Microcytic Anemia

Question 1

What is microcytic anemia?

Answer 1

Deficiency in oxygen carrying erythrocytes Microcytic & hypochromic → small erythrocytes w/insufficient Hb (hence pale)

Question 2

What is a common cause of microcytic anemia?

Answer 2

iron deficiency

Question 3

Who is at risk for microcytic anemia?

Answer 3

→ increased Fe requirements (e.g. pregnancy) → Fe malabsorption → Blood loss *consider those on PPIs have decreased stomach acid (stomach acid increases Fe bioavailability)

Question 4

Expected lab values w/microcytic anemia

Answer 4

Mean Cell Volume (MCV): <80fL
Mean Cell Hemoglobin Concentration (MCHC): <30%
Serum Iron (SI): <30 mcg/dL
Transferrin saturation: <10%
Serum ferritin: <20 mcg/L

Question 5

Where does iron absorption take place?

Answer 5

intestine, primarily in duodenum

Question 6

Dietary sources of iron

Answer 6

organ meats, brewer’s yeast, wheat germ, egg yolks, oysters, green leafy veggies

Question 7

Difference between heme and non heme iron absorption

Answer 7

→ Heme Fe in meat well absorbed → non-heme Fe 1st reduced by ferrireductase to ferrous Fe before absorption

Question 8

How is iron transported?

Answer 8

Transferrin: beta globulin that binds 2 molecules of ferric Fe→ transports Fe in plasma to maturing erythroid cells in bone marrow

Question 9

How is iron stored?

Answer 9

Fe primarily stored as ferritin in intestinal mucosal cells, macrophages in liver, spleen, and bone, parenchymal liver cells

Question 10

Significance of serum ferritin

Answer 10

estimate of total body Fe stores

Question 11

How is iron eliminated?

Answer 11

• No mech for Fe excretion → small loss in feces, trace in bile, urine, sweat • why hepcidin is imp – main Fe hormone, decreases absorption

Question 12

How much iron is lost/excreted daily?

Answer 12

• ~1mg iron lost daily • 10% women lose >2mg/day on menses

Question 13

Types of PO iron

Answer 13

Ferrous sulfate (Feosol) Ferrous gluconate (Fergon) Ferrous fumarate (Feostat)

Question 14

PO iron: adverse reactions

Answer 14

Nausea, epigastric discomfort, abdominal cramps, constipation, diarrhea, black stools GI upset: Fumarate causes most

Question 15

Which type of PO iron is preferred?

Answer 15

Ferrous sulfate

Question 16

What is the benefit of slow release PO iron?

Answer 16

marketed as less GI upset, but releases in ileum, late for absorption. NOT preferred.

Question 17

When is iron best absorbed?

Answer 17

on empty stomach but may take w/food to minimize GI effects

Question 18

How long should iron supplementation continue in IDA?

Answer 18

3-6mths after correcting IDA cause

Question 19

What happens in acute iron toxicity?

Answer 19

causes GI tract corrosion & direct cellular damage

Question 20

Who is most at risk for acute iron toxicity?

Answer 20

Almost exclusively occurs in young kids so store out of reach!

Question 21

How is acute iron toxicity treated?

Answer 21

whole bowel irrigation and iron-chelating agents (e.g., IV deferoxamine)

Question 22

Types of IV Iron

Answer 22

Iron dextran (INFeD)

Sodium ferric gluconate (Ferrlecit)

Iron sucrose (Venofer)

Question 23

What are the indications for the different types of IV iron?

Answer 23

INFeD: IDA

Ferrlecit & Venofer: CKD pts on hemodialysis

Question 24

Side effects of INFed?

Answer 24

HA, lightheadedness, fever, arthralgias, anaphylaxis/death

Question 25

Side effects of Ferrlecit and Venofer

Answer 25

N/V, injection site reaction, hypotension, cramps, dizziness, chest pain, back pain

Question 26

Why choose IV iron over PO iron?

Answer 26

PO Failure OR Extensive chronic anemia unable to be maintained on PO Fe (Fe malabsorption, hemodialysis and/or on erythropoietin, severe PO intolerance )

Question 27

Special consideration for INFed?

Answer 27

requires test dose prior to 1st admin