Ferric citrate may improve transferrin saturation (TSAT) and ferritin concentrations better than ferrous sulfate in patients with chronic kidney disease (CKD).

In a trial (NCT02888171), investigators randomly assigned 60 patients with moderate to severe CKD (estimated glomerular filtration rate [eGFR] of 15 to 45 mL/min/1.73 m2) and iron deficiency (TSAT of 30% or less and ferritin of 300 ng/mL or less) to ferric citrate (2 g thrice daily orally with meals as a phosphate binder) or ferrous sulfate (325 mg thrice daily orally) for 12 weeks. At the end of the intervention, mean TSAT had increased a significant 8% more (P =.02) and ferritin a significant 37 ng/mL more (P =.009) in the ferric citrate than ferrous sulfate group, Orlando Marti Gutiérrez, MD, of the University of Alabama at Birmingham and colleagues reported in the Clinical Journal of the American Society of Nephrology. Ferric citrate also significantly increased mean hepcidin levels by 69 pg/mL more than ferrous sulfate (P =.03).

Mean change in hemoglobin, intact fibroblast growth factor 23 (FGF23), or C-terminal FGF23 did not differ significantly between groups. Serum phosphate levels did not change. By design, patients with severe anemia, defined as hemoglobin less than 8.0 g/dL in men and 7.0 g/dL in women were excluded from the study.

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Ferric citrate contains 210 mg and ferrous sulfate 65 mg of elemental iron per tablet, which might explain the difference in iron increases, according to the investigators.

“These findings add to the current literature by showing that oral ferric citrate not only increases circulating TSAT and ferritin in patients with CKD, but it appears to do so more effectively than ferrous sulfate, the most commonly used oral iron supplement,” Dr Gutiérrez’s team stated. They acknowledged that the clinical implications and relative costs of ferric citrate therapy for iron deficiency anemia of CKD still require further study.

More patients in the ferric citrate group experienced gastrointestinal symptoms such as nausea, diarrhea, constipation, and change in stool color. Otherwise, adverse events did not differ markedly between treatment arms.

Disclosure: This clinical trial was supported by Keryx Biopharmaceuticals, Inc., the makers of ferric citrate (Auryxia®) Please see the original reference for a full list of authors’ disclosures.


Womack R, Berru F, Panwar B, Gutiérrez OM. Effect of ferric citrate versus ferrous sulfate on iron and phosphate parameters in patients with iron deficiency and CKD: a randomized trial. Clin J Am Soc Nephrol. Published online July 21, 2020. doi:10.2215/CJN.15291219