Iron Deficiency Anaemia (IDA)

Causes

• Chronic Blood Loss

  • Menorrhagia, GI losses (peptic ulcer, malignancy, diverticular disease), haemorrhoids

  • In men or postmenopausal women, investigate GI causes (colonoscopy, endoscopy)

• Dietary Deficiency

  • Limited intake of iron-rich foods (e.g. vegetarian/vegan diets)

• Malabsorption

  • Coeliac disease (screen via anti-tTG), H. pylori infection

• Increased Demand

  • Pregnancy, rapid growth (adolescents), lactation

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Clinical Features

• Fatigue, pallor, dyspnoea on exertion, reduced exercise tolerance

• Pica (pagophagia → craving ice), restless legs syndrome

• Brittle nails, koilonychia, angular cheilitis

• Chronic IDA can be well-tolerated until Hb drops significantly

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Investigations

• FBC: Microcytosis (low MCV), hypochromia (low MCH), possibly elevated RDW

• Iron Studies: Low ferritin (<30 µg/L diagnostic), high TIBC, low serum iron, low transferrin saturation

• Other Tests: Coeliac screen (anti-tTG), colonoscopy/gastroscopy if suspicion of GI loss or unexplained IDA in adults, especially men or postmenopausal women

• Peripheral Smear: Pencil cells, target cells, anisopoikilocytosis

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Management

• Dietary Measures

  • Increase iron-rich foods: red meat, organ meats, seafood, leafy greens, iron-fortified cereals

  • Address contributors such as heavy menstrual bleeding, GI pathology

• Oral Iron Supplementation

  • Elemental iron 100–200 mg daily or alternate days improves tolerability

  • Take on an empty stomach with vitamin C (e.g. orange juice) to enhance absorption

  • Avoid concurrent intake of calcium, tea, coffee, PPIs (reduce iron absorption)

  • Common side effects: nausea, constipation, black stools

  • Check reticulocyte count in 1–2 weeks as an early indicator of response

  • Continue iron therapy for at least 3 months after normalisation of Hb to replenish stores

• IV Iron

  • Ferric carboxymaltose or iron polymaltose if severe deficiency, poor oral tolerance, ongoing blood loss, or active inflammatory bowel disease

  • Side effects: transient nausea, flushing, rare anaphylaxis or extravasation with skin staining

  • Rapid repletion of iron stores

• Transfusion

  • Usually reserved for severe or symptomatic anaemia (e.g. Hb <70 g/L or <80 g/L if cardiovascular compromise)

  • Post-transfusion, still require oral/IV iron to correct stores

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Counselling Points

• Oral Iron

  • Take with vitamin C, separate from calcium or antacids by 2 hours

  • Alternate day dosing can reduce GI side effects and maintain efficacy

• IV Iron

  • Short infusion time but risk of hypersensitivity or infusion reactions

  • Inform about possible local skin staining if extravasation occurs

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Special Considerations

• IBD (Crohn’s / Ulcerative Colitis)

  • IDA is the most common systemic complication

  • In active disease, parenteral (IV) iron is preferred to avoid worsening GI inflammation

  • In mild or inactive disease, oral iron can be used, but monitor for flare-ups

  • Recheck ferritin/Hb every 3 months in the first year, then 6–12 months thereafter

• Pregnancy

  • Increased iron requirement, routine supplementation if deficiency confirmed or risk factors present

  • Check for compliance and tolerance

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Notes

• Diagnosis: Confirm low ferritin (gold standard). If microcytosis is unexplained, rule out coeliac disease and chronic GI blood loss

• Duration of Therapy: Continue 3 months beyond normal Hb to replete iron stores

• Monitoring Response: Reticulocyte rise ~1–2 weeks, normal Hb by ~6–8 weeks if well-tolerated and no ongoing losses

• Long-Term Follow-Up: Identify and address the cause of IDA, especially GI pathology in older patients. Recurrent or refractory IDA warrants specialist referral (e.g. gastroenterology)