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

Normalization of puberty and adult height in girls with Turner syndrome: results of the Swedish Growth Hormone trials initiating transition into adulthood

Objective

To study the impact of GH dose and age at GH start in girls with Turner syndrome (TS), aiming for normal height and age at pubertal onset (PO) and at adult height (AH). However, age at diagnosis will limit treatment possibilities.

Methods

National multicenter investigator-initiated studies (TNR 87-052-01 and TNR 88-072) in girls with TS, age 3-16 years at GH start during year 1987-1998, with AH in 2003-2011. Of the 144 prepubertal girls with TS, 132 girls were followed to AH (intention to treat), while 43 girls reduced dose or stopped treatment prematurely, making n=89 for Per Protocol population. Age at GH start was 3-9 years (young; n=79) or 9-16 years (old; n=53). Treatment given were recombinant human (rh)GH (Genotropin^® Kabi Peptide Hormones, Sweden) 33 or 67 µg/kg/day, oral ethinyl-estradiol (2/3) or transdermal 17β-estradiol (1/3), and, after age 11 years, mostly oxandrolone. Gain in height_SDS, AH_SDS, and age at PO and at AH were evaluated.

Results

At GH start, height_SDS was -2.8 (versus non-TS girls) for all subgroups and mean age for young was 5.7 years and that of old was 11.6 years. There was a clear dose-response in both young and old TS girls; the mean difference was (95%CI) 0.66 (-0.91 to -0.26) and 0.57 (-1.0 to -0.13), respectively. The prepubertal gain_SDS (1.3-2.1) was partly lost during puberty (-0.4 to -2.1). Age/height_SDS at PO ranged from 13 years/-0.42 for GH_67young to 15.2 years/-1.47 for GH_33old. At AH, GH_67old group became tallest (17.2 years; 159.9 cm; -1.27 SDS; total gain_SDS, 1.55) compared to GH_67young group being least delayed (16.1 years; 157.1 cm; -1.73 SDS; total, 1.08). The shortest was the GH_33young group (17.3 years; 153.7 cm: -2.28 SDS; total gain_SDS, 0.53), and the most delayed was the GH_33old group, (18.5 years; 156.5 cm; -1.82 SDS; total gain_SDS, 0.98).

Conclusion

For both young and old TS girls, there was a GH-dose growth response, and for the young, there was less delayed age at PO and at AH. All four groups reached an AH within normal range, despite partly losing the prepubertal gain during puberty. Depending on age at diagnosis, low age at start with higher GH dose resulted in greater prepubertal height gain, permitting estrogen to start earlier at normal age and attaining normal AH at normal age, favoring physiological treatment and possibly also bone health, hearing, uterine growth and fertility, psychosocial wellbeing during adolescence, and the transition to adulthood.

Management of cardiac aspects in children with Noonan syndrome - results from a European clinical practice survey among paediatric cardiologists

BACKGROUND

The majority of children with Noonan syndrome (NS) or other diseases from the RASopathy spectrum suffer from congenital heart disease. This study aims to survey cardiac care of this patient cohort within Europe.

METHODS

A cross-sectional exploratory survey assessing the treatment and management of patients with NS by paediatric endocrinologists, cardiologists and clinical geneticists was developed. This report details responses of 110 participating paediatric cardiologists from multiple countries.

RESULTS

Most paediatric cardiologists responding to the questionnaire were associated with university hospitals, and most treated <10 patients/year with congenital heart disease associated with the NS spectrum. Molecular genetic testing for diagnosis confirmation was initiated by 81%. Half of the respondents reported that patients with NS and congenital heart disease typically present <1y of age, and that a large percentage of affected patients require interventions and pharmacotherapy early in life. A higher proportion of infant presentation and need for pharmacotherapy was reported by respondents from Germany and Sweden than from France and Spain (p = 0.031; p = 0.014; Fisher's exact test). Older age at first presentation was reported more from general hospitals and independent practices than from university hospitals (p = 0.031). The majority of NS patients were followed at specialist centres, but only 37% reported that their institution offered dedicated transition clinic to adult services. Very few NS patients with hypertrophic cardiomyopathy (HCM) were reported to carry implantable cardioverter defibrillators for sudden cardiac death prevention. Uncertainty was evident in regard to growth hormone treatment in patients with NS and co-existing HCM, where 13% considered it not a contra-indication, 24% stated they did not know, but 63% considered HCM either a possible (20%) or definite (15%) contraindication, or a cause for frequent monitoring (28%). Regarding adverse reactions for patients with NS on growth hormone therapy, 5/19 paediatric cardiology respondents reported a total of 12 adverse cardiac events.

CONCLUSIONS

Congenital heart disease in patients with NS or other RASopathies is associated with significant morbidity during early life, and specialty centre care is appropriate. More research is needed regarding the use of growth hormone in patients with NS with congenital heart disease, and unmet medical needs have been identified.

GH Responsiveness in Children With Noonan Syndrome Compared to Turner Syndrome

BACKGROUND

Despite different genetic background, Noonan syndrome (NS) shares similar phenotype features to Turner syndrome (TS) such as short stature, webbed neck and congenital heart defects. TS is an entity with decreased growth hormone (GH) responsiveness. Whether this is found in NS is debated.

METHODS

Data were retrieved from combined intervention studies including 25 children diagnosed with NS, 40 diagnosed with TS, and 45 control children (all prepubertal). NS-children and TS-girls were rhGH treated after investigation of the GH/IGFI-axis. GH was measured with poly- and monoclonal antibodies; 24hGH-profile pattern analysed by PULSAR. The NS-children were randomly assigned to Norditropin^® 33 or 66 μg/kg/day, and TS-girls were consecutively treated with Genotropin^® 33 or 66 μg/kg/day.

RESULTS

Higher PULSAR-estimates of 24h-profiles were found in both NS-children and TS-girls compared to controls: Polyclonal GH_max24h-profile (Mean ± SD) was higher in both groups (44 ± 23mU/L, p<0.01 in NS; 51 ± 47, p<0.001 in TS; compared to 30 ± 23 mU/L in controls) as was GH-baseline (1.4 ± 0.6 mU/L in NS; 2.4 ± 2.4 mU/L in TS, p<0.01 for both, compared to 1.1 ± 1.2 mU/L in controls). Pre-treatment IGFI_SDS was 2.2 lower in NS-children (-1.7 ± 1.3) compared to TS-girls (0.6 ± 1.8, p<0.0001). GH_max, IGFI/IGFBP3-ratio_SDS, and chronological age at start of GH accounted for 59% of the variance in first-year growth response in NS.

CONCLUSION

Both prepubertal NS-children and TS-girls had a high GH secretion, but low IGFI/IGFBP3 levels only in NS-children. Both groups presented a broad individual response. NS-children showed higher response in IGFI and growth, pointing to higher responsiveness to GH treatment than TS-girls.

Variation of bone acquisition during growth hormone treatment in children can be explained by proteomic biomarkers, bone formation markers, body composition and nutritional factors

OBJECTIVE

Growth hormone (GH) regulates both longitudinal growth and bone acquisition in children, and has profound metabolic effects. The aim was to investigate the association between proteomic biomarkers, body fat, nutrition and bone formation markers, and longitudinal growth in response to GH during the first year of treatment. The degree to which changes in these factors could explain variations in GH-dependent longitudinal growth and bone mineralization was also assessed.

METHODS

The individualized GH dose trial included 128 short prepubertal children with either normal (non-GH-deficient) or reduced levels of GH secretion (GH-deficient) (mean age ± SD, 8.6 ± 2.6 years; 90 boys), i.e., with a broad range of GH-secretion and GH-responsiveness, receiving GH treatment (mean 43 μg/kg/day). Blood samples were taken and dual-energy X-ray absorptiometry (DXA) measured at baseline and 1 year of treatment. Step-wise multiple regression models were constructed including three steps with different independent variables added at each step to explain the variance in outcome variables (height_SDS, bone mineral content (BMC) and bone mineral density (BMD). Independent variables included in Step I were previously identified proteomic markers related to GH treatment response, bone formation markers (intact PINP, bone-specific alkaline phosphatase and osteocalcin), variables at treatment start (GH dose mU/kg/day, GH maximum secretion, and difference between child's current and mid-parental height_SDS). Step II explored the added influence of body composition data (body mass index or DXA). Step III explored the added influence of serum nutritional markers and hormones.

RESULTS

Step I variables explained 71% of the variation in first year height_SDS gain, median (minimum-maximum) 0.8 (0.24-1.67); and the proportion explained rose to 73% following inclusion of step II variables and 75% following step III. Corresponding values for total body BMC were 58%, 78%, and 80%, respectively. Proportions fell by approximately 20% when BMC was adjusted for height; 33%, 57%, and 57% for steps I, II, and III, respectively. Corresponding values for total body BMD were 29%, 39%, and 45%, respectively.

CONCLUSION

For total BMC, as much as 80% of the variation during the first year of GH treatment could be explained by proteomic biomarkers, body fat, nutrition and bone formation markers, whereas for height-adjusted BMC 57% could be explained. The inclusion of information about either body composition (fat/lean mass) or nutritional markers contributed with approximately 20%. The variation in height_SDS gain could be explained to 75%. Hence, information of fat or nutrition markers was needed for explaining the variation in bone acquisition to the same magnitude as explaining the variation in height response.

Broad variability in pharmacokinetics of GH following rhGH injections in children

OBJECTIVE

Daily subcutaneous self-injection of GH is used worldwide to treat short stature in childhood; longitudinal data on the impact of this regimen on GH-uptake are lacking.

DESIGN

Children with/without GH-deficiency participating in clinical trials were followed prospectively (≤8 times). Blood was sampled pre-GH-injection (dose GH³³/GH⁶⁷ μg/kg) and either every 30 min thereafter for 24 h (Experimental-setting; 59 GH-curves/15 children); or every 2 h thereafter for 16 h (Clinical-setting; 429 GH-curves/117 children). Pharmacokinetics were estimated by time T_max (h) of maximal GH-concentration (C_max, mU/L) and area under the curve for 16 h (AUC, mU/L ∗ h).

RESULTS

In the Clinical-setting, median C_max was 71 mU/L and AUC was 534 mU/L ∗ h, with coefficients of variation for intra-individual variation of 39% and 36%, respectively, and inter-individual variation of 44% and 42%, respectively. 43% of C_max and AUC variability was explained by GH-dose and proxies for injection depth (baseline GH-level, GH_peakwidth, BMI_SDS). In the Experimental- versus Clinical-setting, 85% and 40% of GH-curves, respectively, reached zero-levels within 24 h. A longer duration was found following a more superficial GH-injection. Spontaneous GH-peaks were identified already 6 h after the GH-injection in about half of the curves of both GHD and non-GHD patients.

CONCLUSION

Very broad intra-individual and inter-individual variability was found. A high GH-peak will optimize growth effects; the highest C_max was found after a deep injection of GH at the higher dose and concentration. In as many as 60% of the children, GH remained detectable in serum after 24 h; a constant GH-level will promote IGF-I and metabolic effects.

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).

Growth Hormone Treatment Improves Cognitive Function in Short Children with Growth Hormone Deficiency

BACKGROUND/AIMS

We investigated the association between cognition and growth hormone (GH) status and GH treatment in short prepubertal children with broadly ranging GH secretion.

METHODS

A total of 99 children (age 3-11 years), 41 with GH deficiency (GHD) and 58 with idiopathic short stature (ISS), were randomized to a fixed dose (43 µg/kg/day) or a prediction model-guided individualized dose (17-100 µg/kg/day) and followed up for 24 months. In a longitudinal and mixed within- and between-subjects study, we examined clinical effect size changes, measured by Cohen's d, in full-scale IQ (FSIQ) and secondary IQ indices.

RESULTS

Significant increases giving medium effect size in FSIQ (p = 0.001, Cohen's d = 0.63), performance IQ (p = 0.001, Cohen's d = 0.65) and processing speed (p = 0.005, Cohen's d = 0.71) were found in the GH-deficient group. In contrast, perceptual organization only increased in the ISS group (p = 0.001, Cohen's d = 0.53). Baseline IQ was normally distributed with small but significant differences between the groups: GH-deficient children had lower FSIQ (p = 0.042) and lower performance IQ (p = 0.021). Using multiple regression analysis, 40% of the variance in delta processing speed scores (0-24 months) was explained by GHmax and IGF-ISDS at baseline.

CONCLUSION

IQ, specifically fluid intelligence, increased in the GH-deficient children. The pretreatment status of the GH/IGF-I axis was significantly predictive for these changes. © 2015 S. Karger AG, Basel.

Combined treatment with GH and IGF-I: additive effect on cortical bone mass but not on linear bone growth in female rats

The growth-promoting effect of combined therapy with GH and IGF-I in normal rats is not known. We therefore investigated the efficacy of treatment with recombinant human (rh)GH and/or rhIGF-I on longitudinal bone growth and bone mass in intact, prepubertal, female Sprague-Dawley rats. rhGH was injected twice daily sc (5 mg/kg·d) and rhIGF-I continuously infused sc (2.2 or 4.4 mg/kg·d) for 28 days. Longitudinal bone growth was monitored by weekly x-rays of tibiae and nose-anus length measurements, and tibial growth plate histomorphology was analyzed. Bone mass was evaluated by peripheral quantitative computed tomography. In addition, serum levels of IGF-I, rat GH, acid labile subunit, IGF binding protein-3, 150-kDa ternary complex formation, and markers of bone formation and degradation were measured. Monotherapy with rhGH was more effective than rhIGF-I (4.4 mg/kg·d) to increase tibia and nose-anus length, whereas combined therapy did not further increase tibia, or nose-anus, lengths or growth plate height. In contrast, combined rhGH and rhIGF-I (4.4 mg/kg·d) therapy had an additive stimulatory effect on cortical bone mass vs rhGH alone. Combined treatment with rhGH and rhIGF-I resulted in markedly higher serum IGF-I concentrations vs rhGH alone but did not compromise the endogenous secretion of GH. We conclude that rhIGF-I treatment augments cortical bone mass but does not further improve bone growth in rhGH-treated young, intact, female rats.

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.

Protein markers predict body composition during growth hormone treatment in short prepubertal children

OBJECTIVE

A high-throughput pharmaco-proteomic approach has previously been successfully used to identify lipoprotein biomarkers related to changes in longitudinal growth and bone mass in response to growth hormone (GH) treatment. The aim of this study was to identify protein markers involved in the diverse anabolic and lipolytic remodelling of body composition during GH treatment.

DESIGN, PATIENTS AND MEASUREMENTS

The study population consisted of 128 prepubertal children receiving GH treatment. Thirty-nine were short as a result of GH deficiency, and 89 had idiopathic short stature (ISS). Serum protein expression profiles at study start and after 1 year of GH treatment were analysed using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS). Body composition was analysed by dual-energy X-ray absorptiometry (DXA), reliably estimating muscle mass from appendicular (arms and legs) lean soft tissue mass (LST). DXA was also used to estimate appendicular bone mineral content (BMC) and fat mass for the total body.

RESULTS

Specific protein expression patterns associated with GH response in different body compartments were identified. Among identified proteins, different isoforms of nutrition markers such as apolipoproteins (Apo) were recognized: Apo C-I, Apo A-II, serum amyloid A4 (SAA4) and transthyretin (TTR). In addition, unidentified peaks were associated with GH effects on specific body compartments.

CONCLUSIONS

Our results suggest that unique protein markers are associated with remodelling of different body compartments during GH treatment, which in the future might be useful to optimize GH treatment not only with regard to longitudinal growth.