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

Objective To evaluate melatonin secretion in adult hypopituitary patients with Growth Hormone deficiency (AGHD) on and off replacement therapy. Subjects and methods We studied 48 subjects: 12 (6 males) untreated AGHD (AGHDnt), 20 (10 males) treated AGHD (AGHDt) and 16 healthy subjects (8 males) as control group (CG). We measured urinary 6-sulfatoxymelatonin (6-SM) in total (24 h samples), nocturnal (6-SMn): 1800-0800 and diurnal samples (6-SMd): 0800-1800. Results Significant differences were observed among the 3 groups of male subjects, in total 6-SM (p < 0.05), nocturnal 6-SM (p < 0.02) and nighttime-daytime delta values (p < 0.003). CG had significantly higher values than the AGHDnt in total 6-SM (p < 0.01), nocturnal 6-SM (p < 0.05) and nighttime-daytime delta values (p < 0.01). AGHDt patients showed significantly higher levels in nighttime-daytime delta values than AGHDnt patients (p < 0.05). In females, no significant differences were found among the 3 groups studied in total, nocturnal, diurnal or nighttime-daytime delta values. In males, significant correlations were found among total 6-SM (r = 0.58; p = 0.029), nocturnal 6-SM (r = 0.70; p = 0.006) and nighttime-daytime delta values (r = 0.71; p = 0.004) vs. serum IGF-1 levels in subjects evaluated. In females, significant correlations were found among total 6-SM (r = 0.57; p = 0.02) vs. serum IGF-1 levels in subjects evaluated. A tendency towards a significant correlation was found in diurnal 6-SM (r = 0.48; p = 0.07). Conclusions Our findings show a sexual dimorphism in 6-SM excretion in AGHD patients and provide an interesting approach to a further understanding of some chronobiological disorders involved in GH deficiency.