Table 5. Two studies that analyzed hepcidin as a potential biomarker and/or the correlation between hepcidin and ferritin.

Author	Year	Journal	Setting	Biomarker	Hepcidin / ferritin
Tessitore[36]	2010	Nephrol Dial Transplant.	56 hemodialysis patients, treatment with 1g of IV iron (ferric gluconate), measurement of hepcidin to predict haemoglobin increase after iron treatment and the correlation with markers of the iron status, inflammation and erythropoietic activity, distinction between responders (>1g/dl) and non-responders according Hgb-increase after iron treatment	-	+
Gaillard[37]	2016	PLoS One.	626 patients with non-dialysis CKD and iron deficiency, randomized to IV iron (ferric carboxymaltose) targeting higher or lower ferritin or oral iron, hepcidin measurement in 61 patients. Initial dose of iron was administered on day 0: 1000mg FCM (high ferritin group) and 200mg FCM (low ferritin group) if ferritin was <100μg/l, administration of FCM every four weeks during weeks 4–48 FCM at a dose of 500mg or 1000mg FCM (high ferritin group) depending on the ferritin level and in the low at a dose of 200mg iron (low ferritin group) if ferritin was <100μg/l. Oral iron therapy: ferrous sulfate (100mg iron) twice daily, analysis of correlations between hepcidin and ferritin within each treatment group at weeks 8 and 24, Hgb increase also measured in week 8 and week 24.	-	+

Table 5 lists two studies, that also investigated the potential of hepcidin as a biomarker for the response to iron treatment and/or the correlation between hepcidin and ferritin. Both studies were performed in CKD patients. Both publications did not support hepcidin as a biomarker (-), but indicated a statistically noticeable correlation between hepcidin and ferritin (+).