Growth hormone treatment strategy for short children born small for gestational age

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

BACKGROUND

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

METHODS AND AIMS

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

RESULTS

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

CONCLUSION

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

One-Year Data from a Long-Term Phase IV Study of Recombinant Human Growth Hormone in Short Children Born Small for Gestational Age

Background

This prospective, open-label, non-comparative, multicentre, long-term phase IV study is examining the efficacy and safety of somatropin [recombinant human growth hormone (rhGH)] in short children born small for gestational age (SGA) and its impact on the incidence of diabetes. This report is the first interim analysis of patients who have completed 1 year of treatment.

Methods

A total of 278 pre-pubertal patients were enrolled. Key eligibility criteria included height standard deviation score (HSDS) <−2.5; parental adjusted SDS <−1; birth weight and/or length <−2 SD and failure to show catch-up growth by ≥4 years of age. Patients were treated with rhGH 0.035 mg/kg/day. The primary objective was to evaluate the long-term effect of rhGH on carbohydrate metabolism [including fasting glucose, stimulated glucose (2-h oral glucose tolerance test, OGTT) and glycated haemoglobin (HbA_1c)]. Secondary objectives included evaluation of height parameters [body height, HSDS, height velocity (HV), HVSDS]; insulin-like growth factor 1 (IGF-I) and insulin-like growth factor-binding protein 3 (IGFBP-3) serum levels during treatment; and incidence and severity of adverse events (AEs).

Results

None of the children developed diabetes mellitus within the first year of treatment. Mean levels of fasting glucose, HbA_1c and 2-h OGTT values remained stable during the study period. Treatment with rhGH was effective, as documented by all height parameters. Mean HSDS improved from −3.39 at baseline to −2.57 at Year 1. Mean HV increased markedly from 4.25 cm/year at baseline to 8.99 cm/year during the first year. Similarly, mean peak-centred HVSDS increased from −2.13 at baseline to +4.16 at Year 1. Mean IGF-I SDS and IGFBP-3 SDS also increased within the first year (by +1.80 and +0.41, respectively). 13 patients (4.7%) did not respond adequately to treatment (HVSDS <1); they were withdrawn from the study. In total, 192 children (69.3%) experienced treatment-emergent AEs; most (98.7%) were mild-to-moderate, and the majority (96.5%) were unrelated to study treatment.

Conclusion

This interim analysis shows that short children born SGA can be effectively and safely treated with rhGH and that rhGH treatment has no major impact on carbohydrate metabolism after the first year of treatment.

Electronic supplementary material

The online version of this article (doi:10.1007/s13554-014-0014-4) contains supplementary material, which is available to authorized users.

Latin American consensus: children born small for gestational age

BACKGROUND

Children born small for gestational age (SGA) experience higher rates of morbidity and mortality than those born appropriate for gestational age. In Latin America, identification and optimal management of children born SGA is a critical issue. Leading experts in pediatric endocrinology throughout Latin America established working groups in order to discuss key challenges regarding the evaluation and management of children born SGA and ultimately develop a consensus statement.

DISCUSSION

SGA is defined as a birth weight and/or birth length greater than 2 standard deviations (SD) below the population reference mean for gestational age. SGA refers to body size and implies length-weight reference data in a geographical population whose ethnicity is known and specific to this group. Ideally, each country/region within Latin America should establish its own standards and make relevant updates. SGA children should be evaluated with standardized measures by trained personnel every 3 months during year 1 and every 6 months during year 2. Those without catch-up growth within the first 6 months of life need further evaluation, as do children whose weight is ≤ -2 SD at age 2 years. Growth hormone treatment can begin in SGA children > 2 years with short stature (< -2.0 SD) and a growth velocity < 25th percentile for their age, and should continue until final height (a growth velocity below 2 cm/year or a bone age of > 14 years for girls and > 16 years for boys) is reached. Blood glucose, thyroid function, HbA1c, and insulin-like growth factor-1 (IGF-1) should be monitored once a year. Monitoring insulin changes from baseline and surrogates of insulin sensitivity is essential. Reduced fetal growth followed by excessive postnatal catch-up in height, and particularly in weight, should be closely monitored. In both sexes, gonadal function should be monitored especially during puberty.

SUMMARY

Children born SGA should be carefully followed by a multidisciplinary group that includes perinatologists, pediatricians, nutritionists, and pediatric endocrinologists since 10% to 15% will continue to have weight and height deficiency through development and may benefit from growth hormone treatment. Standards/guidelines should be developed on a country/region basis throughout Latin America.