Megaloblastic Blood Film Findings
February 15th, 2021
Overview
Megaloblastic anaemia is a condition where the bone marrow produces large immature red blood cells called megaloblasts which go on to become large, ineffective red blood cells.
Blood Film Findings in Megaloblastic Anaemia
- Macrocytic hyperchromic anaemia (may be normocytic in early disease)
- Anisocytosis: variation in size of red blood cells
- Macroovalocytes: large, round cells
- Teardrop cells
- Hypersegmented neutrophils (5 or more nuclear lobes)
- A hypersegmented neutrophil in a patient with megaloblastic anaemia:
![A hypersegmented neutrophil in a patient with megaloblastic anaemia]()
Causes of Megaloblastic Anaemia
Haematinic Deficiency
- B12 deficiency - pernicious anaemia, H pylori gastritis, malabsorption, resection of the stomach or terminal ileum, chronic pancreatitis
- Folate deficiency - nutritional deficiency, alcohol abuse, malabsorption, pregnancy, folate antagonists
Drugs
- Folate antagonists - methotrexate, trimethoprim
- Purine analogues - azathioprine, 6-mercaptopurine, allopurinol, cladribine, fludarabine
- Pyramidine antagonists - 5-fluorouracil, cytarabine, gemcitabine, capecitabine
- Anticonvulsants - valproate, phenytoin
- Reverse transcriptase inhibitors - abacavir, emtricitabine, entecavir, lamivudice, zidovudine, tenofovir, efavirenz
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