Phases of fluid and electrolyte homeostasis in the extremely low birth weight infant.

Abstract

Extremely low birth weight infants manifest three phases of fluid and electrolyte homeostasis, as do more mature infants, independent of thermal environment. Diuresis and natriuresis are the result of abrupt increases in GFR and FENa. We speculate that this may be the result of expansion of the neonatal extracellular space as fetal lung fluid is reabsorbed.