IRON

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IRON

• M.Prasad Naidu
• MSc Medical Biochemistry, Ph.D,.

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Iron (Fe)

• 2 types of body iron
• heme iron
• hemoglobin, myoglobin, catalases, peroxidases,
  cytochromes (a, b and c involved in electron
  transport), cytochrome P450 (involved in drug
  metabolism)
• non-heme iron
• ferritin, hemosiderin, hemofuscin, transferrin,
  ferroflavoproteins, aromatic amino acid
  hydroxylases
• food iron is also classified as heme and non-heme

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Food iron

• heme iron
• meats
• poultry
• fish
• 20-23 of heme-iron is absorbable

• non-heme iron
• vegetables
• fruits
• legumes
• nuts
• breads and cereals
• only 3 on non heme iron is absorbed

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Iron absorption

• occurs in upper part of small intestine
• about 10 of food iron is absorbed
• requires gastric HCl (releases ionic iron)
• also requires copper
• ferrous is better absorbed than ferric form
• Fe forms chelates with ascobic acid, certain
  sugars and amino acid

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Iron distribution and storage

• carried in blood stream via transferrin (a b
  globulin)
• stored in 2 forms
• ferritin (a water soluble complex consisting of a
  core of ferric hydroxide and a protein shell
  (apoferritin)
• hemosiderin (a particulate substance consisting
  of aggregates of ferric core crystals)
• stored in liver, spleen, bone marrow, intestinal
  mucosal cells and plasma

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Iron elimination

• there is no mechanism for excretion of iron
• iron is normally lost by exfoliation of
  intestinal mucosal cells into the stools
• trace amounts are lost in bile, urine and sweat
  (no more than 1 mg per day)
• bleeding (vaginal, intestinal) is a more serious
  mechanism of elimination

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IRON DEFICIENCY

• Initial symptoms are vague and ill-defined
• easy fatigability
• lack of appetite
• headache
• dizziness
• palpitations
• then hypochromic-microcytic anemia
• microcytosis (small RBCs)
• hypochromia (poor fill of hemoglobin)
• poikilocytosis (bizarre shapes)
• anisocytosis (variable sizes)

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IRON DEFICIENCY

• Causes
• excessive blood loss (parasitic, accidental,
  menstrual) is most common cause
• rapid growth in children with limited intake of
  iron
• malabsorption
• gastric resection
• sprue
• increased metabolic requirement
• pregnancy, lactation or neoplasia

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Diagnosis of iron deficiency

• hematology (microcytic hypochromic cells)
• low serum iron
• low serum ferritin( indicates low body stores)
• in some conditions (inflammation, hepatitis)
  ferritin may be high
• low hemosiderin
• high total iron binding capacity (TIBC)

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Iron absorption

• average diet contains 10 - 15 mg of iron perday
• a normal person absorbs 5 -10 of this iron or
  0.5 - 1.0 mg daily
• iron absorption increases in response to low iron
  stores
• menstruating women 1 - 2 mg per day
• pregnant women 3 - 4 mg per day
• absorption is via active process

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Different types of iron

• Ferrous sulfate 20
• Exsiccated ferrous sulfate
• ferrous gluconate 11.6
• ferrous fumarate 33
• ferrocholinate 12
• polysaccharide-iron complex
• iron dextran (Imferon)

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Treatment of iron deficiency

• give 200 - 400 mg of iron per day
• up to 25 of the iron preparation may be absorbed
• 50 - 100 mg of iron may be utilized in case of
  deficiency
• give on an empty stomach
• enteric coated iron tablet should not be used
  since we want absorption to occur in the stomach
  and proximal duodenum

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Treatment of iron deficiency

• parenteral iron is used in patients who have had
  bowel resections or in cases of inflammatory
  bowel disease
• normally given IM (painful) Z-track minimizes
  tatoo
• oral iron causes black stools, constipation,
  cramping
• do not administer with antacids or metal
  chelators (tetracyclines)

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Acute iron toxicity

• common in small children ingesting large doses
  of soluble iron compounds
• toxicity is usually divided into 4 phases
• 1. 30 - 60 min. following ingestion
• abdominal pain
• nausea and vomiting
• signs of acidosis and cardiovascular collapse may
  be seen

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Acute iron toxicity

• 2. Period of improvement - last about 8 to 16
  hours
• 3. Period of progressive cardiovascular collapse
  (about 24 hrs after ingestion)
• convulsions
• coma
• high mortality
• 4. Gastrointestinal obstruction from scarring of
  stomach and small intestine

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Deferoxamine mesylate (DFOM)
A chelating agent which reacts with ferric ion to
form a 11 chelate known as ferrioxamine Marketed
as Desferal Injection (Ciba) Produced by
Streptomyces pilosus
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Chronic iron toxicity

• causes
• hereditary hemochromatosis
• hemosiderosis
• symptoms
• cirrhosis iron deposition in the liver
• diabetes iron deposit in the pancreas (damage to
  beta cells)
• skin pigmentation
• cardiac failure
• treatment phlebotomy ( 1 unit of blood removes
  about 250 mg of iron

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