The experience with transdermal T patches to induce puberty is sparse. Finally, treatment with T gel resulted in appropriate and adequate increases in serum T concentrations in 104 boys with Klinefelter syndrome, although specific doses and regimens were not described . In this study, proper dosing became an issue, given the variable responses in individual adolescents . Transdermal preparations of T (patches or gel) are appealing options for TRT because they combine ease of administration with physiological and constant T levels. To overcome the erratic absorption of oral TU, a new oral formulation that is less affected by the lipid content of meals was approved by the FDA for hypogonadism in men . Two double-blind, randomized, placebo-controlled trials tested 2 different doses of TU (20 mg daily for 6 months in one vs 40 mg daily for 3 months in another) in small numbers of boys with CDGP 59, 60. However, it has a short, unpredictable half-life, requiring multiple daily doses in adults, and its absorption can be unreliable and particularly sensitive to food intake, especially the lipid content of meals 1, 92.
T replacement therapy (TRT) has recently expanded in adults because of its increased use among men with functional hypogonadism . The results indicate that short-term use of  T enanthate (TE) or oral  T undecanoate is safe and effective in inducing puberty and increasing growth in males with CDGP. We searched PubMed for articles (in English) on testosterone therapy, androgens, adolescence, and puberty in humans. Agnathans (jawless vertebrates) such as lampreys do not produce testosterone but instead use androstenedione as a male sex hormone. In women, mean levels of total testosterone have been reported to be 32.6 ng/dL. Androgen receptors occur in many different vertebrate body system tissues, and both males and females respond similarly to similar levels.
The technical term for these compounds is "anabolic-androgenic steroids" (AAS). Misusing anabolic steroids can be harmful to your health. The 2025 season started inauspiciously as well with Profar's 80-game suspension on March 31 for human chorionic gonadotropin, a hormone typically made during pregnancy that can encourage testosterone production.
The testes are often small and firm and produce low amounts of testosterone. Klinefelter syndrome is caused by a chromosome abnormality in which boys have 2 X chromosomes and 1 Y chromosome. Primary hypogonadism occurs when there is a problem in the testes. The pituitary gland secretes the hormones follicle-stimulating hormone and luteinizing hormone, which are called gonadotropins. Testosterone can also be diminished as the result of testicular damage caused by alcoholism, physical injury, viral diseases (eg, mumps), and in certain malignancies.
Several congenital conditions (ie, Klinefelter syndrome, Kallmann syndrome, Prader-Willi syndrome) can result in decreased testosterone production. With TE being the main T option for adolescents, TRT practice in this patient population remains far from this ideal recommendation. Many new T formulations have entered the market recently, but all are designed for adults. Clearly, more studies with better designs are required to determine the rate and reasons for dissatisfaction with current TRT options in adolescents. TE appears to be the predominant T formulation used to induce puberty. For hypogonadal adolescents, measurement of BMD may influence decisions concerning TRT initiation and titration ; however, there are no specific pediatric data to guide such decisions.
5α-DHT binds to the same androgen receptor even more strongly than testosterone, so that its androgenic potency is about 5 times that of T. Free testosterone (T) is transported into the cytoplasm of target tissue cells, where it can bind to the androgen receptor, or can be reduced to 5α-dihydrotestosterone (5α-DHT) by the cytoplasmic enzyme 5α-reductase. Androgens such as testosterone have also been found to bind to and activate membrane androgen receptors. Only the free amount of testosterone can bind to an androgenic receptor, which means it has biological activity.
External and internal genitalia formation, secondary sexual characteristics, spermatogenesis, growth velocity, bone mass density, psychosocial maturation, and metabolic and cardiovascular profiles are closely dependent on testosterone exposure. Genetic disorders cannot be cured, but hormone therapy may help sexual characteristics develop. The levels of luteinizing hormone and follicle-stimulating hormone help doctors determine whether hypogonadism is primary or secondary. To confirm the diagnosis, doctors do blood tests to measure the levels of testosterone, luteinizing hormone, and follicle-stimulating hormone.