1449 ANTHROPOMETRIC CORRELATES OF CREATININE EXCRETION IN PREMATURE INFANTS

Abstract

Urinary creatinine excretion has been utilized to assess malnutrition, prorate the excretion of urinary metabolites and measure renal function. Creatinine output (mg per kg body weight) increases throughout childhood. There are no data describing the anthropometric correlates of creatinine excretion in the premature infant. Accordingly,we measured urinary creatinine output in timed 24-hour urine specimens obtained in the second week of life on 15 premature infants (mean weight 1.21kg, range 0.760 to kg; mean gestational age 29 weeks, range 26 to 33 weeks). The following regression equations were obtained: Stepwise regression yielded no linear combination of these variables that improved the estimate based on weight alone. In a similar manner, consideration of weight and length for age (expressed as percent of 50th percentile) did not improve the estimate based on weight alone. These data demonstrate that creatinine output in mg per kg increases by 15% between 0.7 and 1.5 kg birthweight. This increase parallels that in body protein content per kg obtained from published fetal body composition data in similarly aged infants. Creatinine output in premature infants therefore can serve as a reflection of growth of lean body mass.