Macrocytic Anemias Flashcards
megaloblastic anemia: cause
folate and cobalamin def
megaloblastic
large immature RBCs which often have Howell Jolly bodies
anisocytosis
varied RBC size
poikilocytosis
varied RBC shape
microcytosis
decrease in RBC size
hypochromasia
pale RBCs
reticulocytosis
increased RBC production
reticulocytopenia
decreased RBC production
macrocytic MCV
> 100 fl
increased RBC turnover in macrocytic anemias may cause elevated:
plasma LDH and iron.
plasma bilirubin –> icterus/jaundice
Howell Jolly bodies: cause
disorder of DNA synthesis in the bone marrow
B12 def anemia: size & shape
will be variation in size (anisocytosis) and shape (poikilocytosis) of RBCs
B12 def anemia: blood sample
may have Howell-Jolly bodies, cabot rings or nucleated RBCs. abnormal WBCs like hypersegmented neutrophils (PMN) cells
B12 biochemical status
plasma or serum vit B12 deficient = 150-200 pg/mL
B12 def: s/s
weak, tired, yellow icterus, paresthesia, hyperreflexia/decreased reflexes, ataxia, stocking and glove sensoty loss, incontinence, neuropathy and Lhermitte’s sign
pernicious anemia (PA): cause
syndrome of cobalamin def caused by gastric mucosal defect that diminishes IF synthesis in parietal cells
PA: risk factors
rare in ppl <40.
common in northern European origin, runs in families, linked to helicobacter pylori infection and autoimmune diseases
B12 def: autoimmune risk factors
antibodies to parietal cells are present in 90% of cases. lack of IF causes malabsorption of B12
B12 def: congenital defects risk factor
congenital PA (no/defective IF production). ismerlund-Grasbeck syndrome - defects of cubilin, the ileal receptors for IF
B12 def: transcobalamin II defects risk factor
can’t transport B12 into cells. cause probs similar to PA, failure to thrive, mental retardation. all these defects respond to high dose parenteral B12 therapy
B12 def: gastric probs risk factor
low IF production. gastrectomy, bypass, zollinger, severe gastritis
B12 def: ileal probs risk factor
poor absorption d/t damage/removal of terminal ileum. ileal resection, ileitis, Crohn’s in ileum, GSE, AIDS or scleroderma
B12 def: competitive parasites risk factor
fish tape worm, bacteria in intestine may compete for cobalamin
B12 def: pancreatic enzyme related risk factor
pancreatic proteases are needed to release cobalamin from R proteins. pancreatitis, pancreatectomy
B12 def: high B12 requirement risk factor
pg, high RBC production as in chronic hemolytic anemias, some cancers, hyperthyroidism, nitric oxide anesthesia.
Elderly have difficulty freeing B12 from food due to low stomach acid, sups are wll absorbed.
meds that impact B12 status/absorption
nitrous oxide, cholestyramine, clofibrate, paraaminosalicylic acid, INH, neomycin, netformin, phenformin, colchicine, H2 receptor blockers, PPIs (Prilosec, prevacid, nexium), anticonvulsants (phenobarbital, Dilantin)
cobalamin def: mgmt
B12 injection, or absorbed via passive diffusion in terminal ileum.
folate & B12 def elevation of:
serum iron, liver enzymes, bilirubin
folic acid biochemical value
def = <3 ng/mL
folic acid def : s/s
weakness, tiredness, glossitis, red tongue
folate def: dietary
poor folate intake has improved w/fortification. some foods contain conjugase inhibitors which prevent folate digestion and lowers bioavailability but effect is minor.
folate def: risk factors
alcohol, malabsorption syndroms (GSE, intestinal resection, enterisits, Crohn’s)
folate def: higher needs in
pg, hyperthyroidism, increased hematopoiesis, liver cirrhosis
folate & methotrexate
structurally similar to folate. do not take folate w/med taken for chemo. for other disorders, folate is fine
folate & Dilantin
folate status may decline w/Dilantin. folate may decrease med’s anticonvulsant effect, so take min amt of folate needed if deficient
folic acid & other meds
antacids, anticonvulsants, aspirin, barituates, bile acid sequestrants, Colestipol, cycloserine, diuretics, famotidine, lithium, isoniazid, metformin, triamterene
folate def mgmt typical dose
250 - 1,000 mcg/day
severe folate def mgmt dose
such as in megaloblastic anemia and malabsorption disorders: 1-5 mg (1,000-5,000 mcg)/day
