A reappraisal of neonatal blood chemistry reference ranges using the Nova M electrodes

The objective of this study is to establish new reference ranges for whole blood electrolytes, gases, and selected chemistries in normal healthy newborn infants obtained from cord blood and at 2-4 hours of life based on modern analytic techniques. Healthy appropriate-for-gestational age (AGA), term infants were studied. Whole venous cord blood and blood drawn at 2-4 hours of life were analyzed for gases, sodium, potassium, chloride, ionized calcium, ionized magnesium, hemoglobin, and hematocrit. Concentrations for blood glucose and blood urea nitrogen were close to older published concentrations. Na(+), K(+), and Cl(-) were significantly different and had much narrower normal margins. New norms are included for blood gases, lactate, iCa, and iMg. We offer a range of values for often-measured blood chemistries in term, healthy infants, using modern laboratory methods. These values could serve as more up-to-date references compared with older values found in major textbooks of Neonatology.