How do I differentiate between aplastic anaemia and other causes of bone marrow failure in primary care?

In a primary care setting, differentiating aplastic anaemia (AA) from other causes of bone marrow failure primarily relies on clinical suspicion and initial blood tests, as definitive diagnosis requires specialist referral and bone marrow examination NICE NG12. Key clinical features include pancytopenia symptoms such as fatigue, infections, and bleeding tendencies without organomegaly or lymphadenopathy, which are more typical of malignancies like leukaemia DeZern & Churpek 2021. Initial blood tests should show pancytopenia with low reticulocyte count, indicating marrow hypoplasia rather than peripheral destruction or sequestration NICE NG12. Peripheral blood smear typically reveals normocytic, normochromic anaemia without abnormal cells, helping to exclude myelodysplastic syndromes or leukaemia Marsh et al. 2009. Other causes of bone marrow failure such as myelophthisis, infiltrative diseases, or nutritional deficiencies often present with additional clinical or laboratory clues, including organomegaly, abnormal cell morphology, or macrocytosis Barone et al. 2015. Referral for urgent haematology assessment is essential for bone marrow biopsy to confirm hypocellularity without fibrosis or malignant infiltration, which is diagnostic of AA NICE NG12. Thus, in primary care, the differentiation hinges on recognising unexplained pancytopenia with hypocellular marrow features suggested by blood tests and clinical context, followed by prompt specialist referral DeZern & Churpek 2021Marsh et al. 2009.