Screening for hypoglycemia with plasma in neonatal blood of high hematocrit value.

A model utilizing human umbilical cord blood was used to screen for hypoglycemia in a simulated neonatal situation. The aims of the study were to assess the effect of increasing Hct concentration on Dextrostix readings, and to determine whether plasma samples, in contrast to conventional whole blood samples, were acceptable for Dextrostix determinations in selected cases. Dextrostix readings were determined on 65 whole blood samples of varying Hct, and on plasma specimens, 48 of which were paired with whole blood samples. The results were compared with plasma true glucose values. Plasma Dextrostix readings correlated well with true glucose values throughout the entire Hct range (r = .94, slope = 1.16). Whole blood Dextrostix readings, on the other hand, were Hct-dependent and, with increasing Hct values, became falsely low. As a result, a Hct values greater than 70%, whole blood Dextrostix readings were less than 50% of the true glucose value (r = .94, slope = 0.45). Plasma Dextrostix determinations may offer an accurate means of screening for neonatal hypoglycemia in asymptomatic infants with high Hct, pending laboratory glucose results.