Using the non-covariate analysis and Younden’s index, the optimum cut-off value of GDF-15 for diagnosing absolute IDA among CKD participants was 1129.3 mg/dl (at a sensitivity of 83.64%and specificity of 66.03%) Similarly, the optimum cut-off for hepcidin was 22.5 ng/dl (at a sensitivity of 66.7% and specificity of 70.8%); (Supplementary Table 3). The gene discussed is GDF15; the disease is chronic kidney disease.