Background Adult growth hormone deficiency (AGHD) is often diagnosed after surgery for nonfunctioning pituitary neuroendocrine tumor (NF‐PitNET). While a growth hormone stimulation test (GHST) is required to establish its diagnosis, it is associated with a large burden on patients and healthcare providers alike. Currently, the recommended indicators for the diagnosis of AGHD include the IGF‐1 standard deviation score (IGF‐1SDS) from a random blood sample and the number of deficiencies in pituitary hormones other than GH; however, there are also some challenges associated with these indicators. Therefore, to predict the need for GHST, this study focused on the interrelationship between GH and pituitary hormones to investigate whether postoperative thyroid‐stimulating hormone (TSH), free triiodothyronine (FT3), and free thyroxine (FT4) levels measured before GHST could represent novel predictors of AGHD. Methods Among 166 patients who underwent GHST following surgical treatment for NF‐PitNET, 60 patients who were diagnosed with NF‐PitNET based on clinical and pathological criteria were included in this analysis. Exclusion criteria were as follows: missing data ( n = 16), data collection outside the specified timeframe ( n = 4), positive thyroid autoantibodies ( n = 2), and oral levothyroxine administration during GHST ( n = 3). Clinical parameters of the 35 patients were compared between the AGHD group ( n = 11) and the non‐AGHD group ( n = 24) using Fisher’s exact test and Mann–Whitney U test. Results Patients with AGHD showed significantly lower postoperative levels of FT3 and FT4 prior to GHST, with median values of 2.10 pg/mL (1.97–2.34) and 0.98 ng/dL (0.77–1.19), respectively, than those without postoperative AGHD, who showed median levels of 2.45 pg/mL (2.28–2.67) and 1.18 ng/dL (1.03–1.26) ( p < 0.001 and p = 0.008, respectively). In contrast, no significant difference in TSH levels was observed between the two groups. Receiver operating characteristic (ROC) analysis identified the optimal cutoff values for predicting AGHD as 2.125 pg/mL for FT3 and 1.010 ng/dL for FT4. Conclusion These findings suggest the potential utility of FT3 and FT4 as novel predictors for the diagnosis of postoperative AGHD.
Tsujimoto et al. (Thu,) studied this question.