HAMP and chronic kidney disease: Serum ferritin (r = 0.5, P-value < 0.0001), and serum creatinine levels (r = 0.21, P-value = 0.0368) were positively correlated with hepcidin, while GFR (r = − 0.19, P-value = 0.0493) was negatively correlated with hepcidin among the participants with CKD, supplementary Table 1.