Macrocytic anaemia

Question 1

Define Macrocytic Anaemia

Answer 1

Anaemia (reduced Hb) with high MCV >100fL

Question 2

Aetiology of Macrocytic Anaemia

Answer 2

Megaloblastic
Vitamin B12 deficiency (pernicious anaemia, post-gastrectomy, terminal ileal resection, Crohn's, vegan diet)
Folate deficiency (alcoholics, elderly, coaliac, preganancy, lactation)
Drugs e.g. methotrexate, hydroxyurea, azathioprine, zidovudine 

Non-megaloblastic 
Alcohol excess
Haemolysis 
Liver disease
Myelodysplasia
Multiple Myeloma 
Hypothyroidism 
Drugs e.g. imatinib

Question 3

Epidemiology of Macrocytic anaemia

Answer 3

More common in elderly and females

pernicious anaemia is the most common cause of vit B12 deficiency worldwide

Question 4

Symptoms of Macrocytic anaemia

Answer 4

Anaemia: SOB, pallor, fatigue
Symptoms of cause: weight loss, diarrhoea, steatorrhoea, malnutrition, jaundice, hypothyroidism
Pernicious anaemia: jaundice, glossitis, angular stomatitis, weight loss

Hx of autoimmune disease, GI surgery etc.

Question 5

Signs of Macrocytic anaemia

Answer 5

Anaemia: pallor, tachycardia

Pernicious anaemia: jaundice (lemon skin), glossitis (red, sore), angular stomatitis, weight loss
Vit B12: Peripheral neuropathy, Ataxia, Subacute combined degeneration of the spinal cord, Optic atrophy, Dementia

Question 6

Investigations for Macrocytic Anaemia

Answer 6

FBC: Reduced Hb, raised MCV >100, pancytopenia (megaloblastic), cytopenia (myelodysplasia)
LFTs: raised bilirubin (ineffective erythropoiesis or haemolysis)
ESR: checking for causes
TFTs: exclude hypothyroidism
Serum B12: Exclude B12 deficiency
Serum antibodies: pernicious anaemia
Serum protein electrophoresis: exclude multiple myeloma
Blood film: large erythrocytes (macrocytes) or macro-ovalocytes and hyper-segmented neutrophil (megaloblastic)

Schilling’s test: B12 (rarely used)
Bone marrow biopsy: megaloblasts (nucleated red cells), myelodysplastic changes

Question 7

Management for Macrocytic anaemia

Answer 7

Pernicious anaemia: IM hydroxycobalamin (3x weekly for 2 weeks, every 3 months for life)

Vitamin B12 deficiency: treated first if present (worsens neurological/subacute combined degeneration of the cord complications if second)

Folate deficiency: Oral folic acid (1–4 months or until recovery)

Question 8

Complications of Macrocytic anaemia

Answer 8

Pernicious anaemia: Increased risk of gastric cancer

Folate deficiency and pregnancy: spina bifida