L6-iron Metabolism

Question 1

What is iron

Answer 1

Essential trace elements needed for various metabolic process in every cell of the body

Question 2

What are the functions of iron

Answer 2

O2 transport: iron is essential component of both hemoglobin and myoglobin
Cellular respiration: Iron is present in the iron sulfur clusters of the election transport chain proteins and therefore plays an important part in the generation of energy from cellular respiration
Antioxidant mineral:catalase Is a heme enzyme that is present in nearly all aerobic cells
catalase converts the reaction reactive oxygen species hydrogen peroxide to water and oxygen and iron is a cofactor for this antioxidant enzyme

Question 3

How does iron participate in the formation of hydroxide and hydroxyl radical

Answer 3

As it exists in its 2 stable states Ferrous and ferric iron by reaction between iron two and hydrogen peroxide known as Fenton reaction
Reaction is most dangerous in free radical-mediated toxicity in cells

Question 4

What is the total body content of normal iron in normal adult and how much is required per day for hb synthesis

Answer 4

4 g
Approximately 30 mg per day is required for hemoglobin synthesis in new red cells and the majority of this is supplied from the reticuloendothelial macrophages that recycle iron from senescent red cells

Question 5

What is the recommended daily allowance in males and females for iron

Answer 5

10 mg in males and 18 mg in females

Question 6

What are the two forms of dietary iron

Answer 6

Heme and non-heme
Heme is the derived from the hemoglobin and myoglobin of food sources like meat poultry and seafood
non heme is found in plant foods seeds, legumes etc.

Question 7

Where does absorption of ferrous iron occur

Answer 7

In proximal Duodenum

Question 8

What aids in the absorption of Ferris iron

Answer 8

Low pH of the hydrochloric acid secreted in the gastric lumen and the presence of reducing agent such as ascorbic acid which helps maintain the iron in the more soluble Ferrous form

Question 9

What inhibits absorption of ferrous iron

Answer 9

Tannis,phytates and phosphates also lowered gastric acidity

Question 10

What happens when ferric iron is reduced to ferrous iron

Answer 10

A protein on the apical membrane of enterocytes called divalent metal cation transporter 1(DMT1) transports iron across the apical membrane and into the cell

Question 11

What are the options for iron ones it’s inside the enterocyte

Answer 11

Can be oxidized and stored as ferritin or transported to the basolateral membrane into the circulation bound to ferroportin

Question 12

How is control of absorption of iron regulated and how does it work

Answer 12

Action of hepcidin an iron regulating hormone made in the liver
it controls the delivery of iron to blood from intestinal cells
Acts by binding to and in activating ferroportin

Question 13

What simulates production of hepcidin

Answer 13

By increase plasma iron which leads to decreased iron absorption matching iron supply to demand

Question 14

What are the important proteins for iron transport and storage

Answer 14

Ferritin: oxidizes Fe2+ to Fe 3+ for storage of normal amounts of Fe3+ in tissues
Hemosiderin: produced under conditions of iron overload and generated from ferritin denaturation
Binds excess Fe3+ to prevent its escape in to blood where its toxic
Ferroxidase/ceruoplasmin: oxidizes Fe2+ to Fe3+ for transport
Transferrin:carries Fe3+ in blood and delivers it to tissues for synthesis of heme

Question 15

What are the two cases of abnormal iron metabolism

Answer 15

Iron deficiency anemia and iron overload

Question 16

What is the definition of abnormal iron metabolism

Answer 16

Failure to maintain iron levels within the healthy damage can lead to clinical consequences i

Question 17

What is iron deficiency anemia

Answer 17

One of the most common causes of anemia worldwide
it is a hypochromic Microcytic anemia with clinical features including pallor, fatigue koilonychia and brittle hair causing alopecia

Question 18

What are the causes of iron deficiency anemia

Answer 18

▪️Decreased iron loss: iron deficiency is most commonly secondary to excessive bleeding usually from gastrointestinal or menstrual sources
▪️hookworm infestation resulting in gastrointestinal blood loss is the commonest cause of iron deficiency anemia
▪️Decreased iron uptake: ex:diet low in iron rich foods or malabsorption due to diseases associated with flattening of the duodenal mucosal villi

Question 19

Describe iron overload

Answer 19

Systemic iron overloaded leads to pathological increase in body iron stores leading to the deposition diseases

Question 20

What are the causes of iron overload

Answer 20

▪️Hemochromatosis: Due to genetic disorder caused by hepicidin deficiency and is characterized by excessive intestinal absorption of dietary iron resulting in systemic deposition of iron in the liver,pancreas,heart and other organs causing serious tissue damage
▪️primary hemochromatosis is sometimes referred to as bronze diabetes because it can lead to darkening of the skin
▪️Hemosiderosis: is the deposition of hemosiderin in the reticuloendothelial system which includes the reticuloendothelial cells of the spleen and bone marrow and the kupffer cells of the liver usually due to multiple blood transfusion or hemorrhage itself
▪️when reticuloendothelial system is saturated deposition occurs in other body tissues leading to secondary hemochromatosis

Question 21

How can both conditions be treated(overload)

Answer 21

Iron chelation therapy using defroxamine

Question 22

Test that Measures the amount of iron in the blood

Answer 22

Serum iron level

Question 23

What does the serum ferritin test determine

Answer 23

Ferritin is a cytoplasmic iron storage protein
small amount of secreted in the serum where its functions as iron carrier providing an accurate reflection of iron stores

Question 24

What does the level of transferrin total iron binding capacity determine

Answer 24

In plasma Each molecule of transferrin binds up to two atoms of ferric iron and serum transferrin are normally only 1/3 saturated with iron
The total iron binding capacity of plasma reflects the amount of transferrin in blood that’s available to attach to iron therefore in case of iron deficiency where Iron level is expected to be low the total iron binding capacity will be high and an iron overload where the eye level is high the total iron binding capacity will be low