Etiology (Causes)
It is most commonly caused by either vitamin B12 deficiency due to causes like pernicious anemia or inadequate absorption, or folate deficiency from nutritional causes or increased utilization in pregnancy. Defects in intracellular B12 metabolism can also contribute.
Pathophysiology
Megaloblastic anemia occurs due to reduced DNA synthesis caused by biochemical abnormalities involving folate or vitamin B12. This leads to ineffective erythropoiesis characterized by megaloblasts that are large, immature precursors with delayed nuclear maturation relative to the cytoplasm. It results in macrocytic anemia and hypersegmented neutrophils. Bone marrow demonstrates characteristic megaloblastic changes.
Sample Type
1. EDTA blood for complete blood count and smear
2. Serum for vitamin B12 and folate levels
3. Bone marrow aspirate
Tests Required to Diagnose Megaloblastic Anemia
Complete Blood Count:
1. Perform automated CBC
2. Check for macrocytic anemia with elevated MCV
3. Examine blood smear for hypersegmented neutrophils
Vitamin Assays:
1. Measure serum vitamin B12 levels by immunoassay
2. Determine serum and RBC folate levels
Additional Tests:
1. Lactate dehydrogenase
2. Homocysteine
3. Methylmalonic acid
Bone Marrow Examination:
1. Extract bone marrow and prepare smears
2. Examine for megaloblastic changes like nuclear-cytoplasmic dyssynchrony
Result Interpretation
Interpretation:
1. Macrocytic RBCs With Hypersegmented Neutrophils
2. Low B12 or folate
3. Megaloblast Cells in the bone Marrow (Megaloblastic marrow)
4. Elevated homocysteine and MMA
Notice
Refrence ranges for all the Above tests are provided in the link below
Normal Range
Megaloblastic Anemia
M. Sulieman
mohammad@mlsgaate.com
Collect sufficient blood volume in EDTA and plain tubes. Transport samples to lab promptly. Process serum for B12, folate assays. Perform CBC, peripheral smear review.
