Bologna K, Cesana-Nigro N, Refardt J, et al. - Researchers conducted this prospective study to examine the impact of arginine on adrenocorticotropic hormone (ACTH) and cortisol in individuals with and without vasopressin deficiency. Participants in the study were 38 patients with central diabetes insipidus, 58 patients with primary polydipsia, and 50 healthy controls. Findings suggested an association of diabetes insipidus with increased responsiveness of ACTH/cortisol to arginine. Conversely, in healthy controls or in primary polydipsia, arginine does not stimulate the hypothalamic–pituitary–adrenal axis.