IDO1 and pituitary gland adenoma: According to the model results, IDO (ng/mL) (OR = 2.736, 95% CI: 1.223–6.122, p = 0.014), kynurenic acid (ng/mL) (OR = 1.155, 95% CI: 1.031–1.293, p = 0.013), and kynurenine (ng/mL) (OR = 1.104, 95% CI: 0.992–1.229, p = 0.009) levels were determined to be statistically significant and independent predictors of pituitary adenoma.