Management of Iron Deficiency in Gastroenterology: Evidence‑Based Recommendations

Continuity of Care and Initial Investigation

Upper and lower endoscopy constitute the appropriate first‑line investigation for iron deficiency according to the British Society of Gastroenterology (BSG) guidelines. 1
Changing providers would require the new physician to review all prior findings and could lead to repeat procedures, causing diagnostic and therapeutic delays. 4
The gastroenterologist who performed the initial bidirectional endoscopies is best positioned to interpret those results and decide whether additional studies (e.g., capsule endoscopy of the small bowel) are needed. 3

If iron deficiency persists or recurs despite adequate oral iron replacement, capsule endoscopy of the small bowel should be performed. 2
When a high‑quality bidirectional endoscopy is negative and the response to iron therapy is inadequate, further evaluation of the small bowel and the renal tract is recommended to search for occult bleeding sources. 3
Identifying the bleeding source remains the primary goal and is achieved through systematic investigation rather than switching physicians. 1

Oral ferrous sulfate (200–325 mg daily or on alternate days) should be started immediately; deferring iron therapy while awaiting further investigations is not recommended unless a colonoscopy is imminent. 5
Initiating oral iron does not interfere with subsequent diagnostic work‑up and improves patient quality of life while investigations continue. 2

Hemoglobin should be re‑checked 2–4 weeks after starting oral iron; a rise of ≥10 g/L within 2 weeks indicates an appropriate response when iron deficiency is the primary issue. 2
Hemoglobin and ferritin should be monitored every 3 months for the first year and then annually to ensure sustained correction. 6

Even after complete upper and lower endoscopy, 10–15 % of patients have dual pathology (lesions in both upper and lower GI tracts) that may be missed without meticulous examination. 5
Long‑term proton‑pump inhibitor (PPI) therapy can mask gastroduodenal lesions and contribute to iron deficiency by impairing absorption. 4

Celiac disease serology (anti‑tTG or anti‑endomysial antibodies) should be performed, as 3–5 % of iron‑deficiency cases are attributable to celiac disease. 1
Urine microscopy for microscopic hematuria is advised to exclude renal pathology as a source of chronic blood loss. 1
Helicobacter pylori testing (urea breath test or stool antigen) is recommended if not previously performed, given its association with iron deficiency. 5

Intravenous iron is reserved for patients with ongoing significant blood loss where rapid repletion is required; it is not first‑line for those with normal hemoglobin and no contraindicating conditions. 6