19b) Iron Flashcards

1
Q

how is free iron toxic?

A

participates in chemical reactions that generate free radicals

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2
Q

iron compartments

A

Hemoglobin (majority)
Tissue iron
Myoglobin
A labile pool

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3
Q

men: —- g iron
women: —- g iron

A

4
2-3

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4
Q

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

A

ferric - 3+
ferrous - 2+

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5
Q

dietary iron is reduced by…

A

vitamin C or ferric reductases present in the intestinal epithelium

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6
Q

Fe— is bound to transferrin

A

3+

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7
Q

2 binding sites of transferrin

A

for Fe3+
for bicarbonate

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8
Q

transferrin SPEP

A

B1 globulin

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9
Q

function of transferrin cycle

A

move Fe from outside the cell to inside

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10
Q

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

A

transferrin captor cells/receptors

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11
Q

Formed when ferritin is denatured by secondary lysosomes

A

hemosiderin

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12
Q

Outer shell of ferritin is composed of…

Interior is composed of…

A

apoferritin

ferric oxyhydroxide [Fe(OH)3] crystalline core

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13
Q

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

A

hemosiderin

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14
Q

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

A

hemosiderin

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15
Q

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

A

ferritin

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16
Q

measured by immunochemical methods

17
Q

negative acute-phase reactant protein

concentrations will be decreased in inflammation or malignancy.

A

transferrin

18
Q

serum transferrin =

A

0.007 x TIBC (ug/dL)

19
Q

iron sat % =

A

100(serum iron/TIBC)

20
Q

normal transferrin %sat

A

<45%
usually about 33%

21
Q

serum iron method

A

spectrophotometry

22
Q

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

A

the iron contained in serum as free hemoglobin

23
Q

serum iron measurement steps (3)

A
  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
24
Q

Bathophenanthroline
Ferrozine
Tripyridyl triazine

A

chromogens used to measure serum iron

25
TIBC =
serum iron + UIBC
26
max iron concentration that transferrin can bind
TIBC
27
steps to determine UIBC
- 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
28
factors that affect iron profile
Diurnal variation Menstruation Pregnancy Ingestion of iron Progesterone-like oral contraceptives Hepatitis Acute and chronic inflammation
29
Iron overload without associated tissue injury
hemosiderosis
30
Genetic condition in which the body accumulates excess amounts of iron
hereditary hemochromatosis
31
HH triad
Bronzing of the skin Cirrhosis Diabetes | also -- cardiomyopathies, arrhythmias, endocrine deficiencies
32
Linked to HLA loci on chromosome 6
HH
33
hemachromatosis dietary recommendations
* Reduction of red meats or organ meat * Avoid iron supplements and alcohol consumption * Avoid Vitamin C because they tend to increase intestinal iron absorption