Growth Hormone Therapy in Short Children Born Small for Gestational Age

Catch-Up Growth as a Risk Factor for Rapid Weight Gain, Earlier Menarche and Earlier Pubertal Growth Spurt in Girls Born Small for Gestational Age (SGA)-A Longitudinal Study

Most children born small for gestational age (SGA) have rapid postnatal growth. Despite its positive aspects, catch-up growth may affect the level of adipose tissue in the pre-pubertal and pubertal periods and therefore affect the age of puberty. The aim of this study was to determine the associations between size at birth, catch-up growth in infancy, BMI in peripubertal period, age at menarche, and the parameters of adolescent growth spurt of body height in girls born SGA. For 297 girls (22.6% SGA; 77.4% appropriate for gestational age (AGA)) complete body weight and height measurements and age at menarche were obtained. Adolescent growth spurt parameters were estimated using the JPA2 model (AUXAL SSI 3.1). Calculations were made in the Statistica 13 program using the Kruskal-Wallis and Kaplan-Meier tests. Girls born SGA with catch-up had the highest BMIs at the age of 8 years (H = 94.22, p < 0.001) and at menarche (H = 58.21, p < 0.001), experienced menarche earliest (H = 21.77, p < 0.001), same as the onset (H = 6.54, p = 0.012) and peak height velocity (H = 11.71, p = 0.003) of their adolescent growth spurt compared to SGA girls without catch-up and AGA girls. In SGA girls, catch-up growth has far-reaching consequences such as increased risk of fat accumulation and a rapid transition to puberty.

Mouse Model of Small for Gestational Age Offspring with Catch-up Growth Failure and Dysregulated Glucose Metabolism in Adulthood

Background

We aimed to build mouse models of small for gestational age (SGA), recapitulating failure of catch-up growth and dysregulated metabolic outcomes in adulthood.

Methods

Pregnant C57BL/6 mice were given a protein-restricted diet (PRD; 6% kcal from protein) during pregnancy without (model 1) or with cross-fostering (model 2). Model 3 extended the PRD to the end of the lactation period. Model 4 changed to a 9% PRD without cross-fostering.

Results

Model 1 yielded a reduced size of offspring with a poor survival rate. Model 2 improved survival but offspring showed early catch-up growth. Model 3 maintained a reduced size of offspring after weaning with a higher body mass index and blood glucose levels in adult stages. Model 4 increased the survival of the offspring while maintaining a reduced size and dysregulated glucose metabolism.

Conclusion

Models 3 and 4 are suitable for studying SGA accompanying adulthood short stature and metabolic disorders.

Determinants of Final Height in Patients Born Small for Gestational Age Treated with Recombinant Growth Hormone

INTRODUCTION

About 8% of children born small for gestational age (SGA) do not reach a final height within the normal range. Recombinant human growth hormone (rhGH) has been shown to be effective in increasing the final height in children born SGA. Our objective was to identify predictive factors of final height in children born SGA treated with rhGH.

MATERIALS AND METHODS

In this retrospective study, conducted in a tertiary pediatric endocrinology referral center, we recruited all patients born SGA (defined as birth length or weight <10th percentile) treated with rhGH for more than 12 months for whom final height data were available. Some patients had received gonadotropin-releasing hormone (GnRH) analog therapy.

RESULTS

We included 252 patients with an average birth length of -2.0 ± 0.7 SD and birth weight of -1.7 ± 1.0 SD. After 4.6 ± 2.8 years of rhGH treatment, their height increased from -2.2 ± 0.9 SD to -1.5 ± 0.9 SD. In multivariate analysis, we identified 8 factors that predict 46% of the final height, namely, cause of SGA (p < 0.0001), GnRH analog therapy >2 years (p = 0.006), birth length (p < 0.02), height at the start of rhGH (p < 0.0001), IGF-1 level at the start of rhGH (p = 0.0002), growth velocity during the 1st year of treatment (p = 0.0002), and age and height at the onset of puberty (p < 0.0001, p = 0.0007, respectively).

CONCLUSION

In this large cohort of SGA patients who had reached their final height, we were able to confirm that growth hormone increases final height in short SGA children. In addition, we identified several factors associated with a better response to growth hormone treatment.

New Horizons in Short Children Born Small for Gestational Age

Children born small for gestational age (SGA) comprise a heterogeneous group due to the varied nature of the cause. Approximately 85-90% have catch-up growth within the first 4 postnatal years, while the remainder remain short. In later life, children born SGA have an increased risk to develop metabolic abnormalities, including visceral adiposity, insulin resistance, and cardiovascular problems, and may have impaired pubertal onset and growth. The third "360° European Meeting on Growth and Endocrine Disorders" in Rome, Italy, in February 2018, funded by Merck KGaA, Germany, included a session that examined aspects of short children born SGA, with three presentations followed by a discussion period, on which this report is based. Children born SGA who remain short are eligible for GH treatment, which is an approved indication. GH treatment increases linear growth and can also improve some metabolic abnormalities. After stopping GH at near-adult height, metabolic parameters normalize, but pharmacological effects on lean body mass and fat mass are lost; continued monitoring of body composition and metabolic changes may be necessary. Guidelines have been published on diagnosis and management of children with Silver-Russell syndrome, who comprise a specific group of those born SGA; these children rarely have catch-up growth and GH treatment initiation as early as possible is recommended. Early and moderate pubertal growth spurt can occur in children born SGA, including those with Silver-Russell syndrome, and reduce adult height. Treatments that delay puberty, specifically metformin and gonadotropin releasing hormone analogs in combination with GH, have been proposed, but are used off-label, currently lack replication of data, and require further studies of efficacy and safety.

Evaluation of Changes in Insulin Sensitivity in Prepubertal Small for Gestational Age Children Treated with Growth Hormone

BACKGROUND

Although growth hormone (GH) therapy for children born small for gestational age (SGA) has been approved for many years, there are still concerns about increasing their risk for insulin resistance and diabetes mellitus type 2. Monitoring of glucose homeostasis is therefore generally recommended, but there is no consensus on either the methods or consequences.

METHODS AND AIMS

The aim of our study was to analyze the oral Glucose Tolerance Tests (oGTTs) which were performed yearly from baseline to 4 years of GH therapy in a collective of 93 SGA children, who were prepubertal during the whole follow-up. We looked for correlations with auxological and laboratory data as well as predictive baseline results for glucose homeostasis during further treatment.

RESULTS

While glucose levels remained constant, insulin secretion increased from baseline to the first year of GH therapy. Insulin sensitivity index (ISI) showed no significant change afterwards; HOMA1, HOMA2, and QUICKI stabilized after the second year. For all indices mean values never reached pathological levels and no cases of diabetes mellitus were induced. Higher gestational age, lower birth length, and older age at start of GH therapy were associated with lower insulin sensitivity. No predictive factors for later insulin resistance could be found.

CONCLUSION

As expected, in GH-treated prepubertal SGA children insulin resistance was induced, but not to pathological levels. No special risk factors for disturbed glucose homeostasis could be identified. Based on our opinion, performing oGTTs in GH-treated SGA children at baseline and in puberty should remain mandatory, but the current study recommendations regarding further surveillance of glucose homeostasis are questionable.

Diagnosis and management of postnatal fetal growth restriction

Fetal growth restriction (FGR) can result from multiple causes, such as genetic, epigenetic, environment, hormonal regulation, or vascular troubles and their potential interaction. The physiopathology of FGR is not yet fully elucidated, but the insulin-like growth factor system is known to play a central role. Specific clinical features can lead to the identification of genetic syndromes in some patients. FGR leads to multiple global health concerns, from the perinatal period, with higher morbidity/mortality, through infancy, with neurodevelopmental, growth, and metabolic issues, to the onset of puberty and later in life, with subfertility and elevated risks of cardiovascular and kidney diseases. Adequate follow-up and therapeutics should be offered to these patients. We first review the main molecular etiologies leading to FGR and their specificities. We then highlight the main issues that FGR can raise later in life before concluding with the proposed management of these children.

Growth Promotion Ethics and the Challenge to Resist Cosmetic Endocrinology

The advancement of "human growth hormone (hGH)-for-height" - increasing height attainment in children short for reasons other than GH deficiency - arose from intuitive, deep-seated assumptions about the disability of short stature, its improvement with hGH-mediated height gain, and the safety of escalating dosages of hGH in healthy children. Evidence challenging these assumptions now strengthens criticism of hGH-for-height as cosmetic endocrinology. To counter this characterization, collective acceptance of guidelines is needed that advise nontreatment of the vast majority of short children, support strategies that minimize treatment duration and dosage, and restrain enhancement of normal adult stature. Through a clinical case analysis, ethical issues underlying these recommendations are explored. These include duties to provide informed assent and re-assent, protect children from unnecessary treatment, consider fairness to nontreated children, and allocate healthcare resources responsibly. Informed assent for hGH-for-height should ensure awareness of modest, variable height gain expectations, limited evidence for psychosocial benefit, ongoing studies for potential posttreatment adverse effects, and options for less expensive/invasive approaches, including nontreatment and counseling. Approaching growth pro-motion in this way fosters therapeutic restraint, resists the al lure of enhancement therapy, and minimizes contributions to society's perception that to be taller is to be better.
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Different long-term response to growth hormone therapy in small- versus appropriate-for-gestational-age children with growth hormone deficiency

BACKGROUND/AIMS

The role of birth weight on growth hormone (GH) therapy response in GH-deficient (GHD) children has not been fully elucidated. Therefore, we examined the growth of 23 small-for-gestational-age GHD children (SGA-GHD, 11 females and 12 males), 26 appropriate-for-gestational-age GHD children (AGA-GHD, 11 females and 15 males) during the first 5 years of GH therapy and that of 22 non-GH-treated SGA children (12 females and 10 males).

METHODS

We collected height and height velocity measurements yearly.

RESULTS

In AGA-GHD children, height was always greater than in the SGA groups and significantly increased from the fourth year of treatment. Height velocity was higher (SGA-GHD: 1.72 ± 0.30 standard deviation score, SDS, AGA-GHD: 2.67 ± 0.21 SDS; p = 0.039) in AGA-GHD children during the first year of treatment. The AGA-GHD group showed the highest percentage (52.4%) of subjects surpassing mid-parental height and the greatest height gain after 5 years of follow-up.

CONCLUSION

Our results show that birth size is an important factor affecting the response to GH therapy in GHD children during the first 5 years of treatment. The paediatric endocrinologist should be aware of this factor when planning the management of GHD children born SGA.

The GH/IGF-1 system in critical illness

The Growth Hormone and Insulin-like Growth Factor-1 (IGF-1) axis plays a pivotal role in critical illness, with a derangement leading to profound changes in metabolism. Protein wasting with skeletal muscle loss, delayed wound healing, and impaired recovery of organ systems are some of the most feared consequences. The use of human recombinant Growth Hormone (rhGH) and Insulin-like Growth Factor-1 (IGF-1) - alone and in combination - has been studied extensively in preclinical and clinical trials. This article reviews the current knowlegde and clinical practice of the use of rhGh and IGF-1 in critically ill patients, with a special focus on the trauma and burns patient population.

Randomized controlled trial to determine the efficacy of long-term growth hormone treatment in severely burned children

BACKGROUND

Recovery from a massive burn is characterized by catabolic and hypermetabolic responses that persist up to 2 years and impair rehabilitation and reintegration. The objective of this study was to determine the effects of long-term treatment with recombinant human growth hormone (rhGH) on growth, hypermetabolism, body composition, bone metabolism, cardiac work, and scarring in a large prospective randomized single-center controlled clinical trial in pediatric patients with massive burns.

PATIENTS AND METHODS

A total of 205 pediatric patients with massive burns over 40% total body surface area were prospectively enrolled between 1998 and 2007 (clinicaltrials.gov ID NCT00675714). Patients were randomized to receive either placebo (n = 94) or long-term rhGH at 0.05, 0.1, or 0.2 mg/kg/d (n = 101). Changes in weight, body composition, bone metabolism, cardiac output, resting energy expenditure, hormones, and scar development were measured at patient discharge and at 6, 9, 12, 18, and 24 months postburn. Statistical analysis used Tukey t test or ANOVA followed by Bonferroni correction. Significance was accepted at P < 0.05.

RESULTS

RhGH administration markedly improved growth and lean body mass, whereas hypermetabolism was significantly attenuated. Serum growth hormone, insulin-like growth factor-I, and IGFBP-3 was significantly increased, whereas percent body fat content significantly decreased when compared with placebo, P < 0.05. A subset analysis revealed most lean body mass gain in the 0.2 mg/kg group, P < 0.05. Bone mineral content showed an unexpected decrease in the 0.2 mg/kg group, along with a decrease in PTH and increase in osteocalcin levels, P < 0.05. Resting energy expenditure improved with rhGH administration, most markedly in the 0.1 mg/kg/d rhGH group, P < 0.05. Cardiac output was decreased at 12 and 18 months postburn in the rhGH group. Long-term administration of 0.1 and 0.2 mg/kg/d rhGH significantly improved scarring at 12 months postburn, P < 0.05.

CONCLUSION

This large prospective clinical trial showed that long-term treatment with rhGH effectively enhances recovery of severely burned pediatric patients.

Impact of high and low folate diets on tissue folate receptor levels and antitumor responses toward folate-drug conjugates

Herein, we present a detailed analysis on the effects of feeding laboratory mice both high and low folic acid (folate)-containing diets as related to associated changes in serum and red blood cell (RBC) folate levels, tissue-derived folate receptor levels, and the ability of folate-drug conjugates to bind and effectuate activity against folate receptor (FR)-positive tumor xenografts. Our data show that serum and RBC folate concentrations sharply drop immediately after mice are switched to low folate diets; however, both parameters reach steady-state, "human-like" levels after 6 weeks. Interestingly, tissue-related folate binding capacities were also lowered during the dietary modulation period, whereas the net uptake of a radiolabeled folate conjugate was simultaneously increased 2.6- and 5-fold in FR-positive kidney and tumor tissue, respectively. Finally, the performances of several clinically and preclinically relevant folate-drug conjugates were evaluated against tumors in mice that were fed high or low folate diets. Except when administered at a dose level 6-fold less than that required to saturate endogenous FRs, no significant loss of antitumor activity was observed. From these findings, we conclude that lowering the dietary intake of folates in mice has little impact on the biological activity of repetitively dosed folate-targeted agents but that low folate diet regimens will reduce serum and RBC folate levels down to levels that more closely approximate the normal human ranges.

Growth hormone treatment and fat redistribution in children born small for gestational age

OBJECTIVE

To determine whether in children born small for gestational age (SGA) high-dose growth hormone (GH) treatment is not only associated with catch-up of growth and with gain of lean mass, but also with a more central fat distribution.

STUDY DESIGN

Short children who were SGA (n = 25; age [mean +/- SD], 5.3 +/- 1.5 years) were randomly assigned to remain untreated (n = 14) or to receive GH (n = 11; sc 66 mug/Kg/d). Growth status and body composition were assessed at the study's start, after 1 year, and after 2 years with anthropometry and absorptiometry.

RESULTS

Children who were treated with GH gained more height and weight than children who were untreated and developed a less adipose body composition (all P < .0001), as expected. However, these changes were also accompanied by a relatively more centripetal distribution of fat mass (0-2 year change in ratio of trunk fat to limb fat; 0.26 +/- 0.23 versus 0.02 +/- 0.15; P < .0001).

CONCLUSION

In children who are SGA, catch-up growth induced by exogenous GH in high doses is accompanied by a less adipose body composition and a more central fat distribution.

Regulation of fetal growth: consequences and impact of being born small

The first trimester of pregnancy is the time during which organogenesis takes place and tissue patterns and organ systems are established. In the second trimester the fetus undergoes major cellular adaptation and an increase in body size, and in the third trimester organ systems mature ready for extrauterine life. In addition, during that very last period of intrauterine life there is a significant increase in body weight. In contrast to the postnatal endocrine control of growth, where the principal hormones directly influencing growth are growth hormone (GH) and the insulin-like growth factors (IGFs) via the GH-IGF axis, fetal growth throughout gestation is constrained by maternal factors and placental function and is coordinated by growth factors. In general, growth disorders only become apparent postnatally, but they may well be related to fetal life. Thus, fetal growth always needs to be considered in the overall picture of human growth as well as in its metabolic development.

Growth hormone treatment of non-growth hormone-deficient growth disorders

Although a large body of data on efficacy and safety of growth hormone (GH) treatment for various non-growth hormone-deficient (GHD) growth disorders has accumulated from a combination of clinical trial and postmarketing sources in the last 20 years or more, there remain limitations. Clinical trial data have the advantage of direct comparison of well-matched, randomized patient groups receiving treatment (or not) under comparable conditions and, as such, provide the highest quality evidence of efficacy. Clinical trials, however, are typically too small for any statistically valid assessment for safety, which is more comprehensively addressed using postmarketing data. Consequently, while the efficacy of GH treatment in children with non-GHD growth disorders has been solidly established and, based on the combination of the rigor of the clinical trial data and numerical power of the postmarketing data, no major concerns exist regarding safety, additional long-term data are required.