Severe Iron Deficiency Anemia: Treatment Approach

Immediate Iron Replacement

The American Gastroenterological Association recommends starting oral iron therapy immediately with ferrous sulfate 325 mg (65 mg elemental iron) once daily as first-line therapy, and if gastrointestinal side effects occur, reduce to one tablet every other day rather than discontinuing, to maintain efficacy while improving tolerability 1, 2
Expect hemoglobin to rise ≥10 g/L within 2 weeks if true iron deficiency, which confirms the diagnosis even with equivocal labs, according to the European Society of Gastrointestinal Endoscopy 1, 3, 4

The American College of Gastroenterology states that adults with iron saturation <20% and elevated TIBC need bidirectional endoscopy, including upper endoscopy with small bowel biopsies and colonoscopy, to exclude celiac disease, gastric cancer, angiodysplasia, colorectal cancer, inflammatory bowel disease, and angiodysplasia 1, 5, 6
This applies to both men and postmenopausal women universally, and for premenopausal women, consider if age >40 years or heavy menstrual bleeding doesn't fully explain severity, as recommended by the National Institute for Health and Care Excellence 7

Check hemoglobin in 2 weeks, and a rise of ≥10 g/L confirms iron deficiency and adequate response, according to the American Society of Hematology 1, 4
Monitor for recurrent iron deficiency every 3 months for at least one year after correction, especially if inflammatory bowel disease or other chronic conditions present, as suggested by the European Hematology Association 8

The World Health Organization confirms that absolute iron deficiency, not functional iron deficiency or anemia of chronic disease, is indicated by transferrin saturation of 3% (normal >20%) with TIBC of 501 (elevated), and this pattern demands investigation regardless of hemoglobin level 1, 7