Iron Deficiency Anemia Clinical Practice Guidelines (BSG, 2021)

British Society of Gastroenterology (BSG)

These are some of the highlights of the guidelines without analysis or commentary. For more information, go directly to the guidelines by clicking the link in the reference.

September 29, 2021

Guidelines for the management of patients with iron deficiency anemia (IDA) in adults were published in September 2021 by the British Society of Gastroenterology (BSG) in Gut.[1]


Before investigation, iron deficiency should be confirmed via iron studies. Serum ferritin is the most useful IDA marker, but other blood tests (eg, transferrin saturation) can help if a false-normal ferritin is suspected. A good response to iron replacement therapy (IRT) (hemoglobin [Hb] rise ≥10 g/L within 2 wk) is highly suggestive of absolute iron deficiency, even if the results of iron studies are equivocal.

Initial investigation of confirmed IDA should include urinalysis or urine microscopy, screening for celiac disease, and, in appropriate cases, upper and lower gastrointestinal (GI) endoscopy. Celiac disease is found in 3-5% of IDA cases and should be routinely screened for serologically or on small-bowel biopsy at the time of gastroscopy.

Age, sex, Hb concentration, and mean cell volume are independent predictors of risk of GI cancer risk in IDA and must be considered as part of a holistic risk assessment. Fecal immunochemical testing cannot yet be recommended for risk stratification in IDA.

In men and postmenopausal women with newly diagnosed IDA, gastroscopy and colonoscopy should generally be the first-line GI investigations. Computed tomography (CT) colonography is a reasonable alternative in patients not suitable for colonoscopy.

Patients with negative bidirectional endoscopy and either an inadequate response to IRT or recurrent IDA should undergo further investigation of the small bowel and renal tract. Capsule endoscopy is the preferred test for examining the small bowel; in patients not suitable for this test, CT/magnetic resonance (MR) enterography may be considered. After negative capsule endoscopy, further GI investigation need be considered only for ongoing IDA after IRT. Long-term IRT may be appropriate if the cause of recurrent IDA is unknown or irreversible.


IRT should not be deferred while investigations for IDA are awaited, unless colonoscopy is imminent.

Initial treatment of IDA should be with one tablet of ferrous sulfate, fumarate, or gluconate q24hr. If this is not tolerated, a reduced dose (one tablet q48hr), alternative oral preparations, or parenteral iron should be considered.

Limited transfusion of packed red blood cells (PRBCs) may on occasion be required to treat symptomatic IDA; IRT is still necessary after transfusion.

Patients should be monitored in the first 4 weeks for Hb response to oral iron, and treatment should be continued for ~3 months after normalization of the Hb level.

Parenteral iron should be considered when oral iron is contraindicated, ineffective, or not tolerated. Consideration should be at an early stage if oral IRT is judged unlikely to be effective or correction of IDA is particularly urgent.

Invasive investigation is not supported in nonanemic iron deficiency unless there are additional indications, but periodic blood count monitoring is suggested.

After restoration of Hb and iron stores with IRT, the blood count should be monitored periodically (eg, every 6 months initially) to detect recurrent IDA.

For more information, please go to Iron Deficiency Anemia.


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