2.941. Automated techniques, which report hematocrits derived from hemoglobins, are appropriate for use on neonates. Figure

figure 1