Macrocytic anemia Flashcards
Macrocytic anemia causes
B12 and folate deficiency
What is folate needed for?
Conversion of dUMP to dTMP during DNA synthesis
What is B12 needed for?
Takes the methyl group away from THF so it can participate in DNA synthesis, and transfers methyl to homocysteine thus producing methionine
Lack of folate or B12 impairs what?
The division of RBC precursors –> megaloblastic anemia
The division of granulocytic precursors –> hypersegmented neurtrophils
Causes of macrocytic anemia without megaloblastic chnage?
Alcoholism
Liver disease
Drugs (5-FU)
Where is folate absorbed?
Jejunum
Lab and clinical findings in folate deficiency
Macrocytics RBCs and hypersegemented neutrophils (>5 lobes) Glossitis Decreased serum folate Increased serum homocysteine Normal MMA
Where is B12 absorbed?
ileum
How is B12 absorbed?
Salivary gland enzymes liberate B12
B12 binds to R-binder and is carried through stomach
Pancreatic proteases in duodenum detach B12 from R-binder
Vitamin B12 binds intrinsic factor and this complex is absorbed in the ileum
Most common cause of B12 deficiency?
pernicious anemia
Causes of B12 deficiency
Pernicious anemia
Ileal damage (Crohn disease, diphyllobothrium latum)
Pancreatic insufficiency
Dietary deficiency (vegans)
Clinical and lab findings of B12 deficiency?
Macrocytic RBCs and hypersegmeneted neutrophls
Glossitis
Subacute combined degenertion of the spinal cord (from MMA buildup)
Increased serum MMA
Decreased serum B12
Increased serum homocysteine
Symptoms of subacute combined degeneration of the spinal cord
Poor proprioception and vibratory sensation and spastic paresis
