Treatment of growth hormone deficiency

Metabolic alterations in paediatric GH deficiency

Growth hormone (GH) has a large number of metabolic effects, involving lipid and glucose homoeostasis, lean and fat mass. Growth hormone deficiency (GHD) is associated with a metabolic profile similar to the Metabolic Syndrome which is characterized by dyslipidemia, insulin resistance, haemostatic alterations, oxidative stress, and chronic inflammation. GH replacement treatment in GHD children improves these cardiovascular risk factors, while cessation of GH is associated with a deterioration of most of these risk factors. However, it is unclear whether the changes of these risk factors are associated with an increased risk of cardiovascular diseases especially after discontinuing GH treatment. GH treatment itself can lead to insulin resistance, which probably also influences the cardiovascular health status. Therefore, longitudinal studies with the primary outcome cardiovascular diseases are needed in GHD children. Furthermore, new approaches such as metabolomic studies might be helpful to understand the relationship between GHD, GH treatment, and cardiovascular diseases.

Is growth hormone treatment in children associated with weight gain?--longitudinal analysis of KIGS data

OBJECTIVE

Growth hormone (GH) increases lean body mass and reduces fat mass. However, the long-term changes in weight status during growth hormone treatment, according to age and weight status at onset of treatment, have not previously been reported in large data sets.

METHODS

Changes in BMI-SDS between starting GH treatment and attaining near adult height (NAH) were analysed in 2643 children with idiopathic GH deficiency (IGHD), 281 children small for gestational age (SGA), 1661 girls with Turner syndrome (TS), and 142 children with Prader-Willi syndrome (PWS) in the KIGS database.

RESULTS

BMI-SDS increased significantly between onset of GH treatment and NAH (IGHD:+0·29, SGA:+0·69, TS:+0·48) except in PWS (-0·02). These increases were greater in children with younger age at onset of GH treatment (significant in all indications) and with lower doses of GH treatment (significant in IGHD & TS) in multiple linear regression analyses also including gender, duration of GH treatment, BMI-SDS and height-SDS at onset of treatment, and birth weight-SDS. Obese children at onset of GH treatment decreased their BMI-SDS, while underweight and normal weight children at onset of GH treatment increased their BMI-SDS independently of GH treatment indication.

CONCLUSIONS

Long-term GH treatment was associated with changes in weight status, which were beneficial for underweight and obese children independent of the indication for GH. However, the increase in BMI-SDS in normal weight children treated with GH needs to be investigated in future prospective longitudinal studies to analyse whether this represents an increase of fat mass, lean body mass or both.

Effects of growth hormone on craniofacial growth

OBJECTIVE

This study determined the effects of growth hormone (GH) therapy on craniofacial growth in idiopathic growth hormone deficiency (GHD).

MATERIALS AND METHODS

Fifty-seven patients (33 boys and 24 girls; age range 4.5 to 16.7 years) with GHD were investigated and categorized into three groups according to the duration of GH therapy: the untreated group, the short-term therapy group, and the long-term therapy group. Their lateral cephalometric radiographs were studied, and craniofacial measurements were assessed by age and sex by using matched standard deviation scores.

RESULTS

In the untreated group, the anterior cranial base, total facial height, maxillary length, mandibular total length, mandibular body length, and ramus height were smaller than the standard values. In comparison with the untreated group, the long-term therapy group had a significantly larger upper facial height (P < .05), maxillary length (P < .01), and ramus height (P < .01) measurements.

CONCLUSIONS

Children who received long-term GH replacement therapy showed increased growth of the craniofacial skeleton, especially the maxilla and ramus. These findings suggest that GH accelerates craniofacial development, which improves occlusion and the facial profile.

Effects of long-term elevated serum levels of growth hormone on life expectancy of mice: lessons from transgenic animal models

In this study, we characterize transgenic mice carrying fusion genes, in which the genes coding for human (h) or bovine (b) growth hormone (GH) have been put under the transcriptional control of the mouse metallothionein I (MT) or the rat phosphoenolpyruvate carboxykinase (PCK) promoter as models for investigating the long-term effects of elevated GH on life expectancy. Circulating GH concentrations ranged from 3000 to 900,000 ng/ml, from 320 to 2960 ng/ml and from 34 to 1050 ng/ml in transgenic mice belonging to the MThGH, the PCKbGH and the MTbGH groups, respectively, and were high on a short-, medium-, and long-term basis. As a consequence of excess GH in their serum, GH transgenic mice exhibited drastically reduced life span which was primarily due to severe kidney lesions (glomerular hypertrophy, sclerosis and hyalinosis associated with tubulo-interstitial changes) consistently found in these animals. Alterations of the liver observed in transgenic mice included both hepatocellular megaly and various degrees of regressive, regenerative and fibrotic changes. In older MTbGH and PCKbGH transgenic mice, hepatocellular neoplasms including both adenoma and carcinoma were frequently found in addition to non-neoplastic changes. Our study points out the suitability of GH transgenic mice to evaluate the effects of various levels of GH in long-term studies without having to take antibody production against the heterologous hormone into account. Findings in GH transgenic animals suggest that the long-term benefits and risks of GH therapy should be carefully evaluated.

Evaluation of growth hormone secretion and treatment

The secretion of growth hormone (GH) is regulated by a complex system that includes both neurotransmitters and feedback by hormonal and metabolic substrates. Over the last few years it has been recognized that GH release varies over a wide spectrum from deficient to excessive secretion. The diagnosis of GH deficiency is based on a combination of anthropometric and clinical signs on the one hand and an inadequate stimulated and/or spontaneous GH secretion on the other. There is no distinct boundary between deficient and sufficient GH secretion. The cut-off limit for normal GH release is accordingly relative and has increased over the past decade from 5 to 10 micrograms/l. The effect of GH therapy on growth can be evaluated only after treatment for at least 6 months. There is, therefore, an indisputable need for methods that would reflect growth response soon after the start of treatment. There are several promising biochemical candidates, e.g. the aminoterminal propeptide of type III procollagen, the carboxyterminal propeptide of procollagen I and the bone Gla-protein, which may turn out to be useful early indicators of the growth response to long-term GH therapy.

Therapy of growth hormone deficiency

Treatment with human growth hormone in growth hormone deficient patients will improve growth rate significantly, initially demonstrating catch-up growth and later bringing forth a normal growth rate. During childhood, a dose of 0.3-0.6 units/kg body weight per week (or 14 units/m2 body surface area per week) is recommended, but during puberty the dose should be increased by 50-100%. The goal of therapy is the attainment of a normal final height, which in the past has often not been fulfilled. This was partly due to the inadequate supply of growth hormone. Since recombinant human growth hormone is now available in unlimited amounts, all patients can be treated continuously. The shorter the child is at time of presenting for therapy, the lower final height will be. It is mandatory to start therapy as early as possible. Concomitant hormonal deficiencies must be corrected by adequate therapy. Despite the fact that growth hormone is diabetogenic, supplementary therapy will not induce diabetes mellitus. Subtle changes in the immune system can be detected but no clinical correlates, such as increased susceptibility to infection, exist. Induction of leukaemia has been suspected as a possible side-effect of human growth hormone treatment but so far there is insufficient evidence to prove that growth hormone is oncogenic.

Serum osteocalcin and bone isoenzyme alkaline phosphatase in growth hormone-deficient patients: dose-response studies with biosynthetic human GH

Serum osteocalcin and bone alkaline phosphatase (BAP) were measured in samples drawn at 8 a.m. in 7 patients with GH deficiency treated with recombinant human growth hormone (rhGH) (2 IU/day subcutaneously at 8 p.m.), and 7 normal controls. Patients treated with 2 IU/day had lower BAP than controls (P less than 0.05). Further, increasing doses of rhGH were given subcutaneously to each of the 7 patients for 3 consecutive 14-day periods (2, 4, and 6 IU/day at 8 p.m.) followed by 14 days off treatment. At the end of each period, the patient was hospitalized for frequent blood sampling from 8 p.m. to 11 a.m. the following day. A dose-dependent increase in area under the curve (AUC) was seen for osteocalcin (P less than 0.05), whereas the increase in AUC for BAP just failed to reach significance (P less than 0.10). The nocturnal pattern of serum osteocalcin in patients on 4 and 6 IU/day were statistically indistinguishable from those in controls. During treatment with 2 IU/day and the off-treatment period, the pattern was significantly different from controls (P less than 0.05). In conclusion, rhGH has a dose-dependent effect on basal osteoblastic activity and the nocturnal pattern of osteocalcin. Serum osteocalcin increases within hours following rhGH administration. However, 2 IU/day is inadequate to maintain normal levels and nocturnal variation in markers of osteoblastic activity.

Growth response in prepubertal children with idiopathic growth hormone deficiency during the first year of treatment with human growth hormone. Analysis of the Kabi International Growth Study

In order that children with growth hormone deficiency (GHD) reach the goal of normal adult stature, treatment modalities need to be optimized. From the large database of patients enrolled in the Kabi International Growth Study (KIGS), 257 prepubertal patients with idiopathic GHD undergoing their first year of growth hormone (GH) substitution therapy were selected. A multiple regression analysis was performed to determine both auxiological factors characterizing the patients and the factors related to the chosen treatment modalities which are of significance for the observed magnitude of the growth response. Due to the structure of the data, pretreatment height velocity and bone age-derived auxiological data were not considered. It was observed that the magnitude of the growth response was inversely correlated with chronological age and relative height (HT SDS) at the start of GH treatment but was positively correlated with mid-parental height. The growth response was also positively correlated with the GH dose (IU/kg/week) and the frequency of GH injections per week. A regression equation using these five parameters was derived, allowing the growth response of these patients to be predicted. The extension of this analytical approach in the future will allow the treatment of patients with GHD to be tailored to individual requirements.

[Do growth-promoting hormones have an effect on dentition development in dwarfism?]

In children with nanism we differentiate between hypophyseal ateleiosis, constitutional retarded development with slow bone maturation and familiar ateleiosis. The somatotrope hormone is responsible for growth. With this hormone we can stimulate the growing process in hypophyseal ateleiosis and in constitutional retarded development. Human growth hormone accelerate growth and bone maturation in the same way, also anabolics stimulate growth, especially bone maturation. They also accelerate the development of the dentition, as shown by the example quoted. The best time for orthodontic treatment is during intensive growth periods the specific skeletal age taking into account.

Clinical experience with authentic recombinant somatropin--German Collaborative Study

A multicentre clinical trial with recombinant somatropin was initiated in West Germany in early 1986. Acceptance of patients to the study was determined according to criteria outlined in a detailed study protocol. To the present time, 41 patients with hGH deficiency not previously treated (naïve) and 28 patients previously treated with pituitary hGH have been admitted. Recombinant somatropin is given, 12 IU/m2/week s.c., divided into six doses. Height velocities during treatment rose dramatically for naïve patients from 3.5 cm/year (n = 40, before treatment), to 15.0 cm/year (n = 19, calculated at 3 months), and 13.3 cm/year (n = 8, calculated at 6 months). For previously treated patients, the increase in height velocity was from 5.8 cm/year (n = 20) to 9.2 cm/year (n = 19, after 3 months) and 8.6 cm/year (n = 9) at 6 months. Tolerance of recombinant somatropin was good, and no anti-hGH antibodies were detected in any of the patients.