Macrocytic anaemia

Question 1

What is it

Answer 1

Large RBCs + fall in HB levels in blood

Question 2

What is macrocytosis

Answer 2

Large RBCs (problems synthesis RBCs) 
- presence macrocytes w. raised MCV on blood film

Question 3

What causes it

Answer 3

• PERNICIOUS ANAEMIA - most comon cause
• Megaloblastic (nuclear maturation delayed) - B12 def (5%), folate def, cytotoxic drugs
• Non-megaloblastic = alcohol, reticulocytosis (e.g. in haemolysis), liver disease, hypothyroidism, pregnancy
• Haematological disease - myelodysplasia, myeloma, myeloproliferative disorders, aplastic anaemia

Question 4

What’s the pathophysiology behind Vit B12 deficiency

Answer 4

• Megaloblastic anaemia caused by this = pernicious anaemia
• Autoimmune Addisonian pernicious anaemia= 98%
• Post-surgery e.g. gastrectomy/ ileal resection
• HIV infection/ bacterial overgrowth / parasitic infection

Question 5

What is the pathophysiology behind folate deficiency

Answer 5

• Dietary deficiency
• Malabsorption
• Increased demands incl haemolysis, leukaemia + rapid cell turnover (skin diseases)
• Macrocytosis w/out anaemia –> 30% women in late pregnancy if not taking folate supplements
• Drug-induced deficiency includes alcohol, anticonvulsants, methotrexate, sulfasalazine, trimethoprim (only long-course + high dose)

Question 6

What are the symptoms

Answer 6

• Usually asymptomatic, most are incidental findings
• SOBOE
• Fatigue
• Palpitations + exacerbation of angina

Question 7

What are the signs

Answer 7

• Pallor - look at nail beds + tongue
• Bounding pulse
• Systolic pulmonary flow murmur ?

Question 8

What investigations would you perform

Answer 8

• FBC with blood film – hypersegmented polymorphs in B12/folate
• Serum B12 + folate (or red cell folate – more reliable) levels
• LFTs – abnormal may indicate alcohol abuse + liver disease
• TFT + Coombs’s Test (rules out haemolytic anaemia)
• Bone marrow biopsy – if leukaemia suspected/ not explained by above tests

Question 9

What is the treatment

Answer 9

• Treat underlying cause
• Folic acid 5mg/day 4 months
• Never without B12 – unless pt known to have normal B12 –> low levels precipitate subacute combined degeneration of the cord