Control subjects were outpatients of the Pediatric Surgery Unit of the Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico - Milan, Italy, aged 1-20 years, who underwent a blood sample collection before a surgical intervention for the treatment of minor diseases that did not impair renal or endocrine function (i.e. phimosis, hydrocele, inguinal hernia).