A randomized controlled trial comparing oral and intravenous iron supplementation after Roux-en-Y gastric bypass...

Iron deficiency (ID) is one of the most common postoperative deficiencies that may develop after Roux-en-Y gastric bypass (RYGB). The optimal mode of treatment is uncertain.

To compare the efficacy of oral ferrous fumarate (FF), oral ferrous gluconate (FG), and a single intravenous infusion of ferric carboxymaltose (FCM) in women with ID after RYGB.

Multicenter randomized controlled trial including 120 women with a serum ferritin <20 μg/l during follow-up after RYGB. They were randomized into three groups: 41 patients were treated with FF 200 mg three times a day (total daily dose: 195 mg elemental iron), 39 received FG 695 mg twice a day (total daily dose: 160 mg elemental iron) for three months, and 39 patients were treated with a single intravenous dose of FCM (1000 mg elemental iron). Serum ferritin levels were measured at six weeks, and three, six and twelve months after the start of supplementation.

At three months, persistence of ID was observed in 29.4% and 42.4% of the patients treated with FF and FG, respectively, but in none of those treated with FCM (p < 0.001). Over the next nine months, recurrence of ID was observed in 56.5% of patients treated with FF, in 52.9% treated with FG, and in 27.8% of those treated with FCM. Adverse effects were most common during oral treatment.

In women developing ID after RYGB, a single dose of intravenous FCM is more effective and better tolerated than the standard treatment with either FF or FG.

The study was registered at clinicaltrials.gov under number NCT02271997.