macrocytic anemia

Question 1

macrocytic anemias can be broken down into…

Answer 1

megaloblastic and non-megaloblastic

Question 2

name the megaloblastic anemias

Answer 2

B12 deficiency
folate deficiency
medications (AZT, hydroxyurea)

Question 3

name the non-megaloblastic anemias

Answer 3

• reticulocytosis
• hypothyroidism
• liver disease
• alcoholism
• myelodysplastic syndromes

Question 4

what is a macrocyte

Answer 4

RBC with greater than 100 fL

Question 5

explain relationship between reticulocytosis and macrocytosis

Answer 5

reticulocytes have a higher volume than mature RBCs, and they are held in the marrow at 120-150 fL. If a process produces more reticulocytes than needed, then the blood with show signs of macrocytosis

Question 6

explain relationship between EPO administration and macrocytosis

Answer 6

EPO administered for anemia causes fewer cell divisions leading to greater amount of cytoplasm per cell

Question 7

explain relationship between liver disease and macrocytosis

Answer 7

macrocytosis ALWAYS accompanies liver disease between diseased liver deposits greater amount of lipids in RBCs

Question 8

explain relationship between DNA synthesis and macrocytosis

Answer 8

when DNA can’t reproduce fast enough. RNA production is unaffected so cytoplasmic elements are produced and cytoplasm grows faster in comparison and causes larger cells

Question 9

what is a megaloblast?

Answer 9

large bone marrow immature RBC, the result of slow DNA synthesis and increased cytoplasm

Question 10

impaired DNA synthesis can be secondary to…

Answer 10

• B12 or folate deficiency
• antiviral drugs that inhibit DNA synthesis
• chemotherapy

Question 11

where is B12 found?

Answer 11

• animal products

- vegetarians can develop deficiency

Question 12

what builds up when there is not enough B12?

Answer 12

homocystein and methylmalonic acid (MMA)

Question 13

explain B12 absorption

Answer 13

stomach - B12 binds haptocortin
duodenum - pancreatic proteases break down B12-HC, B12 binds intrinsic factor (IF) from parietal cells of stomach
terminal ileum - B12-IF absorbed

Question 14

mechanisms of B12 deficiency

Answer 14

• decreased oral intake
• decreased absorption (defect in IF, or decrease in surface are due to gastrectomy or ileal resection)
• other factors that interfere (Chrohn’s, gastritis, pancreatic insufficiency, drugs that block absorption)

Question 15

what is pernicious anemia?

Answer 15

• subset of B12 deficiency, autoantibodies against parietal cells that make IF, so B12 can’t be absorbed.

Question 16

diagnosis of B12 deficiency

Answer 16

• hypersegmented neutrophils on smear
• test B12 to confirm
• if borderline, test MMA and homocystein, both should be elevated
• if suspect pernicious anemia, check for antibodies to IF or parietal cells

Question 17

treatment for B12 defiency

Answer 17

IV or oral B12, hemotologic issues will resolve in days, neurological in weeks

Question 18

contrast symptoms of folate deficiency and B12 deficiency

Answer 18

• hematological indistinguishable

- neurological signs don’t occur with folate deficiency

Question 19

causes of folate deficiency

Answer 19

• decreased oral intake
• decreased absorption
• drugs

Question 20

diagnosis of folate deficiency

Answer 20

• check folate levels

- homocysteine levels will be elevated in both folate and B12 deficiency but MMA only in B12 deficiency

Question 21

treatment and cautions for folate deficiency

Answer 21

• oral folate
• do not give to megaloblastic anemic without checking B12 levels. giving folate when B12 is low can lead to subacute combined degeneration of the cord

Question 22

how long do folic acid body stores last?

Answer 22

4-5 months

Question 23

how long do B12 body stores last?

Answer 23

2-12 years

Question 24

vitamin B12 or folate deficiency should be suspected in anyone with one of the following:

Answer 24

• oval macrocytes on smear
• hypersegmented neutrophils on smear
• pancytopenia
• unexplained neuro signs
• older, malnutrition, alcoholism