Quiz 4: Iron Flashcards Preview

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Flashcards in Quiz 4: Iron Deck (15):
1

Iron Distribution in Body

• Iron is distributed mostly in RBCs (65%), bone marrow, in myoglobin, and in metabolic reactions.
• Stored as Ferritin and hemosiderin in bone marrow
- 1st iron store to be diminished during iron deficiency
• Transported by transferrin

2

Dietary Iron

• Ferric (Fe+3) in foods must be converted by intestinal mucosal cells to Ferrous (Fe+2)
• (Fe+3) (Fe+2) reduced by Vit C
• In plasma, transferrin carries and releases Fe to the bone marrow and does the reverse when RBC breakdown
Iron deficiency, anemia, hypoxia causes more transport of iron from stores (ferritin)

3

Iron Storage

• Ferritin: The storage protein for iron (mostly in the liver)
• Hemosiderin (aggregated form of ferritin), stored in the liver.

4

Iron Assays

• Total Iron in serum (colormetric)
• Transferrin (nephelometry) and ferritin levels (immunoassay)
• Total Iron Binding Capacity (TIBC)
• Transferrin Saturation = Total Iron/TIBC x 100

5

TIBC Analysis

• TIBC: The serum is mixed with Fe solution to saturate the Fe binding sites of the transferrin molecules. Excess Fe is removed and the remaining Fe is measured.
• Indirectly calculates the unsaturated Fe binding sites
• UIBC= [Total Fe added] - [excess Fe]
• TIBC = Fe + UIBC
• Measures the extent to which transferrin can be saturated
• Fe, TIBC and Transferrin saturation are often ordered for Fe Deficiency anemia.

6

TIBC Ranges

RI 250 to 450 ug/dL

7

Iron Dietary Intake Levels

• Of total dietary intake of 10 -1 5mg/day only 0.5 to 1 mg/day required for normal RBC production.
• Blood reference intervals 50 - 100 ug/dL
• Only the reduced ferrous salts of iron are absorbed from GI (jejunum), Fe++

8

Causes of Iron Deficiency Anemia

• Pregnancy
• Menstruation (30 mg loss of Fe/period)
• Diet (up to 20-40% of the population in some countries)
• Blood Loss
• Interference in Iron absorption, (tropical sprue etc)
• Defects in iron transport and storage proteins

9

Anemia Treatments

• Essential nutrients required for RBC production: Iron, Vitamin B12, Folic Acid
• Microcytic Hypochromic Anemia- Iron depletion (nutritional anemia)
• Megaloblastic Anemia- B12 or Folic Acid
• Pernicious Anemia- Intrinsic Factor loss
• Hemolytic Anemia- Accumulation of Iron Stores.

10

Iron Oral Therapy

• Only ferrous form (Fe++) of Iron administered.
• About 25% of typical dose po can be absorbed.
• About 50 - 100 mg of daily dose can be absorbed and utilized to make Hb.
• Adverse reactions (ADR) include nausea, vomiting, abdominal cramps, constipation, epigastric discomfort.

11

Iron Transport

Transferrin and Haptoglobin, serum Iron is highest in the morning

12

Ferritin

Shows iron storage, decreasing early in iron-deficiency diseases
Found using immunoassays

13

Transferrin

Increased in iron deficiency disorders, decreased in iron overload
Used for measuring total serum iron content by releasing Fe3+ from transferrin and combining it with a chromagen

14

Serum Iron

Decreased: iron-deficiency anemia, malnutrition, blood loss, and chronic infection
Increased: Iron overdose, sideroblastic anemia, viral hepatitis, and hemochromatosis

15

% Transferrin Saturation

Shows the amount of iron transferrin is capable of binding
Calculated from serum iron and TIBC
%TS = [serum iron/ TIBC] x 100