19b) Iron

Question 1

how is free iron toxic?

Answer 1

participates in chemical reactions that generate free radicals

Question 2

iron compartments

Answer 2

Hemoglobin (majority)
Tissue iron
Myoglobin
A labile pool

Question 3

men: —- g iron
women: —- g iron

Answer 3

4
2-3

Question 4

Most iron from diet is in the ——– state (Fe–), but it needs to be in the ——– state (Fe–) to be absorbed.

Answer 4

ferric - 3+
ferrous - 2+

Question 5

dietary iron is reduced by…

Answer 5

vitamin C or ferric reductases present in the intestinal epithelium

Question 6

Fe— is bound to transferrin

Answer 6

3+

Question 7

2 binding sites of transferrin

Answer 7

for Fe3+
for bicarbonate

Question 8

transferrin SPEP

Answer 8

B1 globulin

Question 9

function of transferrin cycle

Answer 9

move Fe from outside the cell to inside

Question 10

Transferrin binds to the ———– and becomes part of the interior of the cell

Answer 10

transferrin captor cells/receptors

Question 11

Formed when ferritin is denatured by secondary lysosomes

Answer 11

hemosiderin

Question 12

Outer shell of ferritin is composed of…

Interior is composed of…

Answer 12

apoferritin

ferric oxyhydroxide [Fe(OH)3] crystalline core

Question 13

Has a higher iron concentration than ferritin, but it releases iron more slowly.

Answer 13

hemosiderin

Question 14

Fe predominantly in the cells of the liver, spleen, and bone marrow

Answer 14

hemosiderin

Question 15

Elevated in pts with rheumatoid arthritis, renal disease, heart disease, lymphomas, leukemia, and patients with iron storage disorder

Answer 15

ferritin

Question 16

measured by immunochemical methods

Answer 16

ferritin

Question 17

negative acute-phase reactant protein

concentrations will be decreased in inflammation or malignancy.

Answer 17

transferrin

Question 18

serum transferrin =

Answer 18

0.007 x TIBC (ug/dL)

Question 19

iron sat % =

Answer 19

100(serum iron/TIBC)

Question 20

normal transferrin %sat

Answer 20

<45%
usually about 33%

Question 21

serum iron method

Answer 21

spectrophotometry

Question 22

Serum iron concentration reflects the Fe3+ bound to serum transferrin, does not include…

Answer 22

the iron contained in serum as free hemoglobin

Question 23

serum iron measurement steps (3)

Answer 23

1. Releasing iron from transferrin using an acid
2. Reduction of Fe3+ ions to Fe2+ ions using ascorbic acid
3. Reaction of the Fe2+ ions with a chromogen to give a colored complex

Question 24

Bathophenanthroline
Ferrozine
Tripyridyl triazine

Answer 24

chromogens used to measure serum iron

Question 25

TIBC =

Answer 25

serum iron + UIBC

Question 26

max iron concentration that transferrin can bind

Answer 26

TIBC

Question 27

steps to determine UIBC

Answer 27

• adding sufficient Fe3+ to saturate iron binding sites on transferrin
• excess is removed by adsorption with a compound (magnesium carbonate or sodium hydrogen carbonate)
• assay for iron content is then repeated

Question 28

factors that affect iron profile

Answer 28

Diurnal variation
Menstruation
Pregnancy
Ingestion of iron
Progesterone-like oral contraceptives
Hepatitis
Acute and chronic inflammation

Question 29

Iron overload without associated tissue injury

Answer 29

hemosiderosis

Question 30

Genetic condition in which the body accumulates excess amounts of iron

Answer 30

hereditary hemochromatosis

Question 31

HH triad

Answer 31

Bronzing of the skin
Cirrhosis
Diabetes

also – cardiomyopathies, arrhythmias, endocrine deficiencies

Question 32

Linked to HLA loci on chromosome 6

Answer 32

HH

Question 33

hemachromatosis dietary recommendations

Answer 33

• Reduction of red meats or organ meat
• Avoid iron supplements and alcohol consumption
• Avoid Vitamin C because they tend to increase intestinal iron absorption