Iron Metabolism and M/H Anemias

Question 1

Primary function of iron in the body

Answer 1

Oxygen transport

Question 2

6 iron compartments of the body (largest to smallest) (%)

Answer 2

1. Hb (~67% of TBI)
2. Storage (~27%)
3. Myoglobin (~3.5%)
4. Labile pool (~2.2%)
5. Tissue iron department (~0.2%)
6. Transport compartment (~0.08%); smallest but most active

Question 3

6 iron compartments of the body (forms of iron)

Answer 3

1. Hb → Hb molecule
2. Storage → ferritin
3. Myoglobin → myoglobin molecule
4. Labile pool → Fe bound to cell membrane
5. Tissue iron department → Fe in cytochromes and intracellular enzymes
6. Transport compartment → Fe bound to transferrin

Question 4

4 factors that influence iron absorption

Answer 4

1. Amount and type of iron accessible from food
2. Functional state of GI mucosa and pancreas
3. Current iron stores
4. Erythropoietic needs

Question 5

3 conditions that result in an increased need for iron

Answer 5

• Growth periods
• Blood loss
• Diversion of iron to the fetus

Question 6

Anatomic site at which iron is absrobed most efficiently

Answer 6

Duodenum of intestinal mucosa

Question 7

Function of transferrin

Answer 7

Transports iron to nRBCs in BM

- iron is reduced to ferrous state and proceeds to mitochondria for insertion into protoporphyrin ring

Question 8

Organelle that contains iron in erythrocyte precursors

Answer 8

Mitocondria

Question 9

What is being measured

- Serum iron

Answer 9

Amount of iron (bound to transferrin) in serum/plasma

Question 10

What is being measured

- TIBC

Answer 10

Amount of iron that transferrin can bind

Question 11

What is being measured

- Serum ferritin

Answer 11

BM iron stores

Question 12

What is being measured

- BM macrophage iron

Answer 12

Iron held by RE cells (“erythroblastic island”)

Question 13

What is being measured

- BM sideroblasts

Answer 13

nRBCs that contain iron

Question 14

What is being measured

- ZPP (zinc protoporphyrin) or FEP (free erythrocyte protoporphyrin)

Answer 14

Availability of insufficient iron to developing nRBCs; erythrocyte protoporphyrin accumulates in cell

Question 15

Relationship b/w serum ferritin and bone marrow iron stores in healthy individual

Answer 15

↑ serum ferritin, ↓ TIBC

Question 16

Peripheral smear RBC morphology that would prompt the ordering of iron studies

Answer 16

?

Question 17

Iron deficiency anemia (IDA)

- Causes

Answer 17

↓ dietary intake
- infants–“milk anemia”
- children–“fast food diet lacking iron”
- adults–poor diet, GI bleeds, pregnancy
↑ loss of iron
Malabsorption

Question 18

Iron deficiency anemia (IDA)

- Clinical signs and symptoms

Answer 18

Classic: pallor, fatigue, lethargy, shortness of breath

More specific: koilonychia, heart mumur, cravings for non-food items

Question 19

Iron deficiency anemia (IDA)

- RBC count and/or Hb

Answer 19

• RBC may be normal initially…↓ in stage 3

- ↓ H&H (Hb

Question 20

Iron deficiency anemia (IDA)

- PLT count

Answer 20

Increased, esp. w/ blood loss

Question 21

Iron deficiency anemia (IDA)

- RBC morphology

Answer 21

• Hypochromia
• Microcytes
• Aniso
• Some poik, varies

Question 22

Iron deficiency anemia (IDA)

- MCV

Answer 22

Decreased

Question 23

Iron deficiency anemia (IDA)

- MCHC

Answer 23

Decreased

Question 24

Iron deficiency anemia (IDA)

- RDW

Answer 24

Increased

Question 25

Iron deficiency anemia (IDA)

- Retic count

Answer 25

Slight to moderately increased (esp after blood loss and in response to iron therapy)

Question 26

Iron deficiency anemia (IDA)

- Treatment

Answer 26

Supplemental iron (ferrous sulfate)

Question 27

Pathology/mechanism for iron deficiency anemia

Answer 27

• Decreased dietary intake
• Increased loss of iron
• Malabsorption

Question 28

Pathology/mechanism for anemia of chronic inflammation

Answer 28

BM macrophages fail to give up Fe to developing RBC precursors; RBCs develop iron deficient

Question 29

Pathology/mechanism for sideroblastic anemia

Answer 29

Group of disorders characterized by accumulation of iron in the mitochondria of nRBCs…“gets trapped”
- due to defect in heme synthesis (porphyria)

Question 30

Why shouldn’t long-term iron therapy be given to a patient w/ anemia of chronic inflammation?

Answer 30

Keep building up in the BM macrophages??

Question 31

Reasons for presence of “ringed sideroblasts” upon BM iron exam of patient w/ lead poisoning

Answer 31

Due to iron overload caused by decresed survival of RBCs w/ inclusions and ineffective erythropoiesis

Question 32

Characteristic RBC histogram appearance one would expect to see in a patient w/ siderblastic anemia (esp. hereditary form)

Answer 32

pic

Question 33

Color of skin w/ excess iron

Answer 33

Bronze diabetes

Question 34

Major form in which iron is stored in the liver

Answer 34

Ferritin

Question 35

Disease of iron metabolism characterized by excess deposition of iron in tissues; may be inherited or may develop from complication of hemolytic anemia, such as B-thalassemia major

Answer 35

Hemochromatosis

Question 36

APR that’s incrased in inflammation; as a result iron absorption is decreased and iron release from mcrophages is blocked

Answer 36

Hepcidin

Question 37

nRBC precursor w/ “rings of iron”

Answer 37

Ringed sideroblast

Question 38

BM erythrocyte precursor w/ excessive iron granules (siderotic granules); visible w/ Prussian blue staining

Answer 38

Sideroblast

Question 39

Nonnucleated RBC visible w/ Prussian blue staining

Answer 39

Siderocyte