Diagnosis of Growth Hormone Deficiency in Children: Comparative Performance of Arginine Versus Glucagon as the First Stimulation Test

OBJECTIVE: Growth hormone deficiency (GHD) diagnosis typically requires the performance of two sequential stimulation tests. Glucagon stimulation test (GST) and arginine stimulation test (AST) are widely used. This study aimed to determine the most suitable order of tests. DESIGN: A retrospective study comparing GST-first group and AST-first group. PATIENTS: Children aged 1 to 17 years with suspected GHD who underwent testing between 2017 and 2022 using either GST or the AST initially. Exclusion criteria included patients with genetic syndromes or obesity and those who performed the tests more than 6 months apart. MEASUREMENTS: In order to determine the optimal order of tests, the study calculated the error rate of the first test in light of the final diagnosis after the second test using a peak GH cut-off 7.5 ng/mL. Variables such as sex, age, BMI, and socioeconomic status were analysed for their influence on outcomes. RESULTS: A total of 881 children were included. Based on the initial GHST performed, the study population was divided into two subgroups: GST-first group (712 subjects) and AST-first group (171 subjects). The proportion of discordant results was significantly lower in the GST-first group - 37.4% compared to 50.7% in the AST -first group (p = 0.048). In stepwise logistic regression none of the examined characteristics such as gender, age, BMI, priming of sex hormones prior to the tests or socioeconomic status demonstrated a statistically significant effect on the probability of discordant results in our study. CONCLUSIONS: This study demonstrated that GST is associated with a lower rate of discordant results compared to AST and potentially reduces the need for a second test, minimising patient inconvenience, lowering healthcare expenses, and decreasing time-consuming hospital visits for families.