Normal Renal Function in the First Two Days of Life

Abstract

Comparing the renal function of infants in the first 2 days of life on a limited water intake with hydropenic, starving adults it is found that (1) the former excrete urine volumes averaging 13.8 cc/1 of body water/day; the latter 16.7 cc/1 of body water/day. (2) The infants pass urine having an osmolar concentration of 420 milliosmols/1: the adults'' value being 1224. (3) The osmolar concentration is made up in a similar way in both groups except that the fraction due to K is higher in the infants. (4) N- K ratio in the urine of the infants averages 3.4, that in the adults 8.5. (5) There is a close relation among themselves between the osmotically active material or the total N excreted and the urine volume excreted by the infants. (6) Infants have low urea clearances and glomerular filtration rates compared to the adults. (7) Infants excrete very little phosphate after birth but increase by the end of the 2d day.