The erythrocyte indices of neonates, defined using data from over 12000 patients in a multihospital health care system

Objective: The erythrocyte indices ( mean corpuscular volume ( MCV), mean corpuscular hemoglobin concentration ( MCHC) and mean corpuscular hemoglobin ( MCH)) were originally reported using hand-calculated values, based on a centrifuge-spun hematocrit, a counting-chamber erythrocyte count and a hemoglobin concentration measured by any number of hemoglobinometry methods. Modern blood cell analyzers measure the MCV, and calculate the MCHC and MCH, on the basis of logs higher sample sizes than employed in the original methods. Study Design: With a single type of automated blood cell counter ( Beckman Coulter LH 750; Fullerton, CA, USA), we determined the ranges of erythrocyte indices among neonates of 22 to 42 weeks gestation. Data were accumulated during a 3-year period from a multihospital health care system, using all indices reported on untransfused neonates during their first day of life. Result: Erythrocyte indices were obtained from 17634 tests performed on 12016 neonates. The MCV and the MCH decreased with advancing gestational age. For instance, the MCV diminished from 119 +/- 7 fl ( mean +/- s. d.) in neonates <= 25 weeks gestation to 106 +/- 4 fl at 40 weeks. The MCH diminished from 40 +/- 2 pg in neonates <= 25 weeks gestation to 36 +/- 2 pg at 40 weeks. The MCHC did not change appreciably with gestational age ( 34 +/- 1 pg dl(-1)). Conclusion: The results describe the expected values for erythrocyte indices on the first day of life among untransfused neonates. Additional study is needed to determine the relevance of very high or low erythrocyte indices in this population and to understand any physiological advantage of these very large erythrocytes during fetal development.