Children born small for gestational age may demonstrate continued growth retardation, resulting in persistent short stature. In the majority of the cases, this is linked with abnormal growth hormone secretion and also abnormal insulin-like growth factor levels. This review discusses the treatment of such children with recombinant human growth hormone. It illustrates the importance of starting therapy early, the dose-dependent response, and the advantages of continuous therapy and describes safety considerations.

We report an epi-analysis of 6-yr growth responses obtained with GH treatment in short children born small for gestational age (SGA). Four randomized, multicenter studies explored the effects of continuous and discontinuous regimens of GH treatment in short, non-GH-deficient SGA children. A total of 49 untreated and 139 treated children were followed over 2 and 6 yr, respectively. At the start of the study, the age of these 188 children averaged 5.2 yr (range, 2-8 yr), height was -3.4 SD score, and height adjusted for parental height was -2.4 SD score. Onset of puberty was observed in 46% of the GH-treated cohort, on the average, at 10.7 yr in girls and 11.7 yr in boys. Two studies essentially investigated the effects of continuous GH treatment at a dose of 33 or 67 microg/kg, day, and two studies focused on the growth characteristics during an initial GH treatment for 2-3 yr (dose range, 33-100 microg/kg x day), followed by a withdrawal phase of 1-2 yr, and then by either no or 1 or more episodes of further GH treatment (33 or 67 microg/kg x day). Continuous GH treatment for 6 yr resulted in height increments of 2.0 +/- 0.2 SD (33 microg/kg x day; n = 35) and 2.7 +/- 0.2 SD (67 microg/kg x day; n = 27). Discontinuous GH treatment was given to 77 children, most of them experiencing only 1 (n = 47) or 2 (n = 26) treatment phases with an average duration of 2.0 yr. All these children received GH during the first 2 yr; the dose was only 32 microg/kg x day when averaged over 6 yr. Some individualization of treatment schedules was allowed, and the majority of investigators seemed to aim for a low normal height level, adjusted for parental height. After 2 yr, the mean adjusted height SD score had increased to -0.4 +/- 0.1 and stabilized thereafter. Bone maturation progressed similarly in all treatment subgroups, and after 6 yr of study, bone age remained slightly delayed compared to chronological age. Multivariate analysis identified the average GH dose over 6 yr, parental-adjusted height SD score, and age at start as prime predictors of the growth response. GH treatment was well tolerated. In conclusion, this epi-analysis of growth responses over 6 yr confirms the administration of GH as an effective approach to normalize the stature of short, non-GH-deficient SGA children, at least during childhood and early puberty. In addition, it is now increasingly apparent that a relatively broad spectrum of GH regimens is effective, and this experience should facilitate the design of more individualized treatment schedules in the future, in particular for young children.

Intra-uterine growth retardation (IUGR) and Silver-Russell syndrome (SRS) are born short for gestational age and many of them do not show post-natal catch-up growth Although post-natal catch-up growth frequently occurs, significant number of both IUGR and SRS newborns often fail to catch up. This may result in very short adult height (more than 2 standard deviations (SD) below the mean) in up to 20% of these patients, in association with poor school and social performance.In order to try to induce catch-up growth and hopefully increase final height, attempts have been made in clinical trial to treat these growth hormone (GH) sufficient patients with human GH.Using the Kabi Pharmacia International Growth Study patient data base, a group of 106 IUGR (83 males and 23 females) and 45 SRS with persistent post-natal growth failure were studied. IUGR clinical characteristics included a birth length and weight more than 2 SD below the mean for gestational age. Height deficit at start of the GH treatment was -3.0 standard deviation scores (SDS) for chronological age (CA), at a median CA of 8.7 years with a median bone age (BA) of 7.0 years. Mean parental heights were 166 cm for fathers and 153 cm for mothers. Median dose of recombinant human GH (rhGH) in 106 IUGR patients was 0.5 IU/kg/week, given at a median frequency of 5 injections per week. The median height SDS for CA at the start and at 1, 2 and 3 years of hGH treatment were -3.0, -2.5, -2.1 and -1.9 respectively.45 patients presented with SRS. Their median CA and BA at start of treatment were 6.7 and 3.2 years respectively. Mean parental heights were 167.5 cm for fathers and 160 for mothers. Median dose of rhGH in these 45 SRS was 0.7 IU/kg/week, with a median frequency of 6 injections per week. Median height SDS of SRS patients at start, 1, 2 and 3 years of hGH treatment were -3.5, -2.9, -2.8 and -2.2 respectively. One difference between these IUGR and SRS groups is that SRS patients tended to be born of normal height parents, in contrast to IUGR with persistent post-natal growth failure. In these two groups, exogenous GH treatment tended to induce catch up growth, although long term follow up is sufficient to allow conclusions to be draw regarding these patients' final adult height.

Growth hormone insensitivity syndrome (GHIS) is a pathological state characterised by disturbance of the normal relationships between growth hormone (GH) secretion, insulin-like growth factor I (IGF-I) synthesis and GH action. Laron syndrome (LS) is the most severe form and is related to defects of the GH receptor gene. Twenty-seven cases of IS from 8 European countries and Australia were characterised clinically and endocrinologically. Clinical features (median) were; age 2.8-22.6 years, 12 males, 15 females, birth weight -0.72 SDS, birth length -1.59 SDS. Hypoglycaemia occurred in 33% and micropenis in 58% of males. Height was -6.0 SDS, weight -3.2 SDS, % weight for height 111.3. Bone age was delayed in 19 of the 27 patients. Endocrine values (median) were; GH 17μg/L, IGF-I<5th centile, with% increment during IGF-I generation test <20%. IG1411313-3 was <5th centile, GH-BP was low or undetectable in 20 and normal in 7 subjects.Treatment with recombinant IGF-I offered the only form of effective therapy. Treatment of 13 patients with IGF-I, 120μg/kg bid induced a change in mean height velocity from 4.1cm/year before treatment to 10.2cm/year at 6 months and 8.8cm/year at 12 months. Adverse effects were minimal. Facial appearance showed a change in maturity associated with capital hair growth. Further studies to define the optimum dose regimen of IGF-I are in progress.

Growth Velocity (GV) In response to recombinant GH Rx was analyzed using KIGS data base. IGHD was based on classical criteria : short stature, slow growth velocity; GH peak response at 2 provocative tests below 10 ng/ml; thyroid and adrenal status were based on conventional hormonal evaluation (local assays). Organic GHD was ruled out by brain imaging. 1256 prepubertal IGHD GH treated patients in KIGS data base were analysed. At start of Rx median chronological Age (CA) was 7.3 years, median height Standart Deviation Score (SDS) was - 2.7. Median number of injections was 6/week and medians GV were 8.2 & 6.9 cm/year during Rx year 1 & 2 respectively. Out of ten potential predictors, multiple regression analysis resulted in a five predictors model for growth response to Rx : Target Height (SDS), Height SDS for CA, CA at start, GH Dose & GH injection Frequency (R-square = 0.37). The effect of GH dose at 3 versus 7 injections/week according to CA are shown in the figure. The 2 predictors not shown are fixed at their median value. Conclusions :These data provide useful information for optimizing GH treatment in IGHD and predicting growth response.

Local regulation of testicular function depends upon multiple interactions between testicularcells, some of them mediated by soluble factors (Fig. 2). Under physiological conditionsgonadotropins are required for testicular maturation and function, but the responsiveness ofsomatic testicular cells to these hormones is modulated by factors produced and acting withinthe testis. Moreover, the production of these factors, and sometimes the responsiveness oftesticular cells to these factors, are gonadotropin-dependent. While the paracrine regulation ofSertoli function by Leydig cells seems to be mediated mainly by a direct or indirect effects oftestosterone, several factors seem to be involved in the FSH-stimulated effects of Sertoli cellson Leydig cells. The nature of the factors implicated in Sertoli-germ cell interactions ispractically unknown. The amounts of these factors might be very low, although sufficient toact in a paracrine, autocrine, juxtracrine or cryptocrine manner, and their isolation andpurification would be a very difficult task.

The release of growth hormone (GH) during the 120 min following a bolus venous injection of 1-44 GH-releasing hormone (GHRH) 2 micrograms/kg was studied in 52 prepubertal children aged 8.4 +/- 2.1 years, having a nonfamilial growth deficiency of prenatal onset (-3.26 +/- 1.13 SDS at birth, -3.22 +/- 0.88 SDS at the time of study) and a normal response to conventional GH stimulation tests. GH release reached a peak level of 96.1 +/- 60.2 microU/ml, being significantly higher than that found in 68 non-GH-deficient very short children whose growth failure had a postnatal onset, and not significantly correlated with the response to conventional tests. 26 of the 52 intrauterine growth retardation (IUGR) patients were re-tested with GHRH in similar conditions after 6-12 months of daily subcutaneous injections of GH and 2 days without. They reached at the second test a peak plasma GH level of 91.7 +/- 56.1 microU/ml, not different from their response to the first test. These data could be taken into consideration for long-term studies of the clinical effects of GH in IUGR children with persisting severe growth deficiency.

We have characterized Sm-C secretion and regulation by immature porcine SC cultured (ESPE 86). The present study evaluates the autocrine action of Sm-C on SC. The presence of IGF type I receptors on SC was identified by binding (Kd = 10−9 M) and cross-linking. No detectable insulin receptor was found. FGF and Sm-C stimulate SC DNA synthesis with observed ED50 of 2.0 and 7.5 ng/ml respectively. Synergistic effect of FGF+Sm-C was found at saturating concentration of both factors. SC multiplication was increased compared to controls by Sm-C, FGF, Sm-C + FGF by a factor of 1.65, 2.05 and 3.2 respectively. When SC function was studied, FSH receptor number was increased by 1.65, 2.05 and 3.2 respectively. When SC function was studied, FSH receptor number was increased by 1.6 by FGF alone with no effect per se nor synergistic of Sm-C. FSH stimulated cAMP secretion by SC was enhanced by FGF (140%), FGF+Sm-C (195%), but not Sm-C alone. When Plasminogen Activator-secretion by SC was measured, a 3.0 and 22 time increase in basal secretion was observed with FGF and FGF+Insulin respectively compared with controls; furthermore, in the presence of FGF and FGF+Insulin, additional 3.3 and 1.24 respective increment factors were observed after FSH stimulation. All the insulin effects were observed at 5 μg/ml and are likely to be mediated through IGF type 1 receptors. Conclusions: These data demonstrate that Sm-C/IGF-1 secreted by SC may have an autocrine effect expressed by the stimulation of SC multiplication and by the synergistic effect with FGF on SC function. These effects of Sm-C on SC, combined to its paracrine effects on Leydig cells (ESPE 86) emphasize the complex but key actions of Sm-C on testicular function and its maturation.