SUMMARYThe bone mineral content (BMC) and body height were measured in 301 normal children and adolescents aged 7-20 years, and in 8 boys with constitutional delayed puberty aged 14-17 years. Serum testosterone was measured in the last group as well as in a subpopulation of the normal children and adolescents. The growth spurt, which coincided with a steep increase of serum testosterone in boys, indicated a great change in skeletal growth and mineralisation in both sexes. After the growth spurt, linear growth slowed down considerably while bone mineralisation rose steeply. When low levels of serum testosterone were maintained, as in delayed puberty, these combined changes of skeletal growth and mineralisation did not occur. It is suggested that gonadal hormones are the true initiators of the short-lived growth spurt as well as of prolonged acceleration of bone mineralisation.

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Central precocious puberty (CPP) is characterized by early activation of the pituitary-gonadal axis, which leads to increased growth velocity and development of secondary sexual characteristics. It is generally believed that gonadal sex steroids stimulate pulsatile GH secretion, which, in turn, stimulates insulin-like growth factor I (IGF-I) and IGF-binding protein 3 (IGFBP-3) production. However, little is known about GH, IGF-I, and IGFBP-3 serum levels in children with precocious puberty. Treatment of CPP by GnRH agonists has become the treatment of choice. However, the effect of long term treatment with GnRH in combination with an antiandrogen (cyproterone acetate) to block the possible effect of adrenal androgens has not previously been evaluated. We, therefore, studied 40 patients with idiopathic CPP that were treated for 24 months with either GnRH analog (Buserelin) in combination with cyproterone acetate (Androcur; n = 23) or with long acting GnRH analog (Decapeptyl Depot; n = 17). We found that serum IGF-I levels were increased before treatment in both groups (mean +/- SE, 446 +/- 35 and 391 +/- 35 micrograms/L; P < 0.0001, respectively) compared to those in normal age-matched prepubertal children. Similarly, IGFBP-3 levels were significantly elevated (4675 +/- 209 and 4305 +/- 162 micrograms/L, respectively; P < 0.0001) in the two groups. Treatment with GnRH analog in combination with cyproterone acetate significantly decreased height velocity and serum IGF-I and IGFBP-3 levels to normal levels after 2 yr of treatment (P < 0.0001). Serum IGF-I levels remained unchanged during monthly im treatment with long acting GnRH analog, whereas IGFBP-3 levels significantly increased during the first year of this treatment despite unmeasurable estradiol levels. Thus, in both groups, the molar ratio between IGF-I and IGFBP-3 (i.e. free biologically active IGF-I) declined concomitantly with a decrease in growth velocity. Serum levels of IGF-I and IGFBP-3 (expressed as the SD score for bone age), but not those of estradiol, correlated with height velocity before and during treatment (r = 0.34; P < 0.0001 and r = 0.24; P = 0.003, respectively). Six of the patients with a subnormal GH response to clonidine had similar IGF-I and IGFBP-3 serum levels and growth velocity compared to the other 34 girls with CPP and a normal GH response.(ABSTRACT TRUNCATED AT 400 WORDS)

In a longitudinal study of male puberty 20 boys were examined every three months for at least two years. Haemoglobin concentration was determined and related to changes in serum testosterone concentrations. The data show a steep increase in serum testosterone during puberty (p less than 0.001) followed with a five months delay, by a significant increase in haemoglobin concentration (p less than 0.001). It is concluded that the steep increase in serum testosterone during puberty produces an acute stimulation of erythropoietin leading to an increase in erythrocyte production and thereby to a detectable increase in haemoglobin concentration a few months thereafter. The present study supports the idea that the selection of the relevant reference range for haemoglobin in boys should depend on the state of physical developments as expressed by serum testosterone.