Prospective clinical trial of human growth hormone in short children without growth hormone deficiency

Growth failure: 'idiopathic' only after a detailed diagnostic evaluation

The terms 'idiopathic short stature' (ISS) and 'small for gestational age' (SGA) were first used in the 1970s and 1980s. ISS described non-syndromic short children with undefined aetiology who did not have growth hormone (GH) deficiency, chromosomal defects, chronic illness, dysmorphic features or low birth weight. Despite originating in the pre-molecular era, ISS is still used as a diagnostic label today. The term 'SGA' was adopted by paediatric endocrinologists to describe children born with low birth weight and/or length, some of whom may experience lack of catch-up growth and present with short stature. GH treatment was approved by the FDA for short children born SGA in 2001, and by the EMA in 2003, and for the treatment of ISS in the US, but not Europe, in 2003. These approvals strengthened the terms 'SGA' and 'ISS' as clinical entities. While clinical and hormonal diagnostic techniques remain important, it is the emergence of genetic investigations that have led to numerous molecular discoveries in both ISS and SGA subjects. The primary message of this article is that the labels ISS and SGA are not definitive diagnoses. We propose that the three disciplines of clinical evaluation, hormonal investigation and genetic sequencing should have equal status in the hierarchy of short stature assessments and should complement each other to identify the true pathogenesis in poorly growing patients.

A 4-Year, Open-Label, Multicenter, Randomized Trial of Genotropin® Growth Hormone in Patients with Idiopathic Short Stature: Analysis of 4-Year Data Comparing Efficacy, Efficiency, and Safety between an Individualized, Target-Driven Regimen and Standard Dosing

BACKGROUND/AIMS

Growth hormone (GH) treatment regimens for children with non-GH-deficient, idiopathic short stature (ISS) have not been optimized. To compare the efficacy, efficiency, and safety of an individualized, target-driven GH regimen with standard weight-based dosing after 4 years of treatment.

METHODS

This is a 4-year, open-label, multicenter, randomized trial comparing individualized, formula-based dosing of Genotropin® versus a widely used ISS dose of Genotropin®. Subjects were prepubertal, had a bone age of 3-10 years for males and 3-9 years for females, were naive to GH treatment, and had a height standard deviation score (Ht SDS) of -3 to -2.25, a height velocity <25th percentile for their bone age, and peak stimulated GH >10 ng/ml. After the first 2 years, the individualized-dosing group was further randomized to either 0.18 or 0.24 mg/kg/week.

RESULTS

At 4 years, subjects in all treatment regimens achieved similar average height gains of +1.3 SDS; however, the individualized dosing regimen utilized less GH to achieve an equivalent height gain.

CONCLUSION

Individualized, formula-based GH dosing, followed by a dose reduction after 2 years, provides a more cost-effective growth improvement in patients with ISS than currently employed weight-based regimens.

Growth hormone treatment in short children--short-term and long-term effects on growth

Short children with normal GH responses to arginine-insulin provocation testing and various amounts of spontaneously secreted GH over 24 hours participated in an ongoing study with GH, 0.1 IU/kg/day. A total of 40 prepubertal children have been treated for 1 year. Their mean height velocity increased from 4.6 to 7.5 cm/year. The children with the slowest pretreatment height velocity showed the best increment. An inverse relationship was found between the endogenous GH secretion and the increment in growth; 80% of the children had an endogenous GH secretion of less than 300 milliunits/litre/24 hours, estimated as area under the curve above the calculated baseline. They all showed an increment in height above 2 cm. The remaining 20% all had an endogenous GH secretion of more than 300 milliunits/litre/24 hours, estimated as area under the curve above the calculated baseline. Twenty-four of the children were prepubertal for the following 4 years, and their GH therapy continued. Their height velocity changed from 4.2 cm/year before therapy to 8.1, 6.7, 6.0 and 4.9 cm/year for the 1st, 2nd, 3rd and 4th years on treatment. Many of them have passed their expected final height, but have still not stopped growing. Those children who were in early puberty when GH treatment started went into a rapid growth spurt and have now stopped growing. They have all reached but not improved their expected final height. In 15 of the children GH treatment was stopped after 1-3 years. Their mean height velocity for the first post-treatment year was 5.1 cm/year; thus, for the group as a whole no 'catch down' was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of recombinant growth hormone treatment on children with Crohn's disease and short stature: a pilot study

BACKGROUND

Growth failure frequently complicates Crohn's disease in childhood. Abnormalities in the growth hormone (GH)/insulin-like growth factor-1 axis may occur. The effects of administered GH on growth have not been studied previously in a randomized trial.

METHODS

Seven children (6 boys and 1 girl; age, 11.9-16 yr) with Crohn's disease and growth failure were enrolled. In phase 1, patients were randomized to either GH (0.05 mg/kg per day) or placebo; in phase 2, patients who received placebo during the first year received GH for various time periods. Follow-up was every 3 months for up to 2 years.

RESULTS

During placebo treatment (4 patients), mean height-for-age z score (haz) increased 0.23 in the first half year and 0.55 in the second half year. The mean improvement in haz during the first half year of GH treatment (7 patients) was 0.13; during the second half year (5 patients), haz decreased 0.01. Effects of GH varied among patients; 2 patients grew only when nutritional supplementation was added. Observed changes were not statistically significant; however, the number of patients studied was small, and statistical analyses could have been affected by sample size. Serum insulin-like growth factor-1 levels correlated with height velocity. Only 2 patients later reached expected adult height.

CONCLUSIONS

In this pilot study, GH treatment at the dose given did not stimulate growth in children with Crohn's disease and short stature. Whether or not GH plus nutritional therapy would be effective in promoting sustained catch-up growth remains to be determined.

Evaluation of insulin-like growth factor (IGF)-I and IGF binding protein-3 generation test in short stature

BACKGROUND

Differentiation between growth hormone deficiency (GHD) and idiopathic short stature (ISS) based on GH tests and basal IGF-I and IGFBP-3 levels may be difficult. The aim of this study was to evaluate the role of pharmacological GH tests, IGF-I and IGFBP-3 generation test and height velocity off-treatment in the evaluation of GHD and ISS.

METHODS

Thirty-three (17 M, 16 F) prepubertal short (height SDS < -2) children were divided into two groups: Group 1 (n = 19) with peak GH level <10 tg/l (GHD) and Group 2 (n = 14) GH > or =10 microg/l in two sex steroid primed pharmacological GH tests. Having excluded other diagnoses, Group 2 was regarded as having ISS. The generation test was performed concomitantly (0.1 IU/kg GH s.c. for 4 days) with IGF-I and IGFBP-3 measured on the 4th day in both groups. The patients were followed for a year for height velocity (HV).

RESULTS

Group 1 and 2 had comparable height SDS (-2.3 +/- 0.4 and -2.3 +/- 0.3) at comparable ages (7.8 +/- 2.8 and 7.0 +/- 2.7 yr). Although the deltaIGF-I response was low (<2.0 nmol/l 115 ng/ ml]) in seven (37%) children in the GHD group, all GHD patients with low height velocity had adequate (> or =14 nmol/I [400 ng/ml]) deltaIGFBP-3 response. deltaIGFBP-3 in the generation test showed a negative correlation with HV (p = 0.021, r = -0.570) and also with basal IGFBP-3 (p <0.001, r = -0.743) in the GHD group. In the ISS group, deltaIGF-I and deltaIGFBP-3 responses were low in 31% and 7%, respectively, and the correlation between basal IGF-I, IGFBP-3 and HV and between delta values in the generation test were significantly positive, pointing to a difference in the growth response of these children.

CONCLUSION

In the GHD group, based on pharmacological tests, an adequate deltaIGFBP-3 response in the generation test predicts poor height velocity at follow up and thus strengthens the diagnosis of true GHD.

Insulin-Like Growth Factor (IGF) Parameters and Tools for Efficacy: The IGF-I Generation Test in Children

Serum levels of growth hormone (GH)-dependent peptides could provide important and valuable measures of GH sensitivity and, potentially, responsiveness. In normal individuals, serum insulin-like growth factor I (IGF-I) concentrations are dependent on the dose of GH given, with IGF-I responsiveness not decreasing with age. Individuals heterozygous for the E180 GH receptor (GHR) splice mutation have normal IGF-I generation, but those homozygous for the E180 splice mutation have very low basal and stimulated IGF-I concentrations. Similar results are observed for the serum IGF-binding protein 3 (IGFBP-3) response to GH, with a correlation between changes in serum concentrations of IGF-I and changes in IGFBP-3 in normal, heterozygotic, GH-insensitive and GH-deficient participants. In individuals with the E180 splice mutation, IGF-I and IGFBP-3 tests show sensitivity and specificity for detecting GH insensitivity (GHI). In children with idiopathic short stature, it appears that some individuals have selective resistance to GH, with their ability to generate IGF-I more impaired than their ability to generate other GH-dependent peptides. This heterogeneous group may require individualization of GH dosage. IGF generation tests remain the best short-term, in vivo test for classic GHI, although diagnostic tests will undoubtedly require further modification to identify milder pathophysiologic abnormalities.

Neuroendocrine control of growth hormone secretion

The secretion of growth hormone (GH) is regulated through a complex neuroendocrine control system, especially by the functional interplay of two hypothalamic hypophysiotropic hormones, GH-releasing hormone (GHRH) and somatostatin (SS), exerting stimulatory and inhibitory influences, respectively, on the somatotrope. The two hypothalamic neurohormones are subject to modulation by a host of neurotransmitters, especially the noradrenergic and cholinergic ones and other hypothalamic neuropeptides, and are the final mediators of metabolic, endocrine, neural, and immune influences for the secretion of GH. Since the identification of the GHRH peptide, recombinant DNA procedures have been used to characterize the corresponding cDNA and to clone GHRH receptor isoforms in rodent and human pituitaries. Parallel to research into the effects of SS and its analogs on endocrine and exocrine secretions, investigations into their mechanism of action have led to the discovery of five separate SS receptor genes encoding a family of G protein-coupled SS receptors, which are widely expressed in the pituitary, brain, and the periphery, and to the synthesis of analogs with subtype specificity. Better understanding of the function of GHRH, SS, and their receptors and, hence, of neural regulation of GH secretion in health and disease has been achieved with the discovery of a new class of fairly specific, orally active, small peptides and their congeners, the GH-releasing peptides, acting on specific, ubiquitous seven-transmembrane domain receptors, whose natural ligands are not yet known.

Effect of growth hormone treatment on adult height of children with idiopathic short stature. Genentech Collaborative Group

BACKGROUND

Short-term administration of growth hormone to children with idiopathic short stature results in increases in growth rate and standard-deviation scores for height. However, the effect of long-term growth hormone therapy on adult height in these children is unknown.

METHODS

We studied 121 children with idiopathic short stature, all of whom had an initial height below the third percentile, low growth rates, and maximal stimulated serum concentrations of growth hormone of at least 10 microg per liter. The children were treated with growth hormone (0.3 mg per kilogram of body weight per week) for 2 to 10 years. Eighty of these children have reached adult height, with a bone age of at least 16 years in the boys and at least 14 years in the girls, and pubertal stage 4 or 5. The difference between the predicted adult height before treatment and achieved adult height was compared with the corresponding difference in three untreated normal or short-statured control groups.

RESULTS

In the 80 children who have reached adult height, growth hormone treatment increased the mean standard-deviation score for height (number of standard deviations from the mean height for chronologic age) from -2.7 to -1.4. The mean (+/-SD) difference between predicted adult height before treatment and achieved adult height was +5.0+/-5.1 cm for boys and +5.9+/-5.2 cm for girls. The difference between predicted and achieved adult height among treated boys was 9.2 cm greater than the corresponding difference among untreated boys with initial standard-deviation scores of less than -2, and the difference among treated girls was 5.7 cm greater than the difference among untreated girls.

CONCLUSION

Long-term administration of growth hormone to children with idiopathic short stature can increase adult height to a level above the predicted adult height and above the adult height of untreated historical control children.

Short-term increments of insulin-like growth factor I (IGF-I) and IGF-binding protein-3 predict the growth response to growth hormone (GH) therapy in GH-sensitive children

The present study included a cohort of 42 children aged between 1.7 and 15.4 years, who presented with short stature and growth failure. Basal and generated serum levels of insulin-like growth factor-I (IGF-I) and IGF-binding protein-3 (IGFBP-3), measured in an IGF generation test following four or seven daily injections of growth hormone (GH), 0.1 IU/kg (0.033 mg/kg), were analysed in these patients. The growth response to 1 year of GH treatment, 0.6 IU/kg/week (0.2 mg/kg/week), was also investigated. Median height velocity of these patients increased from -1.6 SDS (range, -4.6 to -0.3 SDS) to 3.3 SDS (range, -0.2 to 7.1 SDS) after 1 year of GH treatment, and median height SDS increased by 0.7 SDS (range, 0.1 to 2.2 SDS). Strong correlations were observed between basal and generated IGF-I and IGFBP-3 levels. The increase in IGFBP-3 levels in response to GH in the generation test was a strong predictor of the growth response to GH therapy. All the patients in the present study could be differentiated from patients with GH insensitivity syndrome (GHIS) using the criteria of a diagnostic scoring system for GHIS. The most valuable parameters were the increases in IGF-I and IGFBP-3 levels in the generation test, which excluded 95.2% of the patients from a diagnosis of GHIS.

Potential role of insulinlike growth factors in fracture healing

Several lines of evidence suggest that the insulinlike growth factors play a role in fracture healing. They promote cell proliferation and matrix synthesis by chondrocytes and osteoblasts, the two cell types largely responsible for the formation of fracture callus. Circulating levels of insulinlike growth factor I and bone mineral density decrease with increasing age, and administration of insulinlike growth factor I increases bone turnover in patients with low bone mineral density. Insulinlike growth factor I may accelerate the normal healing of intramembranous bone defects, inducing the healing of defects that otherwise would not heal. An important role of insulinlike growth factor I is to mediate many of the actions of growth hormone on the skeleton. Considerable effort has been devoted to testing the effect of growth hormone and, thereby, indirectly that of insulinlike growth factor I on fracture healing. These studies have yielded such disparate results that no general conclusions regarding the effect of growth hormone (or of growth hormone dependent insulinlike growth factor I) on fracture healing currently can be drawn. Additional studies are needed to clarify the role of the insulinlike growth factors in the fracture healing process and to determine how their anabolic actions can be enlisted in the clinical enhancement of fracture healing.

Increased height in patients with medulloblastomas

OBJECTIVE

Medulloblastomas demonstrate histological features similar to neuroendocrine tumors. Expression of various receptors for growth factors and production of growth hormones have been identified to occur with medulloblastomas. We studied the preoperative height of patients with medulloblastomas.

METHODS

We studied 85 patients (64 children and 21 adults) with medulloblastomas and 42 patients (27 children and 15 adults) with cerebellar astrocytomas who served as a control group. All of the patients had their height and weight documented on standardized growth charts. In addition, age, sex, symptoms, radiographic findings, treatment, and survival were examined.

RESULTS

Preoperatively, 22.4% of the patients with medulloblastomas were above the 95% curve in height and 80.0% were above the 50% curve for height. Compared with patients with cerebellar astrocytomas, 7.1% were above the 95% curve for height and 54.8% were above the 50% curve for height. The distribution of patients along the weight curves for both tumor types demonstrated a slight prevalence for lower weights but was not significantly different from the national average. A significant number of patients presenting with medulloblastomas attained increased height, which was disproportionate to the weight loss generally observed with neoplasms. To our knowledge, the disproportionate number of patients with medulloblastomas and increased height has not been reported before. A similar deviation in height distribution from the normal population could not be identified in patients with cerebellar astrocytomas.

CONCLUSION

This study suggests that medulloblastomas may be influenced by growth hormone production or may produce growth factors in vivo.

Insulin-like growth factor binding protein-3 generation: an index of growth hormone insensitivity

GH insensitivity may be an inherited condition or may arise as a consequence of disease of malnutrition. Laron syndrome is the most severe form of GH insensitivity, arising from an absent or defective GH receptor. Less severe forms of GH insensitivity, however, may exist, resulting in short stature but in few other features of Laron syndrome. We have identified a heterogeneous group of children with short stature and either high basal (> 10 mU/L) or high peak GH levels (> 40 mU/L) on GH provocation testing, to examine biochemical markers of GH sensitivity. These children received 4 d of GH (0.1 U/kg) and the increment in IGF-I, IGF binding protein (BP)-3, and GHBP was determined. Eight GHD children, commencing GH therapy, were recruited as positive controls. The two groups could not be differentiated by age, height SDS (SD score), height velocity SDS, or body mass index. IGF-I and IGFBP-3 generation were correlated in all children (delta SDS IGF-I versus delta SDS IGFBP-3, r = 0.49, p = 0.03). Neither basal GHBP levels or the increment in GHBP were predictive of the IGF-I or IGFBP-3 response to GH. The GHI group had a significantly reduced IGFBP-3 response to stimulation with 4 d of GH (median percent increment in IGFBP-3, 26%, versus 72% in the GHD group, P = 0.03); their IGF-I response to GH was also reduced (median % increment in IGF-I 75% versus 144% in the GH deficient group), but this did not achieve significance, p = 0.06. In all children, the percentage rise or delta SDS in both IGF-I and IGFBP-3 inversely correlated with the GH peak obtained on provocation testing, the latter being the most significant determinant of GH peak. We propose that the "IGF generation test", in particular IGFBP-3 generation, can be used in the investigation of partial GH insensitivity. Further work, however, is required to establish diagnostic criteria for partial GH insensitivity.

A partial transient effect of short-term growth hormone (GH) treatment in short non-GH deficient prepubertal children

This study reports the growth of 11 short non-GH deficient children before, during short-term GH therapy for 1 year and for 2 years after the cessation of treatment. The mean growth velocity increased significantly (p < 0.0001) from the pretreatment mean of 4.6 (SD = 0.95) cm/year to 8.4 (SD = 1.1) cm/year after 1 year of GH treatment without accelerated advancement of skeletal maturation. The serum IGF-1 levels also increased significantly with treatment. In nine children who remained prepubertal followed for one year after GH treatment, the mean growth velocity increased from 4.5 (SD = 0.69) cm/year before treatment to 8.7 (SD = 1.28) cm/year after 1 year of GH treatment (p < 0.0001). After stopping GH treatment, the growth velocity decreased significantly (p < 0.001) to 2.4 (SD = 0.68) cm/year during the first year of follow-up. In the six prepubertal children followed up for 2 years after treatment, the mean growth velocity was 4.1 (SD = 1.04) cm/year which was not significantly different from the pretreatment growth velocity. The significant decrease in growth velocity during the first post-treatment year could not be explained by the usual fall of growth velocity with increasing age in prepubertal children. Our results indicate that the effect of one year of GH treatment on height gain is partly transient and cast doubt on the efficacy of short-term GH therapy in short non-GH deficient patients.

The insulin-like growth factor I generation test in the investigation of short stature

Genotypic and phenotypic heterogeneity in patients with growth hormone (GH) insensitivity syndrome suggests that partial defects exist in the GH receptor. The insulin-like growth factor I (IGF-I) generation test was assessed as a means of identifying partial GH receptor defects in a heterogeneous group of 22 prepubertal children with short stature. In a subgroup of nine patients with peak GH levels of 63.7 +/- 3.7 mU/l during a glucagon tolerance test, the response to the IGF-I generation test was no different from that for the group as a whole (peak GH, 43.3 +/- 4.5 mU/l), despite the fact that this subgroup exhibited a negative relationship between height SDS and peak GH and a positive relationship between height SDS and IGF binding protein-3. This preliminary study therefore suggests that the IGF-I generation test in its present form will not be useful as a primary screening test for partial GH insensitivity. Despite this, the IGF-I generation test has been extremely useful in the confirmation of the diagnosis of GHIS and may therefore also prove useful in the confirmation of partial defects in the GH receptor. A subgroup of short children with peak GH levels above 40 mU/l had some characteristics of partial GH receptor deficiency. These children, to whom GH therapy would not normally be given, may respond better to recombinant human IGF-I.

Use and abuse of human growth hormone

Recombinant human growth hormone (hGH) has been available for nearly a decade. Side effects are rare. Its efficacy in promoting growth acceleration has been widely confirmed in children with GH deficiency (GHD), Turner syndrome, idiopathic short stature, chronic renal failure, and a variety of other conditions. The dramatic increase in height velocity in the first year of therapy partially attenuates in subsequent years in all patient groups, and convincing final height data are only available in GHD and Turner syndrome. Pediatric endocrinologists continue to be troubled by definitions of GHD. Although profound GHD is relatively obvious, other patients with severe growth failure but borderline or normal endocrine testing also respond to hGH therapy. Thus many endocrinologists use auxologic criteria [e.g. low growth velocity, height < -3 standard deviation (SD), poor predicted adult height] as the de facto basis for therapy, leading to a blurred distinction between treatment of disease and enhancement of normal characteristics and, finally, raising questions about the ultimate benefit of hGH therapy. Brief clinical trials of hGH therapy in adults both with and without GHD have reported increased muscle mass, decreased fat, and improvement in quality of life. Internists may soon be faced with treatment decisions analogous to those confronting pediatricians, i.e. whether to use hGH to repair aspects of the normal aging process.

Clinical diagnoses of children with extremely short stature and their response to growth hormone

This study was undertaken to determine the prevalence of clinical diagnoses in a group of children with extremely short stature (standard deviation score for height, < -2.5) and to determine whether the classification might help in predicting response to human growth hormone (hGH) treatment. We classified 49 children referred consecutively to our outpatient clinic for evaluation of short stature with heights < -2.5 standard deviation score and bone ages < 9 years for girls or < 10 years for boys (to avoid an effect of puberty on the response to hGH). The diagnostic categories were growth hormone (GH) deficiency, constitutional delay, familial short stature, and primordial short stature. After referral, Turner syndrome was diagnosed in two children. The remaining 47 children were classified according to primary criteria, considered essential for the diagnosis, and secondary criteria, considered necessary but of lesser importance. There were five children, four children, no children, and one child classified, respectively, with GH deficiency, constitutional delay, familial short stature, and primordial short stature by using the most rigorous definitions of the diagnoses. There was significant overlap in the diagnoses other than GH deficiency. Growth hormone deficiency defined by the primary criterion of peak stimulated GH values < 5 micrograms/L was the most definitive. Of the 47 children, 7 were classified as GH deficient by this criterion and 5 were classified as GH deficient by the primary and secondary criteria. The mean pretreatment growth rate (3.1 +/- 1.9 cm/yr) of the group with stimulated GH values < 5 micrograms/L was significantly less than that in the other groups (4.2 +/- 1.5 cm/yr). The mean growth rate of the children with GH deficiency during treatment with hGH was greater than that in the other groups and was 3.4 times greater than the pretreatment growth rate. The mean growth rate of children in the other groups during hGH treatment was twofold greater than the pretreatment growth rate. We conclude that except for GH deficiency, children with an extreme degree of short stature are not easily classified by standard diagnostic criteria, and that most short children have a positive response to hGH therapy regardless of the diagnosis; therefore a specific clinical diagnosis should not be used to exclude children from hGH therapy.

The influence of growth hormone (rhGH) therapy on tooth formation in idiopathic short statured children

The purpose of this preliminary study was to evaluate tooth formation in children with idiopathic short stature, before and during treatment with recombinant growth hormone (rhGH). Twenty-nine short-statured children ages 6 to 13 years were assigned into two treatment groups, an "experimental" group (n = 18), which received rhGH, and a "control" group (n = 11), which was observed for 1 year before commencing rhGH treatment. Clinical and radiographic records were obtained at the initial, year 1, and year 2 visits. Tooth formation and stature were assessed by calculating Z-scores, appropriate for the age and gender of each child. Delta-Z scores, which measure the change in Z-score over time, were also calculated between annual visits. Height was measured and recorded every 3 months, and Z-score statural norms for age and gender were derived from the 1977 National Center for Health Services national probability sampling. Tooth formation standards were derived from Moorrees et al. A matched control sample for tooth development was derived from untreated children. Tooth formation was initially delayed although the degree of reduction in stature exceeded the initial degree of delay in tooth formation. During this 2-year study, rhGH therapy had a significant influence on acceleration or gain in stature, but did not have a significant influence on tooth formation.

Metabolic effects of growth hormone treatment: an early predictor of growth response?

Fourteen children receiving one year of recombinant human growth hormone (rhGH) treatment underwent measurement of serial changes in body composition (measured by skinfold thickness, bioelectrical impedance, and H2(18)O dilution), resting energy expenditure (REE, estimated by ventilated hood indirect calorimetry), and total free living daily energy expenditure (TEE, measured by the doubly labelled water technique). Mean height velocity increased from 4.9 to 8.6 cm/year after six months of treatment. Fat free mass (FFM) increased more during the first six weeks (24.4 g/day) than from six to 26 weeks of treatment (6.8 g/day); fat mass decreased by 7.2 g/day and 1.1 g/day respectively. The six week increase in REE (kJ/day) was maintained after six months of treatment, though expressed per kilogram FFM (kJ/kgFFM/day), returned to pretreatment values by three months. Height velocity increases at six months correlated with six week changes in fat mass measured by skinfold thickness and REE, though use of this relationship to predict growth response in individuals is limited by the wide 95% prediction intervals. No significant changes in growth, body composition, or energy expenditure were observed between six and 12 months of treatment, in either patients who had initially responded well to treatment or those who were poor initial responders to treatment and who had their dose of rhGH doubled after six months.

Conventional and nonconventional uses of growth hormone

Although GH has been available as a therapeutic agent for the GH-deficient child for more than 30 years, the conditions of its use have yet to be optimized. The availability of biosynthetic material has provided researchers with the opportunity to develop the protocols necessary to begin to finally answer the most fundamental questions pertaining to dose, frequency, and duration of treatment. It has also permitted the initiation of prospective trials in a large number of conditions that result in childhood short stature, with the expectation that some or many of them will be treated effectively and safely. Finally, it has opened the door to an entire spectrum of potentially new uses of GH and other growth factors for so-called nonconventional indications. That these have implications that range from the short-term rapid healing of a burn graft site, to the more efficient induction of ovulation, to the long-term preservation of lean body mass has excited the interest of investigators in many fields of medicine and physiology. Thus, the recent progress reported in this paper is really the beginning of the new research that will take place with GH and growth factors.

Constitutional delay of growth and adolescence

Constitutional delay of growth and adolescence (CDGA) is characterized by simultaneous retardation of growth, skeletal maturation and sexual development. Primarily longitudinal growth is impaired. The late occurrence of puberty is a secondary phenomenon brought about by the retarded physical development. Plasma levels of sex hormones and gonadotrophin correlate with bone age, not with chronological age. The provocation tests for growth hormone (GH) show normal results. In contrast, the spontaneous secretion of GH, measured half-hourly through the night or over 24 hours, is markedly reduced. Plasma somatomedin C is diminished. According to these data, CDGA is not a genuine GH deficiency but represents a cybernetic disorder coinciding with a false threshold for GH. As shown by large series of investigations, the final height of the patients lies on average 1.85 SD below the mean of healthy adults, with large individual variations. The decision as to whether treatment by growth promoting hormones should be performed should be made with regard to the individual height prognosis. With GH in physiological doses growth velocity can be considerably increased. Bigger doses of the hormone appear to be necessary in order to enhance final height. Treatment by anabolics and testosterone increases height velocity only, not adult height.

Predictors of growth response to growth hormone in otherwise normal short children

Sixty prepubertal short children (39 boys) with heights less than 2 SD for age and gender were treated daily for 1 year with recombinant human growth hormone (GH), either 0.1 IU/kg (group 0.1, n = 32) or 0.05 IU/kg (group 0.05, n = 28). Reserve of GH was determined by at least one GH provocative stimulus and 24-hour continuous blood withdrawal to determine the integrated concentration of GH (IC-GH). All participants had a GH response to provocative tests greater than 10 micrograms/L. The height velocity (mean +/- SD) of the group as a whole increased from 4.46 +/- 1.02 to 7.59 +/- 1.65 cm/yr (p less than 0.001). The growth velocity of group 0.1 was significantly greater than that of group 0.05 (8.1 +/- 1.5 vs 7.0 +/- 1.65 cm/yr; p less than 0.01). Bone age did not advance more than 1 year during the treatment period. Growth velocity after 1 year of GH therapy was inversely correlated with the IC-GH in both groups, as was the pretreatment height velocity. We found no correlation of growth velocity during GH therapy with other measures such as parental heights, bone age/chronologic age ratio, maximal GH response to provocative tests, chronologic age, or pretreatment insulin-like growth factor I levels. We conclude that the best predictors for the 1-year growth outcome of short children with a normal GH response to provocative tests are the pretreatment growth velocity and the IC-GH. The short-term benefit from GH therapy in children with a normal growth velocity and a normal IC-GH is poor, whereas marked growth acceleration is noted in children with a low growth velocity and a low 24-hour IC-GH.

Long-term treatment with growth hormone of children with short stature and normal growth hormone secretion

Children with short stature but normal growth rate and/or normal growth hormone response to sleep and secretagogues were treated with recombinant methionyl human growth hormone, 0.3 mg/kg per week. In each year of treatment, about 80% of the subjects maintained an increase in growth rate greater than the defined limit (greater than 1 cm/yr above pretreatment growth rate) for continuation of human growth hormone treatment. Comparison of the group that continued to respond to human growth hormone with the group that did not maintain an accelerated growth rate did not reveal differences in bone age delay, sleep or secretagogue-stimulated human growth hormone secretion, degree of short stature either absolute or relative to target height, and somatomedin C concentration before or after initiation of therapy. The group that failed to respond to the human growth hormone treatment in the first year of treatment was younger and had a higher pretreatment growth rate. Review of the longitudinal growth curves revealed five patterns of response to human growth hormone treatment: (1) failure to increase growth rate in two subjects with height SD scores within 1 SD of target height, (2) failure to increase growth rate in five subjects with height SD scores greater than 1 SD less than the target height, (3) acceleration in growth rate in three subjects that was not maintained until achievement of a height within 1 SD of the target height, (4) acceleration of growth rate in five subjects that was maintained until achievement of a height within 1 SD of the target height, and (5) acceleration in growth rate that was maintained during the 3 years of treatment in 15 subjects who had not attained a height within 1 SD of the target height. We conclude that human growth hormone treatment of some but not all short children with "normal" growth hormone secretion will result in sustained acceleration of growth rate and attainment of prepubertal heights that are closer to but do not exceed their genetic height potential. A clinical trial of human growth hormone may be necessary to determine which subjects will benefit from the treatment.

Predicting and monitoring of growth in children with short stature during the first year of growth hormone treatment

Fifteen prepubertal short stature children (10 girls, 5 boys), mean age 9.6 years (range 5.2-12.7 years), with normal response to growth hormone stimulation tests (group A) or partial growth hormone deficiency (GHD) of idiopathic nature (group B) were included in a controlled longitudinal study for evaluation of predictive parameters for the long-term growth response after administration of biosynthetic human growth hormone (B-hGH). The average knee-heel length velocity for the first 3 months was significantly correlated to total body height velocity during the following 9 months (p less than 0.0008). By contrast, this association could not be found for height velocity during the same period. The increase in serum values of alkaline phosphatase and insulin-like growth factor I (IGF-1) during the first month of treatment was not significantly correlated to height velocity during the first year. During one year of treatment with B-hGH the mean height velocity for groups A and B increased from 4.4 cm/year (range 2.5-6.5) to 7.6 cm/year (range 4.7-10.6). Bone age advanced by 1.08 +/- 0.60 per chronological year. The ratio between total height and knee-heel length prior to treatment was 3.34 +/- 0.10 and after one year 3.33 +/- 0.10, suggesting a proportional linear growth. An inverse relationship was observed between the ratio and chronological age. In conclusion, early knee-heel measurement may be a useful non-invasive predictor of long-term linear growth in children during treatment with growth hormone, and the ratio of total height to lower leg length may be of importance in detecting dysproportional growth.

Near normalization of adolescent height with growth hormone therapy in very short children without growth hormone deficiency

Ten prepubertal children with stature at or below the 1st percentile for height and without growth hormone deficiency received 0.3 U recombinant growth hormone per kilogram daily for 2 years before puberty. Their growth velocity increased from 4 +/- 0.3 cm/yr before treatment to 10.7 +/- 0.6 and 8.8 +/- 0.6 cm, respectively, during the first and second years of treatment, and then remained at 5.7 +/- 0.7 cm the year after the end of growth hormone administration. This resulted in a near normalization of adolescent height. Bone maturation paralleled chronologic age, and therefore the expected final height of the children increased by approximately 10 cm. Administration of growth hormone induced a reversible hyperinsulinemia, with moderate and transient changes in glucose metabolism. A prospective, randomized study, including an untreated cohort, will be needed to confirm the effects on final height and to determine the magnitude of the response in familial short stature.

Growth hormone and insulin-like growth factor I: nutritional pathophysiology and therapeutic potential

The growth hormone--insulin-like growth factor I axis has been appreciated for more than 30 years and the effects of malnutrition on this axis for more than 20 years. Over the last decade, advances in molecular biology have permitted enhanced understanding of feedback regulation between growth hormone and IGF-I at the gene level, including limited information on nutritional influences. Similarly, the availability of recombinant human growth hormone has allowed controlled clinical studies demonstrating its net anabolic actions at hypocaloric dietary energy intake levels and its ability to enhance height velocity in children with various causes of diminished growth. Although investigational use of recombinant IGF-I in humans has been limited, its actions are likely to complement those of growth hormone during periods of profound dietary energy deficit. From the information presented, two hypotheses are developed. First, recombinant IGF-I administration will enhance substrate anabolic events during the acutely malnourished state when dietary intake is severely limited. Second, administration of recombinant human growth hormone will accelerate protein anabolism and catch-up growth during the period of recovery from protein-energy malnutrition. Given current clinical investigational tools and the availability of both recombinantly-produced hormones, these are testable hypotheses.

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 therapy for short stature: panacea or Pandora's box?

Increased availability of growth hormone (GH) because of increased production using recombinant DNA technology has led to increased demand. Many children who do not have classic GH deficiency may respond to GH therapy. These observations require rethinking of the medical indications for GH therapy, and raise two central ethical questions: (1) Is it justified to discriminate on the basis of GH deficiency? (2) Whatever the indication for GH treatment, at what height should GH therapy be considered an entitlement? We argue, first, that GH responsiveness, not GH deficiency, should be the criterion for GH treatment, and that prior arguments emphasizing GH deficiency are based on vague or faulty notions of disease, handicap, or potential. Second, we argue that children who are handicapped (arbitrarily defined as including those whose height is below the 1st percentile) and GH responsive are entitled to treatment. Children above that height, whether GH deficient or not, may permissibly be treated, but there is no societal obligation to do so. Such an approach would reduce, though not eliminate, some of the more severe burdens of short stature without aggravating the pernicious effects of "heightism" in American society.

Height screening in the community. The commercialization of growth. The role of the pediatrician

The availability of unlimited but costly supplies of biosynthetic growth hormone has led to pressure for pharmacologic use (as opposed to replacement therapy in proven deficiency states). Commercial and altruistic motives have converged to promote community height screening among individuals who have been perceived by themselves or parents as short. This does not meet accepted criteria for health screening. Height screening of large populations of children yields few unrecognized medical conditions. If the goal of community screening is to identify abnormally short individuals (less than 3%) who might benefit from growth hormone treatment and if the unproven assumption is correct that stature correlates with success and happiness, then those less likely to appear for screening need to be recruited to avoid elitist domination. The annual cost of such growth promotion would be greater than $10 billion, with no evidence for substantial health benefits. Growth monitoring of all children through improved height measurement in schools and in physicians offices, as part of health supervision, is a more sound community approach than height screening.

High-dose growth hormone treatment of non-growth hormone-deficient children: preliminary results after 2 years

The growth response to high-dose growth hormone (GH) therapy was investigated in 10 short, prepubertal, slowly-growing children. Two years treatment with recombinant human GH at a dose of 0.3 IU/kg daily 7 days per week resulted in a mean height increase of 19.5 cm (range 17-23 cm). There was a slight but not significant acceleration of bone age maturation. The treatment also induced a sustained increase in insulin secretion without detectable changes in glucose tolerance.

Effects of 3 years of growth hormone therapy in short normal children

The effect of 3 years of growth hormone (GH) treatment on growth rate, predicted height, carbohydrate and metabolic status, and thyroid function was studied in 16 short prepubertal children growing with a normal pretreatment growth rate. The height velocity SDS increased from a pretreatment value of -0.44 +/- 0.33 (mean +/- SD) to a value of +2.20 +/- 1.03 during the first year of treatment. It was maintained at a value above zero over the subsequent 2 years. By the end of the third year of treatment, the predicted final height had increased by 6.8 cm in the boys and by 4.2 cm in the girls (p less than 0.001 and p less than 0.01, respectively). Increasing the dose of GH on a body surface area basis reduced the deceleration of growth observed during the second year of treatment, leading to an improvement in height prognosis over that year. Glucose homoeostasis was achieved initially at the expense of an elevation in fasting serum insulin concentration, but this had returned to pretreatment values by the end of the second year of therapy.

Response to growth hormone in children with idiopathic short stature

A multicentre randomized trial of human growth hormone (GH) treatment was carried out in 121 children with short stature who did not meet the classic criteria for GH deficiency. In the first year of the trial, half of the children received treatment with recombinant somatropin 0.1 mg/kg (0.27 IU/kg) three times weekly and showed a significant increase in mean growth velocity from a pretreatment value of 4.6 +/- 1.1 to 7.5 +/- 1.2 cm/year (mean +/- SD). The growth velocity of the untreated children did not change significantly. The growth velocity of the control group (including 10 pubertal children) increased from 4.2 +/- 1.3 to 5.0 +/- 1.4 cm/year. In the second year, half of the control group received treatment with somatropin, 0.1 mg/kg (0.27 IU/kg) three times weekly, while the remainder received the same weekly dose on a once-daily basis. The mean growth velocity increased in both cases to 8.2 +/- 1.4 and 9.0 +/- 1.6 cm/year, respectively. The group treated during the first year was also divided into two groups in the second year. One group continued with the original treatment regimen, resulting in a mean growth velocity of 6.8 +/- 1.8 cm/year. The other group changed to once-daily treatment at the same weekly dose and the mean growth velocity for this group in the second year was 7.8 +/- 1.4 cm/year. The gain in height age in both of these groups exceeded the bone age in both the first and second years of treatment, suggesting a gain in predicted adult height.(ABSTRACT TRUNCATED AT 250 WORDS)

Growth hormone treatment in non-growth hormone-deficient children: effects of stopping treatment

Overnight physiological growth hormone (GH) secretion was evaluated in 95 short, prepubertal children (73 boys, 22 girls). All the children were below the 3rd centile for height and achieved GH levels greater than 15 mU/l following pharmacological stimulation. The mean average GH level was 7.1 mU/l and the mean sum of pulse amplitudes 80.4 mU/l. No relationship was found between age, height or height velocity and any of the parameters of GH secretion. The group was randomized to receive placebo, GH or remain under observation for the first 6 months and then all patients received GH treatment for a further 6 months. Those treated with GH, 0.27 IU/kg (0.1 mg/kg) three times weekly, in the first phase, demonstrated a mean increase in height velocity SDS of 3.24. There was no difference in growth response between the placebo or observation groups. In the second 6-month period, all children received GH according to the same dose regimen; they were then observed for a further 6 months following its discontinuation. In the 6 months following withdrawal of GH, all groups showed a significant fall in height velocity SDS, which returned to pretreatment levels, without demonstrating 'catch-down' growth. Repeat sampling of overnight GH secretion within 3 days of discontinuing GH showed normal secretory patterns with a small reduction in mean peak amplitude. These results suggest that short children without classic GH insufficiency respond well to exogenous GH in the short term and return to pretreatment height velocities afterwards. Consequently, it may be possible to increase final adult height in such children by GH treatment.

Changes in leg length and height during treatment with somatotropin

Knemometry has been used in a short term double blind placebo controlled trial in 13 patients with normal variant short stature receiving treatment with somatropin to assess the power of the change in lower leg velocity at one month to predict the increase in height velocity at six months. Used in this way the method has a positive predictive value and sensitivity of 90% and a negative predictive value and specificity of 50%. Although not a perfect discriminatory test, knemometry is a more reliable and less invasive way of analysing the likely value of a growth promoting treatment than metabolic assays in individual patients. Given the possible future rapid expansion of the use of somatropin in short stature of various aetiologies there is a need for a relatively simple and inexpensive means of evaluating response to treatment.

Idiopathic short stature: results of a one-year controlled study of human growth hormone treatment. Genentech Collaborative Study Group

A multicenter randomized trial of human growth hormone treatment was carried out in 121 children with short stature who did not meet the classic criteria for growth hormone deficiency. Patients treated for 1 year with recombinant somatropin, 0.1 mg/kg three times a week, had a significant increase in mean growth rate from 4.6 +/- 1.1 to 7.5 +/- 1.2 cm/yr, whereas untreated children's growth rate did not change significantly (4.2 +/- 1.3 vs 5.0 +/- 1.4 cm/yr). There was a 1-year advance in bone age for each group; thus there was a significant increase in the predicted height of the treated but not the control group. Among the treated children, the growth response did not differ among those classified on the basis of parental height and bone age as having familial short stature or constitutional delay of growth and development. Prestudy anthropomorphic features were not related to subsequent growth in either the treated or control groups. The baseline plasma insulin-like growth factor I concentration was inversely related to the growth response to growth hormone treatment (r = -0.50, p = 0.0003). By contrast, the serum growth hormone concentration measured in samples obtained at 20-minute intervals for 12 or 24 hours or after clonidine administration did not predict the future growth rate. There were no side effects of growth hormone treatment. The results suggest that children who have significant short stature and slow growth may benefit from a trial of growth hormone therapy.

Effects of two years of methionyl growth hormone therapy in two dosage regimens in prepubertal children with short stature, subnormal growth rate, and normal growth hormone response to secretagogues. (Dutch Growth Hormone Working Group)

Thirty short, slowly growing children with normal plasma growth hormone response to standard provocation tests were randomly assigned to a group (n = 20) undergoing therapy with methionyl growth hormone, 2 IU/m2 subcutaneously once daily, (group 1) or a control group (n = 10, group 2). The mean (+/- SD) height velocity increment in group 1 was 3.0 +/- 1.9 cm/yr in the first year, compared with -0.2 +/- 0.7 cm/yr in group 2. Of the 18 children who completed the first year of treatment, 12 had a height velocity increment of more than 2 cm/yr and 11 of them continued treatment for a second year (group 1A). The remaining six children also reached height velocities greater than the mean for bone age, but because of a low height velocity increment they were termed nonresponders and their growth hormone dosage was increased to 4 IU/m2/day (group 1B). Of the 10 children in the control group, seven received authentic biosynthetic growth hormone in the second year of the study (group 2); the remaining three received no therapy (group 3). The mean height velocities (measured in centimeters per year) before and during the first and second years of therapy were 3.6, 7.6, and 6.1 in group 1A; 5.7, 6.9, and 7.3 in group 1B; 4.2, 4.0, and 6.7 in group 2; and 5.0, 4.9, and 5.2 in group 3. The effect of doubling the dosage was a further increase of 1.9 cm/yr. Bone age advance paralleled growth acceleration, resulting in an unchanged height standard deviation score for bone age and ambiguous results on final height prediction. Growth hormone therapy in such short children appears to be safe and efficacious in increasing growth velocity for 2 years, but its efficacy in terms of increasing final height is uncertain.

Growth hormone testing in short children and their response to growth hormone therapy

Because current concepts of growth hormone (GH) testing and GH treatment have become controversial, we investigated the GH secretory patterns in children with normal and short stature. Twenty-four-hour serum GH levels were evaluated in three groups of children. Group 1 was composed of children with normal height (mean height = 0.02 SD, n = 33); group 2 was composed of short children (less than 5th percentile, n = 63) with normal results on provocative GH testing; and group 3 was composed of short children (less than 5th percentile, n = 7) with subnormal results on provocative GH testing. Mean +/- SD (range) GH levels during 24-hour studies of GH secretion were 1.6 +/- 1.1 (0.5 to 5.6), 1.8 +/- 1.2 (0.6 to 6.3), and 0.9 +/- 0.4 (0.5 to 1.7) ng/ml in groups 1, 2, and 3, respectively. No statistical difference existed in mean GH levels between groups 1 and 2 or between groups 1 and 3. The mean GH concentration from 24-hour studies in group 2 children did not correlate with chronologic age, height standard deviation, growth rates, or insulin-like growth factor 1 levels. The linear growth rate of 26 of 28 children in group 2 who received GH therapy for 6 months improved by 2 cm/yr or more; the mean +/- SD growth rate was 4.0 +/- 1.3 and 8.8 +/- 2.0 cm/yr during control and treatment periods, respectively, for these 28 children. Mean GH levels from testing did not predict response to GH during 6 months of therapy. Children with slower growth rates responded better to GH therapy (p less than 0.05). We conclude that (1) in 24-hour studies, GH levels in normal children overlapped with those of short children, including those with classic GH deficiency, (2) in 24-hour studies, GH levels did not predict responses of linear growth to short-term GH treatment, nor did they correlate with children's heights or growth velocities, and (3) the majority of short children in group 2 treated with GH for 6 months had an increase in linear growth velocity, the mean +/- SD change being 4.8 +/- 2.0 cm/yr.

A controlled trial of methionyl growth hormone therapy in prepubertal children with short stature, subnormal growth rate and normal growth hormone response to secretagogues. Dutch Growth Hormone Working Group

Thirty short and slowly growing children with normal plasma growth hormone (GH) responses to standard provocation tests were randomly assigned to either a group (n = 20) undergoing treatment with methionyl GH (somatrem), 2 IU per m2 body surface s.c. daily, or a control group (n = 10). Twelve out of 18 children who completed the first year of treatment showed a height velocity increment of more than 2 cm/year. The mean (SD) growth velocity of the treatment group increased by 3.0 (1.9) cm/year over the first year, compared with -0.2 (0.7) cm/year in the control group. Neither parameters of endogenous GH secretion nor plasma IGF-I levels showed a significant correlation with the growth response. Of the auxological variables studied, pre-treatment growth velocity (r = -0.8) and the short-term height velocity increment (r = 0.7-0.9) showed significant correlations with the growth response in the first year of treatment. Somatrem therapy was without side effects, except in one child who developed anti-GH antibodies in combination with a poor growth response.

Incidence of neurosecretory dysfunction among children aged 6-14 years in Rehovot, Israel

Screening of 7500 children aged between 5.8 and 14.4 years, out of a total population of 39,690 in this age group in the Rehovot region, revealed 111 children with heights 2.5 SD below the mean for their age, according to the Tanner-Whitehouse standards. Included among these short children were eight with hypochondroplastic skeletal disease, two with Down's syndrome, four with thalassaemia, four with Turner's syndrome, three with coeliac disease, four with classical growth hormone (GH) deficiency, four with intrauterine growth retardation, four with systemic disease and 78 without obvious underlying causes. In 35 of the 78 children in the last group, the 24-hour integrated concentration of GH was in the hypopituitary range (less than 3.2 ng/ml), and GH neurosecretory dysfunction (NSD) was accordingly diagnosed. This represents an incidence of GH neurosecretory dysfunction of 45% among abnormally short children without underlying pathology, and is consistent with the authors' previous findings. The overall frequency of GH neurosecretory dysfunction in the screened population was 4/1000.