antianemics – Flashcards
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| what is normocytic MCV? microcytic? macrocytic? |
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| normocytic MCV: 80-94 cubic microns, microcytic MCV: <80 (characteristic of iron deficiency), and macrocytic mcv:>99 (usually due to B12 deficiency) |
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| what happens to iron in the body? |
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| it is mostly recycled (90&), the only real normal loss of it occurs with exfoliation of cells in the GI (and menstrual cycle in females) |
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| when does the body know to absorb more iron? |
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| when tissue stores (liver/bone marrow) are depleted - otherwise iron moves through GI and is not absorbed |
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| what state is Fe in the body? |
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| Fe is never in its free state (corrosive -. leads to metabolic acidosis, death), it is complexed with ferritin in circulation and transported by transferrin |
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| why might females have lower Fe stores? |
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| menstrual cycle, lower muscle mass, lower dietary intake, pregnancy |
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| what is the definition of anemia? |
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| men: less than 13 g/dL and women: less than 12 g/dL (upper number is around 14-16 g/dL - don't want to surpass due to risk of thrombus esp with erythropoietin) |
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| what are reasons for anemia? |
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| pregnancy (due to increased Fe req), blood loss due to hemorrage/ulcers, malabsorbtion syndrome (due to intestinal sx), renal dialysis |
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| what is dietary Fe intake? how much of that is absorbed? |
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| 14-15 mg/day, 1 of which is absorbed usually which correlates with what is lost (can be 2 mg during menstruation, 4-6 during pregnancy) |
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| how is iron absorbed through the GI? |
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| ionic iron must be reduced by the reductase enzyme in the GI mucosa and is then brought in via a divalent cation transporter and stored in the form of ferritin, Fe 3+ iron still in heme from meat can be directly absorbed |
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| how is iron transported into plasma? |
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| by transferrin (of which there are a lot of receptors for erythrocyte precursors (in bone marrow), hepatocytes (storage point), and macrophages in the spleen (conserve hgb at site of RBC degradation)) |
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| how do tumor cells treat transferrin? |
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| they downregulate it, it represents maturation which cancer is not interested in |
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| where is 50-60% of iron in the body? 27%? |
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| 50-60% is in hgb, 27% is in reticuloendothelial cells in bone marrow (2/3 of which in ferritin form) |
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| what is hemodesiderin? |
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| larger molecules of ferritin |
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| if the body has a lot of Fe in storage how much more will it absorb? |
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| very little (alternately: low storage - body will absorb Fe much more efficiently) |
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| what is transferrin? what does it represent? what happens to this in iron deficicency? |
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| the main protein transporting Fe in the blood. it represents the total iron binding capacity of blood (TIBC). in iron deficiency, the body will try to compensate by increasing transferrin conc. to pick up anything it can. ->the body needs O2! |
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| in cases with erythropoietic and iron deficiency anemia, what will you see? |
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| increased iron absorption, less plasma iron, less transferrin saturation, microcytic/hypoochromic erythrocytes (esp w/iron deficient anemia), and increased RBC protoporphyrins (precursor cells) |
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| in iron store depletion how do hematocrit, hgb, RBC, TIBC, iron stores levels look? what are symptoms? |
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| hematocrit, hgb, RBC, TIBC levels are normal, iron stores (ferritin)are depleted, but there are minimal symptoms - maybe some tiredness/fatigue |
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| in iron deficient anemia due to erythropoiesis how do hematocrit, hgb, RBC, TIBC, iron stores levels look? what are symptoms? |
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| the hematocrit is decreased, RBCs are decreased (some microcytic/hypochromic), TIBC saturation is low but increased, and moderate sympotms of tiredness, fatigue, and shortness of breath on exertion are seen |
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| in iron deficiency anemia how do hematocrit, hgb, RBC, TIBC, iron stores levels look? what are symptoms? |
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| hematocrit is very low, RBC level is significantly decreased, microcytosis/hypochromia/irreg shapes and sizes are seen, TIBC is increased, but saturation is very low. symptoms are more severe: extreme fatigue, esp in pts with cardio/resp conditions, palpitations, dizziness, dyspnea, syncope - if prolonged: cardiac ischemia/CHF/edema/L ventricular hypertrophy possible |
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| what is the tx for iron deficiency? |
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| oral administration of 325 mg ferrous sulfate will provide 65 mg elemental iron (20%). to correct anemia, you need 150-200 mg to reach absorbtion of 40-50 mg (25%) <-max absorption, thus why it can take 6 mo to restore iron stores. dextran can be administered IM/IV (usually with erythropoietin for renal disease), and an allergic screening should be performed. |
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| who does acute iron toxicity usually occur to? how does it present? |
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| children. initially nausea/vomiting/diarrhea, GI pain/corrosion for up to 12 hours. gastric lavage/bicarb is administered b/c excess iron in circulation will cause shock due to metabolic acidosis -> can lead to coma/death. in these cases, TIBC will be at or around 100%. scarring of the GI and obstruction can result. iron chelation with deferoxamine is also a viable therapy for this (but is contraindicated in pregnancy and renal dysfunction). |
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| what tissues can be damaged by excess iron? |
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| heart, liver, pancreas, other tissues |
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| what is hemochromatosis? |
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| an autosomal recessive disorder where the intestine can lose its ability to selectively refuse iron absorption -> leads to organ failure |
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| what is folic acid needed for? when is it needed more |
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| folic acid is needed for DNA synthesis, and a higher amount is needed during pregnancy to prevent neural tube defects |
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| what is the active form of folic acid? what is the inactive form useful for? |
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| dihydrofolate reductase activates folate into tetrahydrofolate, the active form. the inactive form is methylated and is the transportable/storage form of folate (can contributes to megaloblastic forms in some disorders) |
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| what are the leading causes of folic acid deficiency? |
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| malnutrition, alcoholism (enterohepatic circulation that reabsorbs folic acid is impaired), pregnancy, lactation, malignancies, intestinal disease, and liver disease (less reabsorption) |
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| what is the relationship between folate and vit B12/cobalamine? |
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| vit B12 demethylates folate (activates it), and this methyl group is used to make methionine from homocysteine (methionine is needed for needed to make myelin sheath - link to neurologic problems, and backing up homocysteine is releated to coronary artery disease/athersclerosis). activated folate (TH4) is needed for **dUMP->dTMP AND purine synthesis |
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| what can cause a folate deficiency? |
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| diet, small intestine disease, decrease in plasma binding protein, interruption in hepatic cycle (liver disease), and methyl folate trap (B12 lack, folate can't be activated) |
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| what is more reliable: folate level in serum or RBC? |
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| RBC b/c half life in serum is very short |
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| what is a problem with treating a B12 deficiency with folate? |
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| folate can treat non-neurologic symptoms of a B12 deficiency, but mask and allow neurologic problems to continue (lack of methionine -> demyelination) |
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| what are some drugs that can inhibit/interact with folic acid? |
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| trimethoprim/methotrexate |
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| how can the shilling test tell the difference between pernicious anemia and dietary deficiency? |
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| the test is done with and without intrinsic factor (which is essential for GI absorption of B12). this test is no longer performed and anti intrinsic factor/antiparietal cell antibodies that block the absorption of B12 are simply tested for) |
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| what is transcobalamin needed for? |
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| transcobalamin II needed for plasma transport |
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| how is B12 administered? |
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| IV/IM |
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| what is deoxyadenosylcobalamin? |
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| a cofactor for myelin sheath synthesis |
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| what would affect B12 absorption? |
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| diet, lack of intrinsic factor, illial disease, decrease in transcobalamin II, abnormal increases in transcobalamin I and III, depletion of hepatic storage |
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| what can B12 deficiency be involved in? |
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| myelin sheath synthesis (though mostly attributed to methionine), as well as neurologic damage, memory loss, and psychiatric disturbances |
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| what are clinical features of B12 deficiency? |
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| megaloblastosis of bone marrow due to backup of methyl folate trap and neurological disturbanced |
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| what is dx/tx for B12 deficiency? |
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| dx - shilling test?, (intrinsic factor/pareietal antibody test more likely). tx - monthly injections |
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| what are some other anemias? |
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| ADC (anemia of chronic disease) - inability of bone marrow to release iron from reticuloendothelial cells, increased cytokines decreases erythropoietin and red blood cell production. anemia of renal failure - decrease in erythropoietin synthesis, would also decrease red blood cell production |
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| what will increase under hypoxic conditions? |
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| erythropoietin |
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| when might erythropoietin be given? |
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| to cancer pts under chemotherapy b/c it is a progenitor to induce blood cell formation |
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| what does G-CSF stimulate? why is it used? |
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| granulocyte colony stimulating factor stimulates neutrophils. it is known as filgrastim and has less side effects than M-CSF. it is given to pts recovering from chemo, AIDS, and transplantation immunosupression |
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| what is GM-CSF? |
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| this stimulates neutrophils and other white blood cells in addition to monocytes and is known as sargramostim. it is not used as much due to more ADRs |
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| if a pt has normal B12 but has macrocytic anemia (along w/pregnancy and increased serum transferrin) what is the likely cause of the deficiency? |
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| folic acid |
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| if pregnant woman has a lack of folic acid what is the fetus at risk for? |
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| neural tube defects |
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| if a pregnant pt has microcytic anemia what is optimal tx? |
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| ferrous sulfate tablets |
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| what are clinical results of iron overload? |
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| necrotizing gastroenteritis, shock, and metabolic acidosis |
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| why is G-CSF administered to pts on chemo? |
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| to prevent systemic infection |
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| megaloblastic anemia that results from B12 deficiency is due to inadequate production of? |
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| dTMP |
