Abstract 1543

Hct determinations in neonates by an automated hematology analyzer (auto Hct) have been shown to yield lower levels than those obtained by microhematocrit tube centrifugation (sHct.) Based on random clinical observations, we tested the hypotheses that the difference (Δ) between auto Hct. and sHct is higher in IDM and in LGA than in C infants, and that this Δ is correlated positively with MCV. Infants were studied within (24) hours after birth. The sHct was determined in each sample before submission to the hospital clinical lab. The Hct difference (Δ%) between the two methods was expressed as ((sHct - autoHct)/autoHct) × 100 and the mean Δ% values for each of the 3 study groups were compared by use of the student "t" test.

Within each study group, a Pearson correlation test was performed between automated MCV value and Δ% Hct. (Table)

Table 1 No caption available
Full size table

In all samples, sHct was higher than autoHct. The mean Δ% Hct was not significantly different among the groups. A significant negative correlation was found between MCV and Δ% Hct in the LGA group (p<0.001), and a trend in the IDM group (0.10>p>0.05), but no correlation in group C.

Since it has been suggested that some LGA infants might be the offspring of mothers with unrecognized gestational carbohydrate intolerance, we speculate that in some of these infants, and some of the IDM group, changes in the composition, and/or deformability of the red cells might affect the electronic determination of corpuscular size. This could result in inaccurate values for MCV, and hence of derived autoHct.