A previous study by our group reported a prevalence of acute stress-related CAI of 60% in 25 children with PWS (median age 9.7 years) during an overnight single-dose metyrapone (MTP) test, based on an adrenocorticotropic hormone (ACTH) peak cutoff of < 33 pmol/L, according to Steiner et al (13). Here, POMC is linked to Prader-Willi syndrome.