Copeptin Response to Clonidine Stimulation in Healthy Children

Aim: The aim of this study was to evaluate whether clonidine, a centrally acting alpha-2-adrenergic agonist widely used in pediatric endocrinology for growth hormone (GH) stimulation testing, also induces copeptin release in children.Since copeptin is a stable, easily measurable marker of vasopressin, its stimulation could offer a practical diagnostic approach for distinguishing diabetes insipidus (DI) from primary polydipsia. Materials and Methods:We conducted a prospective diagnostic pilot study including ten otherwise healthy children (age 3-14 years) undergoing standardized clonidine stimulation testing for suspected GH deficiency.Following oral administration of clonidine, serial blood samples were collected at predefined intervals in order to measure plasma GH and copeptin concentrations.Additionally, blood pressure and heart rate were continuously monitored in order to assess hemodynamic effects and overall tolerability.Adverse events and subjective tolerability were documented systematically.Results: Administration of clonidine led to a significant reduction in systolic and diastolic blood pressure in all participants.However, contrary to expectations, copeptin levels decreased significantly in all subjects (p=0.013).No serious adverse events occurred, and overall tolerability of the test was rated as high, in line with clinical experience.Conclusion: Contrary to the initial hypothesis, clonidine does not stimulate copeptin secretion in children and is unsuitable as a diagnostic tool for DI.Nevertheless, its high tolerability and consistent copeptin suppression warrant further exploration of its neuroendocrine effects.