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Maturational changes of urinary growth hormone excretion in the premature infant
1Department of Neonatology, Toho University, School of Medicine, Tokyo, Japan.
Insights
Growth hormone (GH) excretion in premature infants changes significantly in the first month. Urinary GH levels correlate with gestational age and birth weight, potentially impacting infant growth.
Area of Science:
- Endocrinology
- Neonatology
- Pediatric Growth
Background:
- Newborn infants exhibit high plasma growth hormone (GH) concentrations.
- Understanding GH secretion patterns is crucial for assessing premature infant development.
Purpose of the Study:
- To characterize the maturational changes in GH secretion in premature infants.
- To investigate the relationship between urinary GH excretion and infant growth parameters.
Main Methods:
- Serial 24-hour urinary GH excretion was measured in 30 premature infants (gestational age 25-37 weeks).
- Measurements were taken at one week of age and followed over time.
- Infants were assessed for intrauterine and postnatal growth retardation.
Main Results:
- Urinary GH excretion at one week was negatively correlated with gestational age, birth weight, and length.
- In infants with 27 weeks mean gestation, urinary GH peaked at week 1 (6.1 µg/day) and declined rapidly.
- Persistent GH hyperexcretion was noted in infants with growth retardation.
Conclusions:
- Postnatal urinary GH excretion patterns in premature infants mirror fetal ontogenic changes.
- GH may play a role in the postnatal growth of premature infants.
- Urinary GH excretion can serve as a marker for growth status in preterm neonates.
Abstract:
High plasma GH concentrations are observed in the newborn infant. To characterize the maturational change of GH secretion in premature infants, we serially measured 24-h urinary GH excretion in 30 premature infants. The gestational age ranged from 25-37 weeks and birth weight from 468-2415 g. Urinary GH excretion at 1 week of age was negatively correlated with gestational age, birth weight, and length of infants with adequate intrauterine growth. In the infants with 27 weeks of mean gestation (range, 25-28 weeks) mean urinary GH excretion was highest (6.1 micrograms/day) at the first week, decreased to 1.2 micrograms/day by the fourth week, and remained between 0.05 and 0.18 micrograms/day thereafter. When compared to the corresponding conceptional age, there was no postnatal difference in the pattern of GH excretion between infants with 27 and 31 (range, 29-32) weeks of mean gestational age. Persistent hyperexcretion of GH was observed in 4 of the 5 infants with intrauterine or postnatal growth retardation. Our results suggest that the postnatal change of 24-h urinary GH excretion is similar to ontogenic changes of plasma GH in fetus, and GH may have some effects on postnatal growth in premature infants.