6-Hydroxymelatonin sulfate excretion in human puberty

Area of Science:

• Endocrinology
• Chronobiology
• Pediatrics

Background:

• Melatonin, a hormone regulating circadian rhythms, plays a role in development.
• Urinary 6-hydroxymelatonin sulfate (SM) is the primary metabolite of melatonin, reflecting its secretion rate.

Purpose of the Study:

• To investigate the relationship between SM excretion rate and pubertal development.
• To determine the day-to-day variability of SM excretion in healthy individuals.

Main Methods:

• Collected timed overnight urine samples from 4-31 year olds.
• Measured SM and creatinine excretion rates.
• Analyzed SM excretion relative to body size and pubertal stage.
• Assessed day-to-day variability of SM and creatinine excretion.

Main Results:

• SM excretion rate per body size was significantly higher in prepubertal children compared to pubertal subjects and adults.
• SM excretion rate decreased from mid to late childhood.
• Variability in nocturnal SM excretion was similar to creatinine, with no correlation to collection timing.

Conclusions:

• Melatonin secretion rate, relative to body size, is higher in mid-childhood, decreases in late childhood, and stabilizes from pubertal stage 2 through adulthood.
• The decline in melatonin secretion coincides with the disinhibition of the gonadotropin-releasing hormone pulse generator, suggesting melatonin may suppress puberty.
• High individual variability in SM excretion necessitates caution in longitudinal studies using single urine collections.