BDNF and chronic kidney disease: Although the prevalence of CKD was significantly associated with the quartiles of BDNF levels at 120 min (P value for trend = 0.004, Additional file 4: Table S3), the OR of CKD in the highest quartile of BDNF levels at 120 min (0.47, 95% CI 0.21‒1.06) was not significantly different from that in the lowest quartile after adjustment for associated risk factors (Additional file 5: Table S4, Additional file 1: Fig. S1c).