Synopsis
Confirm iron deficiency, identify bleeding, malabsorption or increased demand, start effective replacement and prove both haematological response and completion of the source investigation.
- Confirm iron deficiency with ferritin and the inflammatory context rather than diagnosing it from microcytosis alone; early or mixed deficiency may remain normocytic.
- Low ferritin is highly supportive of depleted stores, but inflammation can raise ferritin. Transferrin saturation, CRP, reticulocyte haemoglobin where available and response help when the result is equivocal.
- Find the cause at the same time as starting replacement. Menstrual loss, gastrointestinal symptoms, diet, blood donation, pregnancy, medicines, bariatric surgery and coeliac risk require explicit review.
- Adult men and postmenopausal women with confirmed unexplained deficiency generally require upper and lower gastrointestinal evaluation under BSG guidance, adjusted for frailty, symptoms and prior investigation.
- Offer coeliac screening in confirmed adult iron deficiency anaemia and pursue small-bowel or renal-tract causes when recurrent or refractory deficiency remains unexplained after appropriate initial assessment.
- Preferred initial replacement for most stable adults is one daily tablet of ferrous sulfate, fumarate or gluconate; every-other-day dosing or an alternative preparation can improve tolerance.
- Check early haemoglobin response and continue treatment after haemoglobin normalises long enough to replenish stores, while modifying duration for ongoing loss or malabsorption.
- Use intravenous iron when oral treatment is ineffective, not tolerated, not absorbed or too slow for the clinical need, with product-specific dosing and hypersensitivity and phosphate safety.
Key red flags
Chest pain, syncope, heart failure, shock or severe breathlessness with rapid anaemia indicates threatened oxygen delivery or continuing bleeding, not a routine oral-iron problem.
Investigation priorities
Define severity, morphology, mixed deficiency and marrow response.
Management branches
Anaemia is microcytic, hypochromic, otherwise unexplained or accompanied by symptoms suggesting depleted iron.
- Obtain FBC, reticulocytes, film, ferritin, transferrin saturation and CRP, assess symptoms and haemodynamics, and compare previous haemoglobin and MCV.
- The preferred diagnosis uses depleted stores plus the clinical phenotype; an alternative inflammation-adjusted assessment uses saturation, specialist thresholds and treatment response when ferritin is misleading.
- Escalate active bleeding, rapid decline, chest pain, syncope or heart failure to emergency haemorrhage and transfusion assessment rather than waiting for outpatient iron studies.
Key medicines
Ferrous sulfateA common adult BSG regimen is one 200 mg tablet by mouth once daily; if not tolerated, use one tablet every other day or another oral preparation.Nausea, epigastric pain, constipation, diarrhoea and dark stools affect adherence. Separate from interacting medicines according to the BNF, keep away from children and investigate non-response rather than escalating indefinitely.
Ferric carboxymaltose (intravenous example)Calculate the Ferinject requirement from weight and haemoglobin; an infusion must not exceed 20 mg iron/kg or 1,000 mg, and the cumulative weekly maximum is 1,000 mg.Use trained monitored administration with resuscitation capability and observe for at least 30 minutes afterwards. Stop for hypersensitivity or extravasation; assess phosphate risk with repeated high doses and use extra caution during infection.