Macrocytic Anemia Flashcards
RBCs with increased volume, diameter, and thickness
macrocytes
- MCV > 100
- RBCs will be larger than the nucleus of a small lymph and may lack central pallor
causes and mechanisms of macrocytes
- megaloblastic erythropoiesis
- reticulocytosis: hemolytic anemia, hemorrhage
- macronormoblastic erythropoiesis
megaloblastic erythropoiesis
- abnormalities of DNA metabolism
- vitamin B12 or folate deficiency
- drugs interfering with DNA synthesis
macronormoblastic erythropoiesis
- BM disorders
- lipid abnormalities (liver disease)
- alcoholism
megaloblastic anemia
- impaired DNA synthesis - defective nuclear maturation (cytoplasm no affected)
- primarily caused by vit B12 and folate deficiencies
Vit B12 and folate deficiencies symptoms
- anemia
- GI symptoms
- Glossitis
- neurological symptoms (for vit B12 def only)
screening tests for megaloblastic anemia
- CBC: decreased Hb, pancytopenia with reticulocytopenia, high MCV, increased RDW
- peripheral blood smear: macroovalocytes, hypersegmented neutrophils, tears, schistocytes, HJ bodies, basophilic stippling
Megaloblastoid cell maturation
- hypercellularity
- ineffective myelopoiesis = giant bands and metamyelocytes
- megakaryocytes may also be affecyed
hypercellularity
making lots of precursor cells - filling up bone marrow but not enough good cells to go out into the body
Development of megaloblastic anemia
- vit B12 or folate def
- hypersegmentation of neutrophils in the peripheral blood
- macroovalocytes in the peripheral blood
- megaloblastic changes in bone marrow
- anemia
reticulocytosis
an abundance of reticulocytes
immature RBCs that last in circulation for about 24h ours
reticulocytes
- higher MCV
- contain residual ribosomal RNA
this occurs when cells are released prematurely from the BM in response to high levels of EPO
stress reticulocytes or shift reticulocytosis
increased reticulocytes is seen with:
- hemolytic anemia
- hemorrhage
- hematinic therapy
- hypoxia
T or F. reticulocytes can increase measured MCV
T!
non-megaloblastic macrocytic anemia
peripheral blood smear:
- MCV 100-110 fL
- round macrocytes
- no hypersegmentation
BM
- normocellular or hypercellular
- normoblastic, not megaloblastic
liver disease
- related to increased lipid deposition in the RBC membrane leading to changes in membrane rigidity and shape
- peripheral blood smear may show target cells and acanthocytes
alcohol effects on hematopoiesis:
- direct toxic effect on bone marrow
- alcoholic cirrhosis leading to changes in lipid metabolism
- folate deficiency
- macrocytosis often precedes anemia
Myelodysplastic syndromes
- malignancy featuring abnormal or ineffective hematopoiesis (refractory anemias)
- lots of unknowns:
> may have dimorphic population (high RDW)
> may have megaloblastoid cell maturation
> may show effects in other cell lines
