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PA15.1-3 | Welcome to Megaloblastic Anaemia — Aetiology, Blood Picture & Diagnostic Framework
Learning Objectives
- Distinguish megaloblastic from non-megaloblastic macrocytosis using clinical and laboratory criteria
- Enumerate the causes of megaloblastic anaemia — B12 deficiency, folate deficiency, drugs, and inborn errors
- Interpret the full peripheral blood picture and bone marrow findings in megaloblastic anaemia
- Understand the biochemical basis of the MMA and homocysteine tests and use them to differentiate B12 from folate deficiency
- Construct a systematic diagnostic algorithm for macrocytic anaemia
INSTRUCTIONS
In H4 SDL1 you built a biochemical map of B12 and folate metabolism — how methionine synthase and thymidylate synthase depend on these vitamins, and what happens when they fail. This module converts that biochemistry into the haematologist's toolkit: What does the blood smear show? What does the marrow look like? How do you tell B12 apart from folate deficiency without a bone-marrow biopsy? Macrocytic anaemia carries significant morbidity if misclassified — a folate-supplemented B12-deficient patient can develop irreversible subacute combined degeneration of the cord. By the end of this SDL you will have a reliable, examination-ready diagnostic framework.
References
- Robbins & Kumar — Basic Pathology, 11th ed., Ch 13 (Red Cell Disorders) (textbook)
- Hoffbrand & Moss — Essential Haematology, 7th ed., Ch 5 (textbook)
- Harsh Mohan — Textbook of Pathology, 8th ed., Ch 12 (textbook)
Version 2.0 | NMC CBUC 2024