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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


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)


Iron Storage

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


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


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.


TIBC Ranges

RI 250 to 450 ug/dL


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++


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


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.


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.


Iron Transport

Transferrin and Haptoglobin, serum Iron is highest in the morning



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



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


Serum Iron

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


% Transferrin Saturation

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