Vertebral morphology in aromatase inhibitor-treated males with idiopathic short stature or constitutional delay of puberty

Effect and safety of aromatase inhibitors for the treatment of short stature in male children and adolescents: a meta-analysis of randomized controlled trials

This study is to evaluate the efficacy and safety of aromatase inhibitors (AIs) in the treatment of short stature in male children and adolescents. Pooled estimates of final or near-final height, predicted adult height (PAH), bone age, and potential side effects were calculated using a random-effects model or fixed-effects model. Our search identified 11 studies with a total of 463 participants. AI was associated with a significant increase in final or near-final height (weight mean difference (WMD)=3.61 cm, 95 % CI: 0.96, 6.26; p<0.001) and PAH (WMD=2.52 cm, 95 % CI: 0.32, 4.72; p=0.025) compared to other treatment. The use of AI showed an increased risk of minor side effects (risk ratio (RR)=2.90, 95 % CI: 1.15, 7.33; p=0.025), but no severe adverse effects were reported. Subgroup analysis, stratified by patient disease, revealed that AI significantly enhanced final or near-final height in both patients with idiopathic short stature (ISS) and those with constitutional delay of growth and puberty (CDGP). AIs may contribute to height increase in male children and adolescents with short stature, without significantly advancing bone age. However, the increased risk of minor side effects indicates the need for careful monitoring during AI therapy.

Effects of short-term oral letrozole on fresh semen parameters, endocrine balance, and prostate gland dimensions in domestic dogs

BACKGROUND

Aromatase inhibitors improve male fertility by modifying the hormonal control of spermatogenesis. The present study aimed to investigate the effects of oral administration of letrozole on testosterone and estradiol concentrations and their ratios in blood serum, seminal plasma, prostatic fluid, sperm quality in fresh semen, and prostate gland dimensions. Seven adult male intact mixed-breed dogs were selected. The animals received letrozole (72 µg/kg, PO) daily for four weeks. Blood samplings and semen collections were carried out on days 0 (control), 14 (treatment), 28 (treatment), and 42 (post-treatment).

RESULTS

Our results showed that letrozole administration resulted in a 4.3 fold significant increase in serum, seminal plasma, and prostatic fluid testosterone levels after 14 days. This remained high until the end of the study. Serum and prostatic fluid estradiol levels did not change significantly over the study period. However, the seminal plasma estradiol level showed a significant increase on day 14. The estradiol: testosterone ratio was significantly reduced on day 14 in serum, seminal plasma, and prostatic fluid samples. Letrozole significantly improved the ejaculated spermatozoa viability and concentration after 28 days of oral administration. However, the sperm plasma membrane functional integrity and kinematic parameters were not significantly affected by the treatment. Transabdominal ultrasound examination revealed a significant increase in the height, width, and volume of the prostate gland after 28 days of treatment.

CONCLUSIONS

According to the present research, oral administration of letrozole for 28 days affects local and systemic sex hormone balance leading to an improvement of the ejaculated canine spermatozoa viability and concentration concurrent with an increase in the prostate gland dimensions.

Anastrozole vs Letrozole to Augment Height in Pubertal Males With Idiopathic Short Stature: A 3-Year Randomized Trial

Context

Insufficient efficacy and safety data for off-label use of aromatase inhibitors to augment height in boys with short stature.

Objective

To compare anastrozole and letrozole in treatment of idiopathic short stature in pubertal boys.

Design

Open-label trial with 2 treatment arms.

Setting

Pediatric Endocrine Clinic at Stanford.

Participants

A total of 79 pubertal males ≥10 years with bone age (BA) ≤ 14 years, predicted adult height (PAH) < 5th percentile or >10 cm below mid-parental height.

Intervention

Anastrozole 1.0 mg or letrozole 2.5 mg daily for up to 3 years.

Main Outcome Measures

Annual hormone levels and growth parameters during treatment and a year posttherapy; annual BA and PAH (primary outcome measure); spine x-rays and dual energy X-ray absorptiometry at baseline and 2 years.

Results

Compared with anastrozole (n = 35), letrozole (n = 30) resulted in higher testosterone levels, lower estradiol and IGF-1 levels, and slower growth velocity and BA advance. The PAH increase observed at year 1 in both groups did not persist at years 2 and 3. Change in PAH from baseline was not different between treatment groups. In groups combined, PAH gain over 3 years vs baseline was +1.3 cm (P = .043) in linear mixed models.

Conclusion

Letrozole caused greater deviations than anastrozole in hormone levels, growth velocity, and BA advancement, but no group differences in PAH or side effects were found. Change in PAH after 2 to 3 years of treatment was minimal. The efficacy of AI as monotherapy for height augmentation in pubertal boys with idiopathic short stature may be limited, and safety remains an issue.

Exploring height outcomes with adjuvant aromatase inhibition in growth hormone-deficient male survivors of childhood cancer

BACKGROUND

Aromatase inhibitors (AI) may improve height in short stature conditions; however, the effect in childhood cancer survivors (CCS) is unknown. We assessed final adult height (FAH) in CCS treated with AI and GH compared with those treated with GH alone.

METHODS

Retrospective cohort study of GH-deficient male CCS treated between 2007 and 2023. FAH was noted as the height at the fusion of growth plates or 18 years of age. Multivariable linear regression was used to examine treatment association with FAH, adjusting for other risk factors.

RESULTS

Ninety-two patients were included; 70 were treated with GH and 22 with combination AI/GH. The mean age at GH initiation did not differ between groups. The mean age at AI initiation was 13.7 ± 1.9 years. A greater proportion of patients in the AI/GH group were treated with stem cell transplantation, abdominal radiation, total body irradiation, and cis-retinoic acid (p < .01). Multivariable linear regression demonstrated no significant treatment association with FAH Z-score (β = 0.04, 95% CI: -0.9 to 0.9). History of spinal radiation (β = -0.93, 95% CI: -1.7 to -0.2), lower starting height Z-score (β = -0.8, 95% CI: -1.2 to -0.4), and greater difference between bone age and chronological age (β = -0.3, 95% CI: -0.5 to -0.07) were associated with lower FAH Z-score.

CONCLUSIONS

Adjuvant AI was not associated with increased FAH in male CCS compared with GH monotherapy. Future work is needed to determine the optimal adjunctive treatment to maximize FAH for this population.

Children With Idiopathic Short Stature: An Expanding Role for Genetic Investigation in Their Medical Evaluation

Short stature in children is a common reason for referral to a pediatric endocrinologist. Many genetic, nutritional, psychological, illness-related, and hormonal causes must be excluded before labeling as idiopathic. Idiopathic short stature is not a diagnosis, but rather describes a large, heterogeneous group of children, who are short and often slowly growing. As new testing paradigms become available, the pool of patients labeled as idiopathic will shrink, although most will have a polygenic cause. Given that many of the new diagnoses are involved in growth plate biology, physical examination should assess for subtle dysmorphology or disproportion of the skeleton that may indicate a heterozygous mutation that in its homozygous state would be apparent. When laboratory evaluations are negative, one may consider genetic testing, such as targeted gene or gene panel, comparative genomic hybridization, or whole exome or whole genome sequencing (respectively). With a known genetic diagnosis, targeted therapy may be possible rather than recombinant human growth hormone, where response is generally poorer than that for children with growth hormone deficiency, because the variety of diagnoses may have varying growth hormone sensitivity. A firm diagnosis has heuristic value: to truncate further diagnostic evaluation, alert the clinician to other possible comorbidities, inform the family for genetic counseling, and direct appropriate targeted therapy, if available.

[Pharmacological therapies for height improvement in pubertal children with short stature]

Short stature in puberty significantly affects the physical and mental health of adolescents. The continuous acceleration of skeletal maturation, caused by sex hormones during puberty, limits the time available for growth and poses a considerable challenge for the treatment of short stature. To date, there is still no standardized treatment protocol for this disorder. However, puberty is the last period to improve the final adult height. Currently, commonly used pharmacological treatments in clinical settings include recombinant human growth hormone, gonadotropin-releasing hormone analogs, and third-generation aromatase inhibitors. In recent years, personalized treatment aiming to improve the final adult height has become a key focus in clinical practice. This article provides a comprehensive summary of research on pharmacological therapies for height improvement in pubertal children with short stature, offering valuable insights for healthcare professionals.

Management of Growth Disorders in Puberty: GH, GnRHa, and Aromatase Inhibitors: A Clinical Review

Pubertal children with significant growth retardation represent a considerable therapeutic challenge. In growth hormone (GH) deficiency, and in those without identifiable pathologies (idiopathic short stature), the impact of using GH is significantly hindered by the relentless tempo of bone age acceleration caused by sex steroids, limiting time available for growth. Estrogen principally modulates epiphyseal fusion in females and males. GH production rates and growth velocity more than double during puberty, and high-dose GH use has shown dose-dependent increases in linear growth, but also can raise insulin-like growth factor I concentrations supraphysiologically, and increase treatment costs. Gonadotropin-releasing hormone analogs (GnRHas) suppress physiologic puberty, and when used in combination with GH can meaningfully increase height potential in males and females while rendering adolescents temporarily hypogonadal at a critical time in development. Aromatase inhibitors (AIs) block androgen to estrogen conversion, slowing down growth plate fusion, while allowing normal virilization in males and stimulating longitudinal bone growth via androgen receptor effects on the growth plate. Here, we review the physiology of pubertal growth, estrogen and androgen action on the epiphyses, and the therapeutic impact of GH, alone and in combination with GnRHa and with AIs. The pharmacology of potent oral AIs, and pivotal work on their efficacy and safety in children is also reviewed. Time-limited use of AIs is a viable alternative to promote growth in pubertal males, particularly combined with GH. Use of targeted growth-promoting therapies in adolescence must consider the impact of sex steroids on growth plate fusion, and treatment should be individualized.

Use of letrozole to augment height outcome in pubertal boys: a retrospective chart review

OBJECTIVES

We describe growth patterns and predicted adult height (PAH) in pubertal boys treated with letrozole and evaluate the potential predictors of growth responses.

METHODS

We performed a retrospective analysis of data from 2002 to 2020. All subjects were treated for ≥6 months and had at least 3 height measurements to calculate the growth velocity (GV) before and during treatment. We evaluated growth measurements, bone age, and biochemical parameters before, during and after treatment.

RESULTS

A total of 59 subjects aged 12.7 (± 1.7) years old were included. At treatment initiation, bone age was 13.1 (± 1.5) years and predicted adult height (PAH) was 163.8 (± 9.9) cm compared to mid-parental height of 172.4 (± 5.8) cm. Growth velocity decreased during letrozole therapy and rebounded after completion. Sub-analysis of 26 subjects with bone age data available at baseline and at least 1 year later showed a trend to modest increase in PAH. In boys simultaneously receiving growth hormone (rhGH), the change in PAH was significantly more (3.2 cm, p<0.05) compared to those treated with letrozole alone.

CONCLUSIONS

We show that letrozole appropriately slows down skeletal maturation and GV responses are variable. Possible negative predictors include lower baseline GV and advanced bone age. A small positive trend in PAH with letrozole therapy is augmented by simultaneous use of rhGH. Future randomized controlled trials are needed to better understand which group of patients will benefit from treatment.

Adult height in pubertal boys with short stature treated with GH/letrozole: a hospital record-based retrospective study

Background

The growth potential in pubertal boys with short stature is limited by the effect of estrogen on epiphyseal fusion. This study aims to identify the efficacy and safety of the combination of growth hormone (GH) and letrozole on adult height (AH) in pubertal boys with short stature.

Methods

This is a retrospective record based study. Pubertal boys with short stature who were treated with GH and letrozole were followed up at outpatient clinics in our hospital. Twenty subjects who reached AH are reported here.

Results

Baseline chronological age was 12.12 ± 1.14 yr and bone age was 13.00 ± 0.93 yr. The period of GH/letrozole treatment was 1.94 ± 0.67 yr. Height standard deviation score for bone age was increased from -1.46 ± 0.51 before treatment to -0.12 ± 0.57 after treatment (P < 0.001). The predicted AH before treatment, predicted AH after treatment, AH, and genetic target height were 161.02 ± 4.12 cm, 172.11 ± 4.20 cm, 172.67 ± 2.72 cm, and 167.67 ± 3.56 cm, respectively. There was a significant predicted AH difference before and after treatment (P < 0.001). There was a significant difference between predicted AH before treatment and genetic target height (P < 0.001). Predicted AH after therapy was higher than that of gene target height (P < 0.001), as well as AH and genetic target height (P < 0.001). There was no significant side effect.

Conclusions

GH and letrozole combination can enhance AH in pubertal boys with short stature.

Efficacy and Safety of Letrozole in the Management of Constitutional Delay in Growth and Puberty: A Systematic Review and Meta-analysis

No meta-analysis is available which has analysed the role of letrozole in constitutional delay in growth and puberty (CDGP). Electronic databases were searched for randomized controlled trials (RCTs) involving children with CDGP receiving letrozole. Primary outcomes were changes in predicted adult height (PAH) and pubertal progression. Secondary outcomes were alterations in bone age (BA), hormonal markers of puberty, bone mineral density and side-effects. One hundred-thirty articles were reviewed, from which seven RCTs which fulfilled all criteria were analysed. Letrozole was superior to placebo [mean difference (MD) 4.63 cm (95% confidence interval (CI): 3.90-5.36); p<0.01; I²=0%] but not testosterone [MD: 2.21 cm (95% CI: -1.71-6.16); p=0.27; I²=98%] with regards to improvement in PAH after 12-months use. Letrozole was superior to both placebo [MD: 4.80 mL (95% CI: 0.57-9.03); p=0.03] and testosterone [MD: 3.36 mL (95% CI: 0.58-6.75); p=0.02; I²=0%] with regards to improvement in testicular volume after 12-months use. Letrozole tended to be superior to testosterone [MD: -0.84 years (95% CI: 2.83-8.18); p=0.06; I²=0%] with regards to slowing in BA progression after 12-months use. Serum luteinizing hormone, follicle stimulating hormone, testosterone and inhibin-B were significantly higher after 6-months letrozole use compared to active as well as passive controls. No increased occurrence of adverse events, including spinal deformities, were noted with letrozole. Letrozole is safe and effective for improving height and pubertal outcomes in CDGP, and is better than testosterone with regards to improvement in testicular volume and may be better at delaying bone-age progression.

Serum testosterone and oestradiol predict the growth response during puberty promoting treatment

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.

Tree nut consumption is associated with a lower risk of hyperestrogenism in men

Hyperestrogenism may affect 2% to 8% of men globally. Previous studies indicate that tree nut consumption is associated with sex hormones in women. Whether this is the case in men remains unknown. This study hypothesized that consumption of tree nuts was inversely associated with circulating estradiol and prevalence of hyperestrogenism in men. This cross-sectional study included 3340 men aged ≥20 years from the US National Health and Nutrition Examination Survey from 2013 to 2016. Associations of tree nut consumption with circulating estradiol and prevalence of hyperestrogenism were assessed using weighted linear regression and binary logistic regression, respectively. Among the 3340 men, 207 consumed tree nuts. The mean usual intake of tree nuts among tree nut consumers was 34.2 g/d. Amounts of usual intake of tree nuts were inversely associated with bioavailable estradiol (β = -0.032, P = .037) after adjustment for all confounders. Usual intake of tree nuts of ≥ 30 g/d (vs <30 g/d) or ≥42.52 g/d (vs <42.52 g/d) was associated with a 24% or 7% lower multivariate-adjusted risk of hyperestrogenism, respectively. Further analyses showed that usual intake of tree nuts was positively associated with circulating folate, and the latter was inversely associated with circulating estradiol. In conclusion, higher tree nut consumption was independently associated with lower circulating levels of bioavailable estradiol and a lower risk of hyperestrogenism in men. Further research is needed to verify the effectiveness of using tree nuts to treat hyperestrogenism in men.

Morphology and serum and bone tissue calcium and magnesium concentrations in the bones of male rats chronically treated with letrozole, a nonsteroidal cytochrome P450 aromatase inhibitor

Purpose/Aim of the study: The role of estrogen (E) in the regulation of bone turnover in women is well established, though the contributions of E versus testosterone (T) in the control of bone turnover in men are poorly understood. The aim of this study was to examine the association between chronic treatment with letrozole, a nonsteroidal inhibitor blocking the aromatase activity and thus the conversion of androgens into estrogens, and cortical bone morphology in the femur and humerus of male adult rats.Materials and Methods: Adult male rats were treated with letrozole for 6 months and the body and femur weight, morphology, collagen structure, blood serum, and bone tissue concentrations of calcium and magnesium were examined.Results: Long-term aromatase inhibition resulted in a decrease in femur mass, a wavelike arrangement of bone and lamellae with an altered organization of collagen in compact bone, a increased concentration of calcium in blood serum, and no change in calcium bone tissue concentration, magnesium serum, or bone tissue concentration. MicroCT study of the humerus revealed significant decreases of whole bone tissue volume, cortical bone thickness, cortical bone volume, and external cortical bone thickness with letrozole treatment.Conclusion: Chronic treatment with letrozole affected cortical bone structure and produced histomorphological changes in male rat bone similar to that observed in the aging processes.

Treatment of Short Stature with Aromatase Inhibitors: A Systematic Review and Meta-Analysis

The objective of the study is to determine the risks and benefits of treating idiopathic short stature (ISS) with aromatase inhibitors (AIs). We comprehensively searched PubMed, Embase, and the China National Knowledge Infrastructure between establishment year and January 31, 2020. Mean difference (MD)/Standardized mean differences (SMD) with 95% confidence intervals (CI) of individual studies were pooled using fixed or random effects models. Subgroup and sensitivity analyses were also performed. Publication bias was estimated using funnel plots and Egger tests. Fourteen studies including 388 participants were included. The meta-analysis results showed that AIs significantly increased final height (MD=2.46, 95% CI: 0.8-4.12) and predicted adult height (MD=0.34, 95% CI: 0.11-0.57). Changes in bone age (MD=-0.1, 95% CI: -0.86-0.66) and bone mineral density (MD=-0.05, 95% CI: -0.19-0.1) were not different between intervention and control group. AI significantly increased testosterone level (SMD=2.01, 95% CI: 0.8-3.23) and reduced estradiol level (SMD=-1.13, 95% CI: -1.87 to -0.40); The intervention and control group had no significant differences in the levels of high-density lipoprotein-cholesterol (SMD=-0.31, 95%CI: -0.68-0.06) and IGF-1 (SMD=0.7, 95% CI: -0.66-2.06) levels. Adverse events were more frequent in the intervention group than in the control group (odds ratio=3.12, 95% CI: 1.44-6.73). In conclusion, both AI monotherapy and AI combination therapy can increase predicted adult height and testosterone levels.

Anastrozole Improves Final Adult Height in Severe Hypothyroidism With Rapid Pubertal Progression

Severe prolonged hypothyroidism due to Hashimoto thyroiditis may lead to rapid pubertal progression and compromised adult height after initiation of levothyroxine (LT4) therapy. There are no reports of aromatase inhibitor use to augment height in these patients. We describe a patient with severe hypothyroidism and growth failure who experienced rapid pubertal and bone age maturation on initiation of LT4 therapy. Anastrozole was added after 2 years to delay epiphyseal fusion. A boy aged 12 years and 1 month presented to the endocrine clinic with short stature and a markedly delayed bone age of 6 years. Brain magnetic resonance imaging showed a 1.5 × 1.0 × 1.2-cm enlarged lobular anterior pituitary. On examination, his height was -3.5 SD score (SDS) and weight was -2.87 SDS. Laboratory studies showed elevated thyrotropin (TSH) 850.6 μIU/mL, low free thyroxine 0.25 ng/dL, and elevated antithyroid antibodies. LT4 was initiated with normalization of TSH after 6 months. After 2 years of treatment he demonstrated catch-up growth with rapid bone age maturation, and his predicted adult height was compromised at 164.6 cm vs a midparental target height of 175.4 cm. Anastrozole 1 mg once daily was initiated. After 1.5 years of anastrozole treatment, the rate of his bone age advancement had slowed and his linear growth remained robust. The patient's near-final height (167 cm) was 2.4 cm taller than his height prediction prior to starting anastrozole. Anastrozole slowed the rate of bone age advancement in a patient with severe hypothyroidism and rapidly progressive puberty during treatment with LT4, leading to improvement in near-final height.

Long-term Effect of Aromatase Inhibition in Aromatase Excess Syndrome

CONTEXT

Aromatase excess syndrome (AEXS) is a very rare disorder characterized by prepubertal gynecomastia, bone age acceleration, and early growth arrest. Heterozygote submicroscopic rearrangements within the promotor of CYP19A1 result in overexpression of aromatase and enhanced aromatization of androgens.

OBJECTIVE

The objective was to study long-term treatment effects of an aromatase inhibitor.

METHODS

Data from 7 boys with AEXS were retrospectively collected. Genetic analysis revealed upstream of CYP19A1 a 165 901 bp deletion in 4 German cousins, a 198 662 bp deletion in 2 Japanese brothers, and a 387 622 bp tandem duplication in a Japanese boy.

RESULTS

All boys developed prepubertal gynecomastia, at median 9.0 years of age (range: 7.0-11.0). Height was +1.20 standard deviation score (SDS) (-0.24 to +1.98); predicted adult height was -1.29 SDS (-3.29 to +1.09). Four boys were treated with 1.0 mg of anastrozole daily, while 3 reached adult height untreated. Treatment with anastrozole was stopped after 5.6 years (4.0-6.8). Three treated boys exceeded their prognosis by 2.4, 6.9, and 8.1 cm, while 1 untreated boy fell below the prognosis by 8.6 cm. One treated with a low dose and 2 untreated reached their prognosis. Adult heights were -0.91 SDS with anastrozole (-2.86 to -0.29) and -0.15 SDS without (-2.31 to -0.03). Distance to target height was -0.22 SDS with anastrozole (-1.72 to +0.52) and +0.54 SDS without (+0.23 to +1.30).

CONCLUSION

Spontaneous growth in AEXS varied, even in the same family. Our data suggest that early started, long-term inhibition by anastrozole promotes adult height in boys with AEXS.

Off-label use of letrozole in Chinese short pubertal boys: Effectiveness, safety, and exposure-response analysis

AIMS

Recently, letrozole has been used off-label to treat short pubertal boys. The experience on letrozole effectiveness and safety has been obtained primarily from Caucasian children. A simple extrapolation of the data to Chinese paediatric populations is questionable because of the substantial ethnic differences between the two populations. Therefore, the present study aimed to determine the effectiveness and safety of letrozole use in Chinese short pubertal boys as well as to establish an exposure-response relationship.

METHODS

Forty-one Chinese boys were included in the study. Patients were given letrozole tablets (2.5 mg) once daily in combination with growth hormone, and follow-up visits were made after 1, 3, 6 and 12 months of treatment. Plasma samples were taken from clinical examinations and analysed using high performance liquid chromatography with fluorescence detection.

RESULTS

After 1 year of treatment, 35 (88%) boys showed increased predicted adult heights. However, possible adverse drug reactions were seen in nine boys (22%). Predicted adult heights increased significantly from 168.4 ± 3.7 to 173.0 ± 4.2 cm, while oestrogen levels dropped from 33.2 ± 7.4 to 21.6 ± 7.3 pg/mL. Increments in predicted adult height were significantly correlated with trough letrozole concentrations (r = 0.39, P = .01).

CONCLUSION

Letrozole treatment in Chinese pubertal populations should be further optimized, and more personalized therapies should be developed.

Case Report: Improved Height in a Patient With Myhre Syndrome Using a Combination of Growth Hormone and Letrozole

Myhre syndrome is a rare disorder caused by a heterozygous mutation in the SMAD4 gene. Affected patients may exhibit dysmorphic facial features, intrauterine growth retardation, short stature, obesity, muscle hypertrophy, thickened skin, limited joint movement, hearing impairment, and varying degrees of psychomotor developmental disorder. Serious complications of the cardiovascular and respiratory system may be seen later in life. We report the case of a Chinese boy with Myhre syndrome presenting with a novel symptom of giant testicles where treatment with growth hormone combined with letrozole successfully improved his short stature. This case shows that letrozole combined with growth hormone can improve height in children with Myhre syndrome without adverse effects.

Should Skeletal Maturation Be Manipulated for Extra Height Gain?

Skeletal maturation can be delayed by reducing the exposure to estrogens, either by halting pubertal development through administering a GnRH analogue (GnRHa), or by blocking the conversion of androgens to estrogens through an aromatase inhibitor (AI). These agents have been investigated in children with growth disorders (off-label), either alone or in combination with recombinant human growth hormone (rhGH). GnRHa is effective in attaining a normal adult height (AH) in the treatment of children with central precocious puberty, but its effect in short children with normal timing of puberty is equivocal. If rhGH-treated children with growth hormone deficiency or those who were born small-for-gestational age are still short at pubertal onset, co-treatment with a GnRHa for 2-3 years increases AH. A similar effect was seen by adding rhGH to GnRHa treatment of children with central precocious puberty with a poor AH prediction and by adding rhGH plus GnRHa to children with congenital adrenal hyperplasia with a poor predicted adult height on conventional treatment with gluco- and mineralocorticoids. In girls with idiopathic short stature and relatively early puberty, rhGH plus GnRHa increases AH. Administration of letrozole to boys with constitutional delay of growth puberty may increase AH, and rhGH plus anastrozole may increase AH in boys with growth hormone deficiency or idiopathic short stature, but the lack of data on attained AH and potential selective loss-of-follow-up in several studies precludes firm conclusions. GnRHas appear to have a good overall safety profile, while for aromatase inhibitors conflicting data have been reported.

[Aromatase inhibitors combined with growth hormone in treatment of adolescent boys with short stature]

OBJECTIVE

To assess the efficacy and safety of aromatase inhibitors (AIs) combined growth hormone in treatment of adolescent boys with short stature.

METHODS

One hundred and fifty-one short stature pubertal boys with age of 10-14 years and bone age of 13-15 years, who were admitted to the Department of Pediatrics, the First Affiliated Hospital, Zhejiang University School of Medicine, were included in this trial. According to their own or parents' intention, the children were divided into recombinant human growth hormone (rhGH)+AI group ( n=108) and rhGH group ( n=43). All children were injected subcutaneously with rhGH 0.15-0.2 IU·kg ^-1·d ^-1, and those in rhGH+AI group were additionally given 2.5 mg/d letrozole or 1 mg/d anastrozole, orally for 12 months or longer. The children were followed-up every 3 months. During the follow-up visit, the predicted adult height (PAH), sex hormone level, glucose and lipid metabolism, and other indicators were measured, and adverse reactions were monitored.

RESULTS

After intervention, there were significant differences in ΔBA(bone age)/ΔCA(chronological age), ΔHtSDS _BA(height standard deviation score based on bone age)and ΔPAH between rhGH+AI group and the rhGH group( P &lt; 0.05 or P &lt; 0.01). During follow-up, 63.9%of the children in the rhGH+AI group had elevated uric acid and 51.9%had decreased high-density lipoprotein (HDL); 25.9%showed severe acne, excitement, hyperactivity and irritability, 11.1%had knee pain; 4.6%had fracture; 2.8%had mild renal dysfunction; 1.9%had inactivity, drowsiness, memory loss and performance decline; 1.9%showed mild abnormal liver function; 0.9%showed impaired fasting glucose; 0.9%showed granulocytopenia. In the rhGH group, 11.6%of the children presented with knee pain and 2.3%with impaired fasting glucose.

CONCLUSIONS

AI combined with rhGH can delay the growth of BA and effectively improve the PAH of adolescent boys with larger bone age. However, the occurrence of adverse reactions of AI should be closely monitored during treatment.

Restoration of Height after 11 Years of Letrozole Treatment in 11β-Hydroxylase Deficiency

11β-hydroxylase deficiency (11β-OHD) is the second most common form of congenital adrenal hyperplasia (CAH). Males with 11β-OHD CAH are often diagnosed late with a significantly advanced bone age leading to a poor height prognosis due to early closure of epiphysis. Delaying epiphyseal fusion by treatment of aromatase inhibitors (AIs) might be a useful strategy in patients with very advanced bone ages. However, there are limited data regarding the effect on final height and long-term safety of this approach. We report our experience with 11 years of letrozole treatment and 17 years of follow-up in a boy with 11β-OHD. He presented at 2 years and 11 months of age with a bone age of 13 years (predicted adult height, PAH, 129.5 cm). Letrozole was added after 1 year of glucocorticoid treatment due to no improvement in height prognosis (130 cm), and continued until the age of 14 years and 11 months. He also received GnRH analog treatment at 10 years and 3 months of age for 2.5 years due to central activation of puberty. He reached a final height of 165.2 cm (35.2 cm above his PAH). This long-term treatment with letrozole was associated with changes in vertebral morphology such as vertebral body end-plate changes, Schmorl nodes, and mild protrusions in the intervertebral discs. Testicular volumes, gonadotropins, testosterone, and anti-Müllerian hormone were normal at age 20 years. A spermiogram showed a normal count but impaired sperm motility and morphology. This unique case represents the longest duration of AI treatment reported in CAH and the first case in which letrozole was started before puberty with the final height reported. We conclude that AIs may restore height in selected patients with CAH with very advanced bone age and severely compromised height prognosis.

The Challenge of Defining and Investigating the Causes of Idiopathic Short Stature and Finding an Effective Therapy

Idiopathic short stature (ISS) comprises a wide range of conditions associated with short stature that elude the conventional diagnostic work-up and are often caused by still largely unknown genetic variants. In the last decade, the improvement of diagnostic techniques has led to the discovery of causal mutations in genes involved in the function of the growth hormone (GH)/insulin-like growth factor-I (IGF-I) axis as well as in growth plate physiology. However, many cases of ISS remain idiopathic. In the future, the more frequent identification of the underlying causes will allow a better stratification of subjects and offer a tailored management. GH therapy has been proposed and approved in some countries for the treatment of children with ISS. To improve the efficacy of GH therapy, trials with GH combined with GnRH agonists, aromatase inhibitors, and even IGF-I have been conducted. This review aims to revise the current definition of ISS and discuss the management of children with ISS on the basis of the most recent evidence.

Letrozole Effect on Final Height of Patients with Constitutional Delay of Growth and Puberty

Introduction

The inhibitory effect of aromatase on predicted adult height and near final height has been studied in patients with constitutional delay of growth and puberty (CDGP).

Aim

This is the first study aimed at verifying the letrozole (Lz) effect on final height of patients with CDGP.

Material and Methods

In this study 8 patients with CDGP underwent treatment with Lz (2.5 mg/day) for a year, and 8 patients with CDGP, who did not receive Lz were followed -up to reaching final height. Height discrepancy was calculated by subtracting PAH from final height measurement.

Results

the final height for Lz and Control Groups were 171± 4.5 cm and 168.8±4.1Cm respectively. The final heights for Lz group were significantly (p=0.04) higher than the control group. Final height in comparison with PAH at the beginning of the study showed significant difference (p=0.022) in Lz group whereas the difference was not significant (p=0.8) in control group. For height discrepancy the measurements were +1.9 cm and +0.1 cm for Lz and control group respectively with significant difference (p=0.04).

Conclusion

Our study, which is the first one in evaluating the impact of Lz on FH, illustrated that Lz treatment will ultimately lead to augmentation of FH in boys with CDGP.

Effects of letrozole administration on growth and reproductive performance in Markhoz goat bucklings

This study evaluated the growth performance, testicular and semen characteristics, and hormonal profile of Markhoz (Iranian Angora) bucklings injected with letrozole (LTZ). Twenty-eight 4-4.5 month old bucks were randomly assigned into four groups and received either 0.25 mg/kg body weight (BW) LTZ subcutaneously (sc LTZ) or intramuscularly (im LTZ), and also sc (sc CONT) or im (im CONT) controls every week for 3 months. The study was performed at the beginning of the breeding season in Sanandaj Animal Husbandry Research Station (46.99 °E, 35.31 °N). The results showed that LTZ causes increased final body weight (25.78 ± 1.61 kg), higher average daily gain (104 ± 0.03 g/days), and decreased feed conversion ratio (7.81 ± 2.57) (P < 0.05). The pre-slaughter, hot, and cold carcass weights (27.56 ± 2.40, 11.45 ± 1.07 and 11.11 ± 1.05 kg, respectively) were (P < 0.05) heavier in LTZ groups while other carcass characteristics did not differ between groups. No differences occurred between the groups in biochemical parameters, except high-density lipoprotein levels (35.47 ± 2.43 mg/dL) which was higher in LTZ treatments (P < 0.05). LTZ-treated bucks had larger scrotal circumference (20.12 ± 5.75 cm), higher relative testicular weight (560.91 ± 78.59 mg/100 g BW) and volume (175.5 ± 29.71 cm³), greater diameter of seminiferous tubules (224.5 ± 5.21 μm), and number of Sertoli cells (8.39 ± 0.77) (P < 0.05). Semen volume (0.74 ± 0.16 mL), sperm concentration (2.64 ± 0.19 × 10^-9/mL), total sperm per ejaculate (1.95 ± 0.49 × 10^-9), and semen index (1248 ± 323) increased (P < 0.05) by LTZ treatments, while semen pH (6.77), motility (80.91%), progressive motility (76.75%), viability (83.35%), abnormality (13.70%), acrosome integrity (78.06%), and membrane integrity (80.05%) of sperm remained unaffected. Intratesticular and serum testosterone (T) levels (7.97 ± 0.89 ng/mg protein and 2.47 ± 0.59 ng/mL, respectively), serum luteinizing hormone (LH), growth hormone (GH) levels (1.71 ± 0.24 and 3.62 ± 0.33 ng/mL, respectively) of LTZ groups were elevated, whereas intratesticular and serum estradiol (E2) levels (84.14 ± 8.15 pg/mg protein and 32.33 ± 2.16 pg/mL, respectively) decreased (P < 0.05). No differences were recorded between the sc and im routes of LTZ administration in the measured parameters. To conclude, we have found that LTZ treatment improves growth and reproductive functions of goat bucklings associated with increased serum LH and GH, elevated T and reduced E2 levels in both serum and testis.

Disorders of Puberty: Pharmacotherapeutic Strategies for Management

During puberty, with activation of the hypothalamic pituitary axis that has been quiescent since the neonatal period, linear growth accelerates, secondary sexual characteristics develop, and adult fertility potential and bone mass are achieved, together with psychosocial and emotional maturation.Disordered pubertal onset and progress, either early or late, presents frequently for endocrine care. Where a disorder is found, due either to a central hypothalamic pituitary cause or to primary gonadal failure, pharmacotherapeutic interventions are required to alter the trajectory of disturbed pubertal onset or progress and for maintenance of adolescent and adult sex hormone status. This paper describes pharmacologic interventions used for pubertal disorders but is not intended to address the diagnostic cascade in detail.

Use of an aromatase inhibitor in children with congenital adrenal hyperplasia: Impact of anastrozole on bone mineral density and visceral adipose tissue

OBJECTIVE

Anastrozole, an aromatase inhibitor, has been used off-label in males with short stature to delay bone maturation. No studies have examined anastrozole's effect on bone mineral density (BMD) or body composition in children with congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency. Our objective was to evaluate anastrozole's effect on BMD and visceral adipose tissue (VAT) in children with CAH.

DESIGN

Total body BMD (TBMD) and L2-L4 BMD Z-scores were adjusted for height-for-age Z-scores (TBMD_HAZ and L2-L4_HAZ ). Hydrocortisone doses (mg/m² /d) were averaged over the previous year. Comparison of treated vs not treated with anastrozole used linear regression adjusting for age, pubertal status, sex, CAH type, years on hydrocortisone, BMI Z-scores and bone age Z-scores.

PATIENTS

We compared 25 children with CAH treated with anastrozole (mean age 11.3 [SD 3.0] years, 56% males) vs 31 children with CAH not treated with anastrozole (13.5 [SD 4.6], 29%). Participants underwent a pubertal exam, bone age X-ray and dual X-ray absorptiometry (DXA) scan.

RESULTS

Average bone age Z-score of 4.3 SDs on beginning anastrozole decreased to 1.9 SDs at time of DXA exam (P = 0.0004) 5.2 (SD 2.2) years later. TBMD Z-scores (P = 0.51), L2-L4 BMD Z-scores (P = 0.66), VAT (P = 0.38), TBMD_HAZ Z-scores (P = 0.66) and L2-L4_HAZ Z-scores (P = 0.41) did not differ between children treated vs not treated with anastrozole.

CONCLUSION

Anastrozole significantly reduced bone age advancement in children with CAH and advanced bone age (>2SDs) without adverse effects on BMD or VAT. Longitudinal studies of anastrozole in children with CAH are needed to validate these findings.

Letrozole versus testosterone for promotion of endogenous puberty in boys with constitutional delay of growth and puberty: a randomised controlled phase 3 trial

BACKGROUND

The treatment of constitutional delay of growth and puberty (CDGP) is an underinvestigated area in adolescent medicine. We tested the hypothesis that peroral aromatase inhibition with letrozole is more efficacious than intramuscular injection of low-dose testosterone in inducing puberty in boys with CDGP.

METHODS

We did a randomised, controlled, open-label trial at four paediatric centres in Finland. Boys aged at least 14 years with CDGP who wanted medical intervention and exhibited the first signs of puberty were randomly assigned in blocks of ten to receive either six intramuscular injections of low-dose testosterone (about 1 mg/kg bodyweight) every 4 weeks for 6 months or peroral letrozole 2·5 mg once daily for 6 months. All boys were followed up for 6 months after the end of treatment. The primary outcomes were changes in testicular volume and hormonal markers of puberty at 6 months after treatment initiation, which were assessed in all participants who received the assigned treatment. All patients were included in the safety analysis. This study is registered with ClinicalTrials.gov, number NCT01797718.

FINDINGS

Between Aug 1, 2013, and Jan 30, 2017, 30 boys were randomly assigned to receive testosterone (n=15) or letrozole (n=15). One boy in the testosterone group was excluded from the primary analyses because of a protocol deviation. During treatment, boys in the letrozole group had higher serum concentrations of luteinising hormone, follicle-stimulating hormone, testosterone, and inhibin B than did boys in the testosterone group. Testicular growth from baseline to 6 months was greater in the letrozole group than in the testosterone group (7·2 mL [95% CI 5·2-9·3] vs 2·2 mL [1·4-2·9]; between-group difference per month 0·9 mL [95% CI 0·6-1·2], p<0·0001). Most adverse events were mild. One boy in the testosterone group had aggressive behaviour for 1 week after each injection, and one boy in the letrozole group had increased irritability at 6 months.

INTERPRETATION

Letrozole might be a feasible alternative treatment to low-dose testosterone for boys with CDGP who opt for medical intervention. However, the risks and benefits of manipulating the reproductive axis during early puberty should be weighed carefully.

FUNDING

Helsinki University Hospital, Academy of Finland, and Finnish Foundation for Pediatric Research.

Letrozole Monotherapy in Pre- and Early-Pubertal Boys Does Not Increase Adult Height

Background: Aromatase inhibitors (AIs) have been used in boys with idiopathic short stature (ISS) to promote growth despite the lack of actual data regarding treatment effect on adult height. In this study, we characterized adult heights and long-term follow-up in AI-treated boys with ISS. Methods: Adult heights and long-term follow-up data, including spine MRIs, of a randomized, double-blind, placebo-controlled trial of boys who were treated with letrozole (Lz) (2.5 mg/d) or placebo (Pl) for 2 years during prepuberty and early puberty. The mean bone ages at treatment cessation were 10.2 and 10.8 years, respectively. Results: Adult heights were similar between the boys treated with Lz (n = 10) and those who received Pl (n = 10) (164.8 ± 4.0 vs. 163.7 ± 3.7 cm, p = 0.49, respectively). In either group, the adult heights did not differ from predicted adult heights at start of the study [Pl: 163.7 (3.7) cm vs. 166.9 (3.3), p = 0.06; Lz: 164.8 (4.0) cm vs. 167.6 (7.9), p = 0.20, respectively]. Long-term follow-up data showed that the frequency of subjects with a vertebral deformity was similar between the groups (Lz, 29% and Pl, 22%, p = 0.20), and no single comorbidity was clearly enriched in either group. Conclusions: The Lz-treated boys had similar adult heights with the subjects who received Pl for 2 years, which indicates that the treatment is not beneficial when given to pre- or early-pubertal boys. Previously observed vertebral deformities ameliorated during follow-up, which supports the skeletal safety of Lz therapy in children and adolescents.

The Fragility of Statistically Significant Results in Pediatric Orthopaedic Randomized Controlled Trials as Quantified by the Fragility Index: A Systematic Review

BACKGROUND

The randomized controlled trial (RCT) is the gold standard study design allowing critical comparison of clinical outcomes while minimizing bias. Traditionally clinical trials are evaluated through statistical significance, expressed by P-values and confidence intervals. However, until recently, the robustness of a study's conclusions has been given little attention. A new metric, the fragility index, quantifies the number of patients theoretically required to switch outcomes in order to reverse the study conclusions. The primary aim of our work was to determine the fragility index of RCTs in the pediatric orthopaedic literature. The secondary aim was to determine study factors associated with lower fragility index.

METHODS

Pubmed and Embase were systematically searched for pediatric orthopaedic RCTs published September 1, 2006 to September 1, 2016. Two independent reviewers screened titles, abstracts, and manuscripts to identify studies published in English involving 2 treatment arms. Trials without dichotomous primary or secondary outcomes or with patients >18 years were excluded. Data were extracted from each eligible article in duplicate and the fragility index was determined using Fisher exact test, with previously published methods. Univariate analysis was used to determine factors associated with lower fragility index.

RESULTS

Seventeen trials were eligible for inclusion. The median treatment arm size was 58 and overall sample size was 116 patients. The median fragility index was 3 (range, 0 to 18). A fragility index of 3 means that just 3 patients would need to switch treatment outcomes in order for the trial results to become statistically nonsignificant. In 1 study, the number of patients lost to follow-up exceeded the fragility index, such that the study conclusions could be completely reversed purely depending on the outcomes of the patients lost to follow-up. Lower fragility index was associated with smaller patient sample sizes and greater P-values.

CONCLUSIONS

The fragility index is a useful adjunct metric to the P-value and confidence intervals, allowing analysis of the robustness of study conclusions. RCTs in pediatric orthopaedics often have small sample sizes, many with low fragility indices. Future efforts could focus on encouraging institutional collaboration and patient recruitment with the ultimate goal of improving RCT sample sizes, and potentially improving the robustness of RCT results.

LEVEL OF EVIDENCE

Level I.

Management of hypogonadism from birth to adolescence

Management of patients with hypogonadism is dependent on the underlying cause. Whilst functional hypogonadism presenting as delayed puberty in adolescence is relatively common, permanent hypogonadism presenting in infancy or adolescence is unusual. The main differential diagnoses of delayed puberty include self-limited delayed puberty (DP), idiopathic hypogonadotropic hypogonadism (IHH) and hypergonadotropic hypogonadism. Treatment of self-limited DP involves expectant observation or short courses of low dose sex steroid supplementation. More complex and involved management is required in permanent hypogonadism to achieve both development of secondary sexual characteristics and to maximize the potential for fertility. This review will cover the options for management involving sex steroid or gonadotropin therapy, with discussion of benefits, limitations and specific considerations of the different treatment options.

Adult height in patients with familial male-limited precocious puberty and the role of an aromatase inhibitor in patient management

BACKGROUND

There is little adult height data in patients with familial male-limited precocious puberty (FMPP) and no management consensus. We assessed the treatment and adult height in local patients with FMPP and those reported in the literature.

METHODS

Growth data were obtained on four local patients with FMPP and a search performed to obtain management details and adult height data on cases in the literature. UK (90) population standards were used to calculate standard deviation scores (SDS).

RESULTS

Adult height data were available on 25 men with FMPP of whom 21 were treated. Median adult height SDS of patients was -1.5 SD with a mid-parental target of -0.6 SD (p=0.1). Eight patients (32%) had an adult height above the mid-parental target and seven patients (28%) had a height >2 SD below the mean. The median height SD was -0.03 in untreated patients and +0.5 SD in those receiving an aromatase inhibitor. There was no relationship between height and age at presentation.

CONCLUSIONS

Aromatase inhibitor therapy is associated with a positive height outcome in FMPP but the outcome with and without intervention is unpredictable. Clinicians need to be cautious when counselling families about the potential height outcome in FMPP.

Emerging medication for the treatment of male hypogonadism

INTRODUCTION

Male hypogonadism is characterized by inadequate production of Testosterone (T) (hypoandrogenism) and deficiencies in spermatogenesis. The main treatment of male hypogonadism is T replacement therapy (TRT), but for some of the patients, alternative drugs may be more suitable.

AREAS COVERED

The available literature of T and alternative treatments for male hypogonadism are discussed.

EXPERT OPINION

Transdermal application of T gels are the most commonly used route of T administration. Some oral T formulations are either associated with hepatic toxicity (i.e. methyltestosterone) or short half-lives that require multiple doses per day (i.e. oral testosterone undecanoate). Short acting, injectable T formulations are also available. If the patient prefers not to use daily drugs or short acting injectable formulations, depot formulations such as injectable testosterone undecanoate (TU) may be a good alternative. If the patient has hypogonadotropic hypogonadism and desires fertility or if he is adolescent, instead of TRT, gonadotropins can be started to stimulate testicular growth and spermatogenesis. In obese patients or for the patients having high risks for TRT, off label aromatase inhibitors (AI) and clomiphene citrate (CC), may be considered to stimulate LH, FSH and T levels. In patients with high prostate disease risk, selective androgen receptor modulators may be an alternative treatment but these latter treatments have not had high level evidence.

Are aromatase inhibitors in boys with predicted short stature and/or rapidly advancing bone age effective and safe?

BACKGROUND

The aim of this study was to assess aromatase inhibitor (AI) efficacy in increasing predicted adult height (PAH) and to describe clinical and biochemical safety profiles of AI-treated boys.

METHODS

A retrospective chart review was conducted at an academic children's hospital endocrinology clinic. Twenty-one boys with predicted short stature and/or rapidly advancing bone age, divided as Tanner stage (TS) I-III Group 1 (G1, n=9) and TS IV-V Group 2 (G2, n=12), were treated with AIs, either letrozole or anastrozole (mean duration, G1: 2.4 years and G2: 0.9 years). Primary outcomes included PAH, hormonal/biochemical analytes, and clinical data.

RESULTS

PAH did not significantly change in either group. Mean peak testosterone significantly increased from baseline to 650±458 ng/dL (p=0.008) in G1 and to 1156±302 ng/dL (p=0.002) in G2. Estradiol did not significantly change in either group. Compared to baseline, G2 showed increased mean FSH (p=0.002), LH (p=0.002), hematocrit (p=0.0001), body mass index (BMI) z-score (p=0.0005), and acne (p=0.01).

CONCLUSIONS

AIs did not increase PAH, regardless of TS. Boys in late puberty had significant increases in testosterone, gonadotropins, hematocrit, acne, and BMI, but no reduction in estradiol. The potential consequences of these findings are concerning and require long-term study, especially if AIs are started in late puberty.

Treatment of Hypogonadism: Current and Future Therapies

The treatment of hypogonadism in men is of great interest to both patients and providers. There are a number of testosterone formulations currently available and several additional formulations under development. In addition, there are some lesser-used alternative therapies for the management of male hypogonadism, which may have advantages for certain patient groups. The future of hypogonadism therapy may lie in the development of selective androgen receptor modulators that allow the benefits of androgens whilst minimizing unwanted side effects.

Randomized Trial of Aromatase Inhibitors, Growth Hormone, or Combination in Pubertal Boys with Idiopathic, Short Stature

CONTEXT

Growth of short children in puberty is limited by the effect of estrogen on epiphyseal fusion.

OBJECTIVES

To compare: 1) the efficacy and safety of aromatase inhibitors (AIs) vs GH vs AI/GH on increasing adult height potential in pubertal boys with severe idiopathic short stature (ISS); and 2) differences in body composition among groups.

DESIGN

Randomized three-arm open-label comparator.

SETTING

Outpatient clinical research.

PATIENTS

Seventy-six pubertal boys [mean (SE) age, 14.1 (0.1) years] with ISS [height SD score (SDS), -2.3 (0.0)].

INTERVENTION

Daily AIs (anastrozole or letrozole), GH, or AI/GH for 24-36 months.

OUTCOMES

Anthropometry, bone ages, dual x-ray absorptiometry, spine x-rays, hormones, safety labs.

RESULTS

Height gain [mean (SE)] at 24 months was: AI, +14.0 (0.8) cm; GH, +17.1 (0.9) cm; AI/GH, +18.9 (0.8) cm (P < .0006, analysis of covariance). Height SDS was: AI, -1.73 (0.12); GH, -1.43 (0.14); AI/GH, -1.25 (0.12) (P < .0012). Those treated through 36 months grew more. Regardless of treatment duration, height SDS at near-final height [n = 71; age, 17.4 (0.2) years; bone age, 15.3 (0.1) years; height achieved, ∼97.6%] was: AI, -1.4 (0.1); GH, -1.4 (0.2); AI/GH, -1.0 (0.1) (P = .06). Absolute height change was: AI, +18.2 (1.6) cm; GH, +20.6 (1.5) cm; AI/GH, +22.5 (1.4) cm (P = .01) (expected height gain at -2.0 height SDS, +13.0 cm). AI/GH had higher fat free mass accrual. Measures of bone health, safety labs, and adverse events were similar in all groups. Letrozole caused higher T and lower estradiol than anastrozole.

CONCLUSIONS

Combination therapy with AI/GH increases height potential in pubertal boys with ISS more than GH and AI alone treated for 24-36 months with a strong safety profile.

Aromatase inhibitors for short stature in male children and adolescents

BACKGROUND

As a result of the essential role of oestrogens in epiphyseal closure, aromatase inhibitors have been trialled as an intervention to improve height outcomes in male children and adolescents by inhibiting the conversion of testosterone to oestradiol.

OBJECTIVES

To assess the effects of aromatase inhibitors in male children and adolescents with short stature.

SEARCH METHODS

To identify relevant trials, we searched the Cochrane Library (2014, Issue 7), MEDLINE, EMBASE, and the World Health Organization (WHO) ICTRP trial register from their inception until August 2014. In addition, we conducted citation searches and screened reference lists of included trials.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) if they compared use of an aromatase inhibitor with placebo in male children and adolescents with short stature.

DATA COLLECTION AND ANALYSIS

Two authors independently screened titles and abstracts for relevance. Both authors carried out screening for inclusion, data extraction, and risk of bias assessment, with any disagreements resolved following discussion. We assessed trials for quality of evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) instrument. We contacted study authors regarding missing information. Primary outcomes were final or near-final height, adverse events, and health-related quality of life. Secondary outcomes included all-cause mortality, cognitive outcomes, socioeconomic effects, laboratory measures, short-term growth parameters, and assessment of effects on bone health. Meta-analysis was not appropriate due to the substantial clinical heterogeneity between trials; we presented the findings of the review in narrative format.

MAIN RESULTS

We included four RCTs involving 207 participants (84 on interventions) in the review. Trials included males with constitutional delay of growth and puberty (CDGP), idiopathic short stature (ISS), and growth hormone (GH) deficiency. Three of the trials had an overall low or unclear risk of bias for primary outcomes. Short-term growth outcomes, such as predicted adult height, improved in all trials. Just one trial reported the primary outcome of final and near-final height as an extension under non-randomised conditions. None of the trials assessed health-related quality of life. One publication provided detailed information regarding the incidence of adverse events. A significant proportion (45%) of prepubertal boys with ISS treated with letrozole developed mild morphological abnormalities of their vertebrae, compared with none in the placebo group.

AUTHORS' CONCLUSIONS

Available evidence suggested that aromatase inhibitors improved short-term growth outcomes. There was no evidence to support an increase in final adult height, based on limited data, with only one of four trials publishing final height data under non-randomised conditions.

Novel approaches to short stature therapy

Besides growth hormone, several pharmaceutical products have been investigated for efficacy and safety in increasing short term growth or adult height. Short-term treatment with testosterone esters in boys with constitutional delay of growth and puberty is efficacious in generating secondary sex characteristics and growth acceleration. The addition of oxandrolone to growth hormone (GH) in Turner syndrome has an additive effect on adult height gain. Treatment with GnRH analogs is the established treatment of central precocious puberty, and its addition to GH therapy appears effective in increasing adult height in GH deficient children, and possibly short children born SGA or with SHOX deficiency, who are still short at pubertal onset. Aromatase inhibitors appear effective in several rare disorders, but their value in increasing adult height in early pubertal boys with GH deficiency or idiopathic short stature is uncertain. A trial with a C-natriuretic peptide analog offers hope for children with achondroplasia.

Height augmentation in 11β-hydroxylase deficiency congenital adrenal hyperplasia

Context

11β-hydroxylase deficiency is the second most common form of congenital adrenal hyperplasia. Untreated, this enzyme deficiency leads to virilization, hypertension, and significant height impairment.

Patient

We describe a patient from abroad who first presented to us at age 7 years for follow-up of ambiguous genitalia. He had been investigated and treated in Pakistan at 3-years-of-age following presentation for bilateral cryptorchidism. He was found to have 46, XX karyotype, elevated 17-OH progesterone and was diagnosed with congenital adrenal hyperplasia. In Pakistan, the patient had abdominal hysterectomy, bilateral salpingoophrectomy, and was started on corticosteroid replacement. At 7 years, shortly after immigrating to Canada, height was 138 cm and BMI 19.3 kg/m² (+2.9 SDS and +1.7 SDS, respectively, male growth chart) and blood pressure was greater than the 99th percentile for age and height. The patient had Prader stage III - IV genital anatomy. Bone age was significantly advanced, yielding a severely compromised predicted final adult height. Biochemical evaluation was consistent with 11β-hydroxylase deficiency congenital adrenal hyperplasia.

Intervention and outcome

In an attempt to improve final height, in addition to glucocorticoid replacement, this patient was treated with recombinant growth hormone and a third generation aromatase inhibitor (Letrozole) with an improvement in final height attained as compared with predicted height.

Conclusions

This case of a 46,XX patient raised as male with congenital adrenal hyperplasia due to 11β-hydroxylase deficiency highlights a number of unique and difficult treatment challenges; specifically, the role of new therapeutic options for optimization of growth in the context of prior suboptimal disease management.

A randomized pilot trial of growth hormone with anastrozole versus growth hormone alone, starting at the very end of puberty in adolescents with idiopathic short stature

BACKGROUND

When given during the course of puberty, anastrozole (A), an aromatase inhibitor, has been shown to increase the predicted adult height (PAH) of GH-deficient (GHD) boys treated with recombinant human growth hormone (rhGH). Our study questioned whether this treatment could retain some of its effects in non-GHD adolescent boys if started only at the very end of puberty, a time when rhGH treatment is denied to short adolescents who have almost reached their final height.

OBJECTIVE

To explore the effect on adult height of a combination of rhGH and A, compared with rhGH alone, at the end of puberty in boys with idiopatic short stature (ISS).

METHODS

A prospective randomized study comparing rhGH + A and rhGH was conducted in 24 healthy adolescent boys aged 15.2 ± 1.2 yrs with serum testosterone at adult levels and a faltering growth velocity <3.5 cm/yr leading to a predicted adult height (PAH) <2.5 SDS. Treatments were stopped when growth velocity became <10 mm in 6 months or when height was close to 170 cm. A historical group of ISS adolescents (N = 17) matched for puberty and growth was used for comparison.

RESULTS

IGF1 levels remained within normal limits in all treated patients. Mean treatment duration was 19 months in the rhGH + A group and 11.5 months in the rhGH group (P = 6.10(-4)). Adult height reached 168.4 ± 2.6 cm in the rhGH + A group and 164.2 ± 5.6 cm in the rhGH group (P < 0.02). Adult height was 160.1 ± 2.8 cm in the historical controls.

CONCLUSION

A combination of rhGH and A, started at the very end of puberty, seems to allow boys with ISS to reach a greater adult height than rhGH alone. Larger trials are needed to confirm this preliminary observation.

Letrozole vs anastrozole for height augmentation in short pubertal males: first year data

CONTEXT

Aromatase inhibitors are used off-label to treat short stature in peripubertal boys.

OBJECTIVE

To investigate short- and long-term hormonal and auxologic differences in short pubertal boys treated with letrozole (L) or anastrozole (A).

DESIGN

PATIENTS are seen for laboratory evaluation and physical examination every 6 months, bone age yearly, DEXA and spine film every 2 years. They will be followed until they reach their final height. This is a preliminary report after 1 year of treatment.

SETTING

A single academic children's hospital outpatient clinic.

PATIENTS

Boys with age >10 years, bone age ≤ 14 years, clinical and hormonal evidence of central puberty, and either height < fifth percentile or predicted adult height (PAH) more than 10 cm below mid-parental height (MPH).

INTERVENTION

Letrozole (2.5 mg) or anastrozole (1 mg) was administered orally each day.

MAIN OUTCOME MEASURES

Hormonal and clinical parameters, growth velocity, and change in bone age and PAH.

RESULTS

Thirty-nine boys have completed 1 year of treatment. Baseline means were age 14.1 years, PAH 166 cm, and testosterone 198 ng/dL. At 1 year, letrozole resulted in higher LH (L 6.1 ± 2.5 vs A 3.2 ± 1.7 IU/L) and testosterone (1038 ± 348 vs 536 ± 216 ng/dL) with lower estradiol (2.8 ± 2.8 vs 5.6 ± 2.9 pg/mL) and IGF-1 (237 ± 51 vs 331 ± 79 ng/mL). First year growth velocities were identical (7.2 cm/year), but an increase in PAH was greater in the anastrozole group (4.2 ± 3.5 vs 1.4 ± 4.4 cm, p = 0.03) after 1 year.

CONCLUSIONS

We present first-year data from a direct comparison of anastrozole and letrozole for height augmentation in short pubertal boys. Letrozole was more potent in hormonal manipulation than anastrozole. First-year growth velocities were comparable, but improvement in PAH was greater in the anastrozole group. It remains to be seen if positive PAH trends will translate to increase in final height in either group.

Outcome analysis of aromatase inhibitor therapy to increase adult height in males with predicted short adult stature and/or rapid pubertal progress: a retrospective chart review

BACKGROUND

Aromatase inhibitors (AIs) have been used off-label to increase adult height in short adolescent males. Studies have shown that AIs increase the predicted adult height (PAH) while delaying bone age (BA) maturation. We sought to determine whether AI therapy increases PAH in boys with short stature or rapid pubertal progression, and to evaluate any untoward effects.

METHODS

The charts of 27 boys with BA ≥ 13 and short stature [height ≥ 2 standard deviation (SD) below the mean or ≥ 2 SD below mid-parental target height (MPTH)] or rapid pubertal progress, treated with anastrozole were reviewed. Outcome measures included anthropomorphic, hormonal, and metabolic data.

RESULTS

The AI therapy averaged 21 months (range 14-30 months) for all, with Rx group 1 receiving <18 months therapy (n=7) and Rx group 2 receiving 18-30 months therapy (n=20). Post-therapy, in Rx group 1 and all subjects, there was no significant change in the PAH, height SDS, or BA/chronological age (CA). In Rx group 2, there was a small, nonsignificant increase in PAH, no change in height SDS, and a small decrease in BA/CA. Post-therapy PAH was different from MPTH in all and in both Rx groups 1 and 2, p<0.02. Eight of them achieved near-final height, averaging 6.73 ± 1.40 cm less than MPTH and 1.91 ± 0.86 cm less than the pre-therapy PAH. Post-therapy, the initially decreased estradiol did not persist but mildly increased testosterone and decreased high-density lipoprotein were noted, as was an increase in hematocrit, and decrease in growth velocity.

CONCLUSIONS

We suggest that although bone age progression may be slightly delayed with longer duration of therapy, an overall short-term AI therapy does not lead to a final height that is greater than the predicted pre-therapy height.

Transition in endocrinology: induction of puberty

Puberty is the period during which we attain adult secondary sexual characteristics and reproductive capability. Its onset depends upon reactivation of pulsative GNRH, secretion from its relative quiescence during childhood, on the background of intact potential for pituitary-gonadal function. This review is intended: to highlight those current practices in diagnosis and management that are evidence based and those that are not; to help clinicians deal with areas of uncertainty with reference to physiologic first principles; by sign-posting relevant data arising from other patient groups with shared issues; to illustrate how recent scientific advances are (or should be) altering clinician perceptions of pubertal delay; and finally, to emphasise that the management of men and women presenting in advanced adult life with absent puberty cannot simply be extrapolated from paediatric practice. There is a broad spectrum of pubertal timing that varies among different populations, separated in time and space. Delayed puberty usually represents an extreme of the normal, a developmental pattern referred to as constitutional delay of growth and puberty (CDGP), but organic defects of the hypothalamo-pituitary-gonadal axis predisposing to hypogonadism may not always be initially distinguishable from it. CDGP and organic, or congenital hypogonadotrophic hypogonadism are both significantly more common in boys than girls. Moreover, around 1/3 of adults with organic hypogonadotrophic hypogonadism had evidence of partial puberty at presentation and, confusingly, some 5-10% of these subsequently may exhibit recovery of endogenous gonadotrophin secretion, including men with Kallmann syndrome. However, the distinction is crucial as expectative ('watch-and-wait') management is inappropriate in the context of hypogonadism. The probability of pubertal delay being caused by organic hypogonadism rises exponentially both with increasing age at presentation and the presence of associated 'red flag' clinical features. These 'red flags' comprise findings indicating lack of prior 'mini-puberty' (such as cryptorchidism or micropenis), or the presence of non-reproductive congenital defects known to be associated with specific hypogonadal syndromes, e.g. anosmia, deafness, mirror movements, renal agenesis, dental/digital anomalies, clefting or coloboma would be compatible with Kallmann (or perhaps CHARGE) syndrome. In children, interventions (whether in the form or treatment or simple reassurance) have been historically directed at maximising height potential and minimising psychosocial morbidity, though issues of future fertility and bone density potential are now increasingly 'in the mix'. Apubertal adults almost invariably harbour organic hypogonadism, requiring sensitive acknowledgement of underlying personal issues and the timely introduction of sex hormone replacement therapy at more physiological doses.

Assessment of a nonsteroidal aromatase inhibitor, letrozole, in juvenile rats

BACKGROUND

The timing and duration of letrozole administration was designed to encompass the majority of postnatal development in the rat with the intent of evaluating the potential for a broad range of effects but with emphasis on expected effects on skeletal maturation.

METHODS

Sprague-Dawley rats were administered letrozole via oral gavage at doses of 0.003, 0.03, and 0.3 mg/kg/day beginning on postpartum day (PPD) 7 through 91 followed by a 6-week recovery period. Clinical signs, body weight, food consumption, developmental endpoints, bone, ophthalmology, behavioral assessments, clinical/anatomic pathology, toxicokinetics, and reproductive assessments were conducted.

RESULTS

Growth (body weight gain and crown-to-rump length) and food consumption were increased in females at ≥0.03 mg/kg/day and decreased in males at ≥0.003 mg/kg/day. Delayed sexual maturation in both sexes and adverse effects on reproductive function occurred at all doses. Effects on bone growth and maturation were noted in both sexes at all doses. Evidence of recovery was noted for males at 0.003 mg/kg/day and females at 0.003 and 0.03 mg/kg/day upon withdrawal of treatment. Histopathological changes in the pituitary-adrenal-gonadal axis correlated with effects on reproductive function.

CONCLUSIONS

The observed effects in juvenile rats were considered predictable and primarily related to the mechanism of action of letrozole upon estrogen synthesis.

Somatic and psychological effects of low-dose aromatase inhibition in men with obesity-related hypogonadotropic hypotestosteronemia

INTRODUCTION

Reduced testosterone levels are frequently observed in obese men. Increased aromatase activity may be an etiological factor.

OBJECTIVE

In this study, we evaluate the clinical effects of aromatase inhibition in obesity-related hypogonadotropic hypotestosteronemia (OrHH).

METHODS

Double-blind, placebo-controlled, 6-month trial in 42 obese men with a BMI >35 kg/m(2), and a serum total testosterone <10 nmol/l. All patients started on one tablet of 2.5 mg/week, with subsequent dose escalation every month until a serum total testosterone of 20 nmol/l was reached.

ENDPOINTS

Psychological function, body composition, exercise capacity, and glucose, lipid, and bone metabolism.

RESULTS

Thirty-nine patients completed the study according to protocol. Letrozole decreased serum estradiol from 119.1±10.1 to 59.2±6.1 pmol/l (P<0.001), and increased serum LH from 3.3±0.3 to 8.8±0.9 U/l (P<0.0001) and serum total testosterone from 8.6±0.7 to 21.5±1.3 nmol/l (P<0.0001). Significant effects on the predefined endpoints were not observed.

CONCLUSION

Despite a marked rise in serum testosterone, low-dose aromatase inhibition had no somatic or psychological effects in men with OrHH.

Resveratrol treatment delays growth plate fusion and improves bone growth in female rabbits

Trans-resveratrol (RES), naturally produced by many plants, has a structure similar to synthetic estrogen diethylstilbestrol, but any effect on bone growth has not yet been clarified. Pre-pubertal ovary-intact New Zealand white rabbits received daily oral administration of either vehicle (control) or RES (200 mg/kg) until growth plate fusion occurred. Bone growth and growth plate size were longitudinally monitored by X-ray imaging, while at the endpoint, bone length was assessed by a digital caliper. In addition, pubertal ovariectomized (OVX) rabbits were treated with vehicle, RES or estradiol cypionate (positive control) for 7 or 10 weeks and fetal rat metatarsal bones were cultured in vitro with RES (0.03 µM-50 µM) and followed for up to 19 days. In ovary-intact rabbits, sixteen-week treatment with RES increased tibiae and vertebrae bone growth and subsequently improved final length. In OVX rabbits, RES delayed fusion of the distal tibia, distal femur and proximal tibia epiphyses and femur length and vertebral bone growth increased when compared with controls. Histomorphometrical analysis showed that RES-treated OVX rabbits had a wider distal femur growth plate, enlarged resting zone, increased number/size of hypertrophic chondrocytes, increased height of the hypertrophic zone, and suppressed chondrocyte expression of VEGF and laminin. In cultured fetal rat metatarsal bones, RES stimulated growth at 0.3 µM while at higher concentrations (10 μM and 50 μM) growth was inhibited. We conclude that RES has the potential to improve longitudinal bone growth. The effect was associated with a delay of growth plate fusion resulting in increased final length. These effects were accompanied by a profound suppression of VEGF and laminin expression suggesting that impairment of growth plate vascularization might be an underlying mechanism.

Pubertal disorders and bone maturation

Bone age (BA) indicates more clearly than chronologic age how far an individual has progressed toward full maturity, and predicts the potential for further growth. Single or serial skeletal age estimations help to confirm the diagnosis of normal puberty and normal pubertal variants such as constitutional delay of growth and puberty, premature therlache, and precocious adrenarche. BA can aid in the clinical workup of children whose sexual maturation is early or delayed. Although BA is considered a qualitative rather than quantitative measure, it serves to round out the clinical picture, providing information without which diagnosis could not be achieved.