Iron

Question 1

Gut Involvement in Iron Metabolism

Answer 1

Decrease stomach pH solubilizes Fe-containing compounds
Transport molecules facilitate absorption into blood

Question 2

Blood Involvement of Iron Metabolism

Answer 2

Fe3+ bound to Transferrin and transported to tissues
- Maintains solubility
- Keeps Fe unreactive

Question 3

Cells Involvement with Iron Metabolism

Answer 3

Transferrin endocytosis is receptor mediated
Results in Fe3+ release
Fe distributed in cells

Question 4

Usage of Iron in Cells

Answer 4

Protein components (Heme)

Question 5

Storage of Iron in Cells

Answer 5

Ferritin (Fe2+)

Question 6

Excess Iron in cells

Answer 6

Causes toxicity

Question 7

Normal Iron Ranges

Answer 7

55-160 ug/dL (Male)
40-155 ug/dL (Female)

Question 8

Total Iron Binding Capacity

Answer 8

Sites on transferrin saturated with iron
Reference range: 255-450 ug/dL

Question 9

Percent transferrin saturation

Answer 9

20-50%

Question 10

Increased Total Iron Binding Capacity

Answer 10

Situations that cause increase in transferrin
- Late pregnancy
- Iron deficiency anemia (compensation)
- Acute hemorrhage
- Acute destruction of liver cells

Question 11

Decreased Serum Iron

Answer 11

Dietary deficiency or malabsorption
Loss of iron (blood loss or late pregnancy)
Impaired release of stored iron

Question 12

Decreased Total Iron Binding Capacity

Answer 12

Decreased synthesis of Transferrin
Increased loss of protein as in renal disease

Question 13

Total Serum Iron Principle of Assay

Answer 13

Dissociate ferric iron from transferrin and reduce to ferrous form
Iron + Color Reagent = Color Change

Question 14

TIBC Principle of Assay

Answer 14

Saturate transferrin with ferric iron
Remove excess free iron from reaction tube
Dissociate ferric iron from transferrin and reduce to ferrous form
Measure iron as in total serum iron procedure

Question 15

Calculation for % Saturation

Answer 15

(Serum Iron/TIBC) x 100

Question 16

Other forms of Iron

Answer 16

Ferritin
Transferrin
Hemosiderin
Hemochromocytosis

Question 17

Ferritin

Answer 17

Tissue Storage form
Sensitive indicator of Iron Deficiency Anemia

Question 18

Transferrin

Answer 18

Transport molecule for iron

Question 19

Hemosiderin

Answer 19

Insoluble iron deposits in tissue and bone marrow

Question 20

Hemochromocytosis

Answer 20

Excess iron deposition in tissues
Defective iron control
Multiple transfusion

Question 21

Ceruloplasm

Answer 21

Alpha-2-glycoprotein
Enzyme with 6 Cu atoms
Carries >95% of total Cu in plasma
Participates in conversion of ferrous iron to ferric iron
Works in association with transferrin after release from RES

Question 22

Wilson’s Disease

Answer 22

Autosomal recessive disorder
Causes Cu buid-up in tissues
Genetic defect of Cu-ATPase ATP7B
Cu incorporation into ceruloplasmin is diminished

Question 23

Wilson’s Disease Symptoms

Answer 23

Cirrhosis
Kayser-Fleischer rings in cornea
May cause brain and kidney damage from Cu deposition

Question 24

Kayser-Fleischer rings

Answer 24

Ring of golden-brown or brownish-green pigment behind the limbic border of cornea

Question 25

Porphyrin Derivatives

Answer 25

4 Tetrapyrrole ring linked by methane bridges

Question 26

Oxidative compounds of Porphyrins

Answer 26

Hemoglobin Myoglobin Vitamin B12 Chlorophyll Cytochromes

Question 27

Porphyrin ring

Answer 27

Metal chelates Hgb = Iron Myoglobin = Iron Vit B12 = Cobalt Chlorophyll = Magnesium Cytochromes = Cu & Fe

Question 28

Three Clinically Significant Porphyrins

Answer 28

Uroporphyrins (URO) Coprophyrins (COPRO) Protoporphyrins (PROTO)

Question 29

Uroporphyrins

Answer 29

8 Carboxyl groups Highly soluble because of large number of -COOH side chains Excreted primarily in urine Soluble in blood & tissues

Question 30

Coproporohyrins

Answer 30

4 carboxyl groups Demonstrates intermediate solubility Excreted primarily in feces but also appears in urine

Question 31

Protoporphyrins

Answer 31

2 carboxyl groups Least soluble Located primarily within erythrocytes Excreted only in feces Most soluble in lipid solvents

Question 32

Biosynthesis of Porphyrins

Answer 32

Intermediate products in heme biosynthesis Have no role in body function in free form Appear in tissue and body fluids only as an abnormality in enzyme function

Question 33

Lead Toxicity

Answer 33

Binds to any compound with a sulhydryl group Inhibits multiple enzymes in heme biosynthesis Get elevations in delta ALA

Question 34

Lead Toxicity Test

Answer 34

Whole blood screening is the test of choice Hair analysis for lead concentration is alternative marker for exposure

Question 35

Other heavy metals & organic solvents poisoning

Answer 35

Have been associated with porphyria