Iron is an essential nutrient that is important for many biological processes. It exists in hemoglobin, myoglobin, and various enzymes. Iron is absorbed in the diet as heme or non-heme iron and is transported by transferrin in the blood. Disorders can result from iron deficiency or overload. Iron deficiency is common and causes anemia, while iron overload disorders like hemochromatosis result from genetic mutations affecting iron regulation.

1. IRON
Dr.Riddhi H Patel
Dr.Khushbu Soni
3rd
year Residents
Biochemistry

2. ● Iron is very important in the human body because of its occurance in
many hemoproteins such as hemoglobin, myoglobin and cytochromes.
● Other enzymes such as aconitase and ferredoxin have iron co-ordinated
with sulfur, forms “Iron sulfur cluster”.
● Enzymes of the krebs cycle like Aconitase, Isocitrate dehydrogenase,
Succinate dehydrogenase and citrate synthase modulated by iron.
● Iron modulates the expression of the critical citric acid cycle enzyme
aconitase via a translational mechanism involving iron regulatory proteins.
● Iron supplementation results in increased formation of reducing
equivalents (NADH) by the citric acid cycle, and thus in increased
mitochondrial oxygen consumption and ATP formation via oxidative
phosphorylation.

3. Distribution of Iron
● Total body iron in healthy adult male: 3-4 gm

5. Requirement
● For Adult : 20 mg/day (Only 1 mg is absorbed)
● For Children : 20-30 mg/day
● Pregnant women : 40 mg/day

6. Sources of Iron
● Leafy vegetables
● Pulses
● Cereals
● Liver and Meat
● Jaggery
● Cooking in Iron utensil

7. Absorption
● Iron is ingested in diet either as nonheme or heme iron.
● Heme Iron Absorption:
- Heme carrier protein present on microvillous
surface of absorptive enterocyte.

8. ● Non heme iron absorption:

9. Transferrin
● A glycoprotein playing important role in shuttle of iron between
various tissues.
● It is beta-1 globulin.
●
Each molecule binds with 2 Fe+3 molecule.
● Glycosylation of transferrin is impaired in :
- Congenital disorder of glycosylation
- Chronic alcoholism.
● TIBC
●
Transferrin saturation

10. Transferrin Cycle

11. Recycling of Iron by
macrophage

12. Factors influencing Iron
absorption
Physical State
(bioavailability)
heme > Fe2+
> Fe3+
Inhibitors
phytates, tannins, soil
clay, laundry starch, iron
overload, antacids
Competitors
lead, cobalt, strontium,
manganese, zinc
Facilitators
ascorbate, citrate, amino
acids, iron deficiency

13. Storage of Iron
● Iron is stored as a ferritin

14. Serum ferritin
● In serum minute quantities of ferritin present in
concentrations proportional to total body stored iron.
● Serum ferritin is glycosylated.
● Contains mostly L- chain.
● Poor in iron.
● So mostly apoferritin.

15. ● Hemosiderin :
- Aggregated, partially deproteinized ferritin.
- Formed when ferritin is partially degraded in secondary
lysosomes.
-Insoluble in aqueous solution.
- Found predominantly in cells of liver, spleen and bone
marrow.
- iron is released slowly from aggregates of hemosiderin.

17. Intracellular Iron Regulation

19. Systemic iron regulation
● Hepcidin is the chief regulator.
● Hepcidin decreases iron absorption in the intestine
(Mucosal Block)and also prevents the recycling of iron
from macrophages.

21. Hepcidin regulation
● Iron Sensing Complex :
-HFE Protein
-TfR1
-TfR2
-HJV
● Bone Morphogenetic Proteins
● Erythropoietic Signals
● Inflammation : Interleukin-6
● Hypoxia

23. Excretion of Iron
● Iron is one way element and very little of it is excreted.
● Any type of bleeding will cause loss of iron.
● Women up to menopause will loss iron at a rate of about 1
mg/day.
● Male : <0.5 mg/day.
● Almost no iron is excreted through urine.
● Considerable fecal loss.
● Some amount from skin.

24. Clinical Significance
Major disorders of iron metabolism
– Iron deficiency -Iron overload
● Abnormal iron distribution
● Abnormal production of iron related proteins
-Hereditary Hyperferritinemia-cataract syndrome
-Aceruloplasminemia
-Neuroferritinopathy
-Atransferrinemia

25. Iron Deficiency
● One of the most prevalent nutritional deficiency disorder.
● 70% of indians and 85% of pregnant women suffer from it.
● Anemia: a reduction in the oxygen-carrying capacity of the
blood caused by a diminished erythrocyte mass.

26. Pathophysiology
Increase demands of
iron
Increase iron loss
Decrease iron intake

28. Stages of Development
● 3 Stages:
1) Negative Iron balance
2) Iron deficient erythropoiesis
3) Iron deficiency Anaemia

29. 1) Negative Iron balance
● Intestinal iron absorption is insufficient.
● Body's iron stores being mobilized to meet requirements.
● So progressive depletion of iron stores.

30. 2)Iron deficient erythropoiesis
● Hemoglobin synthesis is impaired.

31. 3) Iron deficiency Anaemia

32. Clinical Presentation
●
Iron-deficiency anemia can cause:
brittle nails
cracks in the sides of the mouth

33.  Extreme fatigue (tiredness)
chest pain

34. ● Pale skin
● Dizziness or lightheadedness

35. ● Fast heart rate
● Headache

36. ● An enlarged spleen
● Cold hands and feet
● frequent infections.
● Irritability
● shortness of breath
● swelling or soreness of the tongue

37. Changes in Various laboratory
tests
Parameters Normal Negative iron balance Iron deficient
erythropoiesis
Anaemia
Serum Ferritin (ug/dl) 50-200 <20 <15 <15
TIBC (ug/dl) 300-360 >360 >380 >400
Serum Iron (ug/dl) 50-150 Normal <50 <30
Transferrin saturation
(%)
30-50 Normal <20 <10
RBC Protoporphyrin
(ug/dl)
30-50 Normal Increased Increased
Soluble transferrin
receptor (ug/l)
4-9 Increased Increased Increased
RBC morphology Normal Normal Normal Microcytic
hypochromi
c

38. ● Staining of Bone marrow iron with perls' prussian blue to
allow visualization of ferric ion is probably most reliable but
impractical.
● It may be misleading due to:
-Insufficient sample size
-Patient treated with parentral iron suppliments
-Stainable iron may be present in the phase of deficiency
-Patients with myeloproliferative disorders

39. TREATMENT
IRON SUPPLEMENT

40. Iron overload conditions

41. Hemochromatosis
● Is a Disorder of iron overload :
-Hereditary hemochromatosis (HH)
-Acquired hemochromatosis

42. Hereditary hemochromatosis
● HH: genetic defect in iron metabolism
-Excess iron absorbed from the gut
-Symptoms due to pathologic deposition of iron in body
tissue = iron overload
● Classic Triad:
-Cirrhosis (hepatic damage)
-Diabetes (type II) (pancreatic damage)
-Bronzing of skin (hyperpigmentation)

43. Non-Specific Symptoms and Signs
● Liver: hepatomegaly, elevated liver enzymes
● Cardiac: myocardial infarction, cardiomyopathy
● Endocrine: impotence/amenorrhea, diabetes
● Musculoskeletal: arthritis/arthralgia
● Fatigue: unexplained, severe and chronic
● Generally not evident until 40-60 years of age
● Some patients may present earlier

44. HFE hemochromatosis
● HFE– associated Hemochromatosis accounts for > 90% of
cases and is the most common adult onset form:
● Autosomal recessive inheritance
● C282Y mutation
● Carrier rate 1 in 7 - 10 Caucasians
● Incidence 1 in 200 - 400
● Penetrance is high

45. Bb Bb
BB Bb Bb bb
Unaffected
carrier
Unaffected
Autosomal Recessive
Inheritance
Unaffected
carrier
Susceptible
genotype for
Hemochromatosis
Unaffected
carrier
Unaffected Carrier
Legend
B: Normal HFE
gene
b: HFE gene
with mutation

46. ● HFE gene on chromosome 6p
● Involved in iron homeostasis
● HFE protein normally limits amount of iron uptake by gut and regulates
amount of iron stored in the tissues
● Mutations in HFE:
C282Y allele
H63D allele
S65C allele
● HFE gene mutations produce altered HFE protein unable to
properly regulate iron metabolism - results in an excess of iron
storage in tissues

47. HJV Hemochromatosis
● Rare disorder
● Early age of onset
● Severe multi organ iron overload
● Most common presentation :
-Testicular Atrophy
-Ammenorhea
● Autosomal Recessive
● Mutation : Of HJV on chromosome 1q
● Most common deleterious mutation : G320V

48. HAMP Hemochromatosis
● Mutation: HAMP gene of chromosome 19q13.
● Usually associated with HFE C282Y mutation.

49. TFR2 Hemochromatosis
● Rare Autosomal Recessive disorder.
● Mutations : TFR2 Y250X and R455Q
● TFR2: encodes Transferrin receptor 2
- It mediates uptake of transferrin bound iron by the
liver after the classical TfR1 is down reguated by
iron overload .

50. Ferroportin(SLC40A1)
Hemochromatosis
● Present on the surface of the cell responsible for iron
absorption and recycling of iron from macrophage.
● Mutation : SLC40A1 gene
● Autosomal Dominant

51. African Iron overload and
African american iron overload
● Type of iron overload due to ingestion of large quantities of
iron contained in traditional beer.

52. Iron overload due to Anaemia
with ineffective erythropoiesis
● In this, there is increased GDF 15 expression by
erythroblast.
● Lead to down regulation of hepcidin expression.
● Thus increase iron absorption.
● Anemias with increased GDF 15 expression:
-beta-thalassemia major
-Pyruvate kinase deficiency
-Congenital dyserythropoietic anemia

53. Secondary Iron Overload
● Acquisition of iron from non dietary sources in amounts
that exceeds the body's limited excretory capacity can
cause iron overload.
● Causes : Chronic erythrocyte transfusion
-Excessive iron supplements (I.V or I.M)

54. Analytical methods
● For measurement of Serum Iron:
1) Iron is released from transferrin by decreasing pH of
serum.
2) Reduced from Fe+3 to Fe+2.
3) Complexed with a chromogen like ferrozine.
● Such iron chromogen complexes have an extremely high
absorbance in the visible region that is proportional to iron
concentration.

55. ● For measurement of Serum TIBC:
1) Addition of Sufficient Fe+3 to saturate empty iron
binding site of transferrin.
2) Excess Fe+3 is removed by adsorption with MgCO3,
silica column or ion exchange resin.
3) Assay for iron content is repeated.
● For measurement of Serum Transferrin Saturation :
Transferrin Saturation (%) = (100 X serum iron) / TIBC

56. ● For measurement of Serum UIBC:
1) Add known excess concentration of iron to the serum.
2) pH should be neutral.
3) Add iron binding chromogen.
4) Measure the absorbance
5) Measure blank with no added serum.
● UIBC = O.D of serum free iron blank – O.D of sample
● Advantage: Can be fully automated
less cumbersome

57. Reference Interval
● Differs as much as 35% between commercial methods.
● A generic reference interval is not valid.

58. Factors affecting Serum Iron

59. ● Hemolysis has very little effect on serum iron result
because Hb iron is not released from heme by acid
treatment.
● Iron is ubiquitous in the environment so care is necessary
to ensure that glassware, water and reagents do not
become contaminated with extraneous iron.

60. serum transferrin receptor
● Under normal conditions TfR1 is highly expressed on the surface of
erythroid cells.
● Certain proportion is released into the circulation by proteolytic cleavage.
Referred to as “Soluble TfR”.
● Number of transferrin receptor increases in iron deficiency and decreases in
iron excess.
● Developing erythroid cells in bone marrow are reach in transferrin receptor.
● Variation in transferrin receptor quantity are reflected in soluble serum TfR.
● Measured by standard immunoassay technique.
● Measurement of STfR is usefull to distinguish between anemia due to iron
deficiency and anemia due to chronic disease.

61. Red Cell protoporphyrin
● Its level is increased in Iron deficiency.
● The presence of protoporphyrin in erythrocyte reflects
impaired ferrochelatase catalyzed incorporation of iron into
protoporphyrin IX ring.