As shown in Fig. 1, the area under the ROC curve for differentiating CKD was largest using fasting BDNF (0.645, 95% CI: 0.583‒0.707) compared to BDNF at 30 min (0.547, 95% CI: 0.481‒0.612), BDNF at 120 min (0.598, 95% CI: 0.536‒0.661), and the AUC of BDNF (0.599, 95% CI: 0.537‒0.660). The gene discussed is BDNF; the disease is chronic kidney disease.