AGA Clinical Practice Update on Management of Iron Deficiency Anemia: Expert Review

DescriptionIn this Clinical Practice Update (CPU), we will Best Practice Advice (BPA) guidance on the appropriate management of iron deficiency anemia.MethodsThis expert review was commissioned and approved by the AGA Institute Clinical Practice Updates Committee (CPUC) and the AGA Governing Board to provide timely guidance on a topic of high clinical importance to the AGA membership, and underwent internal peer review by the CPUC and external peer review through standard procedures of Clinical Gastroenterology and Hepatology. These Best Practice Advice (BPA) statements were drawn from a review of the published literature and from expert opinion. Since systematic reviews were not performed, these BPA statements do not carry formal ratings regarding the quality of evidence or strength of the presented considerations.Best Practice Advice 1No single formulation of oral iron has any advantages over any other. Ferrous sulfate is preferred as the least expensive iron formulation.Best Practice Advice 2Give oral iron once a day at most. Every-other-day iron dosing may be better tolerated for some patients with similar or equal rates of iron absorption as daily dosing.Best Practice Advice 3Add vitamin C to oral iron supplementation to improve absorption.Best Practice Advice 4Intravenous iron should be used if the patient does not tolerate oral iron, ferritin levels do not improve with a trial of oral iron, or the patient has a condition in which oral iron is not likely to be absorbed.Best Practice Advice 5Intravenous iron formulations that can replace iron deficits with 1 or 2 infusions are preferred over those that require more than 2 infusions.Best Practice Advice 6All intravenous iron formulations have similar risks; true anaphylaxis is very rare. The vast majority of reactions to intravenous iron are complement activation–related pseudo-allergy (infusion reactions) and should be treated as such.Best Practice Advice 7Intravenous iron therapy should be used in individuals who have undergone bariatric procedures, particularly those that are likely to disrupt normal duodenal iron absorption, and have iron-deficiency anemia with no identifiable source of chronic gastrointestinal blood loss.Best Practice Advice 8In individuals with inflammatory bowel disease and iron-deficiency anemia, clinicians first should determine whether iron-deficiency anemia is owing to inadequate intake or absorption, or loss of iron, typically from gastrointestinal bleeding. Active inflammation should be treated effectively to enhance iron absorption or reduce iron depletion.Best Practice Advice 9Intravenous iron therapy should be given in individuals with inflammatory bowel disease, iron-deficiency anemia, and active inflammation with compromised absorption.Best Practice Advice 10In individuals with portal hypertensive gastropathy and iron-deficiency anemia, oral iron supplements initially should be used to replenish iron stores. Intravenous iron therapy should be used in patients with ongoing bleeding who do not respond to oral iron therapy.Best Practice Advice 11In individuals with portal hypertensive gastropathy and iron-deficiency anemia without another identified source of chronic blood loss, treatment of portal hypertension with nonselective β-blockers can be considered.Best Practice Advice 12In individuals with iron-deficiency anemia secondary to gastric antral vascular ectasia who have an inadequate response to iron replacement, consider endoscopic therapy with endoscopic band ligation or thermal methods such as argon plasma coagulation.Best Practice Advice 13In patients with iron-deficiency anemia and celiac disease, ensure adherence to a gluten-free diet to improve iron absorption. Consider oral iron supplementation based on the severity of iron deficiency and patient tolerance, followed by intravenous iron therapy if iron stores do not improve.Best Practice Advice 14Deep enteroscopy performed in patients with iron-deficiency anemia suspected to have small-bowel bleeding angioectasias should be performed with a distal attachment to improve detection and facilitate treatment. Small-bowel angioectasias may be treated with ablative thermal therapies such as argon plasma coagulation or with mechanical methods such as hemostatic clips.Best Practice Advice 15Endoscopic treatment of angioectasias should be accompanied with iron replacement. Medical therapy for small-bowel angioectasias should be reserved for compassionate treatment in refractory cases when iron replacement and endoscopic therapy are ineffective. In this Clinical Practice Update (CPU), we will Best Practice Advice (BPA) guidance on the appropriate management of iron deficiency anemia. This expert review was commissioned and approved by the AGA Institute Clinical Practice Updates Committee (CPUC) and the AGA Governing Board to provide timely guidance on a topic of high clinical importance to the AGA membership, and underwent internal peer review by the CPUC and external peer review through standard procedures of Clinical Gastroenterology and Hepatology. These Best Practice Advice (BPA) statements were drawn from a review of the published literature and from expert opinion. Since systematic reviews were not performed, these BPA statements do not carry formal ratings regarding the quality of evidence or strength of the presented considerations. No single formulation of oral iron has any advantages over any other. Ferrous sulfate is preferred as the least expensive iron formulation. Give oral iron once a day at most. Every-other-day iron dosing may be better tolerated for some patients with similar or equal rates of iron absorption as daily dosing. Add vitamin C to oral iron supplementation to improve absorption. Intravenous iron should be used if the patient does not tolerate oral iron, ferritin levels do not improve with a trial of oral iron, or the patient has a condition in which oral iron is not likely to be absorbed. Intravenous iron formulations that can replace iron deficits with 1 or 2 infusions are preferred over those that require more than 2 infusions. All intravenous iron formulations have similar risks; true anaphylaxis is very rare. The vast majority of reactions to intravenous iron are complement activation–related pseudo-allergy (infusion reactions) and should be treated as such. Intravenous iron therapy should be used in individuals who have undergone bariatric procedures, particularly those that are likely to disrupt normal duodenal iron absorption, and have iron-deficiency anemia with no identifiable source of chronic gastrointestinal blood loss. In individuals with inflammatory bowel disease and iron-deficiency anemia, clinicians first should determine whether iron-deficiency anemia is owing to inadequate intake or absorption, or loss of iron, typically from gastrointestinal bleeding. Active inflammation should be treated effectively to enhance iron absorption or reduce iron depletion. Intravenous iron therapy should be given in individuals with inflammatory bowel disease, iron-deficiency anemia, and active inflammation with compromised absorption. In individuals with portal hypertensive gastropathy and iron-deficiency anemia, oral iron supplements initially should be used to replenish iron stores. Intravenous iron therapy should be used in patients with ongoing bleeding who do not respond to oral iron therapy. In individuals with portal hypertensive gastropathy and iron-deficiency anemia without another identified source of chronic blood loss, treatment of portal hypertension with nonselective β-blockers can be considered. In individuals with iron-deficiency anemia secondary to gastric antral vascular ectasia who have an inadequate response to iron replacement, consider endoscopic therapy with endoscopic band ligation or thermal methods such as argon plasma coagulation. In patients with iron-deficiency anemia and celiac disease, ensure adherence to a gluten-free diet to improve iron absorption. Consider oral iron supplementation based on the severity of iron deficiency and patient tolerance, followed by intravenous iron therapy if iron stores do not improve. Deep enteroscopy performed in patients with iron-deficiency anemia suspected to have small-bowel bleeding angioectasias should be performed with a distal attachment to improve detection and facilitate treatment. Small-bowel angioectasias may be treated with ablative thermal therapies such as argon plasma coagulation or with mechanical methods such as hemostatic clips. Endoscopic treatment of angioectasias should be accompanied with iron replacement. Medical therapy for small-bowel angioectasias should be reserved for compassionate treatment in refractory cases when iron replacement and endoscopic therapy are ineffective. Iron deficiency (ID) is the most common nutritional deficiency worldwide.1Safiri S. Kolahi A.A. Noori M. et al.Burden of anemia and its underlying causes in 204 countries and territories, 1990-2019: results from the Global Burden of Disease Study 2019.J Hematol Oncol. 2021; 14: 185Google Scholar In the United States, 1% to 4% of men are ID, and an additional 2% have iron-deficiency anemia (IDA).2Centers for Disease Control and PreventionIron deficiency--United States, 1999-2000.MMWR Morb Mortal Wkly Rep. 2002; 51: 897-899Google Scholar At least 39% of premenopausal women and 8% of postmenopausal women are ID, and, overall, 4% to 17% of women have IDA.3Weyand A.C. Chaitoff A. Freed G.L. et al.Prevalence of iron deficiency and iron-deficiency anemia in US females aged 12-21 years, 2003-2020.JAMA. 2023; 329: 2191-2193Google Scholar Ferritin is the most commonly used marker for diagnosing ID, with varying recommendations for the appropriate threshold. A recent American Gastroenterological Association (AGA) guideline recommended use of a ferritin cut-off value of 45 mg/dL in individuals with anemia because this level was believed to have an optimal balance of sensitivity and specificity.4Rockey D.C. Altayar O. Falck-Ytter Y. et al.AGA technical review on gastrointestinal evaluation of iron deficiency anemia.Gastroenterology. 2020; 159: 1097-1119Google Scholar,5Ko C.W. Siddique S.M. Patel A. et al.AGA clinical practice guidelines on the gastrointestinal evaluation of iron deficiency anemia.Gastroenterology. 2020; 159: 1085-1094Google Scholar It is important to recognize that patients with inflammatory conditions may have ID or IDA in the setting of a ferritin level greater than 45 mg/dL (usually <100 mg/dL).6Guyatt G.H. Oxman A.D. Ali M. et al.Laboratory diagnosis of iron-deficiency anemia: an overview.J Gen Intern Med. 1992; 7: 145-153Google Scholar Confirmatory testing with transferrin saturation, soluble transferrin receptor, or reticulocyte hemoglobin equivalent may be helpful in these situations. After identification of ID with or without anemia, an appropriate diagnostic work-up should be undertaken including evaluation of dietary iron intake, review of menstrual blood losses in premenopausal women, and a search for gastrointestinal conditions leading to poor iron absorption or blood loss including Helicobacter pylori infection.5Ko C.W. Siddique S.M. Patel A. et al.AGA clinical practice guidelines on the gastrointestinal evaluation of iron deficiency anemia.Gastroenterology. 2020; 159: 1085-1094Google Scholar Multidisciplinary management including gastroenterologists, hematologists, and nutritionists often is needed in complex cases. Nutritional consultation often is helpful to increase dietary iron intake, and a hematology consultation can help with complex anemia situations or if there is difficulty accessing intravenous (IV) iron. Iron repletion is needed to improve quality of life and decrease the risk of complications related to anemia. Oral iron supplementation usually is initiated first, but often is tolerated poorly because of side effects such as nausea, abdominal pain, and constipation.7DeLoughery T.G. Safety of oral and intravenous iron.Acta Haematol. 2019; 142: 8-12Google Scholar Because of these side effects and the tight regulation of iron absorption,8Charlebois E. Pantopoulos K. Nutritional aspects of iron in health and disease.Nutrients. 2023; 15: 2441Google Scholar increasing intestinal iron absorption can be difficult, which has stimulated the development and increasing use of IV iron formulations. In some patients with severe ID or conditions in which oral iron may not be well absorbed, IV iron may be given initially. The goal of this Clinical Practice Update is to review options for oral and IV iron repletion and to review best practices for management of ID in common gastrointestinal conditions. Recommendations for gastrointestinal evaluation of IDA have been provided in a previous AGA guideline.4Rockey D.C. Altayar O. Falck-Ytter Y. et al.AGA technical review on gastrointestinal evaluation of iron deficiency anemia.Gastroenterology. 2020; 159: 1097-1119Google Scholar,5Ko C.W. Siddique S.M. Patel A. et al.AGA clinical practice guidelines on the gastrointestinal evaluation of iron deficiency anemia.Gastroenterology. 2020; 159: 1085-1094Google Scholar Although most studies in gastrointestinal conditions have used IDA as an end point, similar considerations can apply to patients with ID without anemia. Many formulations of oral iron are available (Table 1), without substantial evidence that any one product is better than another—either in effectiveness or tolerance.9Gamad N. Saha P.K. Sharma P. et al.A randomized controlled trial comparing the efficacy, tolerability, and cost of oral iron preparations in iron-deficiency anemia in pregnancy.J Obstet Gynaecol Res. 2021; 47: 3828-3841Google Scholar, 10Powers J.M. Buchanan G.R. Adix L. et al.Effect of low-dose ferrous sulfate vs iron polysaccharide complex on hemoglobin concentration in young children with nutritional iron-deficiency anemia: a randomized clinical trial.JAMA. 2017; 317: 2297-2304Google Scholar, 11Abdel Moety GAF. Ali A.M. Fouad R. et al.Amino acid chelated iron versus an iron salt in the treatment of iron deficiency anemia with pregnancy: a randomized controlled study.Eur J Obstet Gynecol Reprod Biol. 2017; 210: 242-246Google Scholar, 12Lo J.O. Benson A.E. Martens K.L. et al.The role of oral iron in the treatment of adults with iron deficiency.Eur J Haematol. 2023; 110: 123-130Google Scholar, 13Pasupathy E. Kandasamy R. Thomas K. et al.Alternate day versus daily oral iron for treatment of iron deficiency anemia: a randomized controlled trial.Sci Rep. 2023; 13: 1818Google Scholar The ferrous iron salts (ferrous sulfate, ferrous fumarate, and ferrous gluconate) are a reasonable choice to start with because they are often the least expensive. Although some patients may tolerate other products such as ferrous bisglycinate better, there again is no evidence of superiority in clinical trials.12Lo J.O. Benson A.E. Martens K.L. et al.The role of oral iron in the treatment of adults with iron deficiency.Eur J Haematol. 2023; 110: 123-130Google Scholar Side effects are common with oral iron; a meta-analysis reported constipation in 12% of patients, diarrhea in 8%, and nausea in 11%.14Tolkien Z. Stecher L. Mander A.P. et al.Ferrous sulfate supplementation causes significant gastrointestinal side-effects in adults: a systematic review and meta-analysis.PLoS One. 2015; 10e0117383Google ScholarTable 1Common Oral Iron PreparationsAgentApproximate elemental iron contentAvailable formulationsCost of 30 pillsaCost obtained from Lexi-drugs. Waltham (MA): UpToDate, Inc, 2024. Available from http://online.lexi.com. The cost of ferrous bisglycinate was obtained from Amazon.com, 2024.Ferrous sulfate65 mg per tabletCapsule, tablet, liquid$0.30–$4.50Ferrous gluconate27–38 mg per tabletCapsule, tablet, liquid$1.50–$3.30Ferrous fumarate150–106 per tabletCapsule, tablet, liquid$3.90Polysaccharide–iron complexVaries, but milligrams of iron are listed in the name of the productCapsule, liquid$4.20Ferrous bisglycinate25 mg per tabletTablet, capsule, liquid$2.40a Cost obtained from Lexi-drugs. Waltham (MA): UpToDate, Inc, 2024. Available from http://online.lexi.com. The cost of ferrous bisglycinate was obtained from Amazon.com, 2024. Open table in a new tab When patients take oral iron, levels of serum hepcidin increase in response and will remain increased for up to 48 hours.15Moretti D. Goede J.S. Zeder C. et al.Oral iron supplements increase hepcidin and decrease iron absorption from daily or twice-daily doses in iron-depleted young women.Blood. 2015; 126: 1981-1989Google Scholar This increase in hepcidin blocks further iron absorption. Thus, there is no reason to take iron more than once a day because this will not improve absorption but will increase side effects.16Rimon E. Kagansky N. Kagansky M. et al.Are we giving too much iron? Low-dose iron therapy is effective in octogenarians.Am J Med. 2005; 118: 1142-1147Google Scholar Early data suggest that taking iron every other day appears to improve tolerance, but this needs to be better studied before being implemented.13Pasupathy E. Kandasamy R. Thomas K. et al.Alternate day versus daily oral iron for treatment of iron deficiency anemia: a randomized controlled trial.Sci Rep. 2023; 13: 1818Google Scholar,17Stoffel N.U. Cercamondi C.I. Brittenham G. et al.Iron absorption from oral iron supplements given on consecutive versus alternate days and as single morning doses versus twice-daily split dosing in iron-depleted women: two open-label, randomised controlled trials.Lancet Haematol. 2017; 4: e524-e533Google Scholar,18von Siebenthal H.K. Gessler S. Vallelian F. et al.Alternate day versus consecutive day oral iron supplementation in iron-depleted women: a randomized double-blind placebo-controlled study.EClinicalMedicine. 2023; 65102286Google Scholar Certain dietary manipulations may improve iron absorption. A recent iron isotope study showed that taking iron with 80 mg ascorbic acid on an empty stomach improves iron absorption.19von Siebenthal H.K. Moretti D. Zimmermann M.B. et al.Effect of dietary factors and time of day on iron absorption from oral iron supplements in iron deficient women.Am J Hematol. 2023; 98: 1356-1363Google Scholar Vitamin C improves absorption by forming a chelate with iron that prevents the formation of insoluble iron compounds and by reducing ferric to ferrous iron. However, evidence supporting vitamin C administration to improve iron absorption is mixed,20Li N. Zhao G. Wu W. et al.The efficacy and safety of vitamin C for iron supplementation in adult patients with iron deficiency anemia: a randomized clinical trial.JAMA Netw Open. 2020; 3e2023644Google Scholar,21Loganathan V. Bharathi A. Prince A.M. et al.Treatment efficacy of vitamin C or ascorbate given as co-intervention with iron for anemia - a systematic review and meta-analysis of experimental studies.Clin Nutr ESPEN. 2023; 57: 459-468Google Scholar and further study is needed to clarify the effectiveness of this practice. Tea and coffee are powerful inhibitors of iron absorption and should not be consumed within an hour after taking iron.22Morck T.A. Lynch S.R. Cook J.D. Inhibition of food iron absorption by coffee.Am J Clin Nutr. 1983; 37: 416-420Google Scholar Although oral iron is absorbed better when taken on an empty stomach, some patients will better tolerate taking iron with meals. If feasible, taking iron with meat protein will improve absorption, and the use of 500 mg vitamin C will allow iron absorption even if calcium or fiber is present in the meal.23Hurrell R.F. Reddy M.B. Juillerat M. et al.Meat protein fractions enhance nonheme iron absorption in humans.J Nutr. 2006; 136: 2808-2812Google Scholar,24Hurrell R. Egli I. Iron bioavailability and dietary reference values.Am J Clin Nutr. 2010; 91: 1461S-1467SGoogle Scholar IV iron is indicated if a patient cannot tolerate oral iron or if blood counts or iron stores do not improve with oral iron supplementation. In anemic patients, hemoglobin levels should increase by 1 g/dL within 2 weeks in adherent patients on oral iron supplementation.25Okam M.M. Koch T.A. Tran M.H. Iron supplementation, response in iron-deficiency anemia: analysis of five trials.Am J Med. 2017; 130: 991 e1-991 e8Google Scholar A reasonable expectation is ferritin should increase in a month, and if these parameters are not met then IV iron should be used. IV iron also should be used in situations in which oral iron likely will not be effective owing to impaired absorption, such as in patients after bariatric surgery, with active inflammatory bowel disease (IBD), or when iron loss exceeds absorption of oral iron. However, IV iron is substantially more expensive than oral formulations (Table 2).Table 2Intravenous Iron PreparationsAgentTypical single doseTypical dose scheduleSpecial considerationsMedication cost for typical dose scheduleaCost derived from Lexi-drugs. Waltham (MA): UpToDate, Inc, 2024. Available from http://online.lexi.com. Does not include cost of infusion visits.Ferric carboxymaltose750–1000 mg750 mg × 2 one week apart or 1000 mg as a single doseRisk of hypophosphatemia$3470Ferric gluconate125 mg125 mg × 8 given no closer than every other day–$610Ferric derisomaltose1000 mg1000 mg × 1–$3896Ferumoxytol510–1020 mg510 mg × 2 or 1020 mg × 1Also used as magnetic resonance contrast agent; consult radiology if MRI requested within 3 months of infusion$1963Iron sucrose100 mg200 mg × 5 or 300 mg × 3 weekly–$441.50Low-molecular-weight iron dextran1000 mg1000 mg × 1–$405MRI, magnetic resonance imaging.a Cost derived from Lexi-drugs. Waltham (MA): UpToDate, Inc, 2024. Available from http://online.lexi.com. Does not include cost of infusion visits. Open table in a new tab MRI, magnetic resonance imaging. Several different formulations of IV iron are available that differ in dose and frequency of administration (Table 2). Because there is little difference in overall efficacy of iron repletion and similar risks, formulations that can replace iron deficits with 1 to 2 infusions are preferred. Being truly allergic to IV iron is very rare—almost all reactions are complement activation–related pseudo-allergy, which are idiosyncratic infusion reactions that can mimic allergic reactions.26Rampton D. Folkersen J. Fishbane S. et al.Hypersensitivity reactions to intravenous iron: guidance for risk minimization and management.Haematologica. 2014; 99: 1671-1676Google Scholar For mild reactions, simply stopping the infusions and restarting 15 minutes later at a slower rate will suffice. For more severe reactions, corticosteroids may be of benefit. Diphenhydramine should be avoided because its side effects of mouth dryness, tachycardia, diaphoresis, somnolence, and hypotension can be mistaken for worsening of the reaction.27Barton J.C. Barton E.H. Bertoli L.F. et al.Intravenous iron dextran therapy in patients with iron deficiency and normal renal function who failed to respond to or did not tolerate oral iron supplementation.Am J Med. 2000; 109: 27-32Google Scholar Studies have shown that rates of mild reactions are approximately 1:200 and rates of major reactions are approximately 1:200,000.28Avni T. Bieber A. Grossman A. et al.The safety of intravenous iron preparations: systematic review and meta-analysis.Mayo Clin Proc. 2015; 90: 12-23Google Scholar Large studies have shown that all IV iron formulations are associated with adverse effects, so from a safety standpoint no one product is preferred.29Auerbach M. DeLoughery T.G. Single-dose intravenous iron for iron deficiency: a new paradigm.Hematology Am Soc Hematol Educ Program. 2016; 2016: 57-66Google Scholar, 30DeLoughery T.G. Auerbach M. Is low-molecular weight iron dextran really the most risky iron?-Unconvincing data from an unconvincing study.Am J Hematol. 2016; 91: 451-452Google Scholar, 31Arastu A.H. Elstrott B.K. Martens K.L. et al.Analysis of adverse events and intravenous iron infusion formulations in adults with and without prior infusion reactions.JAMA Netw Open. 2022; 5e224488Google Scholar However, 2 products do have unique considerations. First, ferumoxytol (Feraheme, AMAG Pharmaceuticals) is a superparamagnetic iron oxide coated with carbohydrate that also is approved as a magnetic resonance imaging contrast agent. Thus, the radiologist should be notified if magnetic resonance imaging is obtained within 3 months after infusion. Second, iron carboxymaltose (Injectafer, Daiichi Sankyo Inc) has been associated with hypophosphatemia, particularly with repeated dosing. The hypophosphatemia can be prolonged and lead to complications such as fatigue and osteomalacia.32Martens K.L. Wolf M. Incidence, mechanism, and consequences of IV iron-induced hypophosphatemia.Hematology Am Soc Hematol Educ Program. 2023; 2023: 636-639Google Scholar,33Zoller H. Wolf M. Blumenstein I. et al.Hypophosphataemia following ferric derisomaltose and ferric carboxymaltose in patients with iron deficiency anaemia due to inflammatory bowel disease (PHOSPHARE-IBD): a randomised clinical trial.Gut. 2023; 72: 644-653Google Scholar This formulation therefore should be used only with great care in patients with poor absorption or nutrition. IDA is pervasive after bariatric procedures, especially after procedures such as Roux-en-Y gastric bypass, which disrupts normal duodenal iron absorption.34Obinwanne K.M. Fredrickson K.A. Mathiason M.A. et al.Incidence, treatment, and outcomes of iron deficiency after laparoscopic Roux-en-Y gastric bypass: a 10-year analysis.J Am Coll Surg. 2014; 218: 246-252Google Scholar, 35Gesquiere I. Lannoo M. Augustijns P. et al.Iron deficiency after Roux-en-Y gastric bypass: insufficient iron absorption from oral iron supplements.Obes Surg. 2014; 24: 56-61Google Scholar, 36Gowanlock Z. Lezhanska A. Conroy M. et al.Iron deficiency following bariatric surgery: a retrospective cohort study.Blood Adv. 2020; 4: 3639-3647Google Scholar, 37Sandvik J. Bjerkan K.K. Graeslie H. et al.Iron deficiency and anemia 10 years after Roux-en-Y gastric bypass for severe obesity.Front Endocrinol (Lausanne). 2021; 12679066Google Scholar However, bariatric procedures such as adjustable gastric bands or endoscopic or surgical sleeve gastrectomy also can be associated with IDA,38Nie Y. Tian Z. Wang P. et al.Prevalence of anemia and related nutrient deficiencies after sleeve gastrectomy: a systematic review and meta-analysis.Obes Rev. 2023; 24e13516Google Scholar, 39Xia C. Xiao T. Hu S. et al.Long-term outcomes of iron deficiency before and after bariatric surgery: a systematic review and meta-analysis.Obes Surg. 2023; 33: 897-910Google Scholar, 40Ghoz H. Bryant M. Fritz H. et al.Endoscopic sleeve gastroplasty and postprocedural nutritional deficiencies: results from a single center exploratory study.Eur J Gastroenterol Hepatol. 2021; 33: e1039-e1041Google Scholar as can nonbariatric procedures that interrupt iron absorption. Although the cause of IDA after bariatric surgery often is multifactorial, it most often occurs as a result of inadequate iron absorption. This occurs because iron is absorbed most efficiently in the duodenum and proximal jejunum, which typically is disrupted after most bariatric approaches involving bypass of this part of the gastrointestinal tract, and because acid, secretion of which often is disrupted, helps to release iron from dietary nutrients and to release heme from ingested hemoglobin/myoglobin (very low pH [<3] also enhances Fe2+ and Fe3+ solubilization and thus absorption). Anastomotic ulcers also are common after bariatric surgery, which may cause acute or occult gastrointestinal bleeding.41Rockey D.C. Occult gastrointestinal bleeding.N Engl J Med. 1999; 341: 38-46Google Scholar Given the propensity for development of anastomotic ulcers after bariatric surgery, causing chronic bleeding and iron loss, patients with postsurgical IDA should undergo an esophagogastroduodenoscopy to exclude ulcer disease. Treatment of IDA in patients after bariatric surgery involves addressing both the anemia and nutrient absorption after surgery. Iron supplementation strategies used after bariatric surgery often are highly variable, and many do not provide sufficient iron to prevent or treat IDA.42Anvari S. Samarasinghe Y. Alotaiby N. et al.Iron supplementation following bariatric surgery: a systematic review of current strategies.Obes Rev. 2021; 22e13268Google Scholar Given the anatomic considerations at play after bariatric surgery, IV iron is preferred in patients after bariatric surgery, particularly in more severe cases or when oral supplementation is ineffective.43Sandvik J. Hole T. Klockner C.A. et al.Intravenous iron treatment in the prevention of iron deficiency and anaemia after Roux-en-Y gastric bypass.Obes Surg. 2020; 30: 1745-1752Google Scholar In one study of women developing ID after Roux-en-Y gastric bypass, a single dose of IV iron was more effective and better tolerated than treatment with either oral ferrous fumarate or ferrous gluconate.44Schijns W. Boerboom A. de Bruyn Kops M. et al.A randomized controlled trial comparing oral and intravenous iron supplementation after Roux-en-Y gastric bypass surgery.Clin Nutr. 2020; 39: 3779-3785Google Scholar If iron stores are slow to recover, evaluation of other micronutrient deficiencies or sources of chronic blood loss may be needed. ID and/or IDA have been reported to occur in up to 90% of patients with IBD, including both Crohn's disease and ulcerative colitis.45Gasche C. Berstad A. Befrits R. et al.Guidelines on the diagnosis and management of iron deficiency and anemia in inflammatory bowel diseases.Inflamm Bowel Dis. 2007; 13: 1545-1553Google Scholar, 46Gisbert J.P. Gomollon F. Common misconceptions in the diagnosis and management of anemia in inflammatory bowel disease.Am J Gastroenterol. 2008; 103: 1299-1307Google Scholar, 47Hoivik M.L. Reinisch W. Cvancarova M.