Macrocytic anemia Abdul Waris Khan
Dept: Internal medicine
• Subjective: A 33 years old male presents to ER with
complains of easy fatigueability, SOB, palpitations, and
• H/O presenting illness: the symptoms started 2 weeks
ago and it was gradual in onset.
• No past medical or family history
• Objective: pulse: 78 bpm, RR: 20, BP: 130/ 90
• pale, tachycardia
• Evaluation: anemia, sleep apnea, medication side
• Plan: CBC, blood film
• Elaboration: If anemia B12 and Folate supplements
• A macrocytic anemia is a class of anemia in which
the red blood cells (erythrocytes) are larger than their
normal volume (>96 fl)
• Normal 76-96 fl
• Pernicious anaemia (PA) is an autoimmune disorder in
which there is atrophic gastritis with loss of parietal cells
in the gastric mucosa with consequent failure of intrinsic
factor production and vitamin B12 malabsorption.
Signs of anemia
Lemon-yellow color in eyes
Symptoms (all non-specific)
■ Fatigue, headaches and faintness are all
in the general population
■ Intermittent claudication
■ Systolic flow murmur
■ Cardiac failure.
■ koilonychia – spoon-shaped nails seen in
iron deficiency anaemia
■ jaundice – found in haemolytic anaemia
■ bone deformities – found in thalassaemia
■ Anaemia may be present. The MCV is characteristically > 96 fL unless there is a coexisting cause of
microcytosis when there may be a dimorphic picture with a normal/low average MCV.
■ The peripheral blood film shows oval macrocytes with hypersegmented polymorphs with six or more lobes
in the nucleus.
■ If severe, there may be leucopenia and thrombocytopenia.
• Treatment depends on the type of deficiency.
Treatment of vitamin B12 deficiency
• Hydroxocobalamin 1000 μg can be given IM to a total of 5–6 mg over the
course of 3 weeks.
• 1000 μg is then necessary every 3 months for the rest of the patient’s life.
• it is now recommended that oral B12 2 mg per day is given, as 1–2% of an
oral dose is absorbed by diffusion and therefore does not require intrinsic
• In elderly patients the use of sublingual nuggets of B12 (2 × 1000 μg daily)
has been suggested to be an effective and more convenient option.
Treatment of folate deficiency
• Folate deficiency can be corrected by giving 5 mg of folic acid daily.
• Treatment should be given for about 4 months to replace body stores.
• Any underlying cause, e.g. coeliac disease, should be treated.
• Prophylactic folic acid (400 μg daily) is recommended for all women
planning a pregnancy to reduce neural tube defects.
• Women who have had a child with a neural tube defect should take 5 mg
folic acid daily before and during a subsequent pregnancy.
MACROCYTOSIS WITHOUT MEGALOBLASTIC
• A raised MCV with macrocytosis on the peripheral blood film can occur
with a normoblastic rather than a megaloblastic bone marrow.
• A common physiological cause of macrocytosis is pregnancy.
Common pathological causes are:
■ alcohol excess
■ liver disease
■ some haematological disorders (e.g. aplastic anaemia,
sideroblastic anaemia, pure red cell aplasia)
■ drugs (e.g. cytotoxics – azathioprine)
• In all these conditions, normal serum levels of vitamin
B12 and folate will be found.