Dexamethasone Stimulation Test in the Diagnostic Work-Up of Growth Hormone Deficiency in Childhood: Clinical Value and Comparison With Insulin-Induced Hypoglycemia

Should Pediatric Endocrinologists Consider More Carefully When to Perform a Stimulation Test?

INTRODUCTION

Pediatric endocrinology rely greatly on hormone stimulation tests which demand time, money and effort. The knowledge of the pattern of pediatric endocrinology stimulation tests is therefore crucial to optimize resources and guide public health interventions. Aim of the study was to investigate the distribution of endocrine stimulation tests and the prevalence of pathological findings over a year and to explore whether single basal hormone concentrations could have saved unnecessary stimulation tests.

METHODS

Retrospective study with data collection for pediatric endocrine stimulation tests performed in 2019 in a tertiary center.

RESULTS

Overall, 278 tests were performed on 206 patients. The most performed test was arginine tolerance test (34%), followed by LHRH test (24%) and standard dose Synachthen test (19%), while the higher rate of pathological response was found in insulin tolerance test to detect growth hormone deficiency (81%), LHRH test to detect central precocious puberty (50%) and arginine tolerance test (41%). No cases of non-classical-congenital adrenal hyperplasia were diagnosed. While 29% of growth hormone deficient children who performed an insulin tolerance test had a pathological peak cortisol, none of them had central adrenal insufficiency confirmed at low dose Synacthen test. The use of basal hormone determinations could save up to 88% of standard dose Synachthen tests, 82% of arginine tolerance + GHRH test, 61% of LHRH test, 12% of tests for adrenal secretion.

CONCLUSION

The use of single basal hormone concentrations could spare up to half of the tests, saving from 32,000 to 79,000 euros in 1 year. Apart from basal cortisol level <108 nmol/L to detect adrenal insufficiency and IGF-1 <-1.5 SDS to detect growth hormone deficiency, all the other cut-off for basal hormone determinations were found valid in order to spare unnecessary stimulation tests.

Whole Exome Sequencing Uncovered the Genetic Architecture of Growth Hormone Deficiency Patients

PURPOSE

Congenital growth hormone deficiency (GHD) is a rare and etiologically heterogeneous disease. We aim to screen disease-causing mutations of GHD in a relatively sizable cohort and discover underlying mechanisms via a candidate gene-based mutational burden analysis.

METHODS

We retrospectively analyzed 109 short stature patients associated with hormone deficiency. All patients were classified into two groups: Group I (n=45) with definitive GHD and Group II (n=64) with possible GHD. We analyzed correlation consistency between clinical criteria and molecular findings by whole exome sequencing (WES) in two groups. The patients without a molecular diagnosis (n=90) were compared with 942 in-house controls for the mutational burden of rare mutations in 259 genes biologically related with the GH axis.

RESULTS

In 19 patients with molecular diagnosis, we found 5 possible GHD patients received known molecular diagnosis associated with GHD (NF1 [c.2329T>A, c.7131C>G], GHRHR [c.731G>A], STAT5B [c.1102delC], HRAS [c.187_207dup]). By mutational burden analysis of predicted deleterious variants in 90 patients without molecular diagnosis, we found that POLR3A (p = 0.005), SUFU (p = 0.006), LHX3 (p = 0.021) and CREB3L4 (p = 0.040) represented top genes enriched in GHD patients.

CONCLUSION

Our study revealed the discrepancies between the laboratory testing and molecular diagnosis of GHD. These differences should be considered when for an accurate diagnosis of GHD. We also identified four candidate genes that might be associated with GHD.