Abstract 191: Role of IGF-1 as a predictor of outcomes for GH-stimulation testing

Traditionally pharmacological Growth Hormone Stimulation Tests (GHSTs) have been used to distinguish true GHD from ISS and CDGP in pediatric endocrine clinics. However these tests are not physiological and subject the patients to unnecessary stress of multiple samplings and risk of hemodynamic instability. Various clinical and biochemical findings if studied appropriately can predict the need to perform GHSTs in such patients and minimize unnecessary testing. Aim: To study the role of IGF-1 levels as a predictor of and positive GHSTs in children and adolescents presenting with short stature (SS). Materials and Methods: Medical records of children and adolescents presenting with SS were retrieved and their demographic data, IGF-1 centiles and results of GHSTs were studied. A positive GHST was taken as peak GH level (<7 ng/ml). Correlation of IGF-1 centile for chronological age and bone age with GHST results was studied and ROC curves were drawn to study the sensitivity and specificity of IGF-1 centiles in predicting positive GHST. Results: Data of 199 patients presenting with growth failure from 1st January 2010 to 31st March 2021 was collected. 65 females and 134 males were included. Mean age of the cohort was 11 years 4months and mean IGF-1 level was 132.8ng/ml. 166 patients had IGF-1 levels < 30th centile for chronological age. The remainder 33 patients who had IGF-1 centiles > 30th centile for chronological age consistently had negative GHST thus indicating unnecessary pharmacological testing. Conclusion: GHSTs can thus be avoided in children who have IGF-1 centile >30th centile for chronological age and thus avoid unnecessary stress and risk to the patients.