WITH THE development of ultramicromethods of analysis, it is possible to obtain blood-chemistry studies on capillary blood. This enables more and frequent determinations to be performed on the infant, since the need for a venipuncture, which may be harmful and is relatively difficult to perform, is now obviated. As is true of adults, 70% of the weight of a child is water; however, 50% of this is present in the extracellular fluid as against 20% for that of the adult. Therefore, a child exchanges close to half of the fluid of his extracellular compartment per 24 hours. This will cause body water and electrolyte losses to occur more readily than in an adult. For this reason, frequent electrolyte determinations, including sodium, chloride, and bicarbonate levels, are important in the infant.
Very few such studies have been performed on normal full-term newborn babies. Sunderman and Boerner1 list no such normal