Gender-related differences in urinary 6-sulfatoxymelatonin levels in obese pubertal individuals.
The objective of this study was to measure the urinary excretion of the main melatonin metabolite 6-sulfatoxymelatonin in obese and normal weight (wt) boys and girls. The study included 94 subjects, aged 4-15.7 yr (50 obese and 44 normal wt; 48 boys) classified as: mid-childhood (4-7.99 yr), late-childhood (8-12 yr) and pubertal (10.1-15.7 yr, Tanner II-IV). Normal wt subjects were children with a body mass index (BMI) between the 25th and 75th percentiles, and the group of obese subjects included children whose BMI was above the 97th percentile. A 24-hr urine sample was collected during two intervals: (i) 18:00-08:00 hr, and (ii) 08:00-18:00 hr. Analysis of urinary 6-sulfatoxymelatonin levels was performed by radioimmunoassay. Excretion of 6-sulfatoxymelatonin was expressed as: (i) total amount excreted (microg); (ii) mug excreted per time interval, nocturnal or diurnal; and (iii) the difference between nocturnal and diurnal samples (microg, estimated amplitude). A factorial analysis of variance indicated that nocturnal 6-sulfatoxymelatonin excretion and amplitude were significantly higher in the obese individuals. A significant interaction 'BMI x age' was detected, i.e. the effect of BMI was significant in the pubertal group only. Total, nocturnal and diurnal 6-sulfatoxymelatonin excretion was significantly higher in girls. The increase in 6-sulfatoxymelatonin excretion found in obesity occurred only in boys and at the pubertal age. To what extent this increase in melatonin production contributes to a delayed puberty in some pubertal obese males remains to be established.
Fideleff
Hugo L
HL
Departmento de Endocrinología, Hospital T. Alvarez, Buenos Aires, Argentina. hugofideleff@arnet.com.ar
Boquete
Hugo
H
Fideleff
Gabriel
G
Albornoz
Liliana
L
Pérez Lloret
Santiago
S
Suarez
Martha
M
Esquifino
Ana I
AI
Honfi
Margarita
M
Cardinali
Daniel P
DP
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D002940:Circadian Rhythm; D005260:Female; D006801:Humans; D008297:Male; D008550:Melatonin / Q000031:analogs & derivatives* / Q000652:urine; D009765:Obesity / Q000652:urine*; D011627:Puberty / Q000652:urine*; D011628:Puberty, Delayed / Q000209:etiology; D012727:Sex Characteristics
C054513:6-sulfatoxymelatonin; D008550:Melatonin