Anemia after Roux-en-Y gastric bypass. How feasible to eliminate the risk by proper supplementation?

Obes Surg. 2015 Jan;25(1):80-4. doi: 10.1007/s11695-014-1356-1.


Background: Anemia after Roux-en-Y gastric bypass (RYGB) has been reported in 5 to 64 % of patients. Since absorption of specific elements is reduced, proper supplementation is mandatory. The aim of this study was to investigate the frequency of anemia, its causes, and the related deficiencies during the 1st postoperative year after RYGB.

Methods: A retrospective review of our prospectively collected database was performed. A total of 486 patients who underwent RYGB in a 5-year period and completed at least 1-year follow-up were included. Daily supplements as suggested by the AACE/TOS/ASMBS guidelines were routinely prescribed. Blood count, iron profile, folic acid, and B12 measurements 1 year after surgery were reviewed.

Results: One hundred ninety-five males and 291 females were included, with a mean age of 39.9 ± 11.6 years and a mean body mass index (BMI) of 42.4 ± 6.3 kg/m(2). Anemia 1 year after surgery was found in 19 patients (4 %), 6 males and 13 females. In seven women, it was related to iron deficiency. Two additional women had iron deficiency combined with low vitamin B12. Anemia was secondary to inflammation in two and indeterminate in two. In the six males, the cause of anemia was inflammation in three and indeterminate in three. Abnormal bleeding was found in five of these patients.

Conclusions: Frequency of anemia 1 year after RYGB in our population was low (4 %). Anemia non-attributable to malabsorption was frequently present (n = 9/19). Iron deficiency was found exclusively in women. The most common non-malabsorptive types of anemia were inflammation and dysfunctional uterine bleeding.

MeSH terms

  • Adult
  • Anemia / epidemiology
  • Anemia / etiology*
  • Anemia / prevention & control*
  • Body Mass Index
  • Dietary Supplements*
  • Feasibility Studies
  • Female
  • Folic Acid / blood
  • Gastric Bypass / adverse effects*
  • Humans
  • Iron / deficiency
  • Iron / therapeutic use*
  • Male
  • Middle Aged
  • Obesity, Morbid / blood
  • Obesity, Morbid / epidemiology
  • Obesity, Morbid / surgery*
  • Postoperative Complications / epidemiology
  • Postoperative Complications / prevention & control
  • Postoperative Period
  • Retrospective Studies
  • Vitamin B 12 / blood


  • Folic Acid
  • Iron
  • Vitamin B 12