Excretion of Hydroxyproline in Urine by Premature and Normal Full-Term Infants and Those with Intrauterine Growth Retardation During the First Three Days of Life

Abstract

Extract: The mean daily urinary excretion of hydroxyproline on the first day of life was 4.4 mg/24 h for 50full-term normal infants, 3.5 mg/24 h for 17 full-term infants with intrauterine growth retardation (IUGR) and 5.5 mg/24 h for 17 premature infants. The differences were not statistically significane. On the third day of life, all infants excreted significantly higher amounts of hydroxyproline in their urine. The mean amount excreted by full-term normal infants and by premature infants was about the same, 9.9 mg/24 h and 9.6 mg/24 h, respectively, significantly more than that excreted by IUGR infants, 7.0 mg/24 h. Fifteen full-term normal infants fed a soya formula for the first week of life excreted almost the same amount of endogenous creatinie in the urine on the first, third and seventh day of life. The means in mg/24 h were 24.2, 24.3 and 22.5, respectively. The hydroxyproline to creatinine ration doubled on the third day of life. Speculation: The increase in the amount of hydroxyproline excreted in urine during the first few days of life may prove to be of value in assessing normal and abnormal rates of perinatal growth. Measurements of the amount of hydroxyproline in urine may provide a good index of perinatal growth, and the rapid increase in excreation soon after birth seems to indicate the initation of a phase of rapid growth.