DNA/Bone Marrow Failure

etiology of megaloblastic anemia

impaired DNA synthesis

what vitamin deficiency can cause megaloblastic anemia

deficiency of folate or vit B12 can. cause megaloblastic anemia

whenever either of these are deficiency, the production of an amino acid is also impaired

is the DNA functional in megaloblastic anemia

the DNA is nonfunctional because thymidine nucleotide (amino acid) is also impaired and is necessary to produce DNA

three causes of folate deficiency

1. dietary deficiency

2. impaired utilization by drugs

3. excessive loss through kidneys

cause of B12 deficiency

1. inadequate intake (meat, dairy, eggs)

2. increased need during pregnancy

3. impaired absorption due to intrinsic factor deficiency

screening tests for megaloblastic anemia

CBC, neutrophil lobe count, bilirubin and LDH assay

megaloblastic lab findings

1. elevated MCV

2. elevated RDW

3. hypersegmented neutrophils

4. elevated bilirubin

5. elevated LDH

megaloblastic anemia bone marrow findings

megaloblastic appearance to cells (nucleus-cytoplasmic asynchrony)

megaloblastic anemia gastric analysis

measures HCl production

patients with pernicious anemia are unable to produce adequate HCl (achlorhydria)

Schilling test

used to diagnose PA and determine intrinsic factor levels

megaloblastic anemia treatment

treat the vitamin deficiency

bone marrow failure

reduction of blood cell production or increased destruction of RBCs in bone marrow

how does bone marrow failure happen

bone marrow no longer produces adequate number of RBC precursors, differentiation of stem cells is affected, or functionality becomes altered

pancytopenia

decreased numbers of all blood cell types

causes of bone marrow failure

1. biologic

2. chemical

biologic mechanisms of bone marrow failure

stem cell failure, viral infection, overuse due to stress, bone marrow infiltration

chemical mechanisms of bone marrow failure

drugs/chemicals, radiation, infection

why is bone marrow failure a chronic condition

pancytopenia develops gradually

most common and severe of bone marrow failure syndromes

aplastic anemia

characteristics of aplastic anemia

1. depletion of bone marrow cells and replacement of bone marrow with fat

2. peripheral blood pancytopenia

3. delayed plasma iron clearance

classifications of aplastic anemia

1. primary/inherited

2. idiopathic

3. secondary

aplastic anemia treatment

bone marrow transplant