Evaluation of iron stores in hemodialysis patients on maintenance ferric Carboxymaltose dosing.

BACKGROUND: Iron is administered intravenously (IV) to many dialysis patients at regular intervals and iron stores are evaluated through periodic measurements of ferritin and transferrin saturation (TSAT). In patients without kidney diseases, large single doses of IV iron lead to a transient rise in serum ferritin that does not reflect iron stores. It is not known whether and to what extent smaller IV iron doses used to maintain adequate stores in hemodialysis patients lead to transient spurious elevations of ferritin and TSAT. METHODS: Ferritin and TSAT were serially determined over four weeks after the administration of ferric carboxymaltose (FCM) in hemodialysis patients on a stable maintenance FCM dosing regimen of 100 mg or 200 mg every four weeks. RESULTS: Ferritin values increased by 113 ± 72.2 µg/l (P < 0.001) from baseline to the peak value and remained significantly elevated until two weeks after the administration of 100 mg FCM (n = 19). After the administration of 200 mg FCM (n = 12), ferritin values increased by 188.5 ± 67.56 µg/l (P < 0.001) and remained significantly elevated by the end of week three. TSAT values increased by 12.0 ± 9.7% (P < 0.001) and 23.1 ± 20.4% (P = 0.002) in patients receiving 100 or 200 mg FCM, respectively, and returned to baseline within four days. CONCLUSIONS: IV administration of FCM at doses of 100 or 200 mg in hemodialysis patients leads to dose-dependent transient ferritin elevations of extended duration. Temporal coordination of blood sampling for iron status evaluation with the maintenance IV iron dosing schedule is advisable. TRIAL REGISTRATION: ISRCTN12825165 (retrospectively registered 01/02/2019).