AKT · Haematology/Anaemia & red cell

Iron-deficiency anaemia

Iron deficiency (blood loss, malabsorption, poor intake, increased demand) → microcytic hypochromic anaemia

Overview

The commonest anaemia worldwide — a microcytic, hypochromic anaemia from depleted iron stores. The cause matters more than the number: in adults (especially men and post-menopausal women) it signals occult GI blood loss / malignancy until proven otherwise; in menstruating women, menorrhagia; consider coeliac disease (malabsorption) and dietary deficiency. Treat with oral iron and find and treat the cause.

Recognise

Fatigue, pallor, breathlessness; signs of chronic deficiency — koilonychia (spoon nails), angular stomatitis, glossitis, pica
Microcytic hypochromic film (pencil cells, anisocytosis); LOW ferritin (the key test — but ferritin is an acute-phase reactant, can be falsely normal/high with inflammation)
Causes: blood loss (GI — ulcer/cancer/angiodysplasia; menstrual), malabsorption (coeliac), poor intake, increased demand (pregnancy/growth)

Red flags

Iron deficiency in any adult man or post-menopausal woman → urgent investigation for GI cancer (2-week-wait OGD + colonoscopy)
Coeliac disease as a cause of malabsorption → test (anti-TTG)

Differentials & how to tell them apart

Thalassaemia traitmicrocytic with a NORMAL/high ferritin and a disproportionately low MCV for the Hb; haemoglobinopathy screen

Anaemia of chronic diseasenormal/high ferritin, raised inflammatory markers; iron studies show low iron but high ferritin

Sideroblastic anaemiaring sideroblasts on marrow, raised ferritin

Iron-deficiency anaemia — hypochromic microcytic red cells (blood film)
Prof. Osaro Erhabor / CC BY-SA 3.0 — Wikimedia Commons

Investigations

FBC (microcytic hypochromic), ferritin (low — diagnostic; interpret with CRP as it rises with inflammation), iron studies (low iron, high transferrin/TIBC); blood film; coeliac serology (anti-TTG); upper + lower GI endoscopy in adults to find the bleeding source; urinalysis/menstrual history.

Management

Oral iron + find/treat the cause (GI source, menorrhagia, coeliac)

1Confirm with a low ferritin (microcytic hypochromic film) and start oral iron; alternate-day dosing aids absorption and continue for ~3 months after the Hb normalises.Gate: The cause is the priority: iron deficiency in any man or post-menopausal woman → urgent 2-week-wait OGD + colonoscopy for GI cancer; test for coeliac disease; ferritin can be falsely normal with inflammation (check CRP).
2IV iron if oral is not tolerated/absorbed or response is inadequate; transfuse only for symptomatic/severe anaemia; treat the underlying source.

Oral iron (e.g. ferrous sulfate/fumarate) — first-line; alternate-day dosing improves absorption/tolerance; continue ~3 months after Hb normalises to replenish stores; SE — GI upset, black stool

Find and treat the cause — the essential step — GI source, menorrhagia, coeliac disease, diet

IV iron — if oral not tolerated/absorbed (e.g. IBD, CKD) or inadequate response

Transfusion only if symptomatic/severe — not for asymptomatic chronic deficiency — iron replacement is the treatment

Key points

Microcytic hypochromic anaemia + LOW ferritin = iron deficiency → oral iron (alternate-day, continue 3 months after Hb normal) AND find the cause: any man / post-menopausal woman → GI cancer work-up; women → menorrhagia; consider coeliac. Ferritin is an acute-phase reactant (falsely normal with inflammation).

Monitor & prognosis

Hb/reticulocyte response (recheck at 2–4 weeks), ferritin replenishment, the cause.

Excellent once iron is replaced and the source treated.

Source: NICE CKS / BSH iron deficiency