Impact of body mass index on growth hormone stimulation tests in children and adolescents: a systematic review and meta-analysis

Pragmatic Evaluation of Growth Hormone Stimulation Tests in Short Stature

Introduction

To assess the performance of growth hormone stimulation tests (GHSTs) in the evaluation of short stature.

Methods

It was a single-centre retrospective study carried out in children evaluated for short stature between January 2005 to March 2020. The clonidine stimulation test (CST) and glucagon stimulation test (GST) were used to assess growth hormone (GH) reserve (GST was performed only when peak GH levels were between 5 to ≤10 ng/mL on CST). A GH level of <5 ng/mL on CST or ≤10 ng/ml on both was used to corroborate GH deficiency.

Results

A total of 556 children were eligible for this study. The mean (SD) age was 12.9 (3.5) years, and 66.3% were male. The peak GH level [median (IQR)] was 5.50 ng/ml (1.90 - 7.50) on CST (at 60 minutes) and 7.45 ng/ml (2.15 - 10.77) on GST (at 120 minutes). On restricting sampling to two time points, the false positive rate was 13.6% on CST (60, 90 minutes) and 11.5% on GST (120, 150 minutes). Similarly, restricting to three time points was associated with a false positive rate of 8.5% on CST (60, 90, 120 minutes) and 3.8% on GST (90, 120, 150 minutes). Using the treating clinician-determined diagnosis of GHD as a reference standard, the optimal cut-off of peak GH on CST was 7.79 ng/ml (sensitivity: 83.8%; specificity: 89.4%).

Conclusion

Restricting the GH sampling to fewer time points is associated with an increase in the false positivity rate (FPR).

[Diagnostic significance and considerations of growth hormone stimulation testing and insulin-like growth factor 1 in growth hormone deficiency]

The growth hormone (GH)/insulin-like growth factor 1 (IGF-1) axis is an essential component of the hypothalamic-pituitary growth hormone axis and plays a crucial role in childhood growth and development. Disruptions and abnormalities in the GH/IGF-1 signaling pathway and its pathways typically manifest as short stature in children. Children with short stature often undergo GH stimulation testing and IGF-1 level measurements to differentiate growth hormone deficiency (GHD) from other causes of growth delay. This article aims to analyze and elucidate the values of GH stimulation testing and IGF-1 measurement, providing reference for the diagnosis of GHD in children.

Body Mass Index and Associated Medical Expenditures in the US Among Privately Insured Individuals Aged 2 to 19 Years in 2018

Importance

Nearly 40% of US youth aged 2 to 19 years do not have a body mass index (BMI) in the healthy weight category. However, there are no recent estimates for BMI-associated expenditures using clinical or claims data.

Objective

To estimate medical expenditures among US youth across all BMI categories along with sex and age groups.

Design, Setting, Participants

This cross-sectional study used IQVIA's ambulatory electronic medical records (AEMR) data set linked with IQVIA's PharMetrics Plus Claims database from January 2018 through December 2018. Analysis was performed from March 25, 2022, through June 20, 2022. It included a convenience sample of a geographically diverse patient population from AEMR and PharMetrics Plus. The study sample included privately insured individuals with a BMI measurement in 2018 and excluded patients with pregnancy-related visits.

Exposure

BMI categories.

Main Outcomes and Measures

Total medical expenditures were estimated using generalized linear model regression with γ distribution and log-link function. For out-of-pocket (OOP) expenditures, a 2-part model was used that included logistic regression to estimate the probability of positive expenditures followed by generalized linear model. Estimates were shown with and without accounting for sex, race and ethnicity, payer type, geographic region, age interacted with sex and BMI categories, and confounding conditions.

Results

The sample included 205 876 individuals aged 2 to 19 years; 104 066 were male (50.5%) and the median age was 12 years. Compared with those with healthy weight, total and OOP expenditures were higher for all other BMI categories. Differences in total expenditures were highest for those with severe obesity ($909; 95% CI, $600-$1218) followed by underweight ($671; 95% CI, $286-$1055) compared with healthy weight. Differences in OOP expenditures were highest for those with severe obesity ($121; 95% CI, $86-$155) followed by underweight ($117; 95% CI, $78-$157) compared with healthy weight. Having underweight was associated with higher total expenditures at ages 2 to 5 years and 6 to 11 years by $679 (95% CI, $228-$1129) and $1166 (95% CI, $632-$1700), respectively; having severe obesity was associated with higher total expenditures at ages 2 to 5 years, 6 to 11 years, and 12 to 17 years by $1035 (95% CI, $208-$1863), $821 (95% CI, $414-$1227), and $1088 (95% CI, $594-$1582), respectively.

Conclusions and Relevance

The study team found medical expenditures to be higher for all BMI categories when compared with those with healthy weight. These findings may indicate potential economic value of interventions or treatments aimed at reducing BMI-associated health risks.

Clinical Features of Transient Growth Hormone Deficiency

Background: Most patients with idiopathic growth hormone deficiency (iGHD) in childhood have normal GH stimulation test results in adulthood. The present study aimed to investigate the characteristics and possible etiology of transient iGHD. Methods: Patients with childhood-onset iGHD who completed their GH treatment between March 2010 and March 2021 were retrospectively studied. Patients with a clear history of child abuse or constitutional delay of growth and puberty were excluded. Ten patients with a diagnosis of iGHD based on a decreased growth rate and growth hormone stimulation test findings at the time of onset were included. Retesting demonstrated that these patients had a normal GH level. Results: Five patients had insufficient weight gain (BMI SD score < −1.0 at the start of treatment or a decrease in BMI SD score > 1.0 from one year before treatment to the start of treatment). The other five patients had no remarkable clinical features. One patient had decreased height velocity at the same time as their sibling. Conclusion: Insufficient pre-treatment weight gain or a familial cluster of cases may be related to low GH peaks of GHST, leading to a diagnosis of transient GHD.

Demographic characteristics of children with growth hormone deficiency from 1996 to 2015 in Japan: 20 years of data from the foundation for growth science in Japan

Growth hormone (GH) deficiency (GHD) in children is a heterogeneous condition that includes several entities of various severities. GH treatment has been affected by various factors. Because comprehensive analyses for Japanese children with GHD over time are scarce, we investigated the baseline characteristics of patients with GHD at the start of GH treatment between 1996 and 2015 using data from the Foundation for Growth Science in Japan. During the registration period, 19,717 subjects were determined to be eligible for GH treatment as GHD. Overall analyses revealed that there were twice the number of male patients as female patients, and the etiology was idiopathic in 91.1%, central nervous system (CNS) tumor at the hypothalamus-pituitary area in 1.7%, CNS tumor distant from the hypothalamus-pituitary area in 0.68%, other tumors in 0.91%, congenital CNS malformations in 0.83%, and other diseases in 1.1% with their specific characteristics. The latest average age, height standard deviation score (SDS), insulin-like growth factor-1 SDS, and proportion of severe GHD at GH treatment initiation were 8.8 years, -2.76, -1.42, and 19.5%, respectively. The proportions of breech delivery and asphyxia gradually decreased, whereas that of caesarean section gradually increased during the registration period with the latest values of 2.2%, 4.9%, and 14.0%, respectively (all analyses: p < 0.0001). In contrast, the proportion of idiopathic GHD with breech delivery seemed to reach the lowest level among those with a birth year before 2000. This study identified the characteristics and changes of patients with GHD over 20 years.

Inclusion and Withdrawal Criteria for Growth Hormone (GH) Therapy in Children with Idiopathic GH Deficiency—Towards Following the Evidence but Still with Unresolved Problems

According to current guidelines, growth hormone (GH) therapy is strongly recommended in children and adolescents with GH deficiency (GHD) in order to accelerate growth rate and attain normal adult height. The diagnosis of GHD requires demonstration of decreased GH secretion in stimulation tests, below the established threshold value. Currently, GHD in children is classified as secondary insulin-like growth factor-1 (IGF-1) deficiency. Most children diagnosed with isolated GHD present with normal GH secretion at the attainment of near-final height or even in mid-puberty. The most important clinical problems, related to the diagnosis of isolated GHD in children and to optimal duration of rhGH therapy include: arbitrary definition of subnormal GH peak in stimulation tests, disregarding factors influencing GH secretion, insufficient diagnostic accuracy and poor reproducibility of GH stimulation tests, discrepancies between spontaneous and stimulated GH secretion, clinical entity of neurosecretory dysfunction, discrepancies between IGF-1 concentrations and results of GH stimulation tests, significance of IGF-1 deficiency for the diagnosis of GHD, and a need for validation IGF-1 reference ranges. Many of these issues have remained unresolved for 25 years or even longer. It seems that finding solutions to them should optimize diagnostics and therapy of children with short stature.

Leptin Does Not Influence TSH Levels in Obese Short Children

INTRODUCTION

Growth hormone (GH) and thyroid hormones are important for children growing. In some obese children a slightly elevated TSH concentration is observed. This may be an adaptive mechanism: stimulation of pro-TRH biosynthesis in the hypothalamus in response to elevated leptin. The increased TSH may also reflect the necessity of maintaining the resting energy expenditure or may be a result of inappropriate, low FT4 concentration. Thus, we evaluated serum TSH and FT4 concentrations in idiopathic short stature (ISS) children (non GH-deficient) and examined the effect of children's nutritional status and levels of selected adipocytokines on thyroid function, searching for the presence of various forms of subclinical hypothyroidism, which may be the cause of the slow growth rate.

METHODS

The study group included 115 children (50 girls and 65 boys) with ISS, aged (mean ± SD) 10.4 ± 3.34 years. In each child, lipids, TSH, FT4, IGF-1, maxGH during the stimulation tests, leptin, adiponectin and resistin concentrations were determined. Based on BMI SDS, 3 subgroups: slim (n=26), obese (n=21) and normal weight (n=68) were distinguished.

RESULTS

There was no correlation between leptin level and TSH, FT4 levels. The levels of leptin, total cholesterol and LDL-cholesterol in obese short children were significantly higher than in children from other subgroups. In turn, the levels of adiponectin, resistin, TSH and FT4 did not differ between subgroups. In 7% of children, an elevated TSH level was found (but less than 10 mIU/L), with a similar frequency across subgroups. The higher the leptin, the lower maxGH in clonidine stimulation test was recorded.

CONCLUSIONS

It seems that in obese children with idiopathic short stature leptin does not increase TSH secretion. This may be related to a disruption of the effect of leptin on TSH production and could indicate wide ranging disturbances of hypothalamic signals, and consequently be the cause of inappropriate GH secretion.