Quiz 4: Iron

Question 1

Iron Distribution in Body

Answer 1

• 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

Question 2

Dietary Iron

Answer 2

• 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)

Question 3

Iron Storage

Answer 3

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

Question 4

Iron Assays

Answer 4

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

Question 5

TIBC Analysis

Answer 5

• 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.

Question 6

TIBC Ranges

Answer 6

RI 250 to 450 ug/dL

Question 7

Iron Dietary Intake Levels

Answer 7

• 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++

Question 8

Causes of Iron Deficiency Anemia

Answer 8

• 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

Question 9

Anemia Treatments

Answer 9

• 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.

Question 10

Iron Oral Therapy

Answer 10

• 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.

Question 11

Iron Transport

Answer 11

Transferrin and Haptoglobin, serum Iron is highest in the morning

Question 12

Ferritin

Answer 12

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

Question 13

Transferrin

Answer 13

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

Question 14

Serum Iron

Answer 14

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

Question 15

% Transferrin Saturation

Answer 15

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