GHSR and pituitary tumor: A high correlation between the GHRP-2 test and the insulin tolerance test (ITT) (r = 0.8745, P < 0.0001) has been reported in adult preoperative Japanese patients with pituitary tumors [16], and although the GHRP-2 test has been approved in Japan, it is not recommended in the guidelines of the Endocrine Society [14].