5.2 - Microcytic anemia

Question 1

what are the 4 etiologies of microcytic anemia?

Answer 1

• iron deficiency
• anemia of chronic disease
• sideroblastic anemia
• thalassemia

Question 2

where does iron absorption occur?

Answer 2

duodenum

Question 3

which is more readily absorbed: heme or non-heme form of iron?

Answer 3

heme

Question 4

enterocytes transport iron across the cell membrane via ___________

Answer 4

ferroportin

Question 5

___________ transports iron in the blood and delivers it to liver and bone marrow macrophages for storage

Answer 5

transferrin

Question 6

stored intracellular iron is bound to __________

Answer 6

ferritin

Question 7

what laboratory measurement is used to measure iron in the blood?

Answer 7

serum iron

Question 8

what laboratory measurement is used to measure the amount of transferrin molecules in the blood?

Answer 8

TIBC

Question 9

what laboratory measurement assesses the percentage of transferrin molecules that are bound by iron?

Answer 9

% sat

Question 10

what is the normal % sat for iron?

Answer 10

33%

Question 11

what laboratory measurement reflects iron stores in macrophages and the liver?

Answer 11

serum ferritin

Question 12

which hookworms are responsible for iron deficiency?

Answer 12

• ancylostoma duodenale

- necator americanus

Question 13

iron is more readily absorbed in a(n) _____________ (acidic / basic) environment

Answer 13

acidic

Question 14

why does an acidic environment aid iron absorption?

Answer 14

maintains Fe2 state

Question 15

the very initial stage of iron deficiency anemia is ________________ (microcytic / normocytic / megaloblastic)

Answer 15

normocytic

Question 16

what is the RDW in iron deficiency anemia?

Answer 16

increased

Question 17

what are the following values for iron deficiency anemia?

• ferritin
• TIBC
• serum iron
• % sat

Answer 17

• ferritin: low
• TIBC: high
• serum iron: low
• % sat: low

Question 18

what is the free erythrocyte protoporphyrin level in iron deficiency anemia? why?

Answer 18

increased - there is no problem with the protoporphyrin production

Question 19

what is the triad in plummer vinson syndrome?

Answer 19

• iron deficiency
• esophageal web
• glossitis

Question 20

what are the two ways hepcidin sequesters iron in storage sites?

Answer 20

• limiting iron transfer from macrophages to erythroid precursors
• suppressing EPO production

Question 21

what are the following values in anemia of chronic disease?

• ferritin
• TIBC
• serum iron
• % sat

Answer 21

• ferritin: high
• TIBC: low
• serum iron: low
• % sat: low

Question 22

what is the free erythrocyte protoporphyrin value in anemia of chronic disease?

Answer 22

high

Question 23

ALA synthetase converts ____________ to __________ using ___________ as a cofactor

Answer 23

• succinyl CoA
• ALA
• B6

Question 24

__________ attaches protoporphyrin to iron to make heme

Answer 24

ferrochelatase

Question 25

sideroblasts form due to iron laden ____________ which surround the __________ of erythroid precursors

Answer 25

- macrophages | - nucleus

Question 26

lead inhibits which two enzymes of heme biosynthesis?

Answer 26

- ALA dehydratase (ALA to porphobilinogen) | - ferrochelatase

Question 27

what are the following values in sideroblastic anemia? - ferritin - TIBC - serum iron - % sat

Answer 27

- ferritin: high - TIBC: low - serum iron: high - % sat: high

Question 28

thalassemia confers resistance to plasmodium ___________

Answer 28

FALCIPARUM

Question 29

what are the normal types of Hb?

Answer 29

- HbF (a2y2) - HBA (a2B2) - HbA2 (a2d2)

Question 30

alpha thalassemia is due to a gene __________

Answer 30

deletion

Question 31

how many genes are there in alpha thalassemia? which chromosome?

Answer 31

- 4 | - 16

Question 32

which is worse: cis deletion of two alpha chains, or trans deletion? which population has this?

Answer 32

- cis | - Asians

Question 33

HbH is formed by a deletion of ____ alpha genes from chromosome ____

Answer 33

- 3 | - 16

Question 34

Hb Barts is formed by a deletion of _____ alpha genes from chromosome ____

Answer 34

- all 4 | - 16

Question 35

beta thalassemia is due to a gene ___________

Answer 35

mutation

Question 36

how many genes are there in beta thalassemia? which chromosome?

Answer 36

- 2 | - 11

Question 37

which has target cells - alpha thal or beta?

Answer 37

beta

Question 38

electophoresis shows slightly decreased HbA with increased HbA2 and HbF - which type of thalassemia?

Answer 38

beta thal minor (B/B plus)

Question 39

why does beta thal major take several months to present?

Answer 39

HbF (a2y2) is temporarily protective

Question 40

- hepatosplenomegaly - chipmunk facies - crew cut appearance on x ray

Answer 40

beta thal major

Question 41

what treatment is necessary for beta thal major? what is a possible sequela of treatment?

Answer 41

- chronic transfusions | - hemochromatosis (secondary)

Question 42

what does a blood smear show for beta thal major?

Answer 42

- microcytic hypochromic RBCs - target cells - nucleated RBCs

Question 43

what does electrophoresis show for beta thal major?

Answer 43

- HbA2 - HbF little to no HbA