Anaemia
Iron deficiency, B12/folate deficiency, and anaemia of chronic disease — NICE NG24 and BNF aligned
Anaemia — defined as haemoglobin below 130 g/L in men, 120 g/L in non-pregnant women, or 110 g/L in pregnancy — is one of the most common conditions encountered in clinical and community pharmacy practice. It is not a diagnosis in itself but a sign of an underlying condition. The pharmacist's role spans identification of the type of anaemia, ensuring appropriate treatment and monitoring, counselling on adherence, and recognising red flags requiring urgent referral.
Diagnosing the Type of Anaemia
The mean corpuscular volume (MCV) on a full blood count (FBC) guides initial classification. Microcytic anaemia (MCV <80 fL) most commonly indicates iron deficiency (IDA) — confirmed by a low serum ferritin (<30 mcg/L, or <100 mcg/L if CRP elevated). Macrocytic anaemia (MCV >100 fL) suggests vitamin B12 or folate deficiency; a blood film will show oval macrocytes and hypersegmented neutrophils. Normocytic anaemia (MCV 80–100 fL) points toward anaemia of chronic disease (ACD), acute blood loss, or haemolysis. In IDA, check for an underlying cause: upper and lower GI endoscopy is mandatory in men and post-menopausal women (NICE NG12). For B12 deficiency, check intrinsic factor antibodies to identify pernicious anaemia — a lifelong condition requiring indefinite treatment.
Iron Deficiency Anaemia — Treatment
Oral iron is first-line. Ferrous sulphate 200mg three times daily (TDS) provides 65mg elemental iron per tablet. Alternatives include ferrous fumarate 210mg BD/TDS and ferrous gluconate 300mg BD. Iron is best absorbed on an empty stomach; if GI side effects occur (nausea, constipation, black stools), take with food or try alternate-day dosing — NICE evidence supports alternate-day dosing improving net absorption by reducing hepcidin rebound. Treat for at least 3 months after haemoglobin normalises to replenish iron stores. Check FBC at 4 weeks — expect a rise of ≥20 g/L. IV iron (ferric carboxymaltose, ferric derisomaltose, iron sucrose) is indicated when oral iron fails, is not tolerated, or is contraindicated — as in malabsorption (IBD, coeliac, post-bariatric surgery), CKD, or pre-operative anaemia optimisation. After ferric carboxymaltose (Ferinject), check serum phosphate at 4–12 weeks — hypophosphataemia is a recognised complication.
Vitamin B12 and Folate Deficiency
Vitamin B12 deficiency is treated with hydroxocobalamin injections. Without neurological involvement: 1mg IM on alternate days for 2 weeks (6 doses), then 1mg IM every 3 months for life (BNF). With neurological involvement (peripheral neuropathy, subacute combined degeneration of spinal cord): 1mg IM on alternate days until no further improvement, then every 2 months for life. For dietary deficiency (vegans): oral cyanocobalamin 50–150 mcg daily or high-dose 1mg daily. Pernicious anaemia requires lifelong IM treatment and carries an increased risk of gastric cancer — patients should be registered and followed up. Folate deficiency is treated with folic acid 5mg once daily for 4 months (BNF). For pregnancy, 400 mcg daily is recommended for prevention of neural tube defects; 5mg daily for high-risk women (previous NTD, antiepileptic use, diabetes, BMI >30). Critical safety point: never prescribe folic acid alone without excluding B12 deficiency — this can mask the haematological features while neurological damage from B12 deficiency progresses silently.
Pharmacist Counselling Points
For oral iron: warn patients that black stools are normal and harmless. Constipation is common — a stool softener (e.g. lactulose or senna) may be needed. GI upset is the main reason for non-adherence — switching to alternate-day dosing or a different iron salt often helps. Key drug interactions: iron chelates and reduces absorption of tetracyclines, fluoroquinolones, bisphosphonates, levothyroxine, and penicillamine — separate doses by at least 2 hours. Vitamin C (ascorbic acid) enhances iron absorption; tea, coffee, and calcium reduce it. For IV iron infusions: anaphylaxis is rare but resuscitation facilities must be available; monitor patients for 30 minutes post-infusion. For B12 injections: lifelong if pernicious anaemia; mild pain or discolouration at injection site is normal. Anaemia of chronic disease is treated by managing the underlying condition (CKD, rheumatoid arthritis, IBD, malignancy) — iron supplements are only appropriate if concurrent IDA is confirmed.