Effects of dose and gender on the growth and growth factor response to GH in GH-deficient children: implications for efficacy and safety

Effect of long-acting PEGylated growth hormone for catch-up growth in children with idiopathic short stature: a 2-year real-world retrospective cohort study

Several evidence gaps exist regarding the use of long-acting polyethylene glycol recombinant human growth hormone (PEG-rhGH) in children with idiopathic short stature (ISS), particularly studies conducted in real-world settings, with long-term follow-up, involving varied dosing regimens, and in comparison with daily rhGH. The study aimed to evaluate the effectiveness, safety, and adherence of once-weekly PEG-rhGH for catch-up growth in children with prepubertal ISS compared to daily rhGH. A real-world retrospective cohort study was conducted in prepubertal children with ISS in China. Children who voluntarily received once-weekly PEG-rhGH or daily rhGH were included and were followed up for 2 years. Ninety-five children were included, 47 received PEG-rhGH 0.2-0.3 mg/kg weekly and 48 received daily rhGH. Outcome measures included effectiveness in catch-up growth, adverse events, and treatment adherence. Height velocity increased significantly in both groups during rhGH therapy. In children who received PEG-rhGH treatment, height velocity was 10.59 ± 1.37 cm/year and 8.75 ± 0.86 cm/year in the first and second year, respectively, which were significantly more than those who received daily rhGH (9.80 ± 1.05 cm/year, P = 0.002, and 8.03 ± 0.89 cm/year, P < 0.001). The height standard deviation score improved at the end of the second year for all children (P < 0.001). However, children who received PEG-rhGH showed more excellent improvement than those with daily rhGH (1.65 ± 0.38 vs. 1.50 ± 0.36, P = 0.001). In children who received PEG-rhGH, lower missed doses were observed than those with daily rhGH (0.75 ± 1.06 vs. 4.4 ± 2.0, P < 0.001). No serious adverse events were observed.

CONCLUSION

PEG-rhGH demonstrated superior effectiveness and adherence compared to daily rhGH in the treatment of children with ISS. The safety profiles were similar between the two treatments.

WHAT IS KNOWN

• Recombinant human growth hormone (rhGH) has been used to increase adult height in children with idiopathic short stature (ISS), and its safety profile is comparable to other indications for growth hormone treatment. • The use of long-acting rhGH in children with ISS is still an area of uncertainty.

WHAT IS NEW

• This 2-year real-world study provides new evidence that PEGylated rhGH (PEG-rhGH) is more effective than daily rhGH in promoting catch-up growth in children with ISS. • PEG-rhGH also demonstrated superior treatment adherence compared to daily rhGH in children with ISS. • The safety profiles of PEG-rhGH and daily rhGH were found to be similar.

Optimal final adult height achieved by low-dose recombinant human growth hormone therapy

Background

Thailand has been administering the recombinant human growth hormone (rhGH) treatment for >20 years. Due to limited resources being available, efforts have been directed toward utilizing rhGH at the lowest feasible dose. However, there is currently a lack of evidence in terms of the efficacy and outcomes.

Objective

To evaluate the auxological outcomes of growth hormone (GH) treatment and the GH secretion ability after reaching final adult height (FAH) and discontinuing rhGH.

Methods

Data of 40 patients were retrospectively reviewed. The clinical characteristics, auxological data, and results of biochemical and endocrine investigations before and during rhGH treatment were evaluated. In addition, GH retesting was performed in 24 patients using the insulin tolerance test.

Results

Twenty patients (50%) had complete growth hormone deficiency (GHD), defined as peak stimulated GH level <5 ng/mL, and the remaining patients had partial GHD. Most patients were male (n = 25, 62.5%). The mean age at which rhGH was initiated was 8.9 years. Patients with partial GHD received a higher dose of rhGH than those with complete GHD (30.9 µg/kg/d vs. 26.2 µg/kg/d, P = 0.02). Patients with complete and partial GHD reached FAH at height standard deviation scores (SDSs) of -0.65 and -1.47, respectively. The factors associated with obtaining a good clinical response in terms of height gain included peak-stimulated GH level, age of puberty, and age of discontinuing rhGH. After completing the rhGH treatment, 13 of the 24 patients showed normal GH secretion. Patients with multiple pituitary hormone deficiency (MPHD) were likely to have persistent GHD through adulthood (n = 8, 88.9%).

Conclusion

This study has demonstrated that the use of low-dose rhGH could result in healthy populations achieving optimal FAHs. Patients with MPHD might not require retesting as they were likely to have persistent GHD. The results obtained in this research highlight the benefits of the treatment. This treatment can be applied in resource-limited countries.

Importance of Growth Factors and Bone Maturation Ratio in the Response to Growth Hormone Therapy

OBJECTIVE

The aim was to identify the influence of insulin-like growth factor I (IGF-1), IGF-binding protein-3 (IGFBP-3), and bone age (BA)/chronological age (CA) ratio on the response to GH therapy after 1 and 2 years of treatment and upon reaching final height.

METHODS

Longitudinal, retrospective, observational study of 139 patients treated for idiopathic growth hormone deficiency. Variables examined during follow-up: (1) genetic background; (2) perinatal history; (3) anthropometry; (4) height velocity, BA, BA/CA and height prognosis; (5) analytical results (IGF-1, IGFBP-3). Final response variables: adult height (AH), AH with respect to target height, AH with respect to initial height prognosis, AH with respect to height at the start of treatment, and AH with respect to height at onset of puberty.

RESULTS

Lower pretreatment IGF-1 levels and a greater increase in IGF-1 at the end of treatment imply a better response (r = -0.405, P = .007 and r = 0.274, P = .014, respectively), as does a greater increase in IGFBP-3 after 2 years of treatment and at the end of treatment (r = 0.207, P = .035 and r = 0.259, P = .020, respectively). A lower BA/CA ratio pretreatment and at the onset of puberty results in a better response (r = -0.502, P = .000 and r = -0.548, P = .000, respectively), as does a lower increase in BA and BA/CA ratio after the 1 and 2 years of treatment (r = -0.337, P = .000 and r = -0.332, P = .000, respectively).

CONCLUSION

Low pretreatment IGF-1, a greater BA delay with respect to CA pretreatment and at the onset of puberty, a greater increase in IGFBP-3 after 2 years of treatment, and a lower increase in BA and BA/CA ratio after 1 and 2 years of treatment imply a better long-term response.

Difficulties in Interpreting IGF-1 Levels in Short Stature Children Born Small for Gestational Age (SGA) Treated with Recombinant Human Growth Hormone (rhGH) Based on Data from Six Clinical Centers in Poland

The assessment of IGF-1 concentrations is one of the parameters used for evaluating response to rhGH treatment. An increase in IGF-1 concentration positively correlates with growth improvement, whereas IGF-1 concentrations significantly above the reference range may increase the risk of possible side effects. The aim of this study was to evaluate the IGF-1 local reference ranges for the rhGH treatment centers concerned and to compare these values with the population reference ranges. A retrospective analysis was conducted on auxological data from 229 SGA patients who received rhGH treatment between 2016 and 2020 at six university clinical centers in Poland. The IGF-1 levels were assessed at baseline, after 12 and 24 months, and compared to the reference ranges provided by the local laboratory and to the population reference ranges. After 12 months, 56 patients (24%) presented IGF-1 values > 97th percentile for the local reference range, whereas only 8 (3.5%) did so using the population reference ranges; p < 0.001. After 24 months of treatment, the values were: 47 (33%) > 97th percentile by local vs. 6 (4.2%) by population standards; p < 0.001. Thirty-nine patients had rhGH dose reduced after 12 months, of whom twelve (25%) had IGF-1 > 97th percentile according to the local reference ranges and five (13%) > 97th percentile for the population. Our data suggest that different methods used to determine IGF-1 concentration and the different IGF-1 reference ranges result in a significant proportion of rhGH-treated children with elevated IGF-1 concentration and experiencing dose reductions, which may negatively affect growth rate.

[Short stature due to intrauterine growth retardation. Clinical and hormonal-metabolic features, possibilities of growth-stimulating therapy]

The article presents data about short stature due to intrauterine development delay. This type of short stature - separate nosology, unites children born small for gestation age. The majority of them in the first years of life have accelerated growth rates, allowing the child to normalize their weight-growth indicators and catch up in the development of peers. In the absence of an accelerated growth rates, children have a high risk of lagging behind in physical development throughout childhood, achieving low final growth and becoming short adults. In addition, the fact of birth with small body sizes is associated with a number of hormonal and metabolic features, a risk of metabolic syndrome in adult years.It is assumed that the absence of postnatal growth acceleration is due to various damages to the GH-IGF1 axis (partial GH deficiency, partial resistance to GH, partial resistance to IGF1). Growth hormone therapy, initiated early in life, is able to normalize growth rates in childhood and ultimately significantly improve or normalize the final growth of short stature children born small for gestational age.

Integrative traditional Korean medicine treatment for children with idiopathic short stature: A STROBE-compliant case series

Integrative traditional Korean medicine (TKM) treatment including herbal medicine and acupuncture has been used frequently by parents in South Korea for the treatment of children with idiopathic short stature (ISS). We aimed to report the TKM treatments currently being used for children with ISS and explore their therapeutic effects. The medical records of children who met the criteria for ISS and who had been treated with TKM for the management of ISS were retrospectively reviewed. In total, 116 patients (mean [standard deviation] age, 8.07 [3.08] years; 52.6% girls) enrolled in the study. Their mean height percentile was 1.45 and body mass index was 16.19 kg/m2. During the study period of 5 years, participants visited the outpatient clinic an average of 2.93 times; the mean number of days to the next visit was 101 days. All patients received herbal medicine treatment, and the formulation was mainly decoction type. Additional treatments including ear acupuncture and moxibustion were also used. After treatment with TKM, the height percentile and standard deviation scores increased in both girls and boys (P < .001 and P < .01, respectively). Additionally, the predicted adult height, estimated based on bone age, increased in girls (P < .05). This study provided preliminary data for future research in TKM use in children with ISS.

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.

Safety and Efficacy of Lonapegsomatropin in Children With Growth Hormone Deficiency: enliGHten Trial 2-Year Results

PURPOSE

The objectives of the ongoing, Phase 3, open-label extension trial enliGHten are to assess the long-term safety and efficacy of weekly administered long-acting growth hormone lonapegsomatropin in children with growth hormone deficiency.

METHODS

Eligible subjects completing a prior Phase 3 lonapegsomatropin parent trial (heiGHt or fliGHt) were invited to participate. All subjects were treated with lonapegsomatropin. Subjects in the United States switched to the TransCon hGH Auto-Injector when available. Endpoints were long-term safety, annualized height velocity, pharmacodynamics [insulin-like growth factor-1 SD score (SDS) values], and patient- and caregiver-reported assessments of convenience and tolerability.

RESULTS

Lonapegsomatropin treatment during enliGHten was associated with continued improvements in height SDS through week 104 in treatment-naïve subjects from the heiGHt trial (-2.89 to -1.37 for the lonapegsomatropin group; -3.0 to -1.52 for the daily somatropin group). Height SDS also continued to improve among switch subjects from the fliGHt trial (-1.42 at fliGHt baseline to -0.69 at week 78). After 104 weeks, the average bone age/chronological age ratio for each treatment group was 0.8 (0.1), showing only minimal advancement of bone age relative to chronological age with continued lonapegsomatropin treatment among heiGHt subjects. Fewer local tolerability reactions were reported with the TransCon hGH Auto-Injector compared with syringe/needle.

CONCLUSIONS

Treatment with lonapegsomatropin continued to be safe and well-tolerated, with no new safety signals identified. Children treated with once-weekly lonapegsomatropin showed continued improvement of height SDS through the second year of therapy without excess advancement of bone age.

Follow-Up Study of Growth Hormone Therapy in Children with Kabuki Syndrome: Two-Year Treatment Results

INTRODUCTION

Kabuki syndrome (KS) is a genetic disorder with characteristic facial dysmorphisms, short stature, hypertension, and obesity later in life. The aim of this study was to evaluate catch-up growth and cardiovascular markers before and during growth hormone (rhGH) treatment in KS children.

METHODS

This prospective study included 18 children whose KS was genetically established. Each KS subject received rhGH for a period of 2 years. Several measurements were performed before and during treatment: anthropometry, glucose metabolism, lipid profile, markers for endothelial function, and low-grade inflammation.

RESULTS

This study found an increase in delta height standard deviation score (SDS) for the whole group of 1.1 SDS after 2 years of rhGH treatment. Baseline metabolic profiles showed no cardiometabolic abnormalities in these children. Although 4 out of 18 children were obese, there were no signs of the metabolic syndrome. During rhGH treatment, serum low-density lipoprotein cholesterol concentrations decreased significantly (2.16-1.91 mmol/L, p = 0.04). Apolipoprotein B100 concentrations also showed a reduction after 24 months of treatment, but the other lipid and (apo)lipoprotein parameters did not change. While other endothelial function markers were stable, only vascular cell-adhesion molecule-1 concentrations increased (1,084-1,161 pg/mL, p < 0.01) during rhGH therapy. Furthermore, BMI and waist circumference improved during treatment. There were no signs of hypertension.

CONCLUSIONS

At baseline and during rhGH therapy, there were no signs of the metabolic syndrome. This is the first study demonstrating that rhGH treatment in KS children is a safe and effective therapy and that it positively influences linear height without exerting adverse effects on a wide array of cardiovascular risk markers.

Factors affecting IGF-I level and correlation with growth response during growth hormone treatment in LG Growth Study

Growth hormone treatment strategies to achieve the goal include the titration of GH doses according to serum insulin-like growth factor I (IGF-I) concentrations. However, IGF-I levels do not always correlate well with the growth response. This study aims to identify the factors affecting the IGF-I concentration and identify the relationship between IGF-I and the treatment response. The data of prepubertal children treated with recombinant human GH for more than one year were obtained from the LG Growth Study (LGS) Database. This study includes patients with idiopathic growth hormone deficiency (IGHD), organic growth hormone deficiency (OGHD), or Turner syndrome (TS) or small for gestational age (SGA). Among 2,021 participants registered in LGS, 366 subjects were selected, 252 had IGHD, 16 had OGHD, 31 had TS, and 67 were SGA. In the IGHD and SGA groups, IGF-I levels had a positive correlation with weight SDS. There was no significant relationship between the pre-treatment IGF-I level and growth response. However, in the IGHD group, the growth response was significantly higher when the change in the IGF-I SDS value was 1 or more (p = 0.0013). Therefore, IGF-I concentrations should be used as an indicator to monitor the treatment compliance rather than for efficacy determination in Korean children of short stature with GH treatment.

Development of a Predictive Enrichment Marker for the Oral GH Secretagogue LUM-201 in Pediatric Growth Hormone Deficiency

Context

We hypothesize, based on the degree of residual hypothalamic-pituitary function, that some, but not all, children with growth hormone deficiency (GHD) may have beneficial growth responses to the orally administered growth hormone (GH) secretagogue LUM-201.

Objective

To determine if pretreatment testing can identify predictive enrichment markers (PEM) for subjects with adequate residual function who are responsive to LUM-201.

Methods

We performed an analysis of a completed, randomized, placebo-controlled trial of LUM-201, a GH secretagogue receptor agonist, in which all randomized subjects had pretreatment testing.

This international multicenter study conducted in pediatric endocrinology clinics included 68 naïve-to-treatment, prepubertal children with established diagnoses of GHD. Outcome measures included the sensitivity, specificity, and predictive accuracy of potential markers to predict 6-month growth responses to oral LUM-201 and daily rhGH.

Results

Two PEM were identified for use in defining PEM-positive status: (1) baseline insulin-like growth factor I (IGF-I) concentration >30 ng/mL and (2) peak GH response of ≥5 ng/mL upon administration of single-dose LUM-201. PEM-positive status enriches a population for better growth responses to LUM-201. PEM-negative status enriches a population for better growth responses to rhGH.

Conclusion

Combined, the peak GH response to single-dose LUM-201 and the baseline IGF-I concentration are effective PEMs for 6-month growth responses to LUM-201 and rhGH in prepubertal children with GHD.

Corroboration of Height Velocity Prediction Markers for rhGH With an Oral GH Secretagogue Treatment in Children With GHD

Context

Recombinant human growth hormone (rhGH) is approved for treatment of pediatric growth hormone deficiency (GHD), with greatest growth responses observed in those with severe GHD. Orally administered GH secretagogues (GHS) may be useful treatment in patients with moderate GHD. Distinguishing children with severe vs moderate GHD could identify children who would be better treated with rhGH or GHS.

Objectives

Evaluate baseline insulin-like growth factor-I (IGF-I) and stimulated peak GH response as predictors of 12-month height velocity (HV) in children with GHD.

Design

Data on children with GHD were analyzed in a legacy data base (GeNeSIS data).

Participants

514 naïve to rhGH-treatment, prepubertal children with idiopathic isolated GHD for whom stimulated GH, baseline serum IGF-I, and first-year HV during rhGH treatment data are available.

Outcome Measures

Children with severe or moderate GHD were categorized based on GH and IGF-I data and evaluated based on baseline auxologic and hormone profiles and first-year growth response to rhGH.

Results

Cohorts of severe and moderate GHD were 81/514 (15.8%) and 433/514 (84.2%). Cohorts differed significantly with regard to indicators of GHD [eg, baseline height SD score (SDS), height SDS minus target height SDS, HV, HV SDS, and change in height SDS during rhGH treatment]. Multiple regression analysis showed IGF-I and stimulated GH were significant predictors of HV independent of other known variables. Expected first-year HV in moderate GHD was 8.3 cm/y.

Conclusions

The combination of peak GH to GH stimulation testing and baseline IGF-I concentration are predictive enrichment markers for annualized HV responses to rhGH therapy.

Impact of growth hormone treatment on scoliosis development and progression: analysis of 1128 patients with idiopathic short stature

OBJECTIVES

The purpose of this study was to evaluate the impact of recombinant human growth hormone (rhGH) on the development and progression of scoliosis in patients with idiopathic short stature (ISS).

METHODS

Patients with ISS who underwent rhGH treatment from 1997 to 2017 and were followed up for scoliosis screening with serial radiographic examination were included. For assessing scoliosis development, patients who did not have scoliosis at the time of rhGH treatment were included and followed up to determine whether de novo scoliosis developed during the treatment. For evaluating scoliosis progression, patients who already had scoliosis were analyzed. Univariate and multivariate Cox regression analyses of demographic and radiographic variables were performed to determine the related factors in the development and progression of scoliosis.

RESULTS

For assessing scoliosis development, 1093 patients were included. The average duration of rhGH treatment was about 2 years. De novo scoliosis developed in 32 patients (3.7%). The analysis revealed that sex (p=0.016) and chronological age (p=0.048) were statistically significant factors associated with scoliosis development. However, no relationship was observed between scoliosis development and rhGH treatment types or duration. Among 67 patients who already had scoliosis at the time of rhGH treatment, 11 (16.4%) showed scoliosis progression. However, the rhGH types and duration also did not affect scoliosis progression.

CONCLUSIONS

De novo scoliosis developed in 3.7% and scoliosis progressed in 16.4% of the patients during rhGH treatment. However, scoliosis development or progression was not affected by the types or duration of rhGH treatment in patients with ISS.

Combined therapy with GnRH analogue and growth hormone increases adult height in children with short stature and normal pubertal onset

OBJECTIVE

To investigate whether gonadotropin releasing hormone analogue (GnRHa) combined with recombinant human growth hormone (rhGH) can improve the adult height (AHt) of children with short stature and normal pubertal onset.

METHODS

In this retrospective study, GnRHa/rhGH treatment was given to children with normal pubertal onset and short stature. Patients were followed up to measure their AHt. The primary outcomes were the disparity between AHt standard deviation score (AHt SDS) and pre-treatment height standard deviation score (Ht SDS) and the disparity between AHt and target height (THt).

RESULTS

A total of 94 patients were included. Forty-nine boys were treated with GnRHa/rhGH for 24.84 ± 13.01 months, and 45 girls were treated for 23.89 ± 10.43 months. (2) Before treatment, the Ht SDS of boys and girls was -1.82 ± 1.30 and -1.10 ± 1.61, respectively, and the target height was 168.98 ± 3.51 cm and 157.90 ± 3.25 cm, respectively. (3) After treatment, for boys, the AHt SDS increased by 1.37 ± 1.28 (p = 0.000) and the disparity between AHt and THt was 0.98 ± 6.18 cm (p = 0.273); for girls, the AHtSDS increased by 1.28 ± 1.48 (p = 0.000), and the disparity between AHt and THt was 3.64 ± 4.86 cm (n = 45, p = 0.000). (4) Subgroup analysis showed that, for boys with idiopathic short stature (ISS) and non-ISS, AHt SDS increased by 2.00 ± 1.16 (p = 0.000) and 0.71 ± 1.06 (p = 0.003) respectively, compared with the pre-treatment HtSDS; The disparities between AHt and THt were -0.70 ± 6.54 cm and 2.73 ± 5.37 cm respectively. For girls with ISS and non-ISS, AHtSDS increased by 2.73 ± 1.21 (p = 0.000) and 0.748 ± 1.19 (p = 0.001), respectively; AHt increased by 2.63 ± 6.12 cm (p = 0.165) and 4.02 ± 4.37 cm (p = 0.000) compared with THt, respectively. (5) Multiple linear regression analysis showed that the baseline bone age (BA) (β = -0.200, p = 0.003), basal IGF-1(β = -0.002, p = 0.008) and HtSDS (β = -0.679, p = 0.000) had negative effects on increment of AHtSDS.

CONCLUSION

For adolescents with normal pubertal onset and short stature, with or without ISS, GnRHa/rhGH therapy can effectively improve AHtSDS. After treatment, ISS adolescents can reach the THts, and Non-ISS adolescents can exceed their THts.

GH deficiency in cancer survivors in the transition age: diagnosis and therapy

BACKGROUND

Survival rates among childhood cancer survivors (CCSs) have significantly risen in the last 40 years due to substantial improvements in treatment protocols. However, this improvement has brought with it serious late effects that frequently involve the endocrine system. Of the endocrine disorders, GH deficiency (GHD) is the most common among CCSs as a consequence of a history of cancers, surgery, and/or radiotherapy involving the hypothalamo-pituitary region.

METHODS

A comprehensive search of English language articles regardless of age was conducted in the MEDLINE database between December 2018 and October 2019. We selected all studies on GH therapy in CCSs during the transition age regarding the most challenging topics: when to retest; which diagnostic tests and cut-offs to use; when to start GH replacement therapy (GHRT); what GH dose to use; safety; quality of life, compliance and adherence to GHRT; interactions between GH and other hormonal replacement treatments.

RESULTS

In the present review, we provide an overview of the current clinical management of challenges in GHD in cancer survivors in the transition age.

CONCLUSIONS

Endocrine dysfunction among CCSs has a high prevalence in the transition age and increase with time. Many endocrine disorders, including GHD, are often not diagnosed or under-diagnosed, probably due to the lack of specialized centers for the long-term follow-up. Therefore, it is crucial that transition specialized clinics should be increased in terms of number and specific skills in order to manage endocrine disorders in adolescence, a delicate and complex period of life. A multidisciplinary approach, also including psychological counseling, is essential in the follow-up and management of these patients in order to minimize their disabilities and maximize their quality of life.

A rationale for the treatment of short stature in children with the combination of recombinant human growth hormone (rhGH) and recombinant human insulin-like growth factor-I (rhIGF-I)

Both rhGH and rhIGF-I are signaling molecules with the capacity to restore the rate of growth in certain subsets of slowly growing children. In some instances, heights attained at or near the time of cessation of linear growth are indistinguishable from the height distribution of the community as a whole or from the height distribution expected based on the heights of biological parents. The GH: IGF-I signaling system is sequential, forming a continuous loop wherein GH will stimulate production of IGF-I and IGF-I will inhibit production of GH. This feature suggests that a deficiency of GH will be accompanied by a deficiency of IGF-I and that treatment of GH deficiency with rhGH will restore IGF-I and the subnormal growth of combined GH: IGF-I deficiency. Although logical, this proposition is not always true. rhGH and rhIGF-I are distinct polypeptides, with distinct cell surface receptors and distinct intracellular signaling pathways both capable of amplifying distinct, yet overlapping, patterns of gene replication, protein synthesis and metabolic activities. These features suggest that neither treatment with rhGH nor rhIGF-I alone will invariably recapitulate the combined activities of the GH: IGF-I system, At the present time, this proposition appears both logical and true. The possibility that combined rhGH and rhIGF-I treatment can accomplish that which neither monotherapy can has been examined in gene knock-out experiments in animals and direct comparisons of GH, IGF-I and combined GH: IGF- treatments in animals and in children with short stature, normal GH and low IGF-I (primary IGF-I deficiency). In these experimental models, the growth rates with combined rhGH and rhIGF-I treatment exceed those of either monotherapy. The extent to which this proposition can be generalized to various short stature populations remains to be determined.

Predicting First-Year Growth in Response to Growth Hormone Treatment in Prepubertal Korean Children with Idiopathic Growth Hormone Deficiency: Analysis of Data from the LG Growth Study Database

BACKGROUND

The first-year growth in response to growth hormone (GH) treatment seems to be the most important factor in determining the overall success of GH treatment.

METHODS

Data from children (n = 345) who were in the LG Growth Study Database were used to develop a model. All subjects had been diagnosed with idiopathic growth hormone deficiency (GHD) and presented in a prepubertal state during the first year of GH treatment.

RESULTS

The Δheight standard deviation score (SDS) during 1st year of GH treatment was correlated positively with weight-SDS (β = 0.304, P < 0.001), body mass index (BMI)-SDS (β = 0.443, P < 0.001), paternal height-SDS (β = 0.296, P = 0.001), MPH-SDS (β = 0.421, P < 0.001) and MPH SDS minus baseline height SDS (β = 0.099, P < 0.001) but negatively with chronological age (β = -0.294, P < 0.001), bone age (β = -0.249, P < 0.001). A prediction model of 1st year growth in response to GH treatment in prepubertal Korean children with idiopathic GHD is as follows: Δheight SDS during 1st year of GH treatment = 1.06 - 0.05 × age + 0.09 × (MPH SDS minus baseline height SDS) + 0.05 × BMI SDS. This model explained 19.6% of the variability in the response, with a standard error of 0.31.

CONCLUSION

The present model to predict first-year response to GH treatment might allow more tailored and personalized GH treatment in Korean prepubertal children with idiopathic GHD.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01604395.

Gender-Dependent Growth and Insulin-Like Growth Factor-1 Responses to Growth Hormone Therapy in Prepubertal Growth Hormone-Deficient Children

Gender seems to be an important factor influencing the response to recombinant human growth hormone (rhGH) therapy in GH-deficient adolescents and adults. The results of studies evaluating gender-specific response to rhGH therapy in prepubertal GH-deficient children are divergent. The aim of this study was to determine the effect of gender on the growth and insulin-like growth factor-1 (IGF-1) responses in 75 prepubertal GH-deficient children during the first 2 years of rhGH therapy. There were no baseline gender differences in age, bone age, anthropometrical parameters, and IGF-1 SDS for bone age. After the initiation of rhGH therapy, there were no gender-specific differences concerning the reduction of height deficit. Serum IGF-1 levels were higher in the prepubertal GH-deficient girls than in the age-matched boys, but the difference was not significant when expressed as IGF-1 SDS for bone age. The increase in IGF-1 SDS for bone age was significantly greater in girls versus boys after the first 6 months of therapy, comparable between girls and boys after the first year of therapy, and tended to be higher in boys after the second year of therapy. In conclusion, prepubertal GH-deficient girls and boys do not differ significantly in growth response in the first 2 years of rhGH therapy.

Growth Hormone Deficiency: Health and Longevity

The important role of GH in the control of mammalian longevity was first deduced from extended longevity of mice with genetic GH deficiency (GHD) or GH resistance. Mice with isolated GHD (IGHD) due to GHRH or GHRH receptor mutations, combined deficiency of GH, prolactin, and TSH, or global deletion of GH receptors live longer than do their normal siblings. They also exhibit multiple features of delayed and/or slower aging, accompanied by extension of healthspan. The unexpected, remarkable longevity benefit of severe endocrine defects in these animals presumably represents evolutionarily conserved trade-offs among aging, growth, maturation, fecundity, and the underlying anabolic processes. Importantly, the negative association of GH signaling with longevity extends to other mammalian species, apparently including humans. Data obtained in humans with IGHD type 1B, owing to a mutation of the GHRH receptor gene, in the Itabaianinha County, Brazil, provide a unique opportunity to study the impact of severe reduction in GH signaling on age-related characteristics, health, and functionality. Individuals with IGHD are characterized by proportional short stature, doll facies, high-pitched voices, and central obesity. They have delayed puberty but are fertile and generally healthy. Moreover, these IGHD individuals are partially protected from cancer and some of the common effects of aging and can attain extreme longevity, 103 years of age in one case. We think that low, but detectable, residual GH secretion combined with life-long reduction of circulating IGF-1 and with some tissue levels of IGF-1 and/or IGF-2 preserved may account for the normal longevity and apparent extension of healthspan in these individuals.

Factors affecting bone age maturation during 3 years of growth hormone treatment in patients with idiopathic growth hormone deficiency and idiopathic short stature: Analysis of data from the LG growth study

To investigate the progression rate of bone age (BA) and associated factors during the first 3 years of growth hormone (GH) treatment in children with idiopathic GH deficiency (iGHD) and idiopathic short stature (ISS).Data for prepubertal children with iGHD and ISS who were treated with recombinant human GH were obtained from the LG Growth Study Database and analyzed. Height, weight, BA, insulin-like growth factor-1 (IGF-1) level, and GH dose were recorded every 6 months. Differences between BA and chronological age (CA), BA-CA, were calculated at each measurement. This study included 92 (78 iGHD and 14 ISS) subjects.After 3 years of GH treatment, the height z-score was -1.09 ± 0.71 (P < .001 compared to baseline), BA-CA was -1.21 ± 1.18 years (P < .001), and IGF-1 standard deviation score (SDS) was 0.43 ± 1.21 (P < .001) in the iGHD subjects; the change in BA over the 3 years was 3.68 ± 1.27 years. In the ISS subjects, the height z-score was -1.06 ± 0.59 (P < .001), BA-CA was -0.98 ± 1.23 years (P = .009), and IGF-1 SDS was 0.16 ± 0.76 (P = .648); the change in BA over the 3 years was 3.88 ± 1.36 years. The only significant factor associated with the BA progression was the BA-CA at 1 year of GH treatment (OR = 2.732, P = .001). The baseline BA-CA, IGF-1 SDS, and GH dose did not influence BA progression.Prepubertal subjects with iGHD and ISS showed height improvement and mild BA acceleration over the first 3 years of GH treatment. However, because the BA progression rate was considered to be clinically acceptable, GH treatment may increase the predicted adult height during this period.

Delayed Bone Age Might Accelerate the Response to Human Growth Hormone Treatment in Small for Gestational Age Children with Short Stature

PURPOSE

Growth hormone (GH) treatment is recommended to improve growth and psychosocial problems in short stature children born small for gestational age (SGA). Although GH therapy in these patients has been extensively studied, the impact of therapy according to delays in bone age (BA) is not known well.

OBJECTIVE

To investigate the effects of GH therapy in SGA patients with short stature according to BA delay.

METHODS

We retrospectively analyzed changes in height SD score (SDS) and BA/chronological age (CA) after 6 and 12 months of GH therapy in patients grouped according to BA delay. We studied 27 SGA children with short stature in the pediatric endocrinology clinic of Kyungpook National University Children's Hospital.

RESULTS

Of the 27 patients, 9 had <2 years of BA delay, while 18 had >2 years of delay. There were no significant differences between the two groups in terms of gestational age and weight at birth, height SDS, IGF-1 SDS, and growth hormone dosage at the beginning of therapy. However, height SDS increased significantly in the group with >2 years of BA delay after 6 months of GH therapy (-2.50 ± 0.61 vs -1.87 ± 0.82; p=0.037) and 12 months (-2.27 ± 0.70 vs -1.63 ± 0.65; p=0.002). When height SDS was compared between with and without GHD, there were no significant differences.

CONCLUSIONS

Delayed BA (>2 years) may impact the response to GH treatment in SGA children with short stature.

The metabolic outcomes of growth hormone treatment in children are gender specific

OBJECTIVE

To evaluate the impact of gender on the clinical and metabolic parameters in prepubertal growth hormone deficiency (GHD) children at diagnosis and during GH treatment (GHT).

DESIGN

The data of 105 prepubertal children (61 males, 44 females, mean age 6.8 ± 0.7 years) affected by idiopathic GHD were retrospectively evaluated.

METHODS

Body height, BMI, waist circumference (WC), IGF-I, HbA1c, lipid profile, fasting and after-OGTT glucose and insulin levels, insulin sensitivity and secretion indices were evaluated at baseline and after 24 months of GHT.

RESULTS

At baseline, no significant difference was found in all clinical, hormonal and metabolic parameters between males and females. After 24 months of GHT, both males and females showed a significant increase in height (both P < 0.001), BMI (both P < 0.001), WC (P < 0.001 and P = 0.004, respectively), IGF-I (both P < 0.001), fasting glucose (P < 0.001 and P = 0.001, respectively), fasting insulin (both P < 0.001) and Homa-IR (both P < 0.001), with a concomitant significant decrease in insulin sensitivity index (ISI) (both P < 0.001) and oral disposition index (DIo) (P = 0.001 and P < 0.001, respectively). At 24 months of GHT, females showed significantly higher BMI (P = 0.027), lower ISI (P < 0.001) and DIo (P < 0.001), in concomitance with a significant greater change from baseline to 24 months of BMI (P = 0.013), WC (P < 0.001), ISI (P = 0.002) and DIo (P = 0.072), although the latter does not reach statistical significance.

CONCLUSIONS

Twenty-four months of GHT in prepubertal children leads to different metabolic outcomes according to gender, with a greater reduction in insulin sensitivity in females, regardless of auxological and hormonal parameters. Therefore, prepubertal GHD females should probably need a more proper monitoring in clinical practice.

Neurotrophic and Neuroregenerative Effects of GH/IGF1

Introduction. Human neurodegenerative diseases increase progressively with age and present a high social and economic burden. Growth hormone (GH) and insulin-like growth factor-1 (IGF-1) are both growth factors exerting trophic effects on neuronal regeneration in the central nervous system (CNS) and peripheral nervous system (PNS). GH and IGF-1 stimulate protein synthesis in neurons, glia, oligodendrocytes, and Schwann cells, and favor neuronal survival, inhibiting apoptosis. This study aims to evaluate the effect of GH and IGF-1 on neurons, and their possible therapeutic clinical applications on neuron regeneration in human subjects. Methods. In the literature, we searched the clinical trials and followed up studies in humans, which have evaluated the effect of GH/IGF-1 on CNS and PNS. The following keywords have been used: “GH/IGF-1” associated with “neuroregeneration”, “amyotrophic lateral sclerosis”, “Alzheimer disease”, “Parkinson’s disease”, “brain”, and “neuron”. Results. Of the retrieved articles, we found nine articles about the effect of GH in healthy patients who suffered from traumatic brain injury (TBI), and six studies (four using IGF-1 and two GH therapy) in patients with amyotrophic lateral sclerosis (ALS). The administration of GH in patients after TBI showed a significantly positive recovery of brain and mental function. Treatment with GH and IGF-1 therapy in ALS produced contradictory results. Conclusions. Although strong findings have shown the positive effects of GH/IGF-1 administration on neuroregeneration in animal models, a very limited number of clinical studies have been conducted in humans. GH/IGF-1 therapy had different effects in patients with TBI, evidencing a high recovery of neurons and clinical outcome, while in ALS patients, the results are contradictory. More complex clinical protocols are necessary to evaluate the effect of GH/IGF-1 efficacy in neurodegenerative diseases. It seems evident that GH and IGF-1 therapy favors the optimal recovery of neurons when a consistent residual activity is still present. Furthermore, the effect of GH/IGF-1 could be mediated by, or be overlapped with that of other hormones, such as estradiol and testosterone.

Somapacitan, a once-weekly reversible albumin-binding GH derivative, in children with GH deficiency: A randomized dose-escalation trial

OBJECTIVE

To evaluate the safety, local tolerability, pharmacodynamics and pharmacokinetics of escalating single doses of once-weekly somapacitan, a reversible, albumin-binding GH derivative, vs once-daily GH in children with GH deficiency (GHD).

DESIGN

Phase 1, randomized, open-label, active-controlled, dose-escalation trial (NCT01973244).

PATIENTS

Thirty-two prepubertal GH-treated children with GHD were sequentially randomized 3:1 within each of four cohorts to a single dose of somapacitan (0.02, 0.04, 0.08 and 0.16 mg/kg; n=6 each), or once-daily Norditropin^® SimpleXx^® (0.03 mg/kg; n=2 each) for 7 days.

MEASUREMENTS

Pharmacokinetic and pharmacodynamic profiles were assessed.

RESULTS

Adverse events were all mild, and there were no apparent treatment-dependent patterns in type or frequency. Four mild transient injection site reactions were reported in three of 24 children treated with somapacitan. No antisomapacitan/anti-human growth hormone (hGH) antibodies were detected. Mean serum concentrations of somapacitan increased in a dose-dependent but nonlinear manner: maximum concentration ranged from 21.8 ng/mL (0.02 mg/kg dose) to 458.4 ng/mL (0.16 mg/kg dose). IGF-I and IGFBP-3, and change from baseline in IGF-I standard deviation score (SDS) and IGFBP-3 SDS, increased dose dependently; greatest changes in SDS values were seen for 0.16 mg/kg. IGF-I SDS values were between -2 and +2 SDS, except for peak IGF-I SDS with 0.08 mg/kg somapacitan. Postdosing, IGF-I SDS remained above baseline levels for at least 1 week.

CONCLUSIONS

Single doses of once-weekly somapacitan (0.02-0.16 mg/kg) were well tolerated in children with GHD, with IGF-I profiles supporting a once-weekly treatment profile. No clinically significant safety/tolerability signals or immunogenicity concerns were identified.

The response to growth hormone treatment in prepubertal children with growth hormone deficiency in Japan: Comparing three consecutive years of treatment data of The Foundation for Growth Science in Japan between the 1990s and 2000s

Growth hormone (GH) treatment for children with GH deficiency (GHD) is effective in improving adult height. To achieve favorable effects, GH treatment before puberty is very important, because prepubertal height gain is highly correlated with total height gain. However, no report has studied the effects by analyzing a nationwide data from recent GHD patients in Japan. We investigated the response to GH treatment using data compiled in the Foundation for Growth Science in Japan, and compared the effects between the 1990s and 2000s using analysis of covariance. We analyzed 534 prepubertal GHD subjects treated in the 2000s with three consecutive years of data from the start and investigated predictive factors for the effects. The cumulative height standard deviation score (SDS) change over three years of GH treatment was 0.91 ± 0.57 and 1.20 ± 0.62 in the 1990s and 2000s, respectively. Subjects in the 2000s were divided into three groups by severity, and the cumulative height SDS was 1.60 ± 0.93, 1.20 ± 0.54, and 1.00 ± 0.40 indicating severe, moderate, and mild GHD, respectively. Age and height SDS at the start and severity were identified as independent predictive factors. We also found a significant difference in the effects between the two cohorts after adjusting for the different factors (regression coefficient: -0.069, 95% confidence interval: -0.11 to -0.030, p = 0.0006), which might be due to the GH dose effect. We conclude that the effects of GH treatment in the 2000s had improved compared with those in the 1990s.

Impact of the underlying etiology of growth hormone deficiency on serum IGF-I SDS levels during GH treatment in children

CONTEXT

Regular monitoring of serum IGF-I levels during growth hormone (GH) therapy has been recommended, for assessing treatment compliance and safety.

OBJECTIVE

To investigate serum IGF-I SDS levels during GH treatment in children with GH deficiency, and to identify potential determinants of these levels.

DESIGN, PATIENTS AND METHODS

This observational cohort study included all patients (n = 308) with childhood-onset non-acquired or acquired GH deficiency (GHD) included in the database of a single academic pediatric care center over a period of 10 years for whom at least one serum IGF-I SDS determination during GH treatment was available. These determinations had to have been carried out centrally, with the same immunoradiometric assay. Serum IGF-I SDS levels were determined as a function of sex, age and pubertal stage, according to our published normative data.

RESULTS

Over a median of 4.0 (2-5.8) years of GH treatment per patient, 995 serum IGF-I SDS determinations were recorded. In addition to BMI SDS, height SDS and GH dose (P < 0.01), etiological group (P < 0.01) had a significant effect on serum IGF-I SDS levels, with patients suffering from acquired GHD having higher serum IGF-I SDS levels than those with non-acquired GHD, whereas sex, age, pubertal stage, treatment duration, hormonal status (isolated GHD (IGHD) vs multiple pituitary hormone deficiency (MPHD)) and initial severity of GHD, had no effect.

CONCLUSIONS

These original findings have important clinical implications for long-term management and highlight the need for careful and appropriate monitoring of serum IGF-I SDS and GH dose, particularly in patients with acquired GHD, to prevent the unnecessary impact of potential comorbid conditions.

A Randomized Phase 2 Study of Long-Acting TransCon GH vs Daily GH in Childhood GH Deficiency

CONTEXT

TransCon Growth Hormone (GH) (Ascendis Pharma) is a long-acting recombinant sustained-release human GH prodrug in development for children with GH deficiency (GHD).

OBJECTIVE

To compare the pharmacokinetics, pharmacodynamics, safety, and efficacy of weekly TransCon GH to that of daily GH in prepubertal children with GHD.

DESIGN

Randomized, open-label, active-controlled study of three doses of weekly TransCon GH versus daily Genotropin (Pfizer).

SETTING

Thirty-eight centers in 14 European countries and Egypt.

PATIENTS

Prepubertal male and female treatment-naïve children with GHD (n = 53).

INTERVENTIONS

Subjects received one of three TransCon GH doses (0.14, 0.21, or 0.30 mg GH/kg/wk) or Genotropin 0.03 mg GH/kg/d for 26 weeks.

MAIN OUTCOME MEASURES

GH and insulinlike growth factor-1 (IGF-1) levels, growth, adverse events, and immunogenicity.

RESULTS

Both GH maximum concentration and area under the curve were similar following TransCon GH or Genotropin administration at comparable doses. A dose response was observed, with IGF-1 standard deviation scores increasing into the normal range for all three TransCon GH doses. Annualized mean height velocity for the three TransCon GH doses ranged from 11.9 cm to 13.9 cm, which was not statistically different from 11.6 cm for Genotropin. Adverse events were mild to moderate, and most were unrelated to the study drug. Injection site tolerance was good. One TransCon GH subject developed a low-titer, nonneutralizing antibody response to GH.

CONCLUSIONS

The results suggest that long-acting TransCon GH is comparable to daily Genotropin for GH (pharmacokinetics) and IGF-1 (pharmacodynamics) levels, safety, and efficacy and support advancement into phase 3 development.

Predictors of Insulin-Like Growth Factor-I Responses to Growth Hormone Replacement in Young Adults with Growth Hormone Deficiency

BACKGROUND/AIMS

Physiological growth hormone (GH) secretion and insulin-like growth factor-I (IGF-I) levels are greater in young compared to older adults. We evaluated IGF-I levels and predictors of IGF-I responses in young adults on GH replacement.

DESIGN

From the KIMS database, 310 young adults (age 15-26 years) with severe GH deficiency related to childhood-onset disease and commenced on 'adult GH replacement' were identified. 'IGF-I responses' were estimated from first-year increments in IGF-I standard deviation scores (SDS) and adjusted for GH dose. Body composition was assessed by bioimpedance in 143 patients.

RESULTS

IGF-I levels increased markedly from baseline to 1 year of replacement (-3.75 ± 1.94 vs. -1.36 ± 1.86 SDS, p < 0.0001), but remained low compared to normative data despite dose titration. In multivariate models, IGF-I responses were positively associated with age [B (SE) SDS/(mg/m2); 0.52 (0.15), p = 0.0007] and BMI SDS [1.06 (0.25), p < 0.0001] and inversely associated with female gender [-4.45 (0.79), p < 0.0001] and baseline IGF-I SDS [-1.44 (0.20), p < 0.0001]. IGF-I responses were positively associated with first-year increases in lean body mass (r = 0.19, p = 0.003) and haemoglobin A1c (r = 0.15, p = 0.031).

CONCLUSIONS

Low IGF-I levels in young adults on treatment may reflect suboptimal GH replacement. Identification of predictors for IGF-I responses could lead to a more appropriate replacement strategy. Association between IGF-I responses and lean body mass suggests that maintaining age-appropriate IGF-I levels is important during therapy.

A phase 2 trial of long-acting TransCon growth hormone in adult GH deficiency

TransCon growth hormone is a sustained-release human growth hormone prodrug under development in which unmodified growth hormone is transiently linked to a carrier molecule. It is intended as an alternative to daily growth hormone in the treatment of growth hormone deficiency. This was a multi-center, randomized, open-label, active-controlled trial designed to compare the safety (including tolerability and immunogenicity), pharmacokinetics and pharmacodynamics of three doses of weekly TransCon GH to daily growth hormone (Omnitrope). Thirty-seven adult males and females diagnosed with adult growth hormone deficiency and stable on growth hormone replacement therapy for at least 3 months were, following a wash-out period, randomized (regardless of their pre-study dose) to one of three TransCon GH doses (0.02, 0.04 and 0.08 mg GH/kg/week) or Omnitrope 0.04 mg GH/kg/week (divided into 7 equal daily doses) for 4 weeks. Main outcomes evaluated were adverse events, immunogenicity and growth hormone and insulin-like growth factor 1 levels. TransCon GH was well tolerated; fatigue and headache were the most frequent drug-related adverse events and reported in all groups. No lipoatrophy or nodule formation was reported. No anti-growth hormone-binding antibodies were detected. TransCon GH demonstrated a linear, dose-dependent increase in growth hormone exposure without accumulation. Growth hormone maximum serum concentration and insulin-like growth factor 1 exposure were similar after TransCon GH or Omnitrope administered at comparable doses. The results suggest that long-acting TransCon GH has a profile similar to daily growth hormone but with a more convenient dosing regimen. These findings support further TransCon GH development.

Growth Hormone Utilization Review in a Pediatric Primary Care Setting

Objective:

One of the main problems facing public health providers and administrators in many countries is ensuring the rational use of high-cost drugs. In this regard, on-going process of medication use evaluation can be considered as a useful tool. In this study, we evaluated certain usage aspects of a highly-cost medication, that is, recombinant growth hormone (GH).

Methods:

This cross-sectional study conducted from August 2012 to August 2014. Children receiving GH ± gonadotropin releasing hormone (GnRH) analogs were included in the study. A researcher-designed checklist was developed to evaluate the GH utilization in these patients. Baseline demographic characteristics and background clinical and growth data, as well as any aspects of drug therapy including indications, dosing, monitoring, and discontinuation were collected from the patients' medical records.

Findings:

Seventy children receiving GH entered the study, of which 23 patients (32.85%) received GH and GnRH analogs simultaneously. At the baseline, 67 children (95.7%) had GH stimulation test, whereas serum insulin-like growth factor-1 (IGF-1) levels were measured in 63 (90%) patients. Sixty-seven patients (95.71%) had thyroid function test, whereas bone age was determined in 68 children (97.14%). The mean ± standard deviation of GH dose for idiopathic short stature, GH deficiency, Turner's syndrome and born small for gestational age in our study was 0.22 ± 0.025 mg/kg/week, 0.23 ± 0.04 mg/kg/week, 0.22 ± 0.015 mg/kg/week, and 0.23 ± 0.02 mg/kg/week, respectively. Height and weight of all patients were followed every 3–6 months, regularly. Thirty patients were treated with GH for at least 1 year, of which thyroid hormones and IGF-1 levels were measured annually in 25 (83.33%) and 26 (86.66%) patients, respectively; while bone age was evaluated in 13 (43.33%) children, annually. GH treatment was discontinued in 15 patients (21.42%), while financial problem was the major reason.

Conclusion:

Diagnostic tests and monitoring of height, weight, IGF-1 level and thyroid function was properly performed in this setting. However, a number of patients with ISS and Turner's syndrome were under-dosed.

EVALUATION OF FIRST YEAR RESPONSE TO TREATMENT IN CASES WITH GROWTH HORMONE DEFICIENCY

Background/Aims

Growth hormone (GH) treatment has severe cost burden on patients, their families, and healthcare systems. Therefore, accuracy of diagnosis should be confirmed; factors affecting the response to treatment should be defined. The present study is performed to evaluate auxiliary diagnostic parameters and factors affecting treatment in growth hormone deficiency (GHD).

Methods

In this study, 142 patients under the age of 16, with at least one year of treatment, were included. Treatment dose of somatropin was 0.2 mg/kg/week in all cases. Response to treatment was evaluated by measuring annual height and height standard deviation score (SDS) gains every 3 months.

Results

Male to female ratio was 79 to 63, and follow-up duration before the treatment was 0.89±0.38 years. Annual growth rate before the treatment was 2.92±1.02 cm, and age at the treatment initiation was 9.97±3.22 years. Height gain SDS at the end of the first year was significantly higher in cases which were at the prepuberty, had severe short stature, low height SDS-mid parental height SDS (HSDS-MPHSDS), and initiated treatment at earlier ages. Correlations in height gain and height SDS gain at the end of the first year were significant between bone age at treatment baseline, delta SDS factors, L-dopa and clonidine stimulation results (both are p<0.01).

Conclusion

Height gain was positively related to body mass index, whereas negatively to bone age at treatment baseline, responses obtained from stimulation tests, and delta SDS values. In the treatment evaluation, the parameters which can affect according to model chosen by the investigator, may differ.

Recombinant IGF-I: Past, present and future

Normal linear growth in humans requires GH and IGF-I. Diminished GH action resulting in reduced availability of IGF-I and IGF-binding proteins is the hallmarks of GH Insensitivity Syndromes (GHIS). The deficiencies are the perceived mechanisms for the growth failure of affected patients and the therapeutic targets for the restoration of normal growth. Early treatment attempts with pituitary-derived GH had limited effects in GHIS patients. Recombinant human insulin-like growth factor-I (rhIGF-I) treatment initially provides accelerated growth to GHIS children and provides substantial benefit. But, in general, catch up growth is less substantial with rhIGF-I treatment of GHIS than with rhGH treatment of GH Deficiency. Few classic GHIS patients have reached heights in the normal range (height SD score between -2.0 SD and +2.0 SD) with rhIGF-I monotherapy. A potential explanation is that while rhIGF-I treatment increases circulating concentrations of IGF-1 and IGFBP-3, such treatment reduces endogenous GH levels by negative feedback inhibition of pituitary GH release. In as much as both GH and IGF-I are required for good catch up growth, the loss of any residual GH signaling during IGF-I monotherapy in GHIS patients may attenuate possible catch up growth. Consistent with this explanation is the finding that, as predicted by the preclinical studies by Ross Clark, combination of rhGH & rhIGF-1 provides better growth responses than rhIGF-1 monotherapy in prepubertal children with short stature and low IGF-I levels despite normal stimulated GH responses. In the future, rhGH and rhIGF-I combination therapy can potentially improve growth outcomes over that seen with rhIGF-I monotherapy in all GHIS patients except in those with a total lack of functional GH signaling. Future alternative treatments for GHIS subjects may also include the use of post-growth hormone receptor signaling agonists which restore both GH signaling and IGF-I exposures or the addition of long-acting rhGH species to rhIGF-I. Additional etiologic factors for the growth failure in GHIS should be considered if the growth deficits of GHIS do not resolve with treatment.

Does the GH/IGF-1 axis contribute to skeletal sexual dimorphism? Evidence from mouse studies

The contribution of the gonadotropic axis to skeletal sexual dimorphism (SSD) was clarified in recent years. Studies with animal models of estrogen receptor (ER) or androgen receptor (AR) null mice, as well as mice with bone cell-specific ablation of ER or AR, revealed that both hormones play major roles in skeletal acquisition, and that estrogen regulates skeletal accrual in both sexes. The growth hormone (GH) and its downstream effector, the insulin-like growth factor-1 (IGF-1) are also major determinants of peak bone mass during puberty and young adulthood, and play important roles in maintaining bone integrity during aging. A few studies in both humans and animal models suggest that in addition to the differences in sex steroid actions on bone, sex-specific effects of GH and IGF-1 play essential roles in SSD. However, the contributions of the somatotropic (GH/IGF-1) axis to SSD are controversial and data is difficult to interpret. GH/IGF-1 are pleotropic hormones that act in an endocrine and autocrine/paracrine fashion on multiple tissues, affecting body composition as well as metabolism. Thus, understanding the contribution of the somatotropic axis to SSD requires the use of mouse models that will differentiate between these two modes of action. Elucidation of the relative contribution of GH/IGF-1 axis to SSD is significant because GH is approved for the treatment of normal children with short stature and children with congenital growth disorders. Thus, if the GH/IGF-1 axis determines SSD, treatment with GH may be tailored according to sex. In the following review, we give an overview of the roles of sex steroids in determining SSD and how they may interact with the GH/IGF-1 axis in bone. We summarize several mouse models with impaired somatotropic axis and speculate on the possible contribution of that axis to SSD.

Growth, development, puberty and adult height of patients with congenital multiple pituitary hormone deficiencies

OBJECTIVE

Congenital MPHD is a rare condition caused by mutations in pituitary transcription factors genes: PROP1, POU1F1 (PIT1), HESX1, LHX3, LHX4.

DESIGN

We evaluated in a retrospective study the effects on growth and development in 29 patients with congenital MPHD (cMPHD), during hGH replacement therapy alone and combined with sex hormones. Twenty nine patients with cMPHD were included and diagnosed, treated and followed in our clinic from diagnosis to adult age. Measurements on growth and development were taken by the same medical team.

RESULTS

Mean birth weight of 21/29 neonates was 3126 ± 536 g. Mean birth length of 7/29 neonates was 48.7 ± 2 cm. Neuromotor development was normal or slightly delayed. Mean age at referral was 9.5 ± 7 years (m), 6.7 ± 3.5 years (f) (p=0.17). Height (SDS) before treatment was -2.8 ± 1.0 (m), -2.8 ± 1.0 (f) (p=0.99). Mean age at initiation of hGH treatment was 9.9 ± 6.7 years (m), 10.3 ± 4.2 years (f) (p=0.85). Mean age at initiation of sex hormone treatment was 17.0 ± 3.5 years (m), 17.1 ± 2.3 years (f) (p=0.88). Penile and testicular sizes were below normal before and after treatment. Head circumference (SD) was -1.9 ± 0.9 before and -0.6 ± 1.8 at end of treatment (p<0.001). Adult height (SDS) reached -1.1 ± 0.6 (p<0.001) for both males and females.

CONCLUSION

Despite the multiple pituitary hormone deficiencies including hGH, children with congenital MPHD present with a better auxological development than children with congenital IGHD or congenital IGF-1 deficiency. These findings may be due to irregular and incomplete hormone deficiencies increasing with progressive age and late initiation of puberty.

A Randomized Safety and Efficacy Study of Somavaratan (VRS-317), a Long-Acting rhGH, in Pediatric Growth Hormone Deficiency

CONTEXT

Somavaratan (VRS-317) is a long-acting form of recombinant human GH under development for children and adults with GH deficiency (GHD).

OBJECTIVES

To determine the optimal somavaratan dose regimen to normalize IGF-1 in pediatric GHD and to evaluate safety and efficacy of somavaratan over 6 months.

DESIGN

Open-label, multicenter, single ascending dose study followed by 6-month randomized comparison of 3 dosing regimens.

SETTING

Twenty-five United States pediatric endocrinology centers.

PATIENTS

Naive-to-treatment, prepubertal children with GHD (n = 68).

INTERVENTION(S)

Patients received single sc doses of somavaratan (0.8, 1.2, 1.8, 2.7, 4.0, or 6.0 mg/kg) during the 30-day dose-finding phase, then were randomized to somavaratan 1.15 mg/kg weekly, 2.5 mg/kg twice monthly, or 5.0 mg/kg monthly for 6 months.

MAIN OUTCOME MEASURES

Safety, pharmacokinetics, pharmacodynamics, 6-month height velocity (HV).

RESULTS

Somavaratan pharmacokinetics was linearly proportional to dose; dose-dependent increases in the magnitude and duration of IGF-1 responses enabled weekly, twice-monthly or monthly dosing. A single dose of somavaratan sustained IGF-1 responses for up to 1 month. No somavaratan or IGF-1 accumulation occurred with repeat dosing. Mean annualized HVs for somavaratan administered monthly, twice monthly, or weekly (7.86 ± 2.5, 8.61 ± 2.7, and 7.58 ± 2.5 cm/y, respectively) were similar between groups. Adverse events were mostly mild and transient.

CONCLUSIONS

Somavaratan demonstrated clinically meaningful improvements in HV and IGF-1 in prepubertal children with GHD, with no significant differences between monthly, twice-monthly, or weekly dosing.

Growth hormone (GH) dose-dependent IGF-I response relates to pubertal height gain

BACKGROUND

Responsiveness to GH treatment can be estimated by both growth and ∆IGF-I. The primary aim of the present study was to investigate if mimicking the physiological increase during puberty in GH secretion, by using a higher GH dose could lead to pubertal IGFs in short children with low GH secretion. The secondary aim was to explore the relationship between IGF-I, IGFBP-3 and the IGF-I/IGFBP-3 ratio and gain in height.

METHODS

A multicentre, randomized, clinical trial (TRN88-177) in 104 children (90 boys), who had received GH 33 μg/kg/day during at least 1 prepubertal year. They were followed from GH start to adult height (mean, 7.5 years; range, 4.6-10.7). At onset of puberty, children were randomized into three groups, to receive 67 μg/kg/day (GH(67)) given once (GH(67x1); n = 30) or divided into two daily injection (GH(33x2); n = 36), or to remain on a single 33 μg/kg/day dose (GH(33x1); n = 38). The outcome measures were change and obtained mean on-treatment IGF-I(SDS), IGFBP3(SDS) and IGF-I/IGFBP3 ratio(SDS) during prepuberty and puberty. These variables were assessed in relation to prepubertal, pubertal and total gain in heightSDS.

RESULTS

Mean prepubertal increases 1 year after GH start were: 2.1 IGF-I(SDS), 0.6 IGFBP3(SDS) and 1.5 IGF-I/IGFBP3ratio(SDS). A significant positive correlation was found between prepubertal ∆IGFs and both prepubertal and total gain in height(SDS). During puberty changes in IGFs were GH dose-dependent: mean pubertal level of IGF-I(SDS) was higher in GH(67) vs GH(33) (p = 0.031). First year pubertal ∆IGF-I(SDS) was significantly higher in the GH(67)vs GH(33) group (0.5 vs -0.1, respectively, p = 0.007), as well as ∆IGF-I(SDS) to the pubertal mean level (0.2 vs -0.2, p = 0.028). In multivariate analyses, the prepubertal increase in '∆IGF-I(SDS) from GH start' and the 'GH dose-dependent pubertal ∆IGF-I(SDS)' were the most important variables for explaining variation in prepubertal (21 %), pubertal (26 %) and total (28 %) gain in height(SDS).

TRIAL REGISTRATION

TRN 88-177, not applicable 1988.

CONCLUSION

The dose-dependent change in IGFs was related to a dose-dependent pubertal gain in height(SDS). The attempt to mimic normal physiology by giving a higher GH dose during puberty was associated with both an increase in IGF-I and a dose-dependent gain in height(SDS).

Intranasal Human Growth Hormone (hGH) Induces IGF-1 Levels Comparable With Subcutaneous Injection With Lower Systemic Exposure to hGH in Healthy Volunteers

CONTEXT

The development of an improved, efficacious human GH (hGH) product administered by a noninjectable route of delivery such as the nasal route is highly desirable. We have developed a novel nasal hGH product (CP024) that showed excellent nasal absorption in animal models; however, the translation of these results into the clinical setting is essential because past attempts to develop such formulations by other groups have been unable to induce IGF-1 in man.

OBJECTIVE

The objective of the study was to assess the pharmacokinetics, pharmacodynamics, and tolerability of CP024 compared with a sc hGH injection.

DESIGN

This was a single-center, nonrandomized placebo-controlled, open-label, five-way crossover study in eight healthy volunteers.

SETTING

The study was carried out at a contract research organization, Quotient Bioresearch.

VOLUNTEERS

Eight healthy male volunteers, given an iv infusion of octreotide to suppress the endogenous GH secretion during the study period, participated in the study. No volunteers were withdrawn due to side effects.

MAIN OUTCOME MEASURES

Measurement of hGH and IGF-1 levels and tolerability of the drug product was performed.

RESULTS

No serious adverse events were reported and no subjects withdrawn from study due to the treatment. After the nasal administration of CP024, 3-fold higher hGH blood levels were obtained as compared with hGH nasal control. The relative bioavailability was about 3%. CP024 (given twice daily) induced a significant increase in IGF-1 levels up to 19 hours after administration, with no significant difference to those obtained after the sc injection of hGH.

CONCLUSIONS

The study indicates that CP024 is a promising candidate for an efficacious nasal product for the treatment of GH deficiency due to induction of IGF-1 similar to that after a sc injection, despite the lower plasma hGH concentration obtained. A dose-response study is needed to evaluate the optimal nasal dose.

Increased height standard deviation scores in response to growth hormone therapy to near-adult height in older children with delayed skeletal maturation: results from the ANSWER Program

Background

A primary goal of recombinant human growth hormone therapy (GHT) in children is attaining normal adult height. In this study, children with growth hormone deficiency (GHD) (including isolated idiopathic growth hormone deficiency [IGHD] and multiple pituitary hormone deficiency [MPHD]), idiopathic short stature (ISS), and Turner syndrome (TS) were evaluated for near-adult height (NAH) and percent achieving NAH within the normal range after approximately 4 years of GHT.

Methods

Data from the American Norditropin® Studies: Web-Enabled Research (ANSWER) Program were analyzed for NAH from age at treatment start (ATS) (i.e., referral age as defined by age at enrollment in the study) to last clinic visit using one of the following two criteria: 1) age ≥18 years, or 2) if male: ≥16 years and height velocity (HV) <2 cm/year; if female: ≥15 years and HV <2 cm/year. All patients had a baseline height standard deviation score (HSDS) ≤ -2, and either GHD (n = 201), ISS (n = 19), or TS (n = 41). The main outcome measures included HSDS and corrected HSDS (HSDS-target HSDS) in response to GH treatment, and correlation of ATS with NAH HSDS.

Results

Mean (± SD) chronological and bone ages at baseline were 14.0 ± 2.1 years and 11.7 ± 2.0 years, respectively, and mean GHT duration was 4.0 ± 1.6 years. Mean HSDS (baseline to NAH; GHD: -2.7 to -1.0; ISS: -2.8 to -1.4; TS: -3.0 to -1.8) and mean corrected HSDS (baseline to NAH; GHD: -2.1 to -0.3; ISS: -2.1 to -0.6; TS: -1.8 to -0.6) increased across diagnostic indications. Percentages of patients reaching near-adult HSDS > -2 were GHD: 87.6%; ISS: 78.9%; TS: 65.8%. Significant negative correlations were found between ATS and NAH HSDS when analyzed by sex.

Conclusions

Despite a relatively advanced childhood age, the majority of GH-treated patients attained mean near-adult HSDS within the normal range (HSDS > -2). Negative correlations of ATS with near-adult HSDS indicate that an earlier age at treatment start would likely have resulted in greater adult height achieved in both male and female patients.

Efficacy and safety of Samtropin™ recombinant human growth hormone; a double-blind randomized clinical trial

Background

Recombinant human growth hormone (rhGH) can increase the growth rate in growth hormone deficient children (GHD). In this randomized clinical trial, we compared the efficacy and side effects of an Iranian brand; Samtropin with Norditropin.

Methods

The GHD children were randomly treated either with standard dose of Samtropin or Norditropin rhGH for one year. Upstanding height, height standard deviation score (HSDS), growth velocity (GV), serum levels of insulin like growth factor-1 (IGF-1), and bone age (BA) were determined before and during one year treatment concomitant side effects of treatment.

Results

We evaluated 22 subjects; 12 on Samtropin and, 10 on Norditropin. In each group, mean age was 12 yr and 50% of them were male. The mean differences in height, HSDS, IGF-1 and BA by Norditropin before and after 12 months were 8.8 cm, 0.5, 49 ng/ml and 2.8 yr, respectively. These measures by Samtropin were 9.1 cm, 0.6, 133 ng/ml, and 1.7 yr, respectively without any significant difference. The mean of GV by Samtropin was 9.1 vs. 8.8 cm by Norditropin without significant difference. Since the efficacy of Samtropin was found to be similar to Norditropin after 12 months; we switched to use only Samtropin for the next 12 months. The mean differences in height, HSDS, GV and BA in 20 children between months 12 and 24 were 7.0 cm, 1.6, 2.1 cm/yr and 1.0 yr, respectively (P < 0.001). We also found a non-significant decrease in IGF-1 levels. No side effects were observed.

Conclusions

We need to conduct a post marketing surveillance with a large sample size in order to confirm our findings.

Trial registration

Registration code number in the Iranian Registry of Clinical Trials (IRCT): IRCT1138901181414N11.

IGF-1 and growth response to adult height in a randomized GH treatment trial in short non-GH-deficient children

CONTEXT

GH treatment significantly increased adult height (AH) in a dose-dependent manner in short non-GH-deficient children in a randomized, controlled, clinical trial; the mean gain in height SD score (heightSDS) was 1.3 (range 0-3), compared with 0.2 in the untreated group.

OBJECTIVE

The objective of the study was to analyze the relationship between IGF-1SDS, IGF binding protein-3 SDS (IGFBP3SDS), and their ratioSDS with a gain in the heightSDS until AH in non-GH-deficient short children.

DESIGN AND SETTING

This was a randomized, controlled, multicenter clinical trial.

INTERVENTION

The intervention included GH treatment: 33 or 67 μg/kg · d plus untreated controls.

SUBJECTS

One hundred fifty-one non-GH-deficient short children were included in the intent-to-treat (ITT) population and 108 in the per-protocol (PP) population; 112 children in the ITT and 68 children in the PP populations had idiopathic short stature (ISS).

MAIN OUTCOME MEASURES

Increments from baseline to on-treatment study mean IGF-1SDS (ΔIGF-1SDS), IGFBP3SDS, and IGF-1 to IGFBP3 ratioSDS were assessed in relationship to the gain in heightSDS.

RESULTS

Sixty-two percent of the variance in the gain in heightSDS in children on GH treatment could be explained by four variables: ΔIGF-1SDS (explaining 28%), bone age delay, birth length (the taller the better), and GH dose (the higher the better). The lower IGF-1SDS was at baseline, the higher was its increment during treatment. For both the AllPP- and the ISSPP-treated groups, the attained IGF-1SDS study level did not correlate with height gain.

CONCLUSION

In short non-GH-deficient children, the GH dose-related increment in IGF-1SDS from baseline to mean study level was the most important explanatory variable for long-term growth response from the peripubertal period until AH, when IGF-1SDS, IGFBP3SDS, and their ratioSDS were compared concurrently.

Isolated growth hormone deficiency (GHD) in childhood and adolescence: recent advances

The diagnosis of GH deficiency (GHD) in childhood is a multistep process involving clinical history, examination with detailed auxology, biochemical testing, and pituitary imaging, with an increasing contribution from genetics in patients with congenital GHD. Our increasing understanding of the factors involved in the development of somatotropes and the dynamic function of the somatotrope network may explain, at least in part, the development and progression of childhood GHD in different age groups. With respect to the genetic etiology of isolated GHD (IGHD), mutations in known genes such as those encoding GH (GH1), GHRH receptor (GHRHR), or transcription factors involved in pituitary development, are identified in a relatively small percentage of patients suggesting the involvement of other, yet unidentified, factors. Genome-wide association studies point toward an increasing number of genes involved in the control of growth, but their role in the etiology of IGHD remains unknown. Despite the many years of research in the area of GHD, there are still controversies on the etiology, diagnosis, and management of IGHD in children. Recent data suggest that childhood IGHD may have a wider impact on the health and neurodevelopment of children, but it is yet unknown to what extent treatment with recombinant human GH can reverse this effect. Finally, the safety of recombinant human GH is currently the subject of much debate and research, and it is clear that long-term controlled studies are needed to clarify the consequences of childhood IGHD and the long-term safety of its treatment.

Pharmacogenomics of insulin-like growth factor-I generation during GH treatment in children with GH deficiency or Turner syndrome

Individual responses to growth hormone (GH) treatment are variable. Short-term generation of insulin-like growth factor-I (IGF-I) is recognized as a potential marker of sensitivity to GH treatment. This prospective, phase IV study used an integrated genomic analysis to identify markers associated with 1-month change in IGF-I (ΔIGF-I) following initiation of recombinant human (r-h)GH therapy in treatment-naïve children with GH deficiency (GHD) (n=166) or Turner syndrome (TS) (n=147). In both GHD and TS, polymorphisms in the cell-cycle regulator CDK4 were associated with 1-month ΔIGF-I (P<0.05). Baseline gene expression was also correlated with 1-month ΔIGF-I in both GHD and TS (r=0.3; P<0.01). In patients with low IGF-I responses, carriage of specific CDK4 alleles was associated with MAPK and glucocorticoid receptor signaling in GHD, and with p53 and Wnt signaling pathways in TS. Understanding the relationship between genomic markers and early changes in IGF-I may allow development of strategies to rapidly individualize r-hGH dose.

Different thresholds of tissue-specific dose-responses to growth hormone in short prepubertal children

BACKGROUND

In addition to stimulating linear growth in children, growth hormone (GH) influences metabolism and body composition. These effects should be considered when individualizing GH treatment as dose-dependent changes in metabolic markers have been reported.

HYPOTHESIS

There are different dose-dependent thresholds for metabolic effects in response to GH treatment.

METHOD

A randomized, prospective, multicentre trial TRN 98-0198-003 was performed for a 2-year catch-up growth period, with two treatment regimens (a) individualized GH dose including six different dose groups ranging from 17-100 μg/kg/day (n=87) and (b) fixed GH dose of 43 μg/kg/day (n=41). The individualized GH dose group was used for finding dose-response effects, where the effective GH dose (ED 50%) required to achieve 50% Δ effect was calculated with piecewise linear regressions.

RESULTS

Different thresholds for the GH dose were found for the metabolic effects. The GH dose to achieve half of a given effect (ED 50%, with 90% confidence interval) was calculated as 33(±24.4) μg/kg/day for Δ left ventricular diastolic diameter (cm), 39(±24.5) μg/kg/day for Δ alkaline phosphatase (μkat/L), 47(±43.5) μg/kg/day for Δ lean soft tissue (SDS), 48(±35.7) μg/kg/day for Δ insulin (mU/L), 51(±47.6) μg/kg/day for Δ height (SDS), and 57(±52.7) μg/kg/day for Δ insulin-like growth factor I (IGF-I) SDS. Even though lipolysis was seen in all subjects, there was no dose-response effect for Δ fat mass (SDS) or Δ leptin ng/ml in the dose range studied. None of the metabolic effects presented here were related to the dose selection procedure in the trial.

CONCLUSIONS

Dose-dependent thresholds were observed for different GH effects, with cardiac tissue being the most responsive and level of IGF-I the least responsive. The level of insulin was more responsive than that of IGF-I, with the threshold effect for height in the interval between.

A review of guidelines for use of growth hormone in pediatric and transition patients

Growth hormone (GH) is approved by the US Food and Drug Administration (FDA) for use in pediatric patients with disorders of growth failure or short stature and in adults with growth hormone deficiency (GHD) and HIV/AIDS wasting and cachexia. For pediatric patients, guidelines for the use of GH have been developed by several organizations that have identified specific criteria for initiating GH therapy for each FDA-approved indication. Guidelines for adults have also been developed and include recommendations for transition (adolescent) patients with GHD. These patients are often treated with GH as children but may require continued treatment as young adults to attain full skeletal mineralization and improve cardiovascular risk factors. Adult and pediatric guidelines are supported by efficacy and safety studies, which show that, when started at an early age, GH treatment can increase growth velocity and that GH is safe and well-tolerated. We summarize the guidelines that are available for all FDA-approved indications among pediatric and transition patients. Adherence to these guidelines will help to ensure that patients with disorders of growth failure or short stature receive the necessary therapy to increase linear growth and transition smoothly to healthy adulthood.

Microarchitecture, but not bone mechanical properties, is rescued with growth hormone treatment in a mouse model of growth hormone deficiency

Growth hormone (GH) deficiency is related to an increased fracture risk although it is not clear if this is due to compromised bone quality or a small bone size. We investigated the relationship between bone macrostructure, microarchitecture and mechanical properties in a GH-deficient (GHD) mouse model undergoing GH treatment commencing at an early (prepubertal) or late (postpubertal) time point. Microcomputed tomography images of the femur and L4 vertebra were obtained to quantify macrostructure and vertebral trabecular microarchitecture, and mechanical properties were determined using finite element analyses. In the GHD animals, bone macrostructure was 25 to 43% smaller as compared to the GH-sufficient (GHS) controls (P < 0.001). GHD animals had 20% and 19% reductions in bone volume ratio (BV/TV) and trabecular thickness (Tb.Th), respectively. Whole bone mechanical properties of the GHD mice were lower at the femur and vertebra (67% and 45% resp.) than the GHS controls (P < 0.001). Both early and late GH treatment partially recovered the bone macrostructure (15 to 32 % smaller than GHS controls) and the whole bone mechanical properties (24 to 43% larger than GHD animals) although there remained a sustained 27-52% net deficit compared to normal mice (P < 0.05). Importantly, early treatment with GH led to a recovery of BV/TV and Tb.Th with a concomitant improvement of trabecular mechanical properties. Therefore, the results suggest that GH treatment should start early, and that measurements of microarchitecture should be considered in the management of GHD.

Growth Response to Growth Hormone (GH) Therapy in Children with and without GH Deficiency

The diagnosis of growth hormone deficiency (GHD) needs consideration of both clinical and biological aspects such as auxological data, GH provocative tests and active metabolites of GH including IGF-I and IGFBP-3. In children with GHD, recombinant human GH (rhGH) replacement therapy has been used worldwide with minimal serious side effects. This study aimed to report the results of an investigations for GHD, to describe the growth responses to rhGH in deficient children compared to those without GH deficiency, to evaluate the relationship between clinical and biochemical responses, and to describe the experience of diagnosis and treatment with rhGH at Hamad General Hospital, the main hospital in Qatar where most short children are referred for further investigation. The clinical records of 116 short children were reviewed retrospectively. Forty-six failed the clonidine test and 42 of these also failed the glucagon test and were confirmed with GHD. These and 16 children without GDH were treated with rhGH (25 gg/kg/ day) and were evaluated in terms of growth response, HtSDS, changes of IGF-I concentration and the relationship between these parameters. Treatment with GH of short children with GHD does produce a satisfactory growth response but the HtSDS gain was significantly higher in those with GHD compared to children without GHD. Measurement of IGF-I was found not to be a useful diagnostic test in GHD.

The role of GH/IGF-I-mediated mechanisms in sex differences in cortical bone size in mice

Cortical bone dimensions are important determinants of bone strength. Gender differences in cortical bone size caused by greater periosteal expansion in males than in females during the pubertal growth spurt are well established both in humans and in experimental animal models. However, the mechanism by which gender influences cortical bone size is still a matter of investigation. The role of androgens and estrogen in pubertal bone growth has been examined in human disorders as well as animal models, such as gonadectomized or sex steroid receptor knockout mice. Based on the findings that growth hormone (GH) and insulin-like growth factor I (IGF-I) are major regulators of postnatal skeletal growth, we and others have predicted that sex hormones interact with the GH/IGF-I axis to regulate cortical bone size. However, studies conflict as to whether estrogen and androgens impact cortical bone size through the canonical pathway, through GH without IGF-I mediation, through IGF-I without GH stimulation, or independent of GH/IGF-I. We review recent data on the impact of sex steroids and components of the GH/IGF axis on sexual dimorphism in bone size. While the GH/IGF-I axis is a major player in regulating peak bone size, the relative contribution of GH/IGF-dependent mechanisms to sex differences in cortical bone size remains to be established.

Evaluation of insulin-like growth factor-1 in Indian growth hormone-deficient children on growth hormone therapy

OBJECTIVE

To evaluate the impact of recombinant human growth hormone therapy (GHT) on serum insulin-like growth factor 1 (IGF-1) concentrations in Indian children with growth hormone deficiency.

METHODS

Data on anthropometry and serum IGF-1 concentrations were collected from 28 growth hormone-deficient prepubertal children (8.6 ± 2.9 years) on growth hormone therapy, 6 monthly over the period of 2 years.

RESULTS

Height z-scores showed a steady increase from baseline to 24 months. However, IGF-1 z-scores showed a plateau after the first 6 months and then a small dip followed by a rise. The pattern of increase of IGF-1 z-scores was dissimilar to that of the height z-scores.

CONCLUSION

The change in serum IGF-1 z-scores in response to GHT in Indian children may not be a good indicator for monitoring growth hormone responsiveness.