Patients who undergo transsphenoidal surgery (TSS) experience perioperative hormonal changes, but there are few studies on the perioperative changes of serum and hair steroid profiles. This study investigated the perioperative changes in steroid metabolic signatures in patients with nonfunctioning pituitary adenoma (NFPA) who underwent transsphenoidal surgery (TSS). A total of 55 participants who underwent TSS for NFPA at a single center between July 2017 and October 2018 were enrolled. Fifteen serum steroids and their metabolic ratios were profiled using gas chromatography-mass spectrometry (GC-MS) before and 1 day, 1 week, and 3 months after TSS. Five steroids from hair samples collected 1 day and 3 months after TSS were also quantitatively compared. Serum cortisol and its A-ring reductive metabolites, as well as 6β-hydroxycortisol, increased dramatically 1 day after TSS and then gradually decreased. Seven serum steroids, including adrenal androgens and mineralocorticoids, and hair cortisone levels were significantly lower in patients with preoperative adrenocorticotropic hormone (ACTH) deficiency (N = 7) than in those without ACTH deficiency (N = 48). Serum levels of dehydroepiandrosterone (DHEA) levels 1 week after TSS predicted ACTH deficiency 3 months after TSS, with 100 % sensitivity and 86 % specificity. A significant positive correlation between the preoperative serum and hair DHEA levels (r = 0.356, P = 0.008) was observed. These findings suggest that the levels of DHEA in both the serum and hair could be an early marker of ACTH deficiency after TSS. In addition, hair cortisone may be a useful preoperative indicator of chronic ACTH deficiency.