Megaloblastic Anemia - Hematological Findings

Hematological Findings

The blood film can point towards vitamin deficiency:

• Decreased red blood cell (RBC) count and hemoglobin levels
• Increased mean corpuscular volume (MCV, >95 fl) and mean corpuscular hemoglobin (MCH)
• Normal mean corpuscular hemoglobin concentration (MCHC, 32–36 g/dL)
• The reticulocyte count is decreased due to destruction of fragile and abnormal megaloblastic erythroid precursor.
• The platelet count may be reduced.
• Neutrophil granulocytes may show multisegmented nuclei ("senile neutrophil"). This is thought to be due to decreased production and a compensatory prolonged lifespan for circulating neutrophils, which increase numbers of nuclear segments with age.
• Anisocytosis (increased variation in RBC size) and poikilocytosis (abnormally shaped RBCs).
• Macrocytes (larger than normal RBCs) are present.
• Ovalocytes (oval-shaped RBCs) are present.
• Howell-Jolly bodies (chromosomal remnant) also present.

Blood chemistries will also show:

• In increased lactic acid dehydrogenase (LDH) level. The isozyme is LDH-2 which is typical of the serum and hematopoetic cells.
• Increased homocysteine and methylmalonic acid in Vitamin B deficiency
• Increased homocysteine in folate deficiency

Normal levels of both methylmalonic acid and total homocysteine rule out clinically significant cobalamin deficiency with virtual certainty.

Bone marrow (not normally checked in a patient suspected of megaloblastic anemia) shows megaloblastic hyperplasia.