DR Medhat MRCP

Macrocytic megaloblastic anemias
Causes
Function
Vitamine B12 ↓
Autoimmune Addisonian
pernicious anaemia (80%).
After surgery e.g gastrectomy
or ilectomy( ↓ gastric
intrensic f.` from parietal
cells` essential for B12
absorption)
Bacterial overgrowth or
parasitic infestation
HIV infection
Dietary deficiency (milk,egg)
Essential for DNA synthesis
Essential for myelin sheath
Folic a ↓
Dietary deficiency(liver,egg,banana)
↑ Demands e.g pregnancy.
Malabsorption (in duodenum,jejunum)
Increased demands including
haemolysis, leukaemia
↑ Loss : HF , acute hepatitis,HD.
Drugs : Alcohol ,methotrexate,sulpha.
DNA & new cells synthesis e.g RBCs
Neural tube development in the fetus.
- In a patient who has both vitamin B12 and folic acid ↓ ,treat the B12
deficiency first to avoid precipitating subacute combined degeneration of the
سؤال cord
Pernicious anemia (i.e Abs against gastric parietal cells & intrensic factor)
- Pancytopenia with mainly macrocytic anemia + other autoimmune disease e.g
deranged liver functions with very high LDH (autoimmune hepatitis) =
Pernicious anaemia
- Diagnosis :
Anti-intrensic factor Abs in 50% of cases (most specific)
Blood Film : hypersegmented PNL , BM film : megaloblasts.
Schiling test : radiolabled B12 given twice (1 st alone & 2 nd with oral intrinsic
factor → 1 st ↓ urinary B12 excretion , 2 nd (with IF) ↑↑ urinary B12
excretion
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