Long term treatment with low dose testosterone in constitutional delay of growth and puberty: effect on bone age maturation and pubertal progression

Allometric Scaling of Testosterone Enanthate Pharmacokinetics to Adolescent Hypogonadal Males (IM and SC Administration)

Context

Intramuscular (IM) testosterone enanthate (TE) and testosterone pellets were US Food and Drug Administration approved before 1962 for pediatric use but not studied in controlled trials in adolescents.

Objective

An analysis using nonlinear mixed effect (NLME) modeling was designed to evaluate the adult pharmacokinetics (PK) of subcutaneous (SC) and IM TE. This model was used to simulate SC and IM TE administration in adolescents of different weight groups.

Methods

Data from adult male patients in a phase 2 trial were used to characterize the PK of TE using population PK modeling for SC and IM administration: Allometry was used to scale PK parameters from the adult model to simulate adolescent (aged 12 to < 18 years) serum testosterone levels at body weights of 30, 40, 50, and 60 kg after weekly, every-other-week (EOW), and monthly SC and IM administration of 12.5, 25, 50, 75, and 100 mg TE regimens.

Results

The final data set included 714 samples from 15 patients receiving 100 mg SC TE and 123 samples from 10 patients receiving 200 mg IM TE. In simulated populations, average serum concentration SC:IM ratios were 0.783, 0.776, and 0.757 at steady state for weekly, EOW, and monthly dosing groups, respectively. Simulated regimens of 12.5 mg SC TE monthly produced serum testosterone levels representative of early puberty and simulated pubertal stage progression following multiple subsequent testosterone dose increases.

Conclusion

SC TE administration achieved a testosterone exposure-response relationship similar to IM TE in simulated adolescent hypogonadal males, which may reduce size of fluctuations in serum T and related symptoms.

Considerations when treating male pubertal delay pharmacologically

INTRODUCTION

Delayed puberty, defined as the appearance of pubertal signs after the age of 14 years in males, usually affects psychosocial well-being. Patients and their parents show concern about genital development and stature. The condition is transient in most of the patients; nonetheless, the opportunity should not be missed to diagnose an underlying illness.

AREAS COVERED

The aetiologies of pubertal delay in males and their specific pharmacological therapies are discussed in this review.

EXPERT OPINION

High-quality evidence addressing the best pharmacological therapy approach for each aetiology of delayed puberty in males is scarce, and most of the current practice is based on small case series or unpublished experience. Male teenagers seeking attention for pubertal delay most probably benefit from medical treatment to avoid psychosocial distress. While watchful waiting is appropriate in 12- to 14-year-old boys when constitutional delay of growth and puberty (CGDP) is suspected, hormone replacement should not be delayed beyond the age of 14 years in order to avoid impairing height potential and peak bone mass. When primary or central hypogonadism is diagnosed, hormone replacement should be proposed by the age of 12 years provided that a functional central hypogonadism has been ruled out. Testosterone replacement regimens have been used for decades and are fairly standardised. Aromatase inhibitors have arisen as an interesting alternative for boy with CDGP and short stature. Gonadotrophin therapy seems more physiological in patients with central hypogonadism, but its relative efficacy and most adequate timing still need to be established.

An Approach to the Patient With Delayed Puberty

Pediatric endocrinologists often evaluate and treat youth with delayed puberty. Stereotypically, these patients are 14-year-old young men who present due to lack of pubertal development. Concerns about stature are often present, arising from gradual shifts to lower height percentiles on the population-based, cross-sectional curves. Fathers and/or mothers may have also experienced later than average pubertal onset. In this review, we will discuss a practical clinical approach to the evaluation and management of youth with delayed puberty, including the differential diagnosis and key aspects of evaluation and management informed by recent review of the existing literature. We will also discuss scenarios that pose additional clinical challenges, including: (1) the young woman whose case poses questions regarding how presentation and approach differs for females vs males; (2) the 14-year-old female or 16-year-old young man who highlight the need to reconsider the most likely diagnoses, including whether idiopathic delayed puberty can still be considered constitutional delay of growth and puberty at such late ages; and finally (3) the 12- to 13-year-old whose presentation raises questions about whether age cutoffs for the diagnosis and treatment of delayed puberty should be adjusted downward to coincide with the earlier onset of puberty in the general population.

Androgen Treatment in Adolescent Males With Hypogonadism

During adolescence, androgens are responsible for the development of secondary sexual characteristics, pubertal growth, and the anabolic effects on bone and muscle mass. Testosterone is the most abundant testicular androgen, but some effects are mediated by its conversion to the more potent androgen dihydrotestosterone (DHT) or to estradiol. Androgen deficiency, requiring replacement therapy, may occur due to a primary testicular failure or secondary to a hypothalamic–pituitary disorder. A very frequent condition characterized by a late activation of the gonadal axis that may also need androgen treatment is constitutional delay of puberty. Of the several testosterone or DHT formulations commercially available, very few are employed, and none is marketed for its use in adolescents. The most frequently used androgen therapy is based on the intramuscular administration of testosterone enanthate or cypionate every 3 to 4 weeks, with initially low doses. These are progressively increased during several months or years, in order to mimic the physiology of puberty, until adult doses are attained. Scarce experience exists with oral or transdermal formulations. Preparations containing DHT, which are not widely available, are preferred in specific conditions. Oxandrolone, a non-aromatizable drug with higher anabolic than androgenic effects, has been used in adolescents with preserved testosterone production, like Klinefelter syndrome, with positive effects on cardiometabolic health and visual, motor, and psychosocial functions. The usual protocols applied for androgen therapy in boys and adolescents are discussed.

Testosterone Use in Adolescent Males: Current Practice and Unmet Needs

Testosterone replacement therapy (TRT) is routinely prescribed in adolescent males with constitutional delay of growth and puberty (CDGP) or hypogonadism. With many new testosterone (T) formulations entering the market targeted for adults, we review current evidence and TRT options for adolescents and identify areas of unmet needs. We searched PubMed for articles (in English) on testosterone therapy, androgens, adolescence, and puberty in humans. 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. Reassuring evidence is emerging on the use of transdermal  T to induce and maintain puberty. The long-term safety and efficacy of TRT for puberty completion and maintenance have not been established. Current  TRT regimens are based on consensus and expert opinion, but evidence-based guidelines are lacking. Limited guidance exists on when and how  T should be administered and optimal strategies for monitoring therapy once it is initiated. Only  TE and  T pellets are US Food and Drug Administration approved for use in adolescent males in the United States. Despite the introduction of a wide variety of new  T formulations, they are designed for adults, and their metered doses are difficult to titrate in adolescents. In conclusion, TRT in adolescent males is hindered by lack of long-term safety and efficacy data and limited options approved for use in this population. Additional research is needed to identify the route, dose, duration, and optimal timing for TRT in adolescents requiring androgen therapy.

Androgens During Infancy, Childhood, and Adolescence: Physiology and Use in Clinical Practice

We provide an in-depth review of the role of androgens in male maturation and development, from the fetal stage through adolescence into emerging adulthood, and discuss the treatment of disorders of androgen production throughout these time periods. Testosterone, the primary androgen produced by males, has both anabolic and androgenic effects. Androgen exposure induces virilization and anabolic body composition changes during fetal development, influences growth and virilization during infancy, and stimulates development of secondary sexual characteristics, growth acceleration, bone mass accrual, and alterations of body composition during puberty. Disorders of androgen production may be subdivided into hypo- or hypergonadotropic hypogonadism. Hypogonadotropic hypogonadism may be either congenital or acquired (resulting from cranial radiation, trauma, or less common causes). Hypergonadotropic hypogonadism occurs in males with Klinefelter syndrome and may occur in response to pelvic radiation, certain chemotherapeutic agents, and less common causes. These disorders all require testosterone replacement therapy during pubertal maturation and many require lifelong replacement. Androgen (or gonadotropin) therapy is clearly beneficial in those with persistent hypogonadism and self-limited delayed puberty and is now widely used in transgender male adolescents. With more widespread use and newer formulations approved for adults, data from long-term randomized placebo-controlled trials are needed to enable pediatricians to identify the optimal age of initiation, route of administration, and dosing frequency to address the unique needs of their patients.

Growth, sexual and bone development in a boy with bilateral anorchia under testosterone treatment guided by the development of his monozygotic twin

BACKGROUND

Sex steroids are essential for sexual maturation, linear growth and bone development. However, there is no consensus on the optimal timing, dosage and dosage interval of testosterone therapy to induce pubertal development and achieve a normal adult height and bone mass in children with hypogonadism.

CASE PRESENTATION

A monozygotic monochorial male twin pair, of which one boy was diagnosed with anorchia at birth due to testicular regression syndrome was followed from the age of 3 until the age of 18 years. Low dose testosterone substitution (testosterone esters 25 mg/2 weeks) was initiated in the affected twin based on the start of pubertal development in the healthy twin and then gradually increased accordingly. Both boys were followed until age 18 and were compared as regards to linear growth, sexual maturation, bone maturation and bone development. Before puberty induction both boys had a similar weight and height. During puberty, a slightly faster weight and height gain was observed in the affected twin. Both boys ended up however, with a similar and normal (near) adult height and weight and experienced a normal development of secondary sex characteristics. At the age of 17 and 18 years, bone mineral density, body composition and volumetric bone parameters at the forearm and calf were evaluated in both boys. The affected boy had a higher lean mass and muscle cross-sectional area. The bone mineral density at the lumbar spine and whole body was similar. Trabecular and cortical volumetric bone parameters were comparable. At one cortical site (proximal radius), however, the affected twin had a smaller periosteal and endosteal circumference with a thicker cortex.

CONCLUSIONS

In conclusion, a low dose testosterone substitution in bilateral anorchia led to a normal onset of pubertal development and (near) adult height. Furthermore, there was no difference in bone mineral density at the age of 17 and 18 years.

Diagnostic utility of testosterone priming prior to dynamic tests to differentiate constitutional delay in puberty from isolated hypogonadotropic hypogonadism

CONTEXT

Differentiation between constitutional delay in puberty (CDP) and isolated hypogonadotropic hypogonadism (IHH) during adolescence is a great clinical challenge, and the available diagnostic tests are of limited value.

OBJECTIVE

To study the effect of withdrawal of short-term, low-dose testosterone therapy (testosterone priming) on the discriminatory power of dynamic tests for hypothalamo-pituitary-testicular axis to differentiate CDP from IHH.

DESIGN

A prospective study (n = 30) consisting of 20 boys with delayed puberty (group A) and 10 patients with IHH (group B).

INTERVENTION

Patients in groups A and B underwent Triptorelin and hCG stimulation tests, prior to and 2 months after withdrawal of 'testosterone priming' (100 mg intramuscularly 4 weekly for 3 months) and were followed up until the onset of puberty or 18 years of age, whichever was earlier.

RESULTS

At baseline, Triptorelin-stimulated 4 h LH, with a cut-off of 2·8 IU/l, and hCG-stimulated day 7 testosterone with a cut-off of 3·8 nmol/l had sensitivities of 80% each, and specificities of 93% and 87%, respectively, to diagnose CDP. After withdrawal of testosterone, a 4 h LH cut-off of 14·7 IU/l and day 7 testosterone cut-off of 10·3 nmol/l had sensitivities of 93% and 88% respectively, and specificity and positive predictive value of 100% each. A basal inhibin B > 94·7 ng/l was discriminatory for diagnosing CDP after withdrawal of testosterone priming.

CONCLUSIONS

Inhibin B levels or 4 h LH after Triptorelin stimulation are the best discriminatory tests to differentiate CDP from IHH, when performed after withdrawal of 'testosterone priming'.

Treatment situation of male hypogonadotropic hypogonadism in pediatrics and proposal of testosterone and gonadotropins replacement therapy protocols

Male hypogonadotropic hypogonadism (MHH), a disorder associated with infertility, is treated with testosterone replacement therapy (TRT) and/or gonadotropins replacement therapy (GRT) (TRT and GRT, together with HRT hormone replacement therapy). In Japan, guidelines have been set for treatment during adolescence. Due to the risk of rapid maturation of bone age, low doses of testosterone or gonadotropins have been used. However, the optimal timing and methods of therapeutic intervention have not yet been established. The objective of this study was to investigate the current situation of treatment for children with MHH in Japan and to review a primary survey involving councilors of the Japanese Society for Pediatric Endocrinology and a secondary survey obtained from 26 facilities conducting HRT. The subjects were 55 patients with MHH who reached their adult height after HRT. The breakdown of the patients is as follows: 7 patients with Kallmann syndrome, 6 patients with isolated gonadotropin deficiency, 18 patients with acquired hypopituitarism due to intracranial and pituitary tumor, 22 patients with classical idiopathic hypopituitarism due to breech delivery, and 2 patients with CHARGE syndrome. The mean age at the start of HRT was 15.7 yrs and mean height was 157.2 cm. The mean age at reaching adult height was 19.4 yrs, and the mean adult height was 171.0 cm. The starting age of HRT was later than the normal pubertal age and showed a significant negative correlation with pubertal height gain, but it showed no correlation with adult height. As for spermatogenesis, 76% of the above patients treated with hCG-rFSH combined therapy showed positive results, though ranging in levels; impaired spermatogenesis was observed in some with congenital MHH, and favorable spermatogenesis was observed in all with acquired MHH. From the above, we propose the establishment of a treatment protocol for the start low-dose testosterone or low-dose gonadotropins by dividing subjects into two groups to determine different treatment protocols, acquired and congenital MHH, and to conduct them at a timing closer to the onset of puberty, namely, at a timing near entrance to junior high school. We also propose a new HRT protocol using preemptive FSH therapy prior to GRT aimed at achieving future fertility in patients with congenital MHH.

A multicenter, open-label, observational study of testosterone gel (1%) in the treatment of adolescent boys with klinefelter syndrome or anorchia

PURPOSE

To assess the safety and clinical outcomes of 6-month treatment with testosterone gel 1% therapy in adolescent boys with primary hypogonadism resulting from Klinefelter syndrome (KS) or anorchia.

METHODS

This was a subgroup analysis of a multicenter, open-label study of adolescent boys (N = 86) with delayed puberty who received .5-5.0 g testosterone gel 1% daily for ≤6 months. Adolescent boys 12-17 years of age with KS (n = 21) or anorchia (n = 8), bone age ≥10.5 years, and baseline growth data ≥6 months were included in this analysis. Serum hormone levels (total/free testosterone, luteinizing hormone, dihydrotestosterone, follicle-stimulating hormone, and estradiol) were measured using validated assays. Safety was assessed through adverse events (AEs).

RESULTS

At baseline, patients with KS were taller, weighed more, and had higher total testosterone levels (mean 174 vs. 19 ng/dL) than patients with anorchia. At 6 months, total and free testosterone and dihydrotestosterone levels increased 1.8- to 2.3-fold in the KS group and eight- to 10-fold in anorchia patients. Estradiol levels increased 1.9-fold in the anorchia group and 1.4-fold in the KS group after treatment. No clinically significant changes were noted for luteinizing hormone, follicle-stimulating hormone, and sex hormone-binding globulin concentrations in either group. Cough was the most common AE (eight of 29), followed by acne and headache (both four of 29). One anorchia and two KS patients discontinued prematurely.

CONCLUSIONS

Once-daily testosterone gel application increased serum testosterone levels into the pubertal range and maintained pubertal testosterone levels during 6-month treatment. In this study, testosterone gel 1% raised testosterone levels and was associated with cough as the most common AE.

An approach to constitutional delay of growth and puberty

Constitutional delay of growth and puberty is a transient state of hypogonadotropic hypogonadism associated with prolongation of childhood phase of growth, delayed skeletal maturation, delayed and attenuated pubertal growth spurt, and relatively low insulin-like growth factor-1 secretion. In a considerable number of cases, the final adult height (Ht) does not reach the mid-parental or the predicted adult Ht for the individual, with some degree of disproportionately short trunk. In the pre-pubertal male, testosterone (T) replacement therapy can be used to induce pubertal development, accelerate growth and relieve the psychosocial complaints of the adolescents. However, some issues in the management are still unresolved. These include type, optimal timing, dose and duration of sex steroid treatment and the possible use of adjunctive or alternate therapy including: oxandrolone, aromatase inhibitors and human growth hormone.

Etiology and treatment of hypogonadism in adolescents

Adequate functioning at all levels of the hypothalamic-pituitary-gonadal axis is necessary for normal gonadal development and subsequent sex steroid production. Deficiencies at any level of the axis can lead to a hypogonadal state. The causes of hypogonadism are heterogeneous and may involve any level of the reproductive system. This review discusses various causes of hypogonadism, describes the evaluation of hypogonadal states, and outlines treatment options for the induction of puberty in affected adolescents. Whereas some conditions are clearly delineated, the exact etiology and underlying pathogenesis of many disorders is unknown.

Etiology and treatment of hypogonadism in adolescents

Adequate functioning at all levels of the hypothalamic-pituitary-gonadal axis is necessary for normal gonadal development and subsequent sex steroid production. Deficiencies at any level of the axis can lead to a hypogonadal state. The causes of hypogonadism are heterogeneous and may involve any level of the reproductive system. This review discusses various causes of hypogonadism, describes the evaluation of hypogonadal states, and outlines treatment options for the induction of puberty in affected adolescents. Whereas some conditions are clearly delineated, the exact etiology and underlying pathogenesis of many disorders is unknown.

Androgen therapy for delayed male puberty

PURPOSE OF REVIEW

Delayed puberty in men is a commonly presenting problem to paediatricians and an understanding of the available evidence on cause, treatments and outcomes is important to guide practice.

RECENT FINDINGS

Understanding of the regulation of the onset of puberty is gradually unfolding, although the genetic factors that dictate the timing of puberty in individuals and families remain poorly elucidated. Mutations and polymorphisms in candidate genes are being actively studied and it is likely that there is significant overlap between traditional diagnostic categories. Also, environmental endocrine disruptors may interact with the genetic regulation of puberty. Delayed puberty may not always be a benign condition, with increased risks of failing to achieve target height, adverse psychological and educational consequences, delayed sexual and psychosocial integration into society and effects on skeletal proportions and bone mass reported. Appropriate evaluation and follow-up is needed to guide clinical practice, particularly to distinguish constitutional delay in growth and puberty from that associated with other medical disease or permanent disorders.

SUMMARY

In milder cases of delayed puberty, treatment is often not required; however, considerable evidence exists for the efficacy and safety of short courses of low-dose testosterone therapy for appropriately selected individuals. This treatment is associated with high levels of patient satisfaction. There is not yet sufficient evidence for the routine use of other therapies (e.g. growth hormone, aromatase inhibitors) for constitutional delay in growth and puberty and better characterization of cause may lead to more targeted individual therapy.

New facets of androgen replacement therapy during childhood and adolescence

The goals of androgen therapy for adolescents are to promote linear growth and secondary sexual characteristics, at the same time as permitting the normal accrual of muscle mass and bone mineral content. Secondary goals are mainly in the psychosocial sphere, in which pubertally delayed boys feel that they look too young, are not considered a 'peer' in their age group and have difficulty competing in athletic endeavours. These goals are irrespective of the causes of delayed pubertal development: constitutional delay of growth and puberty (CDGP), a transient but very common form of pubertal delay and, much less commonly, primary or secondary permanent hypogonadism. Not all boys with CDGP require testosterone therapy, but those that come to a referral practice are likely candidates, as the watchful waiting period has finished. Although a range of androgen preparations is available for adults (injectable, oral, implantable and cutaneous patches and gels), most are drug delivery devices that are appropriate for full adult androgen replacement. These doses are too large for the induction of puberty. Therefore, at present, the injectable form is the only one that is easily adaptable for the increasing amounts of androgen necessary for the various stages of pubertal development. All preparations deliver testosterone that is readily converted to dihydrotestosterone by 5-alpha reductase. The author's practice is to begin with injecting 50-75 mg of one of the long-acting esters (enanthate or cypionate) per month, and gradually escalate to 100-150 mg/month, before changing to twice monthly dosage. As most adolescents have delayed puberty, the therapy is needed for 6-18 months before the hypothalamic-pituitary-gonadal axis functions at the late adolescent/adult level in those with CDGP. Those with permanent hypogonadism will require lifelong therapy. Once adequate virilisation is induced, and virtually full adult height is reached, any of the therapies noted above can be used in those permanently hypogonadal, whether primarily or secondarily.

Final height outcome and value of height prediction in boys with constitutional delay in growth and adolescence treated with intramuscular testosterone 125 mg per month for 3 months

OBJECTIVES

Constitutional delay in growth and adolescence (CDGA) is common in boys, some of whom request treatment to accelerate growth and attainment of secondary sexual characteristics. The aims of this study were to confirm that a 3-month course of intramuscular testosterone oenanthate does not impair final height in boys with CDGA, and to determine the accuracy of height prediction in this condition.

DESIGN AND PATIENTS

Boys with CDGA who had attended the growth clinic, who were now at or close to final height and who had received either testosterone or declined treatment, were identified by retrospective case note analysis. Bone age assessment was carried out by a single observer, using the RUS (TW2) method of Tanner and Whitehouse.

MEASUREMENTS

The following auxological data were extracted from the case records: age, bone age, height, pubertal stage, parental heights and predicted final height. All subjects were then measured at age 19 years or greater. The main outcome measures were comparison of final height in treated and untreated boys; final height comparison with mid-parental height and with height prediction [RUS (TW2) method] at initial assessment and at subsequent review.

RESULTS

Sixty-four boys met the inclusion criteria, of whom 41 subjects had received testosterone and 23 were untreated. There were no significant differences between the groups (treated mean/SD vs. untreated mean/SD; P-value) in age (14.3/0.7 vs. 14.0/1.1; 0.13), height (144.7/6.2 vs. 144.2/6.2; 0.79), mid-parental heights (170.4/5.5 vs. 171.1/4.5; 0.59), and bone age (12.0/1.2 vs. 12.3/1.3; 0.36). Final heights in both groups (168.9/6.0 vs. 168.2/3.5; 0.65) were closely related to predicted final heights (170.0/5.0 vs. 168.1/4.1; 0.15) and only slightly less than mid-parental heights. Only three subjects had final heights below the initial height prediction range.

CONCLUSIONS

Our data support the hypothesis that this treatment regime does not adversely affect the final height achieved in constitutional delay of growth and adolescence and that height prediction, assessed by a single observer, is a useful and accurate tool.

Diversity of pubertal testosterone changes in boys with constitutional delay in growth and/or adolescence

In a group of 22 boys with constitutional delay in growth and/or adolescence, intermittent testosterone enanthate treatment was employed in a randomized clinical trial at multiple doses ranging from 25-100 mg every two weeks for three month periods extending over 15-21 months. Twelve of the patients displayed a prompt increase in endogenous testosterone levels during the study period, reaching levels in the adult male range (> 250 ng/dl). The remaining 10 boys showed sluggish changes in endogenous testosterone during the investigation, ranging from 35-177 ng/dl. The bone ages and testicular sizes of the two groups at study initiation did not differ though urine LH was significantly less at study entry in the slowly maturing group. The data reveal a great diversity in the pace and pattern of endogenous testosterone changes in the study population. The results also suggest that exogenous sex steroid treatment of such patients does not speed up the central nervous system processes controlling the onset and progression of puberty. Boys with delayed puberty should be followed until endogenous testosterone levels reach the adult male range in order to rule out mild gonadotropin deficits.