Megaloblastic anemias L7 Flashcards
Common cause of macrocytic anemias
Vitamin B12 and folate deficiencies leading to impaired DNA synthesis
Conditions causing non-megaloblastic anemia
Alcoholism
Reticulocytosis
Liver disease
Hemolytic anemia
Difference between megaloblastic and non-megaloblastic anemia
Megaloblastic anemias: elevated MCV, caused by deficiencies in vitamin B12/folate that impairs DNA synthesis, megaloblasts seen in bone marrow.
Non-megaloblastic: elevated MCV with no megaloblastic changes in the bone marrow. DNA synthesis is normal.
Why is DNA synthesis impaired in megaloblastic anemias?
When B12 or folate missing, thymidine is unavailable, leading to a skipped step in the DNA sequence; cell division is halted and die.
General symptoms for B12/folate deficiencies:
Neural problems (demyelination of spinal cord, mental state altered)
Spina bifida in fetuses (folate def.)
Loss of epithelium (tongue, GI tract)
Advanced aging
Which deficiencies is the most common and why?
Folate; is stored for a few months in the liver compared to years for B12.
Causes for B12 deficiencies
Increased use of B12 by other organisms (bacteria, parasites) Diet deficiency Malabsorption Pernicious anemia Carrier of B12 missing (transcobalamin)
Causes for folate deficiencies
Diet related Liver disease Drugs Malabsorption Increased demands (pregnancy)
Cells features of megaloblastic erythropoiesis
Giant metamyelocytes
Nuclear chromatin fine-grained/bag of worms
Cytoplasm color ahead of nucleus (nuclear asynchrony)
Hypersegmentation of neutrophils
Peripheral blood picture of megalo anemias
Ovalocytes, dacryocytes
Howell-Joly bodies, basophilic stippling
Hypersegmentation
nRBC can be present
Bone marrow picture in megalo anemias
Hypercellularity with erythrocytes predominating
Megaloblasts increased compared to normoblasts
Causes of pernicious anemia
B12 deficiency causing gastric atrophy = achlorhydria (less HCl produced) = malabsorption of B12.
Intrinsic factor reduced = malabsorption
