[MCQ] Hemochromatosis- Part 1

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Hemochromatosis- Part 1

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Question 1

Which of the following is the major clinical manifestation of hemochromatosis ?

A	Diabetes mellitus
B	Cardiomyopathy
C	Hypogonadotropic hypogonadism
D	All of the above

Question 1 Explanation:

Major clinical manifestation of hemochromatosis are cirrhosis of liver, diabetes mellitus, arthritis, cardiomyopathy, and hypogonadotropic hypogonadism.

Question 2

Which of the following cell types determine body iron content & distribution ?

A	Duodenal enterocytes
B	Erythroid precursors
C	Reticuloendothelial macrophages
D	All of the above

Question 3

Which of the following is the first step in iron metabolism ?

A	Reduction
B	Absorption
C	Storage
D	Transfer

Question 3 Explanation:

Dietary iron is absorbed primarily by duodenal enterocytes. After the iron is reduced at the apical membrane, it is taken into the cell through the divalent metal transporter 1 (DMT1). Export of iron from enterocytes to plasma occurs through the basolateral transporter ferroportin. Iron is stored as ferritin and is lost on sloughing of senescent enterocyte

Question 4

Which of the following regulates iron metabolism ?

A	Oxygen tension in enterocytes
B	Intracellular iron levels
C	Systemic iron needs
D	All of above

Question 4 Explanation:

Regulation of each step of iron metabolism (reduction, absorption, storage, and transfer) is mediated by signals reflecting oxygen tension in enterocytes, intracellular iron levels, and systemic iron needs.

Question 5

Enterocyte tension regulates iron absorption through ?

A	Hypoxia-inducible factor 2α (HIF-2α)
B	Hypoxia-inducible factor 2β (HIF-2β)
C	Hypoxia-inducible factor 2γ (HIF-2γ)
D	Hypoxia-inducible factor 2δ (HIF-2δ)

Question 5 Explanation:

Enterocyte tension regulates iron absorption through its effects on transcription factor hypoxiainducible factor 2 (HIF-2) & subsequent changes in transcription of DMT1 & ferroportin.

Question 6

Enterocyte iron content regulates iron absorption through ?

A	Iron absorption protein
B	Iron metabolism protein
C	Iron regulatory protein
D	Iron synthesis protein

Question 6 Explanation:

Enterocyte iron content regulates iron absorption through its effects on iron regulatory protein (IRP) types 1 & 2 and their subsequent effects on messenger RNAs (mRNAs) encoding DMT1, ferroportin, ferritin, and HIF-2. The IRPs bind to sequences (iron-responsive elements [IREs]) that influence mRNA translation (with respect to ferroportin, ferritin, and HIF-2) or stability (with respect to DMT1). The IRE-IRP system increases ferritin mRNA translation in response to cellular iron

Question 7

Systemic regulation of iron absorption is mediated by ?

A	Hepcidin
B	Ferroportin
C	Ferritin
D	DMT1

Question 7 Explanation:

Systemic regulation of iron absorption is mediated by hormone hepcidin. Hepcidin binds to iron exporter ferroportin & induces its degradation, thus decreasing transfer of iron from enterocytes to the circulation. Hepcidin blocks release of iron from enterocytes & reticuloendothelial macrophages by degrading the iron exporter ferroportin. In duodenal enterocyte, iron export from RE cells is mediated by ferroportin and regulated by hepcidin.

Question 8

Plasma iron transport protein is ?

A	Hepcidin
B	Ferroportin
C	Transferrin
D	Ferritin

Question 8 Explanation:

Iron released from enterocytes basolateral membrane binds to free sites on the plasma iron transport protein transferrin. Normal transferrin saturation is ~30%).

Question 9

Non transferrin bound iron (NTBI) is best related to ?

A	Acetate
B	Butyrate
C	Citrate
D	Sulphate

Question 9 Explanation:

When transferrin becomes highly saturated, additional iron released into circulation is bound to low-molecular-weight compounds like citrate. This non-transferrin bound iron (NTBI) is readily taken up by hepatocytes & cardiomyocytes. Excess uptake of iron as NTBI produces oxidant-mediated cellular injury. A fraction of circulating NTBI is redox-active & is designated labile plasma iron. NTBI cannot be used for production of heme which requires transferrin-bound iron.

Question 10

Transferrin receptor 1 (TfR1) is best related to ?

A	Non-transferrin bound iron (NTBI)
B	Entry of iron-bound transferrin into cells
C	Labile plasma iron
D	Recycling endosomes

Question 10 Explanation:

Erythroid precursor cells regulate intake of transferrin-bound iron by altering expression of surface transferrin receptor 1 (TfR1). TfR1 mediates entry of iron-bound transferrin (ferri-transferrin) into recycling endosomes.

Question 11

Which of the following represents the most dynamic iron compartment ?

A	Liver
B	Intestinal cells
C	Reticuloendothelial macrophages
D	Bone marrow

Question 11 Explanation:

Reticuloendothelial cells serve as the major hepcidin-regulated iron storehouse. At equilibrium, RE cells release ~25 mg of iron per day. As the pool of circulating transferrin iron is <3 mg, RE cells represent the most dynamic iron compartment, turning over ~10 times per day.

Question 12

Reticuloendothelial cells obtain most of their iron from ?

A	Phagocytosis of senescent erythrocytes
B	Labile plasma iron
C	Circulating transferrin iron
D	Non-transferrin bound iron (NTBI)

Question 12 Explanation:

Reticuloendothelial cells obtain most of their iron from phagocytosis of senescent erythrocytes

Question 13

Ferritin is composed of how many ferritin monomers ?

A	6
B	12
C	18
D	24

Question 13 Explanation:

Ferritin is an iron-storage protein complex composed of 24 ferritin monomers of two subtypes - heavy & light chains. Relative proportion of these ferritin chains in the complex varies in various tissues. Heavy-chain ferritin has ferroxidase activity, which is required for the efficient oxidation of incoming ferrous iron, whereas light-chain ferritin promotes efficient nucleation and mineralization.

Question 14

Hepatocytes are an important site of iron storage in the form of ?

A	Ferritin
B	Hemosidrin
C	Transferrin
D	Ferroportin

Question 14 Explanation:

Hepatocytes are an important site of iron storage in the form of ferritin. NTBI is a major contributor to iron loading in hepatocytes under conditions of elevated transferrin saturation.

Question 15

Which of the following is called as “hypoferremia hormone” ?

A	Ferroportin
B	Hepcidin
C	Transferrin
D	Hemosidrin

Question 15 Explanation:

Hepatocytes serve a central role in iron homeostasis as the site of regulated production of hormone hepcidin. Hepcidin functions as the “hypoferremia hormone” by down-regulating ferroportin-mediated release of iron into circulation. The consequent iron retention in duodenal enterocytes decreases dietary iron absorption. Iron retention in RE macrophages decreases iron turnover.

Question 16

Hepatocellular hepcidin production is regulated by ?

A	Inflammation
B	Iron status
C	Erythropoietic activity
D	All of the above

Question 16 Explanation:

Hepatocellular hepcidin production is regulated by signals reflecting inflammation, iron status, erythropoietic activity, and oxygen tension.

Question 17

Hepcidin is which type of acute-phase protein ?

A	Type I
B	Type II
C	Type III
D	Type IV

Question 17 Explanation:

Hepcidin is a type II acute-phase protein that mediates hypoferremia associated with infection and inflammation.

Question 18

Hepcidin has structural properties similar to those of ?

A	Leukotriene B4
B	E-selectin
C	Cathepsin G
D	Defensins

Question 18 Explanation:

Hepcidin protein was originally identified as an antimicrobial peptide with structural properties similar to defensins. Defensins are a family of cysteine-rich polypeptides with broad antimicrobial activity against bacteria, fungi, and certain enveloped viruses. Other antimicrobial peptides include cathelin, protegrin, granulysin, histatin, secretory leukoprotease inhibitor, and probiotics

Question 19

The inflammatory signal up-regulating hepcidin expression is largely mediated by ?

A	Leptin
B	Interleukin-6
C	Granulocyte-macrophage colony-stimulating factor
D	Lymphotoxin

Question 19 Explanation:

The inflammatory signal up-regulating hepcidin expression is largely mediated by interleukin-6.

Question 20

Hemochromatosis due to hepcidin mutation is referred to as ?

A	Type 1
B	Type 2A
C	Type 2B
D	Type 3

Question 20 Explanation:

Type 1 Hemochromatosis is HFE-related. Type 2A is non-HFE-related caused by hemojuvelin mutations and is called Juvenile hemochromatosis (type 2A). Type 2B is non-HFE-related caused by hepcidin mutation and is called Juvenile hemochromatosis (type 2B). Type 3 hemochromatosis is due to mutated transferrin receptor 2 TFR2 while type 4 hemochromatosis is due to mutated ferroportin 1 gene, SLC11A3. HFE mutation related hemochromatosis results in lack of cell surface expression of HFE (due to the C282Y mutation).

Question 21

Which of the following is a secondary iron overload state ?

A	Sideroblastic anemia
B	Porphyria cutanea tarda
C	Hepatitis C
D	All of the above

Question 22

Which of the following is a secondary iron overload state ?

A	Thalassemia major
B	Aceruloplasminemia
C	Congenital atransferrinemia
D	All of the above

Question 22 Explanation:

Acquired iron overload states include Thalassemia major, Sideroblastic anemia, Chronic hemolytic anemias, Transfusional and parenteraliron overload, Dietary iron overload, Hepatitis C, Alcoholic cirrhosis, Nonalcoholic steatohepatitis, Porphyria cutanea tarda, Dysmetabolic iron overload syndrome, Post-portacaval shunting, Neonatal iron overload, Aceruloplasminemia, Congenital atransferrinemia.

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See all quizzes of Paget’s Disease and Other Dysplasias of Bone at here:

Hemochromatosis- Part 1| Hemochromatosis- Part 2

1 Which of the following is the major clinical manifestation of
hemochromatosis ?
A. Diabetes mellitus
B. Cardiomyopathy
C. Hypogonadotropic hypogonadism
D. All of the above

2 Which of the following cell types determine body iron content &
distribution ?
A. Duodenal enterocytes
B. Erythroid precursors
C. Reticuloendothelial macrophages
D. All of the above

3 Which of the following is the first step in iron metabolism ?
A. Reduction
B. Absorption
C. Storage
D. Transfer

4 Which of the following regulates iron metabolism ?
A. Oxygen tension in enterocytes
B. Intracellular iron levels
C. Systemic iron needs
D. All of above

5 Enterocyte tension regulates iron absorption through ?
A. Hypoxia-inducible factor 2 (HIF-2)
B. Hypoxia-inducible factor 2 (HIF-2)
C. Hypoxia-inducible factor 2 (HIF-2)
D. Hypoxia-inducible factor 2 (HIF-2)

6 Enterocyte iron content regulates iron absorption through ?
A. Iron absorption protein
B. Iron metabolism protein
C. Iron regulatory protein
D. Iron synthesis protein

7 Systemic regulation of iron absorption is mediated by ?
A. Hepcidin
B. Ferroportin
C. Ferritin
D. DMT1

8 Plasma iron transport protein is ?
A. Hepcidin
B. Ferroportin
C. Transferrin
D. Ferritin

9 Non transferrin bound iron (NTBI) is best related to ?
A. Acetate
B. Butyrate
C. Citrate
D. Sulphate

10 Transferrin receptor 1 (TfR1) is best related to ?
A. Non-transferrin bound iron (NTBI)
B. Entry of iron-bound transferrin into cells
C. Labile plasma iron
D. Recycling endosomes

11 Which of the following represents the most dynamic iron
compartment ?
A. Liver
B. Intestinal cells
C. Reticuloendothelial macrophages
D. Bone marrow

12 Reticuloendothelial cells obtain most of their iron from ?
A. Phagocytosis of senescent erythrocytes
B. Labile plasma iron
C. Circulating transferrin iron
D. Non-transferrin bound iron (NTBI)

13 Ferritin is composed of how many ferritin monomers ?
A. 6
B. 12
C. 18
D. 24

14 Hepatocytes are an important site of iron storage in the form of ?
A. Ferritin
B. Hemosidrin
C. Transferrin
D. Ferroportin

15 Which of the following is called as “hypoferremia hormone” ?
A. Ferroportin
B. Hepcidin
C. Transferrin
D. Hemosidrin

16 Hepatocellular hepcidin production is regulated by ?
A. Inflammation
B. Iron status
C. Erythropoietic activity
D. All of the above

17 Hepcidin is which type of acute-phase protein ?
A. Type I
B. Type II
C. Type III
D. Type IV

18 Hepcidin has structural properties similar to those of ?
A. Leukotriene B4
B. E-selectin
C. Cathepsin G
D. Defensins

19 The inflammatory signal up-regulating hepcidin expression is
largely mediated by ?
A. Leptin
B. Interleukin-6
C. Granulocyte-macrophage colony-stimulating factor
D. Lymphotoxin

20 Hemochromatosis due to hepcidin mutation is referred to as ?
A. Type 1
B. Type 2A
C. Type 2B
D. Type 3

21 Which of the following is a secondary iron overload state ?
A. Sideroblastic anemia
B. Porphyria cutanea tarda
C. Hepatitis C
D. All of the above
22 Which of the following is a secondary iron overload state ?
A. Thalassemia major
B. Aceruloplasminemia
C. Congenital atransferrinemia
D. All of the above

Hemochromatosis

[MCQ] Hemochromatosis- Part 1

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Hemochromatosis- Part 1

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[MCQ] Paget’s Disease and Other Dysplasias of Bone

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