Etiology:
Vitamin B12 or folate deficiency
Causes of B12 deficiency:
Pernicious anemia (autoimmune destruction of parietal cells)
Gastric bypass surgery
Chronic pancreatitis
Vegetarian diet (B12 only in animal products)
Causes of folate deficiency:
Alcoholism
Pregnancy
Drugs (methotrexate, trimethoprim)
- Pathogenesis:
B12 & folate are needed for DNA synthesis
Deficiency leads to impaired nuclear maturation → megaloblastic cells (large, immature RBCs)
Ineffective erythropoiesis → macrocytic anemia
Hypersegmented neutrophils seen on smear
- Clinical Features:
General anemia symptoms (fatigue, pallor, dyspnea)
Glossitis (smooth, red tongue)
Neurological symptoms (seen in B12 deficiency, but not folate):
Peripheral neuropathy
Subacute combined degeneration (spinal cord demyelination)
Memory loss & dementia
- Treatment:
B12 replacement (IM injections for pernicious anemia)
Folate supplementation (for folate deficiency)
Identify and treat underlying cause