Decreased 6-Sulfatoxymelatonin Excretion in Male GH-Deficient Children and Adolescents

Abstract

Aim: To evaluate melatonin secretion in a group of untreated and treated male growth hormone (GH)-deficient children and adolescents. Methods: We studied 44 male subjects: 8 untreated GH-deficient patients (GHDnt), 16 treated GH-deficient patients (GHDt) and 20 healthy children and adolescents as control group (CG). We measured urinary 6-sulfatoxymelatonin (6-SM) in total (24-hour samples), nocturnal (18.00-8.00 h) and diurnal samples (8.00-18.00 h). Levels of 6-SM were expressed as micrograms excreted per time interval and Δ values (difference between nighttime and daytime values). Results: Significant differences were observed among the 3 groups of pediatric subjects studied for total 6-SM (p < 0.0001), nocturnal 6-SM (p < 0.0001) and Δ values (p < 0.0001). Subsequent analysis showed significantly higher levels for total 6-SM, nocturnal 6-SM and nighttime-daytime Δ in the CG versus the GHDnt (p < 0.01) and in the CG versus the GHDt group (p < 0.01). No significant correlations were found between 6-SM excretion and insulin-like growth factor-1 values in the children and adolescents studied. Conclusions: GH-deficient patients showed lower levels of 6-SM. Our findings provide a different insight to a further understanding of some chronobiological disorders involved in GH deficiency in children.

Male-female differences in 6-sulfatoxymelatonin excretion in hypopituitary patients

“…Therefore, possible variations in melatonin in GHD patients, with and without replacement therapy, have not been adequately characterized yet. In a recent study evaluating children and adolescents, we have observed that GHD patients, both treated and untreated, showed significantly lower levels than controls in total melatonin, nocturnal levels and nighttime-daytime delta values (11).…”

“…Indirectly, the clock system directs secretion through slow-wave sleep, which is strongly associated with GH release, although the precise mechanism of circadian influence is not understood (10). We have demonstrated in a recent paper decreased 6-sulphatoxymelatonin (6-SM) excretion in male GH-deficient children and adolescents (11). Taking into account that there is sexual dimorphism of plasma GH with distinct male and female patterns of growth, which may be clock-determined (1), and considering that melatonin is a key hormone in the biological clock and in the day/night cycle, we decided to evaluate melatonin secretion in a group of GH-deficient male and female adults on and off replacement therapy, by measuring the excretion of its major urinary metabolite 6-SM (12,13).…”