Abstract
SummaryObjectiveProgress through puberty involves a complex hormonal cascade, but the individual contributions of hormones, particularly IGF‐1, are unknown. We reanalysed Chard growth study data to explore the tempo of puberty based on changes in both height and hormone levels, using a novel method of growth curve analysis.Design and SubjectsSchoolboys (n = 54) and girls (n = 70) from Chard, Somerset, England, recruited in 1981 at age 8/9 and followed to age 16.MeasurementsEvery 6 months, height and Tanner stages (genitalia, breast, pubic hair) were recorded, and in a subsample (24 boys, 27 girls), blood samples were taken. Serum IGF‐1, testosterone (boys) and oestradiol (girls) were measured by radioimmunoassay. Individual growth curves for each outcome were analysed using variants of the super‐imposition by translation and rotation (SITAR) method, which estimates a mean curve and subject‐specific random effects corresponding to size, and age and magnitude of peak velocity.ResultsThe SITAR models fitted the data well, explaining 99%, 65%, 86% and 47% of variance for height, IGF‐1, testosterone and oestradiol, respectively, and 69–88% for the Tanner stages. During puberty, the variables all increased steeply in value in individuals, the ages at peak velocity for the different variables being highly correlated, particularly for IGF‐1 vs height (r = 0·74 for girls, 0·92 for boys).Conclusions IGF‐1, like height, the sex steroids and Tanner stages, rises steeply in individuals during puberty, with the timings of the rises tightly synchronized within individuals. This suggests that IGF‐1 may play an important role in determining the timing of puberty.
Highlights
The period of rapid growth in height that occurs at adolescence is unique to humans
It is generally accepted that the peak in height velocity at adolescence is driven by a cascade of hormones, primarily initiated by a rise in sex steroid and followed by increases in growth hormone and the related insulin-like growth factor 1 (IGF-1).[2,3]
It has been reported that in individuals IGF-1 peaks at Tanner stage 5,4 that raised IGF-1 is associated with early puberty[5,6] and that IGF-1 measured cross-sectionally increases both with age and pubertal stage through puberty, peaking in girls at Tanner stage 4.5,7 there is uncertainty about the longitudinal pattern of change in IGF-1 in individuals, and how it might relate to the timing of the rise in sex steroids or the age at peak height velocity (PHV)
Summary
No other primate species, including the chimpanzee, has such a dramatic increase in height velocity the male chimpanzee does undergo a period of rapid gain in muscle mass.[1] The adolescent growth spurt begins on average 2 years earlier in girls than boys, but within each gender there is enormous variation in the timing of pubertal development. It is generally accepted that the peak in height velocity at adolescence is driven by a cascade of hormones, primarily initiated by a rise in sex steroid and followed by increases in growth hormone and the related insulin-like growth factor 1 (IGF-1).[2,3] deciphering the individual contributions of these hormones, IGF-1, to the timing and intensity of pubertal growth acceleration has proved difficult. It has been reported that in individuals IGF-1 peaks at Tanner stage 5,4 that raised IGF-1 is associated with early puberty[5,6] and that IGF-1 measured cross-sectionally increases both with age and pubertal stage through puberty, peaking in girls at Tanner stage 4.5,7 there is uncertainty about the longitudinal pattern of change in IGF-1 in individuals, and how it might relate to the timing of the rise in sex steroids (testosterone in boys and oestradiol in girls) or the age at peak height velocity (PHV)
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