Effects of growth hormone (GH) therapy withdrawal on glucose metabolism in not confirmed GH deficient adolescents at final height

Haptoglobin Phenotypes Are Associated with the Postload Glucose and Insulin Levels in Pediatric Obesity

PURPOSE

Haptoglobin (Hp) is a protein involved in the acute-phase reaction of inflammation. Humans have three major phenotypes (Hp1-1, Hp1-2, and Hp2-2). Several studies have shown altered Hp regulation in adults with obesity and metabolic alterations. The Hp2-2 phenotype is associated with a high cardiovascular risk. Our aim was to investigate if Hp levels and the Hp2-2 phenotype are associated with glucose metabolism in pediatric obesity.

METHODS

We retrospectively studied 192 participants (92 males and 100 females), aged 4-18 years. Clinical and biochemical data were collected. The Hp phenotype (Hp1-1, Hp1-2, and Hp2-2) was identified through Western immunoblot.

RESULTS

Subjects carrying Hp1-1, Hp1-2, and Hp2-2 phenotypes were 13.6, 50.8, and 35.6%, respectively. Hp serum, fasting glucose, and insulin levels, as well as HOMA-IR, were similar among groups. Postload glucose and insulin levels (as insulin AUC) were progressively higher from the Hp1-1 to Hp2-2 phenotype.

CONCLUSION

To our knowledge, this is the first study on Hp phenotypes conducted in a pediatric population with obesity. We showed that the presence of Hp2 allele is associated with a worse response of glucose load in terms of both glucose and insulin levels. Thus, the Hp2-2 phenotype could predispose in pediatrics, at the same degree of obesity, to a worse glycemic and insulinemic compensation.

Childhood-onset growth hormone deficiency and the transition to adulthood: current perspective

Childhood-onset growth hormone deficiency (CO-GHD) is an endocrine condition associated with a broad range of health issues from childhood through to adulthood, which requires particular attention during the transition period from adolescence to young adulthood. There is uncertainty in the clinical practice of the management of CO-GHD during transition regarding the clinical assessment and management of individual patients during and after transition to obtain optimal follow-up and improved health outcomes. Despite the availability of clinical guidelines providing the framework for transition of young adults with CO-GHD, there remains substantial variation in approaching transitional care among pediatric and adult services. A well-structured and coordinated transitional plan with clear communication and direct collaboration between pediatric and adult health care to ensure optimal management of adolescents with CO-GHD during transition is needed.

High-normal estimated glomerular filtration rate and hyperuricemia positively correlate with metabolic impairment in pediatric obese patients

BACKGROUND

Childhood obesity represents a major health concern worldwide due to its well established detrimental effect on cardiovascular and its potential negative effect on kidney functions. However, biomarkers that can help diagnose early stages of kidney damage in obese children represent an unmet clinical need.

OBJECTIVES

In this study, we asked whether the prevalence of microalbuminuria, estimated glomerular filtration rate (eGFR) or hyperuricemia recorded in a wide cohort of obese children and adolescents would positively correlate with cardiometabolic dysfunction in these subjects.

METHODS

We carried out a cross-sectional study on 360 obese children and adolescents between the ages of 3-18 years, enrolled in a tertiary care center. Clinical and biochemical evaluations including oral glucose tolerance tests (OGTTs) were performed on all patients. Microalbuminuria was defined as urinary albumin-to-creatinine ratio (u-ACR) of 30-300 mg/g. All data are expressed as mean ± standard deviation (SD), absolute values or percentages. Sex age-specific and eGFR SDs were used for statistical analyses. Serum uric acid ≥ 5.5 mg/dL was considered abnormal.

RESULTS

The prevalence of microalbuminuria was 6.4%. Except for a lower insulinogenic-index, no correlations between microalbuminuria and cardiometabolic risk factors were detected. eGFR was < -1 SD and > 1 SD in 1.4% and 60.8% of subjects, respectively. Subjects with an eGFR > 1 SD had higher systolic blood pressure, liver enzymes, insulin resistance, glucose and insulin during OGTT, lower insulin sensitivity and a more prevalent microalbuminuria. Hyperuricemia (27.5%) increased the odds of hypertension, HDL ≤ 10th percentile and glucose ≥ 155.0 mg/dL after 60 minutes of OGTT.

CONCLUSIONS

A worse cardiometabolic profile was observed in subjects with an eGFR > 1 SD compared to other subgroups. Therefore, pediatric obese patients with eGFR > 1 SD or hyperuricemia should be closely monitored for microalbuminuria and post-challenge glucose and insulin secretion, all potential indicators of renal dysfunction in these young patients.

Glucose Metabolism in Children With Growth Hormone Deficiency

BACKGROUND

The growth hormone (GH)/insulin-like growth factor 1 (IGF-1) axis has a fundamental impact on glucose metabolism. Therefore, both untreated GH deficiency (GHD) and GH treatment (GHT) may be associated with some metabolic alterations, although the abnormalities of glucose metabolism have been investigated by relatively few studies as main outcomes.

AIM

The present review summarizes the available data on glucose metabolism in children with GHD, providing an overview of the current state of the art in order to better clarify the real metabolic impact of GHD and GHT.

METHODS

Among all the existing studies, we evaluated all original studies that fulfilled our criteria for analysis reporting parameters of glucose metabolism as the primary or secondary objective.

RESULTS

The reported impact of GHD per se on glucose metabolism is quite homogeneous, with the majority of studies reporting no significant difference in metabolic parameters between GHD children and controls. Conversely, GHT proves to be more frequently associated with a subtle form of insulin resistance, while both fasting glucose and HbA1c levels remain almost always within the normal range.

CONCLUSION

The different methods to study glucose metabolism, the heterogeneity of the populations evaluated, the different doses of GH used together with the variable duration of follow-up may be responsible for discrepancy in the results. Long-term longitudinal studies having glucose homeostasis as their primary outcome are still needed in order better to clarify the real metabolic impact of GHD and GHT in children.

Short-Term Evaluation of Left Ventricular Mass and Function in Children With Growth Hormone Deficiency After Replacement Treatment

Background: Our study was designed to assess the effects of GHD on nutritional and metabolic parameters, brain natriuretic peptide (BNP) levels, and left ventricular mass (LVM) in prepubertal children and after short-term GH replacement therapy. Materials and Methods: This prospective study enrolled 81 children. We compared 40 GHD children (16 males and 24 females) to 41 healthy children (control group) (18 males and 23 females). All subjects were at Tanner Stage I (aged 7-11 years). At the baseline, a blood sample was drawn and echocardiographic images were obtained. These tests were repeated on the GHD subjects after 6 months of GH replacement therapy. Body surface, weight, size, blood pressure, heart rate, glucose, insulin, HOMA-IR, HOMA-β, QUICKI, cholesterol, HDLc, LDLc, triglycerides, IGF1, and IGFBP3 were measured. Indexed LVM, diastolic and systolic diameter (dD-sD), diastolic and systolic LV function, isovolumic relaxation time, right ventricle function, and BNP levels were obtained through echocardiography. These parameters were correlated to growth factors. Data were analyzed using Student's t-test or U-Mann-Whitney-test and Pearson's correlation, considering p < 0.05 to be significant. Results: Indexed LVM was smaller in GHD patients than in controls, whereas diastolic and systolic functions, BNP, metabolic, and nutritional profiles were similar. After treatment, nutritional and metabolic profiles significantly improved, though diastolic and systolic functions did not seem to have changed. There was a significant increase in LVM. Indexed LVM was similar to that of controls. Significant correlations were obtained between LVM-IGF1 and sD-IGFBP3. Conclusions: GHD in childhood is associated with a lower indexed LVM. In the short-term, GH increases the indexed LVM, while maintaining normal systolic and diastolic functions, BNP, and an improved lipid profile.

Insulin resistance, serum uric acid and metabolic syndrome are linked to cardiovascular dysfunction in pediatric obesity

INTRODUCTION

Childhood obesity is associated with cardiovascular abnormalities but little is known on the potential correlation between early cardiovascular and metabolic alterations.

AIM

Aims of this study were 1) to evaluate early cardiovascular abnormalities in a large population of obese children and adolescents compared with a normal weight counterpart, 2) to investigate their potential association with insulin resistance (IR), serum uric acid (sUA) and metabolic syndrome (MetS).

METHODS

This was a single-center case-control study. Eighty obese (OB) subjects (6-16years) and 20 normal weight (NW) matched controls were consecutively recruited. In the whole population we performed an anthropometric and a cardiovascular assessment. OB patients also underwent an OGTT and biochemical evaluations.

RESULTS

OB children showed greater left atrial (LA) and ventricular (LV) dimensions and mass and higher carotid artery intima-media thickness (CIMT), compared with NW controls. The BMI z-score, waist circumference, IR and sUA were positively related with LA and LV dimensions and mass. OB subjects with MetS (46.3%) showed greater LA diameter (p=0.001) and LV area (p=0.01) and volume (p=0.04) compared with OB children without MetS. LA diameter and LV dimensions and mass were significantly dependent on the number of criteria for MetS. Mets, sUA and IR were significant predictors of left heart dimensions and mass in obese children.

CONCLUSIONS

Obesity and MetS are associated with abnormal cardiovascular response during childhood. Hyperuricemia can be an early marker of cardiovascular dysfunction and the routine determination of circulating levels of sUA should be implemented during risk stratification among pediatric age.

Impact of discontinuation of growth hormone treatment on lipids and weight status in adolescents

BACKGROUND

While the main role of growth hormone (GH) replacement therapy in children is to promote linear growth, GH has also an effect on lipids and body composition. There is an ongoing discussion whether discontinuation of GH treatment is associated with deterioration of lipids.

METHODS

We analyzed weight status [as body mass index-standard deviation score (BMI-SDS)], insulin like growth factor (IGF)-1, triglycerides, total, low-density liporptoein (LDL)- and high-density lipoprotein (HDL)-cholesterol at the end of GH treatment and in mean 6 months later in 90 adolescents (53 with GH deficiency, 16 with Turner syndrome [TS] and 21 born small-for-gestational age [SGA]).

RESULTS

After stopping GH treatment, total cholesterol (+10±24 mg/dL vs. -4±13 mg/dL) and LDL-cholesterol (+15±20 mg/dL vs. -6±12 mg/dL) increased significantly higher in severe (defined by GH peak in stimulation test <3 ng/mL) compared to moderate GHD. In patients with TS, total cholesterol (+19±9 mg/dL), LDL-cholesterol (+9±12 mg/dL) and HDL-cholesterol (+4.3±3.5 mg/dL) increased significantly. In adolescents born SGA, triglycerides increased (+34±51 mg/dL) and HDL-cholesterol decreased significantly (-3.8±7.1 mg/dL). In multiple linear regression analyses, changes of total and LDL-cholesterol were significantly negatively related to peak GH in stimulation tests, but not to gender, age at GH start, duration of GH treatment, observation time, changes of BMI-SDS or IGF-1 after the end of GH treatment. The BMI-SDS did not change after the end of GH treatment.

CONCLUSIONS

Discontinuation of GH treatment leads to a deterioration of lipids in TS, SGA and severe but not moderate GHD.

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.

Growth hormone deficiency during young adulthood and the benefits of growth hormone replacement

Until quite recently, the management of children with growth hormone deficiency (GHD) had focussed on the use of recombinant human GH (rhGH) therapy to normalise final adult height. However, research over the past two decades that has demonstrated deficits in bone health and cardiac function, as well as impaired quality of life in adults with childhood-onset GHD (CO-GHD), has questioned this practice. Some of these studies suggested that there may be short-term benefits of rhGH in certain group of adolescents with GHD during transition, although the impact of GHD and replacement during the transition period has not been adequately investigated and its long-term benefits remain unclear. GH therapy remains expensive and well-designed long-term studies are needed to determine the cost effectiveness and clinical benefit of ongoing rhGH during transition and further into adulthood. In the absence of compelling data to justify widespread continuation of rhGH into adult life, there are several questions related to its use that remain unanswered. This paper reviews the effects of growth hormone deficiency on bone health, cardiovascular function, metabolic profile and quality of life during transition and young adulthood.

Influence of Ultraviolet Radiation on the Association between 25-Hydroxy Vitamin D Levels and Cardiovascular Risk Factors in Obesity

OBJECTIVE

To establish if the correction with estimates of ultraviolet (UV) exposure influences the association between 25-OH-vitamin D (25OHD) levels and metabolic variables.

STUDY DESIGN

A cross-sectional study was performed in 575 obese children and adolescents (>6 years of age) in a tertiary referral center. Cardiovascular risk factors were measured. The estimate of UV exposure was evaluated by 3 methods: (1) season; (2) mean of UV radiation (UVR); and (3) mean of UV index (UVI). UVR and UVI were considered at 1 (UVR 1 month prior to testing [UVR1], UVI 1 month prior to testing [UVI1]) or 3 (UVR 3 months prior to testing [UVR3], UVI 3 months prior to testing [UVI3]) months prior to testing. All analyses were corrected for confounders (sex, age, puberty, body mass index, waist circumference, the inclusion and exclusion of estimates of UV exposure).

RESULTS

The 25OHD levels were associated with seasons, UVR1, UVR3, UVI1, and UVI3, and best associations with UVR3 and UVI3. In all models, total cholesterol, low-density lipoprotein cholesterol and triglycerides were negatively associated with 25OHD levels. The strength of the association increased with no correction, correction for seasons, UVR, and UVI. UVR3 and UVI3 performed better than UVR1 and UVI3.

CONCLUSIONS

Higher lipid concentrations were associated with low 25OHD levels in obese children and adolescents with the power of the association dependent on the estimates of UVR. As the mean values 3 months prior to testing for both UVR and UVI determined the best associations, the interval of the steady state time of 25OHD levels could be preferentially used in the metabolic studies. Controlling for an estimate of UVR is important to decrease the heterogeneity of studies.

Efficacy and safety of growth hormone treatment in children with hypochondroplasia: comparison with an historical cohort

BACKGROUND/AIMS

Hypochondroplasia (HCH) is a skeletal dysplasia characterized by disproportionate short stature. The aims of the study are to evaluate efficacy and safety of recombinant human growth hormone (r-hGH) therapy in HCH children, when compared with a historical cohort of untreated HCH children.

METHODS

Nineteen HCH patients with an initial height standard deviation score (SDS) ≤-2 and a mean age of 9.3 ± 3.1 years were treated with a mean r-hGH dose of 0.053 mg/kg/day over 3 years. Growth charts were derived from the historical cohort (n = 40).

RESULTS

Height gain in the treated population was +0.62 ± 0.81 SDS greater than in the general population, and +1.39 ± 0.9 SDS greater than in the historical untreated HCH cohort (mean gain of 7.4 ± 6.6 cm gain). A negative correlation between height gain and age at treatment initiation was reported (p = 0.04). There was no significant difference in response between patients with fibroblast growth factor receptor 3 mutations and those without. No treatment-related serious adverse events were reported.

CONCLUSIONS

r-hGH treatment is well tolerated and effective in improving growth in HCH patients, particularly when started early. The treatment effect varies greatly and must be evaluated for each patient during treatment to determine the value of continued therapy.

Reduction in insulin sensitivity and inadequate β-cell capacity to counteract the increase in insulin resistance in children with idiopathic growth hormone deficiency during 12 months of growth hormone treatment

PURPOSE

To evaluate the performance of various indexes of insulin sensitivity and secretion and to identify the most useful indicator of deterioration of glucose metabolism in a cohort of children with growth hormone (GH) deficiency (GHD) during GH treatment.

METHODS

In 73 GHD children (55 M, 18 F; mean age 10.5 years) at baseline and after 12 months of treatment, we evaluated a number of surrogate indexes of insulin secretion and sensitivity. In a subgroup of 11 children we also performed an euglycemic hyperinsulinemic clamp.

RESULTS

After 12 months, a significant increase in fasting glucose (p < 0.001) and HbA1c levels (p < 0.001) was documented, despite all children remained with a normal glucose tolerance. With regard the insulin secretion, Homa-β did not show any significant change (p = 0.073), while oral disposition index (DIo) showed a significant decrease (p = 0.031). With regard the insulin sensitivity, Homa-IR significantly increased (p < 0.001) with a concomitant decrease in QUICKI (p < 0.001). ISI Matsuda showed a decrease, although not statistically significant (p = 0.069). In the subgroup of 11 children, the M value derived from clamp showed a significant decrease (p = 0.011) and a significant positive correlation was found between M value and ISI Matsuda both at baseline (ρ 0.950; p = 0.001) and after 12 months (ρ 0.980; p = 0.001) but not with Homa-IR and QUICKI.

CONCLUSIONS

12 months of GH treatment lead to a decrease in insulin sensitivity and impairment in insulin secretion relative to insulin sensitivity even without evident changes in glucose tolerance. DIo has proven to be the most useful indicator of deterioration of glucose metabolism even in cases in which the overt glucose abnormalities have not yet appeared.