Anemias and Hematinic Agents Flashcards
what is anemia?
the most common blood disorder- a defect in RBC formation or function
lack of tissue oxygenation
what are the different types of anemia?
nutritional anemias
anemias due to blood loss
anemias due to chronic renal failure (decreased erythropoietin)
hemolytic anemia- oxidative damage- in G6PDH deficient patients
sickle cell anemia
what are the nutritional anemias?
microcytic anemia and macrocytic anemias
what is the cause of microcytic anemia
relative lack of iron
RBCs are relatively small, pale
what is the normal iron metabolism?
iron is highly conserved by the body- no specific mechanism for eliminating iron
normally, we ingest iron and solubilized by HCL in the gut and absorbed as Fe2+ (ferrous iron)
Fe3+ (ferric) is not readily absorbed
Fe2+ is absorbed, converted to Fe3+ by molecule transferrin
transferrin is carrier for iron throughout the body
transferrin increases during times of anemia
excess iron is bound to and stored as ferritin in the liver
what are the probable etiology of iron deficiency?
decreased iron uptake- not enough iron in diet
decreased absorption- if hcl is low or GI dysfunctions
increased iron requirement- in pregnancy, during periods of rapid body growth, px with renal disease
excess loss of iron due to chronic blood loss
what is the primary cause of iron deficiency?
excess loss of iron due to chronic blood loss
what is the drug of choice of microcytic anemia?
iron
FeSO4 is orally absorbed - Fe2+
what are the routes of administration of iron?
oral- can cause gi upset
parenteral- severe deficiency- iron dextran-IM
acute toxicity of iron
oral iron can be very toxic especially in children
lethal doses- as few as 10 tablets
nausea, severe abdominal pain- muscosal damage
drowsiness
cardiovascular collapse
convulsions and death
what is the treatment of acute toxicity of iron?
a chelating agent- deferoxamine
chronic toxicity of iron
too much iron is stored (hemachromatosis)
what is the treatment of chronic toxicity of iron?
phlebotomy
what is macrocytic anemia?
large RBC precursors- multilobed nuclei due to inhibition of DNA synthesis
what is the macrocytic anemia?
folic acid deficiency anemia
why is folic acid important?
folic acid is necessary for DNA replication
lack of folic acid can cause methionine deficiency
what are the symptoms of folic acid deficiency?
macrocytic RBC precursors
etiology of folic acid deficiencies?
intake deficiency
absorption is usually rapid
drugs can inhibit synthesis of the active form
increased requirements- infection, pregnancy, renal dialysis
folic acid deficiency in pregnancy can lead to neural tube defects in fetus
therapy of folic acid deficiency
oral therapy is usually sufficient
parenteral therapy if there is an absorption abnormality
no contraindications, no toxicities
only indication– folic acid deficiency
what is the function of vitamin b12?
b12 is essential for DNA synthesis and methionine synthesis
what are the symptoms of b12 deficiency?
megaloblastic anemia
lack of methionine
cause decrease in myelin synthesis- neuronal damage- weakness, ataxia, spasticity; irreversible spinal cord damage
what are the possible etiologies of b12 defiency?
insufficient intake is very rare
decreased absorption- most common cause due pt may lack ability to make GIF (gastric intrinsic factor made by parietal cells- b12 requires GIF for absorption
what happens if patient lacks ability to make GIF?
pernicious anemia
fatal if not treated
what are the pharmacologic treatment of b12 deficiency not due to lack of GIF?
oral administration
what is the pharmacologic treatment of pernicious anemia?
b12 must be given injection
what is shot gun therapy?
pernicious anemia looks like macrocytic anemia- thus give folic acid as treatment- appears to be treated but still have neuronal damage from pernicious anemia
need accurate diagnosis- give b12
drugs that treat anemias due to chronic renal failure or chemotherapy?
epoietin alfa
darbepoietin
peginesatide
what are the toxicities of epoietin alfa, darbepoietin, peginesatide?
due to an excess of RBC-> increase BP, increase clotting, myocardial infarction, stroke
what is hemolytic anemia caused by?
abnormal lysis of rbc (broken down too readily)
what is the treatment of hemolytic anemia?
iron is generally not useful
erythropoietin may be useful
what is sickle cell anemia?
abnormal flow properties of RBC- RBC gets stuck in small blood vessels
causes severe joint pain
what is used to treat sickle cell anemia?
hydroxyurea
how does hydroxyurea work?
increase formation of fetal hemoglobin, which does not sickle
what are the side effects of hydroxyurea?
mutagenic, pregnancy category D
