MELATONIN AND 6-HYDROXYMELATONIN SULFATE EXCRETION IS INVERSELY CORRELATED WITH GONADAL DEVELOPMENT IN CHILDREN

To delineate the development of melatonin (MLT) production during chil dhood, we measured the excretion of MLT and 6-hydroxymelatonin sulfate (MLTS) in the urine of children (n = 134) from the 26th week of gesta tion until the age of 20 years. MLTS excretion showed a diphasic patte rn with declining values in preterm babies with lowest values around t erm. After birth, the values remained low for the first 6 months of li fe. The highest values were reached between 4 and 7 years of age with a smooth but steady decline thereafter. A night-day difference was not detectable before the age of 6 months; the greatest night-day variati ons occurred at the time of the highest MLTS excretions. The MLT value s showed an identical pattern but with amounts 1,000 times smaller; th e ratio of MLTS to MLT increased from 40:1 in preterm babies to 900:1 in prepubertal children. In summary, the MLT/MLTS excretion exhibits t he highest activity with respect to total secretory capacities as well as night-day differences at the time of gonadal quiescence during chi ldhood. The strong inverse correlation of MLT and MLTS excretion with the hypothalamic-pituitary-gonadal activity points to a causal relatio nship between pineal gland activity and pubertal development.