Effect of growth hormone therapy on serum adiponectin and resistin levels in short, small-for-gestational-age children and associations with cardiovascular risk parameters

Metabolic and immunological assessment of small-for-gestational-age children during one-year treatment with growth hormone: the clinical impact of apolipoproteins

Children born small for gestational age (SGA) are at a higher risk for metabolic disorders later in life. In this study, we aimed to characterize young SGA children without catch-up growth and evaluate the effects of GH treatment on endocrinological, metabolic, and immunological parameters. Study design is a one-year single hospital-based study included prospective observation of SGA patients during 12 months of GH treatment. Clinical and laboratory profiles of SGA children at baseline were compared with controls born appropriate size for age. Twenty-six SGA children (median age, 3.4 years) and 26 control children (median age, 3.8 years) were enrolled. Anthropometric, hematologic, biochemical, immunological, and endocrinological parameters were assessed at baseline and 1, 3, 6, 9, and 12 months after the start of GH treatment. As a result, median height SD score (SDS) of SGA children increased by +0.42 with 12-month GH treatment. Body mass index SDS was lower in SGA children than in controls. Serum apolipoprotein A1 increased, whereas apolipoprotein B decreased during GH treatment. Serum leptin and resistin levels, which were lower in SGA children than in controls at baseline, did not change remarkably with GH treatment. Monocyte counts, which were lower in SGA patients at baseline, increased after GH treatment. Neutrophil counts significantly increased after GH treatment. Natural killer cell ratios, which were higher in SGA patients, decreased after GH treatment. In conclusion, there was no evidence suggesting metabolic abnormalities in SGA children. Serum apolipoprotein changes might predict the beneficial role of GH treatment in lowering cardiometabolic risk.

Comparison between euglycemic hyperinsulinemic clamp and surrogate indices of insulin sensitivity in children with growth hormone deficiency

OBJECTIVE

Data about the impact of growth hormone treatment (GHT) on insulin sensitivity in children are quite controversial, due to the different surrogate indices that have been used.

DESIGN

We evaluated insulin sensitivity through the euglycemic hyperinsulinemic clamp, considered the gold standard technique, in 23 children affected by growth hormone deficiency (GHD) at baseline and after 12months of GHT and in 12 controls with short stature at baseline, and we compared the clamp-derived index (M-value) with the most commonly used surrogate index of insulin sensitivity, as ISI Matsuda, and with circulating plasma markers of insulin sensitivity, as adiponectin and resistin levels.

RESULTS

At baseline, no significant difference in all metabolic parameters between GHD children and control subjects was found. After 12months of GHT, GHD children showed a significant increase in fasting insulin (p<0.001) and resistin (p=0.028) and a decrease in ISI Matsuda (p<0.001) and M-value (p<0.001), without significant change in fasting glucose, HbA1c and adiponectin. In GHD children, M-value showed a significant but weak correlation with ISI Matsuda (rho 0.418, p=0.047) at baseline, while no correlation with other parameters was found. After 12months of GHT, M-value did not show any significant correlation with any other metabolic parameter analyzed.

CONCLUSIONS

This study highlights the limit of the evaluation of insulin sensitivity performed through surrogate indices or circulating markers, which may lead to controversial data and do not correlate with the gold standard technique to evaluate insulin sensitivity.

Low-birth-weight, but not catch-up growth, correlates with insulin resistance and resistin level in SGA infants at 12 months

OBJECTIVE

To investigate the insulin resistance status in SGA infants at 12 months and its relationship with auxological and metabolic parameters.

METHODS

One group of 45 SGA and one of 50 appropriate for gestational age infants were followed from birth to the end of the first year of life. At 12 months, skinfold thickness, waist circumference, and blood levels of glucose, insulin, adiponectin, leptin, resistin, visfatin, retinol-binding protein 4, IGFs, lipids profile were determined, and the HOMA-IR index was calculated.

RESULTS

The SGAs had increased insulin (5.2 ± 2.7 versus 2.9 ± 2.4 μIU/ml, p = 0.012) and HOMA-IR (1.09 ± 0.9 versus 0.59 ± 0.55, p = 0.016). In multiple regression, insulin resistance indices were independently correlated with low-birth-weight (β = -2.92, p = 0.015 for insulin, β = -2.98, p = 0.011 for HOMA-IR) but not with catch-up growth in either height or weight or any other metabolic parameter. Resistin was higher in the SGAs (5.1 ± 2.1 versus 3.9 ± 2.1 ng/ml, p = 0.03) and independently correlated with low-birth-weight but not insulin resistance. Resistin was negatively correlated with total cholesterol (R = -0.33, p = 0.007) and positively with lipoprotein(a) (R = 0.49, p = 0.001).

CONCLUSION

Low-birth-weight, but not catch-up growth or adiposity tissue hormones, was correlated with insulin resistance at 12 months in non-obese SGA infants. The higher resistin in SGA infants and its correlation with total cholesterol and lipoprotein(a) need further clarification.

Serum resistin and insulin-like growth factor-1 levels in patients with hypothyroidism and hyperthyroidism

Introduction. The aim of this study was to evaluate the serum levels of resistin and insulin-like growth factor-1 (IGF-1) and and also the potential relationship between thyroid function and levels of resistin and IGF-1 in hypothyroid and hyperthyroid patients. Methods. Fifteen cases of hypothyroid (HT), 16 of subclinically hypothyroid (SCHT), 15 of hyperthyroid (HrT), 15 of subclinically hyperthyroid (SCHrT), and 17 healthy individuals have been included in the study. Serum resistin levels were measured using enzyme-linked immunosorbent assay and IGF-1 and thyroid stimulating hormone (TSH) levels by chemiluminescence method. Results. Resistin levels in total HT group were significantly higher than in controls (12.66 ± 6.04 and 8.45 ± 2.90 ng/mL, resp.). In SCHrT subgroup resistin levels were significantly higher than those of controls (14.88 ± 7.73 and 8.45 ± 2.90 ng/mL, resp.). IGF-1 levels were significantly lower in total HT than in total HrT and control groups (117.22 ± 52.03, 155.17 ± 51.67, and 184.00 ± 49.73 ng/mL, resp.). Furthermore IGF-1 levels in HT subgroup were significantly lower compared to controls (123.70 ± 44.03 and 184 ± 49.73 ng/mL, resp.). In SCHT subgroup IGF-1 levels were significantly lower than those of control and SCHrT groups (111.11 ± 59.35, 184.00 ± 49.73, and 166.60 ± 47.87 ng/mL, resp.). There were significant correlations between IGF-1 and TSH in HT subgroup and between resistin and TSH in total HrT group. Conclusion. It was concluded that increased resistin levels are directly related to thyroid dysfunction, and GH/IGF-1 axis is influenced in clinically or subclinically hypothyroidism patients.

A review of guidelines for use of growth hormone in pediatric and transition patients

Growth hormone (GH) is approved by the US Food and Drug Administration (FDA) for use in pediatric patients with disorders of growth failure or short stature and in adults with growth hormone deficiency (GHD) and HIV/AIDS wasting and cachexia. For pediatric patients, guidelines for the use of GH have been developed by several organizations that have identified specific criteria for initiating GH therapy for each FDA-approved indication. Guidelines for adults have also been developed and include recommendations for transition (adolescent) patients with GHD. These patients are often treated with GH as children but may require continued treatment as young adults to attain full skeletal mineralization and improve cardiovascular risk factors. Adult and pediatric guidelines are supported by efficacy and safety studies, which show that, when started at an early age, GH treatment can increase growth velocity and that GH is safe and well-tolerated. We summarize the guidelines that are available for all FDA-approved indications among pediatric and transition patients. Adherence to these guidelines will help to ensure that patients with disorders of growth failure or short stature receive the necessary therapy to increase linear growth and transition smoothly to healthy adulthood.

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.

Growth hormone treatment, final height, insulin-like growth factors, ghrelin, and adiponectin in four siblings with Seckel syndrome

OBJECTIVE

To report on the effect of growth hormone (GH) treatment on final height (FH) and to describe the insulin-like growth factor (IGF) system, ghrelin, and adiponectin (ADPN) in children with Seckel syndrome.

SUBJECTS AND RESULTS

Four severely growth-retarded Iraqi siblings (two girls and two boys) with Seckel syndrome were referred at ages 16.5, 14.4, 12.4, and 10.4 years. They were born at term, but their growth was retarded and birth weight ranged between 1 and 1.5 kg. The children were healthy and had a normal response to GH provocative test. Long-term GH treatment of the youngest brother and sister increased the FH by 7.2 and 3.4 cm, respectively, compared with their older brother and sister. At FH, body mass index standard deviation scores (BMISDS) ranged from -3.0 to -3.9. Serum levels of immunoreactive IGF-1, bioactive IGF-1, and IGF-binding protein 3 were all within normal to high range before GH treatment and increased after GH treatment. Fasting plasma ghrelin remained severely reduced. Despite low BMISDS, plasma ADPN was moderately reduced and showed an almost complete absence of the low-molecular-weight subform.

CONCLUSION

This is the first report on the effect of GH treatment on FH in children with Seckel syndrome. GH may have increased FH. In addition to growth defects and reduced BMISDS, patients with Seckel syndrome are characterized by low fasting ghrelin levels, low total ADPN, and near deficiency of the low-molecular-weight ADPN subform. The possible significance of the hormonal changes requires further investigations.

Serum levels of adiponectin and leptin in children born small for gestational age: relation to insulin sensitivity parameters

Children born small for gestational age (SGA) are prone to developing obesity, insulin resistance and type 2 diabetes. Adiponectin and leptin are adipocytokines associated with insulin sensitivity parameters. We aimed to relate serum adiponectin and leptin levels with insulin sensitivity parameters in prepuberal SGA children with and without catch-up growth (SGA+CUG; SGA-CUG, respectively) and to analyze the usefulness of these adipocytokines as early markers of insulin resistance. We analysed adiponectin, proinsulin, leptin, growth factors, insulin, HOMA IR and HOMA beta(cell) in 23 SGA+CUG, 26 SGA-CUG children compared with 48 prepuberal appropiate for gestational age (AGA). SGA children had adiponectin levels comparable to AGA children. Leptin levels were different between sexes, showed to be higher in SGA+CUG group (p=0.040) and these were significantly correlated with insulin sensitivity parameters. These results suggest leptin resistance as an adaptive mechanism to increase energy balance, but an altered functional response of adipocytes cannot be discarded.

Growth hormone therapy in short children born small for gestational age: effects on abdominal fat partitioning and circulating follistatin and high-molecular-weight adiponectin

CONTEXT AND OBJECTIVE

A high sensitivity to insulin and a low amount of sc fat are among the hallmarks of short children born small for gestational age (SGA). We studied the effects of GH therapy on fat partitioning (including in the abdominal region) and circulating levels of triacylglycerol and newly identified adipokines, such as follistatin and high-molecular-weight (HMW) adiponectin in short SGA children.

SETTING

The study was conducted at a university hospital.

PATIENTS

Patients included 35 short SGA children (mean age 7 yr, height -3.1 sd).

DESIGN

All children received GH but they were randomized for an early start (GH for 4 months) vs. a delayed start (untreated for 4 months, then GH for 4 months). Mean GH dose after 4 months was 36 microg/kg x d.

MAIN OUTCOMES

Outcomes included fasting serum glucose, insulin, triacylglycerol, HMW adiponectin, follistatin; body size and composition; and abdominal fat partitioning.

RESULTS

GH therapy was accompanied by robust changes toward the norm (height, weight, lean mass, follistatin) but also by changes away from the norm (low HMW adiponectin, high triacylglycerol). Some baseline anomalies were amplified (more deficit of sc fat, both at total body level and in the abdominal region), whereas other baseline anomalies were overcorrected (from a highly insulin sensitive state to an insulin resistant state).

CONCLUSION

GH therapy in short SGA children is accompanied by not only a more normal body size and follistatinemia but also insulin resistance, hypo-HMW-adiponectinemia, hypertriacylglycerolemia, and an amplification of the deficit in sc fat.

Plasma matrix metalloproteinase-9 levels and blood pressure in short children born small for gestational age and effects of growth hormone treatment

CONTEXT

Short small-for-gestational-age (SGA) children have an increased systolic blood pressure (BP) that decreases during long-term GH treatment. The underlying mechanism is still unknown. Matrix metalloproteinases (MMPs) are zinc-dependent endoproteinases that are involved in the remodelling of the extracellular matrix (ECM) and are thought to play a role in atherosclerosis. High MMP-9 levels are found in hypertensive patients and predict cardiovascular mortality.

OBJECTIVES

To investigate whether GH treatment affects plasma MMP-9 levels in short SGA children and whether these are related to BP.

DESIGN

Case-control study.

INTERVENTION

GH treatment vs. no treatment during 36 months. Patients Thirty-eight short SGA children receiving GH treatment vs. 17 sex- and age-matched untreated short SGA controls.

OUTCOME MEASURE

Plasma MMP-9 levels and BP were measured at baseline, and after 6, 12 and 36 months of study.

RESULTS

MMP-9 decreased significantly during 3 years of GH treatment but remained similar in untreated SGA controls. After 3 years of GH treatment, MMP-9 levels were significantly lower in the GH group than in the untreated SGA controls. Systolic BP SDS significantly decreased in the GH group but remained unaltered in the untreated SGA controls. MMP-9 levels did not correlate with systolic or diastolic BP.

CONCLUSIONS

Plasma MMP-9 levels and systolic BP SDS decreased to almost 50% of baseline values in the GH group but remained unchanged in untreated SGA controls. Our data indicate that GH has a positive effect on both MMP-9 levels and systolic BP SDS.

Recombinant human growth hormone for children born small for gestational age: meta-analysis confirms the consistent dose-effect relationship on catch-up growth

BACKGROUND

The optimal treatment regimen of recombinant human GH (r-hGH) for short children born small for gestational age (SGA) is still under discussion.

METHODS

A meta-analysis was performed of existing clinical trials that investigated the treatment of r-hGH in short children diagnosed SGA or with intrauterine growth retardation to determine the relationship between the daily r-hGH dose (placebo/no treatment; 0.033 mg/kg/day; 0.067 mg/kg/day) and the effect on growth [change in height-SD score (SDS) for chronological age]. A mathematical model describing the dose-response relationship was produced, and growth response (gain in height-SDS) to 2 yr of r-hGH 0.033 mg/kg/day [somatropin (rDNA origin) for injection; Serono] was estimated and compared with the response to other r-hGH formulations.

RESULTS

The relationship between r-hGH dose and 2-yr growth response was described by an equation. The equation yielded a mean difference in height- SDS gain of 0.48 (0.35) between r-hGH 0.033 and 0.067 mg/kg/day in favor of the higher dose. The height-SDS gain after 2 yr of Serono r-hGH formulation, 0.033 mg/kg/day was estimated as 1.2. Comparison of this estimate to the growth response to 2-yr treatment at 0.033 mg/kg/day of other r-hGH formulations (mean difference in height-SDS 0.05, lower limit of the 95% confidence interval=-0.15) confirmed that growth response to Serono r-hGH formulation 0.033 mg/kg/day is an inferred response estimated to be within the range of observed responses to a (non-Serono formulation) r-hGH dose of 0.033 mg/kg/day.

CONCLUSION

There is a clear dose-response relationship for r-hGH in the treatment of short children born SGA and the analysis confirmed that treatment with Serono r-hGH formulation 0.033 mg/kg/day should provide a meaningful therapeutic response.

Long-term GH treatment is not associated with disadvantageous changes of inflammatory markers and adipocytokines in children born small for gestational age

CONTEXT

Low birth weight is associated with increased risks for adult cardiovascular disease (CVD) and diabetes mellitus type 2 (DM2). Adiponectin and resistin are hormones, considered, respectively, protective and disadvantageous regarding these risks. No data exist on the effect of long-term GH treatment on these hormones and inflammatory markers in children born small for gestational age (SGA).

OBJECTIVE

To describe longitudinal changes in inflammatory markers and adipocytokines during and after a long-term dose-response GH study.

DESIGN

Longitudinal dose-response study [group A: 1 mg/m(2) body surface area (BSA) (approximately 0.033 mg/kg/day) vs. group B: 2 mg/m(2) BSA (approximately 0.067 mg/kg/day)] and comparison with age-related controls.

PATIENTS

One hundred and three SGA children.

MEASUREMENTS

We measured adiponectin, resistin, interleukin-6 (IL-6) and C-reactive protein (CRP) levels at baseline, after 1 and 7 years of GH treatment and 6 months after discontinuation of GH.

RESULTS

Adiponectin levels decreased over time, but remained comparable with controls. Resistin levels increased and remained lower or comparable with controls. There were no significant differences between the GH dosage groups. After the GH treatment was stopped, adiponectin was decreased in group B and resistin increased in group A. GH therapy did not affect IL-6 and CRP levels at any time point. An increase in body mass index (BMI) standard deviation score (SDS) over time was associated with a decrease in adiponectin levels. None of the markers were associated with insulin sensitivity.

CONCLUSIONS

Long-term GH treatment is not associated with disadvantageous changes in adiponectin, resistin, IL-6 and CRP levels, neither during nor after GH treatment.

Independent effects of prematurity on metabolic and cardiovascular risk factors in short small-for-gestational-age children

CONTEXT

Both small-for-gestational-age (SGA) and preterm birth have been associated with an increased incidence of adult cardiovascular disease and diabetes mellitus type 2. However, it is unclear whether preterm birth has an additional effect on cardiovascular risk factors in short children born SGA.

OBJECTIVE

Our objective was to investigate whether prematurity has an independent influence on several cardiovascular risk factors within a population of short SGA children.

DESIGN

A cross-sectional observational study was performed.

PATIENTS

A total of 479 short SGA children (mean age 6.8 yr), divided into preterm (<36 wk) and term (> or =36 wk) children, was included in the study.

OUTCOME MEASURE

Insulin sensitivity, beta-cell function, body composition, and lipid levels were studied in subgroups, and blood pressure (BP), anthropometry at birth and during childhood in the total group.

RESULTS

Preterm SGA children were significantly lighter and shorter at birth after correction for gestational age than term SGA children (P < 0.001) but had a comparable head circumference. In preterm SGA children, we found a significantly higher systolic (P = 0.003) and diastolic BP sd score (P = 0.026), lower percent body fat sd score (P = 0.011), and higher insulin secretion (P = 0.033) and disposition index (P = 0.021), independently of the degree of SGA. Insulin sensitivity, serum lipid levels, muscle mass, and body fat distribution were comparable for preterm and term SGA children.

CONCLUSIONS

Within a population of short SGA children, preterm birth has divergent effects on several cardiovascular risk factors. Whereas preterm SGA children had a higher systolic and diastolic BP, they also had a lower percent body fat and a higher insulin secretion and disposition index than term SGA children.

Adipose Tissue: A Metabolic Regulator. Potential Implications for the Metabolic Outcome of Subjects Born Small for Gestational Age (SGA)

Adipose tissue is involved in the regulation of glucose and lipid metabolism, energy balance, inflammation and immune response. Abdominal obesity plays a key role in the development of insulin resistance because of the high lipolytic rate of visceral adipose tissue and its secretion of adipocytokines. Low birth weight subjects are prone to central redistribution of adipose tissue and are at high risk of developing metabolic syndrome, type 2 diabetes and cardiovascular disease. Intrauterine adipogenesis may play a key role in the fetal origin of the pathogenesis of metabolic syndrome, type 2 diabetes and cardiovascular disease. Therefore, knowledge of the behavior of visceral adipose tissue-derived stem cells could provide a greater understanding of the metabolic risk related to intrauterine growth retardation, with potential clinical implications for the prevention of long-term metabolic alterations.

Fasting inhibits the growth and reproductive axes via distinct Y2 and Y4 receptor-mediated pathways

Neuropeptide Y, a neuropeptide abundantly expressed in the brain, has been implicated in the regulation of the hypothalamo-pituitary-somatotropic axis and the hypothalamo-pituitary-gonadotropic axis. Elevated hypothalamic neuropeptide Y expression, such as that occurs during fasting, is known to inhibit both of these axes. However, it is not known which Y receptor(s) mediate these effects. Here we demonstrate, using Y receptor knockout mice, that Y2 and Y4 receptors are separately involved in the regulation of these axes. Fasting-induced inhibition of hypothalamic GHRH mRNA expression and reduction of circulating IGF-I levels were observed in wild-type and Y4(-/-) mice but not Y2(-/-) or Y2(-/-)Y4(-/-) mice. In contrast, fasting-induced reduction of GnRH expression in the medial preoptic area and testis testosterone content were abolished in the absence of Y4 receptors. Colocalization of Y2 receptors and GHRH in the arcuate nucleus (Arc) suggests that GHRH mRNA expression in this region might be directly regulated by Y2 receptors. Indeed, hypothalamic-specific deletion of Y2 receptors in conditional knockout mice prevented the fasting-induced reduction in Arc GHRH mRNA expression. On the other hand, fasting-induced decrease in GnRH mRNA expression in the medial preoptic area is more likely indirectly influenced by Y4 receptors because no Y4 receptors could be detected on GnRH neurons in this region. Together these data show that fasting inhibits the somatotropic axis via direct action on Y2 receptors in the Arc and indirectly inhibits the gonadotropic axis via Y4 receptors.