Hepcidin--a potential novel biomarker for iron status in chronic kidney disease.

BACKGROUND AND OBJECTIVES Hepcidin is a key regulator of iron homeostasis, but its study in the setting of chronic kidney disease (CKD) has been hampered by the lack of validated serum assays. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS This study reports the first measurements of bioactive serum hepcidin using a novel competitive ELISA in 48 pediatric (PCKD2-4) and 32 adult (ACKD2-4) patients with stages 2 to 4 CKD along with 26 pediatric patients with stage 5 CKD (PCKD5D) on peritoneal dialysis. RESULTS When compared with their respective controls (pediatric median = 25.3 ng/ml, adult = 72.9 ng/ml), hepcidin was significantly increased in PCKD2-4 (127.3 ng/ml), ACKD2-4 (269.9 ng/ml), and PCKD5D (652.4 ng/ml). Multivariate regression analysis was used to assess the relationship between hepcidin and indicators of anemia, iron status, inflammation, and renal function. In PCKD2-4 (R(2) = 0.57), only ferritin correlated with hepcidin. In ACKD2-4 (R(2) = 0.78), ferritin and soluble transferrin receptor were associated with hepcidin, whereas GFR was inversely correlated. In PCKD5D (R(2) = 0.52), percent iron saturation and ferritin were predictors of hepcidin. In a multivariate analysis that incorporated all three groups (R(2) = 0.6), hepcidin was predicted by ferritin, C-reactive protein, and whether the patient had stage 5D versus stages 2 to 4 CKD. CONCLUSIONS These findings suggest that increased hepcidin across the spectrum of CKD may contribute to abnormal iron regulation and erythropoiesis and may be a novel biomarker of iron status and erythropoietin resistance.