Related Experiment Video
Updated: Oct 18, 2025
Establishment of Rat Models Mimicking Gender-affirming Hormone Therapies
Published on: January 10, 2025
Serum testosterone and oestradiol predict the growth response during puberty promoting treatment
Heta Huttunen1, Tero Varimo1, Hanna Huopio2
1New Children's Hospital and Pediatric Research Center, Helsinki University Hospital, Helsinki, Finland.
Objective:
The influence of androgens and oestrogens on growth is complex, and understanding their relative roles is important for optimising the treatment of children with various disorders of growth and puberty.
Design:
We examined the proportional roles of androgens and oestrogens in the regulation of pubertal growth in boys with constitutional delay of growth and puberty (CDGP). The study compared 6-month low-dose intramuscular testosterone treatment (1 mg/kg/month; n = 14) with per oral letrozole treatment (2.5 mg/day; n = 14) which inhibits conversion of androgens to oestrogen.
Patients:
Boys with CDGP were recruited to a randomized, controlled, open-label trial between 2013 and 2017 (NCT01797718).
Measurements:
The patients were evaluated at 0-, 3- and 6-month visits, and morning blood samples were drawn. Linear regression models were used for data analyses.
Results:
In the testosterone group (T-group), serum testosterone concentration correlated with serum oestradiol concentration at the beginning of the study and at 3 months, whereas in the letrozole group (Lz-group) these sex steroids correlated only at baseline. Association between serum testosterone level and growth velocity differed between the T and Lz groups, as each nmol/L increase in serum testosterone increased growth velocity 2.7 times more in the former group. Serum testosterone was the best predictor of growth velocity in both treatment groups. In the Lz-group, adding serum oestradiol to the model significantly improved the growth estimate. Only the boys with serum oestradiol above 10 pmol/L had a growth velocity above 8 cm/year.
Conclusions:
During puberty promoting treatment with testosterone or aromatase inhibitor letrozole, growth response is tightly correlated with serum testosterone level. A threshold level of oestrogen appears to be needed for an optimal growth rate that corresponds to normal male peak height velocity of puberty. Serum testosterone 1 week after the injection and serum testosterone and oestradiol 3 months after the onset of aromatase inhibitor treatment can be used as biomarkers for treatment response in terms of growth.
Related Concept Videos
01:27Signs of Puberty
01:17Hormones and Bone Tissue
Hormones That Influence Osteoblasts and/or Maintain the Matrix
Several hormones are necessary for controlling bone growth and maintaining the bone matrix. The pituitary gland secretes growth hormone (GH), which, as its name implies, controls bone growth. This happens in several ways: first, it triggers chondrocyte...
01:26Testosterone: Functions and Regulation
01:22Target Cell Response to Hormones
Notably, the cellular response can be regulated by altering the number of receptors expressed in the cell. For example, prolonged exposure to elevated hormone levels results in a gradual decline or down-regulation in the number of receptors for that specific hormone on the cell surface. Conversely, in response to low hormone levels, cells may use up-regulation, producing an...
01:30Hormonal Control of the Ovarian Cycle
Before puberty, the hypothalamus releases GnRH in a low frequency, low amplitude pulsatile manner. This along with the immature hypothalamic-pituitary-gonadal axis activity, results in low estrogen levels and the absence of a fully functional ovarian cycle. At puberty, GnRH secretion increases in both frequency and...
01:33Hormonal Regulation