Gastric bypass is a highly effective procedure for achieving weight loss, but it is associated with multiple nutritional deficiencies. Iron is an essential component of hemoglobin, the oxygen-carrying protein in red blood cells. Depletion of the body's iron stores will impair the production of hemoglobin, which results in anemia. Iron deficiency and anemia are among the most common nutritional complications of gastric bypass surgery.
Frequency
Iron deficiency develops in approximately 50 percent of gastric bypass patients, and is associated with anemia in a third of cases. It can occur within a few months or several years after surgery, and is far more common in women than in men. A study in the "Journal of Gastric Surgery" in 1998 found postoperative iron deficiency in 51 percent of women, compared to 22 percent of men. Pregnant women and those with heavy menstrual periods are at highest risk.
Causes
Gastric bypass surgery creates a small stomach pouch which is attached to a lower portion of the small intestine. As a result, ingested food bypasses most of the stomach and the first part of the small intestine, where most iron is absorbed. Bypass of the main iron absorption site is the primary cause of iron deficiency.
Acid in the stomach normally releases iron from food and converts it to a more absorbable form. Markedly reduced acid production by the small gastric pouch decreases iron absorption. Diminished intake of iron-rich foods may also contribute to iron deficiency. Red meat is a major source of iron in the diet, but is difficult to digest and poorly tolerated after surgery.
Diagnosis
Iron deficiency develops in stages, beginning with the depletion of stored iron. The diagnosis requires multiple blood tests. Ferritin is a protein that stores iron in the body. A low ferritin level in the blood indicates depleted iron reserves. Several other tests measure the amount of iron in the blood, and the portion carried by a transport protein called transferrin.
Anemia is a deficiency of red blood cells, and a late stage of iron deficiency. A complete blood count, or CBC, checks the hemoglobin level, the number of red blood cells, and the mean cell volume, a measure of the average red cell size. These values are all low in iron-deficiency anemia.
Prevention
Periodic screening for iron deficiency and anemia is important after gastric bypass. Blood tests are performed more frequently during the first year, then at least annually. A daily multivitamin is recommended for all patients. However, the 10 mg to 20 mg of iron in a multivitamin is often not enough to prevent deficiency. Those at high risk require an extra iron supplement. A 1998 study in "Archives of Surgery" showed that a 100 mg supplement prevented iron deficiency after gastric bypass in menstruating women. In contrast, iron deficiency developed in a third of women who took a multivitamin alone.
Treatment
Iron deficiency is treated with supplemental iron. Oral supplements are most commonly prescribed, often with vitamin C, which increases absorption. The relatively high iron doses required after gastric bypass frequently cause gastrointestinal side effects such as nausea, heartburn, diarrhea or constipation. Oral iron supplements are sometimes ineffective after surgery, especially when iron deficiency anemia is severe. Gastric bypass patients often do not absorb iron pills. A study in the "American Journal of Clinical Nutrition" in 2009 showed that absorption from a standard supplement was reduced by 60 percent.
Iron-deficient patients who do not tolerate or respond to iron supplements require intravenous iron. IV iron must be given in a hospital or other health care facility. It can cause side effects such as chills, rashes, muscle and joint aches, and rare serious allergic reactions. After correction of iron deficiency, long-term treatment with oral or IV iron may be necessary to maintain optimal iron stores.
References
- "Journal of Gastrointestinal Surgery"; Are Vitamin B12 and Folate Deficiency Clinically Important After Roux-en-Y Gastric Bypass?; R. Brolin, J. Gorman, R. Gorman, A. Petschenik, L. Bradley, H. Kenler and R. Cody; Volume 2 pg 436-442; 1998
- "American Journal of Hematology"; Obesity, Bariatric Surgery, and Iron Deficiency: True, True, True and Related; A. Love and H. Billett; Volume 83 pg 403-409; 2008
- "Archives of Surgery"; Prophylactic Iron Supplementation After Roux-en-Y Gastric Bypass; R. Brolin, J. Gorman, R. Gorman, A. Petschenik, L. Bradley, H. Kenler and R. Cody; Volume 133 pg 740-744; 1998
- "American Journal of Clinical Nutrition"; Iron Absorption and Iron Status Are Reduced After Roux-en-Y Gastric Bypass; M. Ruz, F. Carrasco, P. Rojas, J. Codoceo, J. Inostroza, A. Rebolledo, K. Basfi-fer, A. Csendes, K. Papapietro, F. Pizarro, M. Olivares, L. Sian, J. Westcott, K. Hambidge and N. Krebs Volume 90 pg 527-532; 2009
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