B12/Folate Deficiencies Flashcards
other name for B12?
cobalamin
other name for folate?
vitamin B9
how do we obtain b12?
can’t synthesize it, so it must come from diet (animal proteins, dairy) –> vegans need supplements
how do we obtain folate?
we synthesize it and obtain it from vegetables, nuts, dairy, meat
what’s wrong with a B12 deficiency?
b12 is crucial to folate synthesis
whats wrong with a folate deficiency?
without it, body cant synthesize thymine and therefore cant synthesize DNA
how can you distinguish between a folate or B12 deficiency?
methylmalonic acids levels will only be elevated if B12 is deficient
function of B12
cofactor for tetrahydrofolate (THF) production, for methionione production from homocysteine (HCY), & for succinyl coA from methylmalonyl (MMA)
tests for B12 deficiency
decreased THF, increased HCY & MMA
hematologic symptoms of B12/folate deficiency
megaloblastic anemia, low platelets, leukopenia
dermatologic symptoms of B12/folate deficiency
rashes, hyperpigmentation, epithelial atrophy
oral/GI symptoms of b12/folate deficiency
diarrhea, malabsorption, chelitis, glossitis
neuropsychiatric symptoms of b12/folate deficiency
neural tube defects, ataxia, paresthesias, megalobastic madness, depression blindness
what can mask symptoms of b12 deficiency?
supplementing folate
intrinsic factor
secreted from gastric parietal cells. promotes absorption of cobalamin in ileum
transcobalamin 2
transports cobalamin to cells
R proteins
protect B12 from degradation in the stomach
where is folate absorbed?
jejunum
where is b12 absorbed?
ileum
where is iron absorbed?
duodenum
Lab results for B12 deficiency
increased MMA & HCY, decreased reticulocytes
cause of B12 deficiency if B12 injection is curative?
nutritional deficiency
cause of B12 deficiency if injection doesn’t cure & IF infusion does
gastric pernicious anemia
cause of B12 deficiency if B12/IF infusions don’t work, but antibiotics do
abnormal bacterial growth in intestines
cause of B12 deficiency if B12/IF/antibiotics don’t work, but addition of pancreatic enzymes does
pancreatic insufficiency
pernicious anemia
autoimmune condition that destroys gastric parietal cells so that IF isn’t available for binding and absorption.
megaloblastic anemia
macrocytic anemia caused by impaired DNA synthesis and nuclear/cytoplasmic maturity imbalance (nucleus is less mature). shortened life
types of microcytic anemia
iron deficiency, thalassemia, anemia of inflammation
types of normocytic anemia
acute blood loss, bone marrow failure, renal disease, sickle cell disease
types of macrocytic anemia
B12/folate deficiency, autoimmune hemolytic (pernicious) anemia, hypothyroidism, antimetabolites
causes of megaloblastic anemia
B12, folate deficiency, antimetabolites
morphology of megaloblastic anemia
RBCs with mature pink cytoplasm, with dark condensed nucleus. hyper segmented neutrophils.
problems that lead to hyper segmented neutrophils
megaloblastic anemia & iron deficient anemia
how severe are the neuropsychiatric pathologies associated with b12 deficiency?
irreversible if b12 deficient for >6mos
effects of b12 deficiency on myelin
elevated levels of MMA destabilize myelin
subacute combined degeneration of spinal cord
progressive onset due to loss of myelination from b12 deficiency.
treatment for b12 deficiency
parenteral b12, IM B12 for more severe cases
treatment for pernicious anemia
oral B12 in high dose following parenteral replacement (can absorb some due to laws of mass action)
treatment for folate deficiency
oral folate
