Urine gonadotropin and testosteron levels in male very-low-birthweight infants

Background/Aims: The postnatal activation of the hypothalamic-pituitary-gonadal axis is more exaggerated in preterm than in full-term-born infants, and may be important for reproductive function. Our objective was to investigate this activation of the hypothalamic-pituitary-gonadal axis in male very-low-birthweight (VLBW) infants. Methods: Twenty-one VLBW boys (gestational age 26.0-30.0 weeks), participating in the NIRTURE trial, were included. Gonadotropin and testosterone levels were measured in serial urine samples collected at 1 and 4 weeks' postnatal age, at 32 weeks' postmenstrual age, at expected date of delivery and at the corrected age of 3 and 6 months. Results: Longitudinal analysis shows that after birth LH and FSH levels peak at a mean postnatal age of 1-4 weeks (mean postmenstrual age of 30-32 weeks) and decrease until 38 weeks' postnatal age (corrected age of 6 months). Testosterone levels decrease with increasing age, and this decrease is faster in infants receiving early insulin therapy. Conclusions: Serial urine sampling for measurement of gonadotropin and testosterone levels provides accurate information about the postnatal activation of the hypothalamic-pituitary-gonadal axis in VLBW boys. FSH and LH levels peak at 1-4 weeks of age. Insulin treatment causes faster decrease in testosterone levels. Copyright © 2012 S. Karger AG, Basel

Urine gonadotropin and estradiol levels in female very-low-birth-weight infants

Background: The postnatal activation of the hypothalamic-pituitary-gonadal axis is more exaggerated in preterm than in full-term born infants and may be important for future reproductive function. Aim: The objective of this study was to investigate the postnatal activation of the hypothalamic-pituitary-gonadal axis in female very-low-birth-weight infants. Study design: We performed serial measurements of gonadotropin and estradiol levels in urine samples of female very-low-birth-weight infants collected at 1 and 4. weeks postnatal age, at 32. weeks postmenstrual age, at expected date of delivery and at the corrected age of three and six months. Subjects: Twenty-two very-low-birth-weight infants (gestational age 25.4-30.1. weeks), participating in the Neonatal Insulin Replacement Therapy in Europe trial, were included in this study. Outcome measures: Gonadotropin and estradiol levels were measured in serial urine samples. Results: Longitudinal analysis shows that after birth FSH and LH levels increase until 32. weeks postmenstrual age (4. weeks postnatal age) and then decrease until 3. months corrected age (26. weeks postnatal age). Estradiol levels decrease from 28. weeks postmenstrual age (1. week postnatal age) until 6. months corrected age (39. weeks postnatal age). Conclusions: Serial urine sampling for measurement of gonadotropin and estradiol levels provides an accurate description of the postnatal activation of the hypothalamic-pituitary-gonadal axis in very-low-birth-weight girls. Levels of FSH and LH peak at a mean postmenstrual age of 32. weeks (postnatal age of 4. weeks) whereas estradiol levels are highest shortly after birth. © 2012 Elsevier Ltd