Microcytic anemias

Question 1

What is hypochromasia?

Answer 1

the red cell central pallor is more than 1/3 of the diameter of the cell

described by a low MCHC (believe it)

Question 2

What makes red cells small?

Answer 2

decreased membrane or decreased hemoglobin

Question 3

What is the only congenital cause of decreased red cell membrane?

Answer 3

hereditary elliptocytosis

Question 4

What is the #1 cause of decreased hemoglobin production?

Answer 4

iron deficiency

Question 5

What is a common cause of IDA in infants?

Answer 5

women who only give their babies breast milk, which has little to no iron

Question 6

What are the most common cuases of IDA in men and postmenopausal women?

Answer 6

Gi/GU bleeding most common
malabsorption
inadequate intake

Question 7

How is iron absorbed?

Answer 7

GI tracT (mostly duodenum), bound to apotransferring to form transferring

that delivers Fe3+ to red cell precusors in the bone marrow

Question 8

The precusors have transferring receptors on their membranes. where in the cell does the iron go?

Answer 8

can either be used right away or delivered to the mitochodnria for storage (form a rung around the precursor red cell nucleus - why you get sideroblastic rings)

Question 9

What enzyme is necessary in the mitochdonria to incorporate iron into protoporphyrine to make heme?

Answer 9

ferrochelatase and vitamin B6

Question 10

IN what form is iron stored in the mitochondria?

Answer 10

ferritin

Question 11

Where are other locations of iron storage?

Answer 11

1111

Question 12

What are the classic lab results for IDA?

Answer 12

low RBC
low mCV
low mCHC
high RDW

Question 13

What’s included in iron studies?

Answer 13

ferritin
transferrin
iron

Question 14

What will ferritin do in IDA?

Answer 14

expected to be low (because there is not enough iron being stored)

HOWEVER - ferritin is an acute phase reactant and can be falsely elevated into the normal or high range

Question 15

What would you expect transferrin to do in IDA?

Answer 15

expected to be elevated (because the body will be mobilizing stored iron)

HOWEVER, it can be in the normal range or low when iron deficiency is combined with anemia of chronic disease

Question 16

Is a serum iron useful in isolation?

Answer 16

No, not at all

Question 17

Why is a serum iron helpful them?

Answer 17

It can be used to calculate % iron saturation which can be used to interpret the ferritin and transferring levels when confusing or complicated

Question 18

How do you treat IDA?

Answer 18

oral ferrous sulfate or ferrous gluconate

or parenteral iron dextran

Question 19

How does anemia of chronic disease happen?

Answer 19

It’s a disorder of iron cycling
chronic inflammation leads to pro-inflammatory cytokines and increased acute-phase reactants that increase plasma viscosity, increase ESR and increase rouleaux and decrease circulating transferring and decreased transferin receptors on the RBC and icnrease delivery of iron to ferritin. So you get all your iron bound to ferritin and not available for cells to use.

Question 20

What molecule in the liver controlls everything about iron circulating and anemia of chronic disease?

Answer 20

hepcidin (increases ferritin, decreases transferrin, etc.)

Question 21

A genetic defect in hepcidin causes what disease?

Answer 21

hemochromoatosis

Question 22

What do the CBC findings look like on anemia of chronic disease?

Answer 22

RBC normal or low
Hgb low
MCV usually low normal but can be low or very low
MCHC can be normal or low
RDW can be normal or high

Question 23

What is the “classic pattern” on iron studies for ACD?

Answer 23

increased ferritin
low transferrin
normal iron saturation (because it’s a relative number)

Question 24

What are the newer tests for ACD?

Answer 24

soluble transferrin receptor assay (checks for the down-regulated transferrin receptors)

serum or urine hepcidin assay (controversial, but should in theory be elevated)

Question 25

How do you treat anemia of chronic disease?

Answer 25

treat underlying disorder
recombinant epo
iron suppl

Question 26

What are the two potential enzymatic defects in heme biosynthesis leading to sideroblastic anemia?

Answer 26

aminolevulinic acid (ALA synthase

ferochelatase

Question 27

How is sideroblastic anemia diagnosed?

Answer 27

routine CBC with microcytic anemia

iron studies will show a very high ferritin level

blood smear very heplful (hypochromic RBCs with stippling)

Question 28

What is the defining test for sideroblastic?

Answer 28

iron staining of the bon emarrow

Question 29

If iron studies are normal for the workup of low mCV, what’s probably going on?

Answer 29

consider a hemoglobin electrophoresis to check for a thalassemia