Haematology

Haematology questions in the AKT typically focus on interpreting blood results, managing anaemia, anticoagulation, and recognising haematological malignancies in primary care.

Iron deficiency anaemia is the most common anaemia worldwide. It presents with microcytic hypochromic anaemia (low MCV, low MCH). Ferritin is the most useful single test, but it is an acute phase reactant, so levels may be falsely normal in infection or inflammation. In men and postmenopausal women, iron deficiency always needs investigation for GI blood loss. NICE recommends both upper and lower GI investigation. In premenopausal women, menorrhagia is the most common cause. Treatment is oral iron (ferrous sulphate 200mg twice daily) for at least 3 months after haemoglobin normalises.

B12 deficiency causes macrocytic anaemia. Common causes include pernicious anaemia (autoimmune destruction of parietal cells, positive intrinsic factor antibodies), dietary deficiency (vegans), and metformin use. Neurological symptoms (peripheral neuropathy, subacute combined degeneration of the spinal cord) can occur with or without anaemia and may be irreversible if treatment is delayed. Treatment is hydroxocobalamin injections: initially every other day for 2 weeks if neurological symptoms present, then every 3 months.

Folate deficiency also causes macrocytic anaemia. Always check B12 before treating folate deficiency, because folate supplementation can mask B12 deficiency and worsen neurological damage.

Anticoagulation management is a major topic. DOACs (apixaban, rivaroxaban, edoxaban, dabigatran) are first-line for most indications including AF, DVT, and PE. Key advantages over warfarin: no routine monitoring, fewer interactions, rapid onset. Key disadvantages: renal dose adjustment required (especially dabigatran), limited reversal agents (idarucizumab for dabigatran, andexanet alfa for factor Xa inhibitors), and cannot be used in mechanical heart valves or moderate-severe mitral stenosis.

Warfarin is still used for mechanical heart valves and antiphospholipid syndrome. INR monitoring is essential. Target INR 2.5 for most indications, 3.5 for mechanical mitral valves. Drug interactions are extensive (antibiotics, NSAIDs, amiodarone all increase INR).

Haematological malignancies to recognise: unexplained lymphadenopathy, unexplained splenomegaly, unexplained bruising, persistent unexplained fatigue with abnormal FBC. Urgent FBC and blood film should prompt urgent referral if abnormalities suggest leukaemia or lymphoma.