Prophylactic iron supplementation after Roux-en-Y gastric bypass: a prospective, double-blind, randomized study.

Objective: To determine whether prophylactic oral iron supplements (320 mg twice daily) would protect women from iron deficiency and anemia after Roux-en-Y gastric bypass.

Design: Prospective, double-blind, randomized study in which 29 patients received oral iron and 27 patients received a placebo beginning 1 month after Roux-en-Y gastric bypass.

Setting: Tertiary care medical center.

Patients And Interventions: Complete blood cell count and serum levels of iron, total iron binding capacity, ferritin, vitamin B12, and folate were determined preoperatively and at 6-month intervals postoperatively in 56 menstruating women who had Roux-en-Y gastric bypass.

Main Outcome Measure: Incidence of iron deficiency and other hematological abnormalities in each treatment group.

Results: Hemoglobin, hematocrit, and vitamin B12 levels were significantly decreased compared with preoperative values in both groups. Conversely, folate levels increased significantly over time in both groups. Oral iron consistently prevented development of iron deficiency in the iron group. Ferritin levels did not change significantly in the iron group. However, in placebo-treated patients, ferritin levels 2 years postoperatively were significantly decreased compared with preoperative levels. There was no difference in the incidence of anemia between the 2 groups. However, the incidence of microcytosis was substantially greater (P=.07) in placebo-treated than iron-treated patients.

Conclusions: Prophylactic oral iron supplements successfully prevented iron deficiency in menstruating women after Roux-en-Y gastric bypass but did not consistently protect these women from developing anemia. On the basis of these results we now routinely recommend prophylactic iron supplements to menstruating women who have Roux-en-Y gastric bypass.