Reliability of clonidine testing for the diagnosis of growth hormone deficiency in children and adolescents

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).

Evaluation of Adult Height in Patients with Non-Permanent Idiopathic GH Deficiency

Background: Several studies have evaluated the role of IGF-1 in the diagnosis of growth hormone deficiency (GHD). According to a recent study, an IGF-1 concentration of a −1.5 standard deviation score (SDS) appeared to be the best cut-off for distinguishing between children with GHD and normal children. This value should always be interpreted in conjunction with other clinical and biochemical parameters for the diagnosis of GHD, since both stimulation tests and IGF-1 assays have poor diagnostic accuracy by themselves. Our study was designed to evaluate the adult height (AH) in children with short stature and baseline IGF-1 concentration ≤ −1.5 SDS. Design: This retrospective analysis included 52 children and adolescents evaluated over the last 30 years for short stature and/or deceleration of the growth rate who underwent diagnostic procedures to evaluate a possible GHD. Only the patients who had baseline IGF-1 values ≤−1.5 SDS at the time of the first test were included in the study. Patients with genetic/organic GHD or underlying diseases were not included. Method: The case group consisted of 24 patients (13 boys and 11 girls) with non-permanent, idiopathic, and isolated GHD (peak GH < 10 μg/L after two provocative tests with arginine (Arg), insulin tolerance test (ITT), and clonidine (Clo), or <20 μg/L after GHRH + Arginine (GHRH+Arg); normal MRI; normal GH; and/or normal IGF-1 concentrations at near-AH). These patients were treated with GH (25–35 μg/kg/die) until near-AH. The control group consisted of 28 patients (23 boys and 5 girls) with idiopathic short stature (ISS, normal peak GH after provocative testing, no evidence of other causes for their shortness). Both groups had basal IGF-1 ≤−1.5 SDS. Results: AH and height gain in both groups were comparable. In the group of cases, mean IGF-1 SDS at the time of diagnosis was significantly lower than the levels found at the time of retesting. Conclusions: In this study, both treated patients with idiopathic GHD and untreated patients with ISS reached similar near-AHs (within target height) and showed similar increases in SDS for their height. Thus, the efficacy of treatment with rhGH in these patients may be questionable. This could be due to the fact that children with ISS are frequently misdiagnosed with GHD.

Growth hormone responses during arginine and clonidine stimulation test: Correlations with patients' auxological and metabolic parameters in a single centre study

BACKGROUND

Children with auxological parameters defining a 'short stature' is routinely subjected to various blood tests and, if necessary, to growth hormone stimulation test (GHST) for differentiating GH deficiency (GHD) and other causes of stunted growth.

AIM

This retrospective monocentric study aimed to evaluate any correlations between GH peaks during GHST in children assessed for short stature and their auxological/metabolic parameters, highlighting differences between GHD and idiopathic short stature.

PATIENTS AND METHODS

We reviewed the medical records of 74 children with short stature (height lower than the third percentile according to standardized growth curves for the Italian population) managed at the Pediatric Day Hospital of our Department of Life Sciences and Public Health in Università Cattolica Sacro Cuore, Rome, who performed at least two GHSTs, using arginine and clonidine as stimulants, for assessment of GH secretion. The results of a total number of 161 GHSTs, performed in 42 children diagnosed with GHD and in 32 children with other causes of short stature, were analyzed.

RESULTS

We found significantly lower serum levels of insulin growth factor-1 (IGF-1) and increased levels of thyroid-stimulating hormone (TSH) in children with GHD, without other metabolic differences in comparison to children with other causes of short stature. There was also a correlation between triglycerides and GH peak during arginine test, while fT4 and LDL concentrations correlated with GH peak during the third test, if performed. Pre-test BMI (rho -0.274, p = 0.01) and weight (rho -0.251, p = 0.03) have influenced GH peak during clonidine stimulation test. Metabolic and auxological parameters could influence GH peak during clonidine and arginine stimulation tests and must be taken into account when interpreting GHST results.

Diagnosis of Growth Hormone Deficiency in Children: The Efficacy of Glucagon versus Clonidine Stimulation Test

INTRODUCTION

The diagnosis of childhood growth hormone deficiency (GHD) requires a failure to respond to 2 GH stimulation tests (GHSTs) performed with different stimuli. The most commonly used tests are glucagon stimulation test (GST) and clonidine stimulation test (CST). This study assesses and compares GST and CST's diagnostic efficacy for the initial evaluation of short children.

METHODS

Retrospective, single-center, observational study of 512 short children who underwent GHST with GST first or CST first and a confirmatory test with the opposite stimulus in cases of initial GH peak <7.5 ng/mL during 2015-2018. The primary outcome measure was the efficacy of the GST first or CST first in diagnosing GHD.

RESULTS

Population characteristics include median age of 9.3 years (interquartile range 6.2, 12.1), 78.3% prepubertal, and 61% boys. Subnormal GH response in the initial test was recorded in 204 (39.8%) children: 148 (45.5%) in GST first and 56 (30%) in CST first, p < 0.001. Confirmatory tests verified GHD in 75/512 (14.6%) patients. Divergent results between the initial and confirmatory tests were more prevalent in GST first than CST first (103/148 [69.6%] vs. 26/56 [46.4%], p < 0.001) indicating a significantly lower error rate for the CST first compared to the GST first. In multivariate analysis, the only significant predictive variable for divergent results between the tests was the type of stimulation test (OR = 0.349 [95% CI 0.217, 0.562], p < 0.001).

CONCLUSIONS

Screening of GH status with CST first is more efficient than that with GST first in diagnosing GHD in short children with suspected GHD. It is suggested that performing CST first may reduce the need for a second provocative test and avoid patients' inconvenience of undergoing 2 serial tests.

The inter - Test variability of growth hormone stimulation tests and factors affecting this variability

OBJECTIVE

To evaluate the variability of growth hormone stimulation tests results and factors affecting it in short children suspected of having growth hormone deficiency.

DESIGN

The cohort included patients with short stature suspected of having growth hormone deficiency, and who underwent a second stimulation test, after the first stimulation test was positive. Testing was done at a single center from May 2014 to October 2017. Patients' weight, height, age, sex, stimulating agents and test results were recorded.

RESULTS

The study population comprised 200 patients, 108 males and 92 females, average age 9.2 years (2.2-16.6 years). The average peak growth hormone was 5.2 μg/L and 7.8 μg/L in the first and second tests respectively and the concordance rate was 56.5%. The probability of a second positive test was increased if the peak growth hormone level in the first test was below 5 μg/L. In the second test, Clonidine and Glucagon led to higher peak growth levels than Arginine with averages of 9.02, 9.97 and 6.88 μg/L respectively. Younger children and children with higher BMI SDS only had lower peaks of growth hormone in the second test. The effect of height SDS on peak growth hormone levels was equivocal.

CONCLUSION

The reproducibility rate of GH simulation tests in our study was low. A few factors may affect the peak levels of growth hormone in the second test, the most prominent being the peak of growth hormone in the first test.

The spectrum of clinical and subclinical endocrinopathies in treatment-naïve patients with celiac disease

INTRODUCTION

Strong association exists between celiac disease and autoimmune endocrinopathies such as type I diabetes and hypothyroidism; there is a lack of data on the involvement of other endocrine organs such as pituitary-gonadal axis. Furthermore, there is lack of data on the spectrum of involvement of endocrine organs varying from organ autoimmunity to subclinical and clinical disease. We evaluated consecutive treatment-naïve patients with celiac disease (CeD) for clinical and subclinical endocrinopathies.

METHODS

Of 154 screened, 74 treatment-naïve patients with CeD were recruited. They underwent hormonal and/or functional assessment of beta cell of pancreas, thyroid gland, pituitary-gonadal axis, and parathyroid glands.

RESULTS

Of the 74 patients with CeD, 31 (41.9%) had at least one clinical or subclinical endocrinopathy and 9 (12.2%) had multiple endocrinopathies. Most common of them were clinical or subclinical type I diabetes and autoimmune thyroid disease. Interestingly, 8 (10.8%) patients also were found to have functional hypopituitarism and 7/54 (12.9%) having isolated hypogonadotropic hypogonadism.

CONCLUSIONS

Patients with CeD have high percentages of not only clinical endocrinopathy including pituitary-gonadal axis dysfunction but also subclinical endocrinopathy. Whether commencement of gluten-free diet will lead to reversal of subclinical endocrinopathies requires further follow up studies.

Diagnosis of Idiopathic GHD in Children Based on Response to rhGH Treatment: The Importance of GH Provocative Tests and IGF-1

Purpose: Serum IGF-1 (Insulin like growth factor 1) and Growth Hormone (GH) provocative tests are reasonable tools for screening and diagnosis of idiopathic GH Deficiency (IGHD). However, the average cut-off points applied on these tests have a lower level of evidence and produce large amounts of false results. The aim of this study is to evaluate the sensitivity, specificity, and accuracy of IGF-1 and GH stimulation tests as diagnostic tools for IGHD, using clinical response to recombinant human GH (rhGH) treatment as diagnostic standard [increase of at least 0.3 in height standard deviation (H-SD) in 1 year]. Methods: We performed a prospective study with 115 children and adolescents presenting short stature (SS), without secondary SS etiologies such as organic lesions, genetic syndromes, thyroid disorders. They were separated into Group 1 [patients with familial SS or constitutional delay of growth and puberty (CDGP), not treated with rhGH], Group 2 (patients with suspicion of IGHD with clinical response to rhGH treatment), and Group 3 (patients with suspicion of IGHD without growth response to rhGH treatment). Then, they were assessed for diagnostic performance of IGF-1, Insulin Tolerance Test (ITT) and clonidine test (CT) alone and combined at different cut-off points. Results: Based on the ROC curve, the best cut-off points found for IGF-1, ITT, and CT when they were used isolated were -0.492 SDS (sensitivity: 50%; specificity: 53.8%; accuracy: 46.5%), 4.515 μg/L (sensitivity: 75.5%; specificity: 45.5%; accuracy: 52.7%), and 4.095 μg/L (sensitivity: 54.5%; specificity: 52.6%; accuracy: 56.9%), respectively. When we had combined IGF-1 with-2SD as cut-off alongside ITT or CT, we found 7 μg/L as the best cut-off point. In this situation, ITT had sensitivity, specificity and accuracy of 93.9, 81.8, and 90.1%, while CT had 93.2, 68.4, and 85.7%, respectively. Conclusion: Our data suggest that diagnosis of IGHD should be established based on a combination of clinical expertise, auxologic, radiologic, and laboratorial data, using IGF-1 at the -2SD threshold combined, with ITT or CT at the cut-off point of 7 μg/L. Additional studies, similar to ours, are imperative to establish cut-off points based on therapeutic response to rhGH in IGHD, which would be directly related to a better treatment outcome.