Indications for growth hormone therapy

Treatment with biosynthetic growth hormone (GH) has been extended in the last 20 years to a wide range of indications. Hormone replacement in GH deficiency, congenital or acquired, can allow children to grow to a normal adult height, though treatment regimen refinements are still required. Extensive post-marketing surveillance has revealed an impressive safety record. Other successful indications include Turner’s syndrome and growth failure associated with chronic diseases such as renal failure, and newer indications such as juvenile chronic arthritis, cystic fibrosis, skeletal dysplasias and congenital adrenal hyperplasia. Condition-specific dose ranges are used. GH deficiency is still principally a clinical diagnosis, needing accurate measurements to demonstrate growth failure supported by tests of poor GH secretory ability. Compliance is improved with a wide range of attractive injection devices.     

Kleinwuchs und Therapie

Short stature is a diagnostic challenge because of the enormous spectrum of physiological maturation and growth patterns in childhood. A carefully drawn growth chart and calculation of the familial target height are required for a correct analysis. A low growth velocity, a height below the familial target, severe short stature and disproportionate or syndromic short stature are rational reasons for referral to a growth specialist. For clinical assessment a small for gestational age (SGA) patient history, presence of minor or major anomalies and skeletal disproportions should guide the diagnostic approach. Bone age estimation may enable the differentiation between inborn (primary) and acquired (secondary) growth failure. Growth hormone (GH) stimulation tests should only be performed if GH deficiency is very likely based on the foregone diagnostics. Constitutional delay of growth and puberty should not be confused with GH deficiency. A GH therapy is effective in GH deficiency and allows a normal growth within the familial target range in the majority of treated children. In addition, the diagnosis and therapy of Turner syndrome, SGA short stature and short stature homeobox-containing gene (SHOX) deficiency are discussed.     

Genetic studies in idiopathic short stature

Idiopathic short stature (ISS) refers to a heterogeneous group of children with marked growth failure of unknown cause, and encompasses familial short stature and constitutional delay of growth. It has been postulated that specific genetic mutations may explain certain cases of growth failure. Some patients with growth hormone (GH) deficiency have mutations in the GH-releasing hormone receptor or GH gene, whereas patients with GH insensitivity syndrome have mutations in the GH receptor or insulin-like growth factor-I gene. It appears that heterozygous mutations of the GH receptor may cause partial GH insensitivity in a subset of patients with ISS. Defects in the short stature homeobox-containing gene (SHOX) in the pseudoautosomal region of the sex chromosomes may cause the growth failure seen in the Leri-Weill and Turner syndromes, and in some familial cases of ISS. Further research into stature-related genes will likely contribute to our understanding of this population.     

Prediction of the growth response in children with various growth disorders treated with growth hormone: analyses of data from the Kabi Pharmacia International Growth Study

Analyses to predict the growth response to recombinant human growth hormone (GH) in prepubertal children during the first year of treatment were performed on data from 472 patients with idiopathic GH deficiency (IGHD), 202 children with Turner's syndrome, 327 children with idiopathic short stature (ISS) and 135 children with intrauterine growth retardation (IUGR). In IGHD, 56% of the variability of the response could be predicted from a model based on six variables. These variables could be ranked in order of importance as follows: target height SDS minus height SDS, chronological age, frequency of GH injections, dose of GH, weight-for-height index, and birth weight SDS. When the model for IGHD was applied to Turner's syndrome, ISS and IUGR, there was a high degree of similarity between the predicted and achieved growth response in ISS and IUGR. However, an uneven distribution within the plot of Studentized residuals in ISS and IUGR suggested heterogeneity within these populations. Prediction of growth in Turner's syndrome was greatly exaggerated by the model for IGHD, suggesting a different pathogenesis as the basis of the growth disorder. Specific prediction models were therefore developed for Turner's syndrome, ISS and IUGR. In all three disorders, the dose of GH was found to be the most important predictor, suggesting that, in contrast to IGHD, first-year growth is governed less by the difference between height and the presumed genetically determined target height. Again, in contrast to IGHD, this suggests that catch-up phenomena are not involved. As the predictability of the variation in growth response in Turner's syndrome, ISS and IUGR did not exceed 32% (for ISS), the search for new predictors should continue in these disorders.     

Growth hormone treatment in Noonan syndrome

Growth responses to growth hormone (GH) treatment in Noonan syndrome are compared with those in short children with the other growth disorders. The responses in Noonan syndrome are much less than those in children with GH deficiency, a little less than those in children with non-endocrine short stature and almost the same as those in children with Turner syndrome. As it is speculated that GH induces puberty earlier that expected in Noonan Syndrome, the efficiency of GH treatment for final height in Noonan syndrome is not promising.     

Estimated cost-effectiveness of growth hormone therapy for idiopathic short stature

OBJECTIVE: To estimate the cost-effectiveness of growth hormone (GH) therapy for idiopathic short stature (ISS). DESIGN: Cost-effectiveness analysis. SETTING: Decision model. PATIENTS: A cohort of 10-year-old prepubertal boys with ISS treated with GH. INTERVENTIONS: Comparison of children treated for 5 years with GH therapy vs children receiving no intervention. MAIN OUTCOME MEASURES: Incremental cost per child, incremental growth per child, and incremental cost per inch of final height gain. RESULTS: The estimated incremental cost-effectiveness ratio of GH therapy for ISS in the base case analysis compared with no therapy was 52,634 dollars per inch (per 2.54 cm), or 99,959 dollars per child, reflecting an incremental growth of 1.9 in (4.8 cm). Alternate treatment strategies such as increased duration of GH treatment and high pubertal dosing of GH did not substantially improve the cost-effectiveness ratio. Probabilistic sensitivity analyses showed that growth variability in response to GH had the greatest impact on the cost-effectiveness of GH therapy. CONCLUSIONS: Targeted treatment of children with ISS with the greatest potential for growth appears critical for maximizing cost-effectiveness of GH treatment. However, the significance of the cost per inch is difficult to judge until the utility gains associated with height gain after GH therapy for ISS can be ascertained.     

Growth hormone for short stature not due to classic growth hormone deficiency

The advent of recombinant DNA technology has resulted in potentially unlimited supplies of growth hormone. Sufficient quantities are now available not only for the long-term, uninterrupted treatment of GH-deficient children but potentially for the treatment of non-GH-deficient patients with other short stature or growth attenuating disorders. Short-term studies have demonstrated an improvement in the growth rates of subjects with isolated short stature, Turner syndrome, and chronic renal failure; and additional studies are under way to assess the efficacy of GH therapy of other short stature syndromes. However, the long-term efficacy and possible adverse effects of GH treatment in these situations is not known. Until there has been more experience, GH deficiency should remain the primary indication for GH treatment. Growth hormone should not be considered routine therapy for other conditions associated with or resulting in short stature. However, research should continue in these areas to define which children may benefit from GH treatment.     

Growth hormone deficiency: new approaches to the diagnosis

International consensus statements based on expert experience recommended guide lines how to diagnose GHD. Most recommendations reached only a low level of evidence. Cut-offs for GH were central part of these recommendations, their definition however was arbitrary. Evidence based cut-offs are needed. Using newborn screening cards from healthy and affected newborns, the GH cut-off to detect severe congenital GHD was reassessed and redefined. A GH cut-off level of 7 microg/L confirmed the diagnosis of severe GHD with 100% sensitivity and 98% specificity on the basis of our assay method, if clinical evidence was present. The previous cut-off of 20 microg/L cited in the international consensus statements was based on old GH assays methods not used anymore. For the calculation of an non-arbitrary GH cut-off for biochemical testing in children, we defined an auxological gold standard for GH deficiency: non-familial short stature due to catch-down growth during the childhood phase of growth in combination with an effective catch-up growth in response to low-dose GH therapy, after exclusion of alternative growth disorders and other potential confounders of growth velocity (true positives). Reference cohorts were normally growing children with Turner syndrome or SGA short stature having the same age (true negatives). Using our in-house GH RIA, highest diagnostic accuracy was provided at a peak GH cutoff during spontaneous secretion at night of 7.3 microg/L (sensitivity, 96.8%; specificity, 82.4%; AUC = 0.93). For arginine, cut-off with the highest number of true test results was 6.6 microg/L (sensitivity, 84.3%; specificity, 75.5%; AUC = 0.83). Importantly, children diagnosed GHD in the past with GH test values above the new cut-offs showed a lower response to GH. In conclusion, by use of retrospective and prospective cohort studies evidence-based cut-offs for GH levels measured in newborns and children can be calculated. By use of these cut-offs, tests can be improved. Because of the well known intrinsic diagnostic inaccuracy of any GH test, the correct selection of the child to be tested remains of utmost importance. The diagnosis of growth hormone deficiency (GHD) in childhood is guided by recommendations of national and international consensus statements which are based on the experience of experts. Most of these recommendations reach only a low level of evidence. Research on two central topics of these guidelines has recently been published by us and will be reviewed here.     

Growth hormone treatment of short children born small-for-gestational-age: the Nordic Multicentre Trial

The aims of this study were to evaluate the efficacy and safety of different doses of growth hormone (GH) treatment in prepubertal short children born small-for-gestational-age (SGA). Forty-eight children born SGA from Sweden, Finland, Denmark and Norway were randomly allocated to three groups: a control group of 12 children received no treatment for 2 y, one group was treated with GH at 0.1 IU/kg/d (n = 16), and one group was treated with GH at 0.2 IU/kg/d (n = 20). In total 42 children completed 2 y of follow-up, and 24 children from the treated groups completed 3 y of treatment. Their mean (SD) age at the start of the study was 4.69 (1.61) y and their mean (SD) height was -3.16 (0.70) standard deviation scores (SDS). The children remained prepubertal during the course of the study. No catch-up growth was observed in the untreated group, but a clear dose-dependent growth response was found in the treated children. After the third year of treatment, the group receiving the higher dose of GH, achieved their target height. The major determinants of the growth response were the dose of GH used, the age at the start of treatment (the younger the child, the better the growth response) and the family-corrected individual height deficit (the higher the deficit, the better the growth response). Concentration of insulin-like growth factor-I (IGF-I) and IGF-binding protein-3 increased during treatment. An increase in insulin levels was found without negative effects on fasting glucose levels or glycosylated haemoglobin levels. GH treatment was well tolerated. In conclusion, short prepubertal children born SGA show a dose-dependent growth response to GH therapy, and their target height SDS can be achieved within 3 y of treatment given GH at 0.2 IU/kg/d. However, the long-term benefit of different regimens of GH treatment in children born SGA remains to be established.     

Growth and puberty in Turner's syndrome

Turner's syndrome is the commonest sex chromosome abnormality in females, resulting from the absence of an X chromosome or the presence of a structurally abnormal X chromosome. Short stature and ovarian failure are the most consistent clinical features and require specific and co-ordinated medical approaches in order to improve final height and well-being in adulthood. High doses of growth hormone (GH) are able to improve adult height in comparison with untreated patients. GH therapy should be started during childhood as soon as the growth curve declines below the 5th percentile and doses adjusted according to clinical response. Some studies reported that combined therapy with GH and an anabolic steroid--oxandrolone--is also beneficial at lower GH doses. Ovarian failure should be treated by appropriate substitutive estrogen therapy. Since estrogen administration may impair growth of patients with Turner's syndrome, the age at beginning of therapy should be individualized taking into consideration potential growth, the need for feminization, bone mineral density and the psychological well-being of each patient. Well co-ordinated endocrine interventions can permit better long-term outcome in adulthood.     

Small for gestation and growth hormone therapy

3 to 10% of neonates are born small for gestation (SGA). This usually occurs because of intrauterine growth retardation (IUGR). After birth most SGA infants show good catch-up growth and normalize their height and weight. About 10% of them continue to remain short (<−2SD) and do not achieve normal adult, height, resulting in psychosocial problems. The mechanism of short stature in these children is poorly understood. Infants who do not show catch-up growth usually have an alteration in the GH-IGF-I axis. Diagnostic and management criteria for short stature in SGA were ill-defined in the past. Growth hormone (GH) therapy for improving height in these children has been approved by the FDA. GH therapy leads to growth acceleration and normalization of height during childhood. Long term GH treatment normalizes adult height above-2 SDS in 85% children, and 98% achieve an adult height within their target height range. GH therapy is safe in SGA children, but it is important to monitor for side effects.     

Insulin-like growth factor-I (rhIGF-I) therapy of short stature

The United States Food and Drug Administration (FDA) approved the use of subcutaneously injected rhIGF-I in late 2005 for treatment of children with severe short stature from growth hormone (GH) insensitivity due to genetic defects in the GH receptor or postreceptor mechanisms or from the development of GH inactivating antibodies. The approval was based on 15 years experience treating these rare conditions with rhIGF-I. Because of the very small numbers of children with these conditions, there has been an effort to justify and promote broader use for rhIGF-I. Attempts to identify GH unresponsiveness in children with idiopathic short stature (ISS) have yielded only a handful of patients with rare genetic disorders. IGF-I treatment for unequivocal GH insensitivity improves but does not correct growth failure, in contrast to the typical experience with GH replacement of GH deficiency. This emphasizes the importance of direct effects of GH at the growth plate, including the stimulation of maturation of cartilage precursor cells and local production of IGF-I, effects that cannot be duplicated by exogenous administration of rhIGF-I. Adverse effects testify to the more than adequate delivery of administered rhIGF-I to other tissues; these include lymphoid hyperplasia, coarsening of the facies, and increased percentage body fat. The absence of convincing evidence of GH insensitivity in a substantial number of children with ISS, the limited ability of endocrine IGF-I to restore normal growth in those with unequivocal GH unresponsiveness, the suppression of endogenous GH (and thereby, local GH effects on growth) that occurs with IGF-I administration, the risk profile, and the absence of data on efficacy in other than proven severe GH insensitivity, led the Drug and Therapeutics Committee of the Lawson Wilkins Pediatric Endocrine Society to conclude that rhIGF-I use is only justified in conditions approved by the FDA and that other growth promotional use should only be investigational. Nonetheless, substantial numbers of children are being treated with rhIGF-I off-label, exuberant estimates of potentially eligible patients are projected, and several uncontrolled clinical trials have been undertaken which are not based on sound preliminary data or established growth principles, and a single four-arm study begun comparing monotherapy with rhGH to combination rhGH with three dosages of rhIGF-I as a single daily injection, a means of administration of rhIGF-I that has not been tested.     

Idiopathic short stature

Idiopathic short stature (ISS) is a term used to describe the status of children with short stature that cannot be attributed to a specific cause. Many children diagnosed as having ISS have partial GH insensitivity, which can result from disturbances at various points of the GH-IGF-I axis. Several clinical studies on spontaneous growth in ISS showed that adult height was almost in the range of target height. GH treatment led to adult height not significantly higher than the pretreatment predicted adult height in most reports. No metabolic side effects have been observed, even when the dose was higher than in GH deficiency. Manipulation of puberty with gonadotrophin releasing hormone analogues reported by a few authors in a small number of children has shown conflicting results. Long-term psychological benefits of GH therapy for short normal children have not been demonstrated to date.     

Growth hormone secretion and long-term growth data in children with psychosocial short stature treated by different changes in environment

OBJECTIVES: We assessed auxological and endocrine data of 65 children (32 girls) from 51 families with an average age of 6.6 years (range, 0.9 to 16.5 years, all but five prepubertal) with psychosocial short stature. METHODS: Fifty-one patients had an assessment of growth hormone (GH) secretion. Thirty-four were subjected to repeated testing with the first test being performed when the child was still in the adverse environment and the next testing after the child was removed. Twenty-five out of those 34 were repeatedly tested during one uninterrupted hospital admission with limited parental access. Thirty patients had a definite, long-term change in their environment (13 were separated from their families) and were assessed concerning their auxological data. RESULTS: Of the 34 patients who had repeated endocrine testing, 11 (32%) showed reversible GH deficiency (GHD), nine (26%) increased their previously normal peak GH concentration, and six (18%) had apparently irreversible GHD. Patients who had a change in environment increased their mean height velocity SDS from -0.9 (SD 1.5) to +1.5 (2.3) (p < 0.0001). Accordingly, height SDS increased from -2.9 (SD 0.8) before to -2.6 (SD 0.8) after the change (p < 0.001). CONCLUSION: One of the diagnostic features of psychosocial short stature is reversible GH insufficiency, which usually normalises after the child is separated from the adverse environment. Catch-up growth is always found after a positive change in the environment, and may occur within the family. However, if a change in environment is not possible, GH therapy may be an option.     

Effect of growth hormone therapy on feeding problems and food intake in children with growth disorders

To assess the effect of therapeutic doses of growth hormone (GH) on the feeding problems, food intake, body fat and mealtime interactions of children with growth disorders, an age-matched group of 46 children with Turner syndrome (TS) or Silver Russell syndrome (SRS) was examined using questionnaire measures and direct observation. The children's body fat was measured using bio-electrical impedance analysis and skinfold thickness measurements. Children receiving GH consumed significantly more energy, protein, fat and carbohydrate than did the children who were not receiving GH, independent of the extent of the child's feeding problems. Children receiving GH had less body fat than did children who were not receiving GH. Children who were not receiving GH distracted their parents from the mealtime significantly more often and received more negative prompting and coaxing from their parents to eat than did children who were receiving GH. This study provides evidence to support the theory that appetite and intake is determined in part by growth and growth potential. Feeding problems seen in children with growth disorders are partly due to parental attempts to impose control over their child's intake, when their child consumes less than the parent believes to be adequate. Conclusion: GH has a significant impact on both the food intake and parent-child interaction at mealtimes of children with SRS and TS.     

Treatment of short stature and delayed adolescence

The treatment of growth failure in children with documented GH deficiency remains the only noncontroversial indication for GH therapy. There are increasing data suggesting that GH may be useful in treating some children with Turner's syndrome and with NVSS. Further studies, however, are necessary to evaluate the long-term efficacy and safety of GH therapy in these children. The treatment of non-GH deficient children whose heights are within two standard deviations of the mean height for age is clearly inappropriate and should be avoided, despite parental protests.     

Twelve-hour spontaneous nocturnal growth hormone secretion in growth retarded patients

Twelve-hour nocturnal GH secretion was studied in 30 children with familial short stature (FSS), constitutional growth delay (CGD), total growth hormone deficiency (TGHD), partial growth hormone deficiency (PGHD), or idiopathic short stature (ISS). No difference was observed between subjects with FSS and children with CGD. The mean 12-hour serum GH concentration was significantly lower in patients with TGHD (p less than 0.001), children with PGHD (p less than 0.01), and subjects with ISS (p less than 0.01) than in subjects with FSS and CGD. No overlap was observed between the range of mean concentration values of children with TGHD and that of subjects with FSS. A significant correlation was found between growth velocity expressed as SD from the mean for bone age and GH concentration (p less than 0.001). All patients with a growth velocity less than 3rd percentile for bone age showed a mean nocturnal concentration less than 4 ng/ml. These data suggest that evaluation of 12-hour spontaneous nocturnal GH secretion with GH sampling every 30 minutes can be usefully employed in the diagnosis of GH deficiency.     

儿童矮小症应用生长激素的长期安全性

生长激素(GH)于1956年首先从人垂体中分离出,其生物化学结构直到1972年才阐明.重组DNA技术和基因工程方法,实现了人生长激素(hGH)的大规模生产,使hGH普遍利用成为可能.文章综述生长激素在儿童生长激素缺乏症、慢性肾功能不全、Turner综合征、Prader-Willi综合征、小于胎龄儿持续矮小、特发性矮小、矮小同源异型盒基因(SHOX)缺陷疾病中的应用方法和安全性.提示重组hGH用于儿童的安全性令人满意,但也需注意有潜在风险的特殊群体.