MEGALOBLASTIC ANEMIA
DR WAQAR
Megaloblastic anemia is a type of macrocytic anemia characterised by the presence of “megaloblasts” in the bone marrow, and is mostly due to Vit.B12 or Folic acid deficiency. The RBCs which enter the blood, are large (macrocytes)
“Megaloblasts” are large, abnormal cells with immature nucleus due to problem in cell maturation. WBCs & platelets are also affected.
ANEMIA
| Normocytic | Microcytic | Macrocytic |
|---|---|---|
| (normal RBC size, so norm. MCV) | (small RBC MCV low) | (big RBCs, so MCV high) ⇒ | | Megaloblastic | Non-megaloblastic |
Normal RBC synthesis in bone marrow
Many substances are required for this normal process of RBC synthesis.
2 things which are very important for RBC synthesis (and also for synthesis of WBC & platelets) are: a) Vitamin B12 b) Folic acid
These are required for normal maturation of cells
What happens in B12 or folic acid deficiency
- Due to deficiency of B12 or folic acid, the cells in the marrow cannot develop normally.
- This results in large abnormal cells with immature nucleus. These cells are called “megaloblasts”
- Some RBC megaloblasts lose the nucleus and go in the blood as large “macrocytes.”
CAUSES OF MEGALOBLASTIC ANEMIA
- Vitamin B12 deficiency commonest causes due Pernicious Anemia
- Folic acid deficiency commonest causes
- Drugs
FOLIC ACID DEFICIENCY
This is another cause of Megaloblastic anemia It causes anemia BUT NO NEURO S/S Folic acid is found in fruits & green leafy vegetables
CAUSES OF FOLIC ACID DEF.
- Decreased intake (not eating KHUDRAA & FAWAAKA, alcoholics, poor diet)
- Increased requirements: a) Pregnancy, lactation b) Dialysis patients (loss of folic acid)
Causes of def. contd
c) Hemolytic anemias (loss of RBCs & bone marrow becomes overactive to compensate & needs more nutrients) d) B12 def. can cause folic acid def.
Causes of folate deficiency contd.
- Drugs: Methotrexate, Phenytoin
- Malabsorption: * Celiac disease
Body stores of folic acid are not too much, so deficiency occurs quickly, in about 4 months
INVESTIGATIONS IN FOLIC ACID DEFICIENCY
- CBC, Peripheral smear & bone marrow findings are same as in B12 def. (low Hb. & macrocytes in the blood, megaloblasts in the marrow)
- Serum folic acid levels are low
- RBC folic acid low (more accurately indicates body stores of folate), so it is test of choice
TREATMENT
- Correct the cause
- Folic acid tablets, 1 or 5 mg daily
- Prophylactic folic acid is given in all hemolytic anemias, eg sickle cell disease, & also in pregnancy, lactation, dialysis patients
- If it is due to B12 def. give that also
Review this slide again
ANEMIA
| Normocytic | Microcytic | Macrocytic |
|---|---|---|
| (normal RBC size, so norm. MCV) | (small RBC MCV low) | (big RBCs, so MCV high) |
| Megaloblastic | Non-megaloblastic |
OTHER CAUSES OF HIGH MCV (but no megaloblasts)
- Pregnancy
- Hypothyroidism
- Drugs (azathioprine)
- Liver disease
APPROACH TO HIGH MCV
- Rule out any drug induced cause, preg., hypothyroidism
- Do peripheral smear
- Check B12 plus folate levels
- If both are low, give both
Never give folic acid alone if there is only B12 def. It will correct the anemia but neuro features will progress
RAPID FIRE QUESTIONS
- Causes of microcytic anemia?
- 2 causes of megaloblastic anemia?
- What 2 things are needed for B12 absorption?
- Which foods contain B12?
- Causes of B12 def?
- Where is B12 absorbed?
- No B12 is absorbed in the duodenum, true or false?
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Besides anemia, what else can occur in B12 def?
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Name 3 neuro problems?
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What will you see on peripheral smear?
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If B12 levels are borderline, what to check next?
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Bone marrow biopsy LAAZIM?
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What is pernicious anemia?
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Name the antibodies of pernicious?
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B12 def due to gastrectomy is called pernicious anemia, true or false?
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Best treatment for pernicious, injections or oral?
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Patient has B12 def. What 2 medicines to give?
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In B12 def., are neuro features reversible?
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Food sources of folic acid?
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Causes of folate def?
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Can B12 def cause folate def?
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Best test to diagnose folate def?
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Folate def causes neuro problems, true?
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Causes of macrocytic anemia without megaloblasts?
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Name 1 drug which causes macrocytic anemia?
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50 year old male. Vegetarian TANMEEL in hands & feet since 1 month No anemia on physical exam CBC normal What will you do next?