Iron Deficiency Anemia

Question 1

Why IV iron used to be contraindicated

Answer 1

“high molecular” weight iron dextran (HMW ID) was associated with anaphylaxis and shock, including fatal events, and which has been largely removed from the market. “low molecular” weight ID is different.

Question 2

Which labs respond first following iv iron

Answer 2

Retic –> hgb –> MCV –> ferritin

Question 3

Efficacy and differences among IV iron formulations

Answer 3

• efficacy is similar among all of them and safety is similar, except for high molecular weight IV dextran, so it just comes down to which is on formulary.

Question 4

Typical IV iron formulation used

Answer 4

typically low molecular weight iron dextran (low cost + can be given in single dose)

Question 5

Determining dosage of IV iron

Answer 5

In practice, there is no evidence that total doses above 1000 mg of elemental iron are clinically useful. We often give a fixed dose of approximately 1000 mg, which is generally sufficient to treat anemia (typical red blood cell iron deficit between 500 and 1000 mg) and provide additional storage iron without causing iron overload.

Question 6

% saturation calculation

Answer 6

(serum iron over TIBC) x 100%

Question 7

Situation in which you would never want to administer IV iron

Answer 7

active infection

Question 8

Does iron deficiency absent anemia require treatment?

Answer 8

Yes

Question 9

What is % saturation

Answer 9

% transferrin saturation

Question 10

How to diagnose IDA in an inflammatory state

Answer 10

***soluble transferrin receptor (measures level of transferrin in blood, which isn’t sensitive to inflammation)

Question 11

Gold standard for IDA diagnosis

Answer 11

BMB – Iron stain (Prussian blue stain) of a bone marrow aspirate smear to assess iron stores in bone marrow macrophages and erythroid precursors (sideroblasts) on marrow spicules.

Question 12

Indications for IV iron

Answer 12

1) severe, ongoing blood loss
2) intolerance (GI SE’s)
3) malabsorption syndrome (bariatric surgery, celiac’s)
4) inflammatory state
5) concern for compliance

Question 13

Percent saturation reference range

Answer 13

15% to 50%

Question 14

Transferrin saturation suggesting iron deficiency

Answer 14

Less than 20%

Question 15

Transferrin saturation suggesting iron overload

Answer 15

Greater than 50%

Question 16

Goal for IDA

Answer 16

Normal ferritin and transferrin saturation

Question 17

Causes of reduced iron absorption

Answer 17

Celiac disease
Autoimmune gastritis
H pylori infection

Question 18

What to emphasize when ferritin and transferrin saturation are discordant

Answer 18

Transferrin saturation

Question 19

What is TIBC measuring

Answer 19

Transferrin but in different units

Question 20

Transferrin saturation is

Answer 20

serum iron/TIBC

Question 21

What is soluble TfR a measure of? what direction does it go in in IDA?

Answer 21

• Erythropoeisis/erythropoetic rate

- Increases with iron deficiency

Question 22

inflammatory regulator of hepcidin

Answer 22

primarily IL-6

Question 23

Term for iron overload from a lot of transfusions

Answer 23

Transfusional iron overload

Question 24

Other RBC morphologies with severe IDA

Answer 24

“pencil” and target cells

Question 25

What to remember about thinking PRBC transfusion will give patient iron

Answer 25

Iron is bound to heme so it will take a while to be recycled and liberated and able to be used for hematopoeisis (so they will still need iron)

Question 26

when to tell patients to take iron

Answer 26

Slower gut transit (will improve absorption)

Question 27

How to test for absorption defect

Answer 27

Oral iron challenge test

Question 28

How oral iron challenge test is performed

Answer 28

- measure serum iron pre and post 2 mg/kg oral ferrous sulfate - serum iron should increase by 50-100 mg/dL at 90 minutes

Question 29

Primary issue with LMW iron dextran

Answer 29

You have to give test dose

Question 30

Cost of IV iron

Answer 30

cheap these days

Question 31

Which IV iron to use

Answer 31

Check to see what's on formulary and become familiar with it

Question 32

Inherited form of iron deficiency anemia

Answer 32

IRIDA -- iron refractory erythrodyspoeisis

Question 33

Soluble transferrin receptor is a measure of

Answer 33

erythropoiesis

Question 34

Lab features of early iron deficiency

Answer 34

no or borderline anemia (this is why iron deficiency needs to be treated) - low transferrin sat - low ferritin - elevated RDW - low relic - high soluble transferrin receptor

Question 35

how long do you treat IDA for?

Answer 35

Duration of treatment based on iron deficit, not normalization of hgb

Question 36

Caveat about thinking transfusion will replete iron

Answer 36

iron isn't immediately available (will have to be recycled and liberated)

Question 37

Rule of thumb for how long it takes to replete iron stores

Answer 37

3-6 months

Question 38

How oral iron test works

Answer 38

- Measure serum iron pre and post 2 mg/kg oral ferrous sulfate - should increase by 50-100 mg/dl at 90 minutes

Question 39

Venofer generic name

Answer 39

iron sucrose

Question 40

Infed generic name

Answer 40

iron dextran

Question 41

oral iron formulation with fewer GI side effects

Answer 41

Ferric maltol

Question 42

what is "iron saturation" on lab report

Answer 42

That is transferrin saturation

Question 43

What is transferrin saturation

Answer 43

Ratio of serum iron to TIBC

Question 44

Iron transport protein (from inside to outside of cell)

Answer 44

Ferroportin