In contrast, eGFR was associated with serum hepcidin level only in patients with advanced (stages 3b–5), but not in early (stage 1–3a), CKD, suggesting that the pathogenesis of elevated serum hepcidin may differ in advanced and early CKD and that decreased renal clearance may significantly contribute to elevated serum hepcidin levels in advanced CKD. Here, HAMP is linked to chronic kidney disease.