P1.01 Iron Metabolism and Storage

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What are the essential nutrients required for the production of functional blood cells?

Iron, Vitamin B12, Folic Acid

Which deficiency results in a condition characterized by deficiency in oxygen-carrying erythrocytes?

Iron deficiency

What is the most common cause of chronic anemia according to the text?

Iron deficiency

Which of the following is a clinical manifestation of iron deficiency anemia?

Pallor

What is the role of hematopoietic growth factors in the regulation of hematopoietic cells?

They regulate the proliferation and differentiation of hematopoietic cells

What is the most common cause of iron deficiency in adults?

Blood loss

Which population has increased iron requirements?

Children during rapid growth periods

What is the most common site of blood loss in men and postmenopausal women?

Gastrointestinal tract (GIT)

How do patients with unexplained iron deficiency anemia should be evaluated?

For occult gastrointestinal bleeding

What is the mechanism for excretion of iron from the body?

There is no mechanism for excretion of iron

What type of iron therapy is reserved for patients who are unable to absorb oral iron and for patients with extensive chronic anemia who cannot be maintained with oral iron alone?

Intravenous iron therapy

Which of the following growth factors was the first to be isolated for human hematopoiesis?

Erythropoietin

Which agent dramatically accelerates the rate of neutrophil recovery after dose-intensive myelosuppressive chemotherapy?

Oprelvekin

Which agent is approved for the therapy of patients with chronic immune thrombocytopenia who have had an inadequate response to other therapies?

Romiplostim

True or False: Folate deficiency results in a megaloblastic anemia that is microscopically indistinguishable from the anemia caused by vitamin B12 deficiency.

True

What is the primary role of folic acid supplementation?

To prevent folic acid deficiency in high-risk patients

What are the hematopoietic growth factors?

Erythropoietin and Granulocyte colony-stimulating factor (GCSF)

What is the source of recombinant human erythropoietin (rHuEPO, epoetin alfa)?

Mammalian cell expression system

Which patients should consider folic acid supplementation to prevent deficiency?

Pregnant women and patients with alcohol dependence

What is the role of colony-stimulating factors?

Regulate the proliferation and differentiation of hematopoietic progenitor cells

What is the most appropriate use of parenteral iron therapy?

Patients who are not able to absorb oral iron and those with extensive chronic anemia

What are the common traditional forms of parenteral iron?

Iron dextran, Sodium ferric gluconate complex, Iron sucrose

In which condition is acute iron toxicity seen almost exclusively?

Young children who accidentally ingest iron tablets

What symptoms are associated with children poisoned with oral iron?

Necrotizing gastroenteritis, vomiting, abdominal pain, and bloody diarrhea

When is treatment with EPO typically required?

In patients with advanced chronic renal disease requiring hemodialysis

What is the specialized storage protein covering the core of ferric hydroxide in intestinal epithelial cells?

Apoferritin B

Which plasma protein is responsible for transporting iron bound to it?

Transferrin

What is responsible for binding and internalizing the transferrin-iron complex in proliferating erythroid cells?

Transferrin receptors

Where is ferric iron released, reduced to ferrous iron, and transported into the cytoplasm for hemoglobin synthesis or storage as ferritin?

Endosomes

After the release of ferric iron in endosomes, what happens to the transferrin receptor complex?

It is recycled to the cell membrane

What is the most common cause of chronic anemia according to the text?

Production of dysfunctional blood cells

Which hematopoietic growth factor is used more frequently than GM-CSF due to better tolerance?

G-CSF

What is a common side effect of G-CSF and pegfilgrastim?

Bone pain

Which condition is associated with a high risk of hemorrhage?

Thrombocytopenia

Which growth factor is important for mobilization of PBSCs in transplantation?

G-CSF

What do TPO and IL-11 appear to be key endogenous regulators of according to the text?

Platelet production

Which growth factors speed the recovery from neutropenia without increasing the incidence of acute graft versus-host disease?

(G-CSF) and GM-CSF

Which is not a severe side effect of GM-CSF at higher doses?

Allergic reactions occurring frequently

What is the primary clinical indication for the use of iron preparations?

Treatment or prevention of iron deficiency anemia

Which population is NOT listed as having increased iron requirements in the text?

Postmenopausal women

What is the manifestation of inadequate iron absorption after gastrectomy or severe small bowel disease?

Microcytic anemia with low MCV and mean cell hemoglobin concentration

What is the only clinical indication for the use of iron preparations according to the text?

Treatment or prevention of iron deficiency anemia

What happens to the transferrin receptor complex after the release of ferric iron in endosomes?

It is recycled to the cell surface

Which hematopoietic growth factor is used for the treatment of patients with chronic immune thrombocytopenia who have had an inadequate response to other therapies?

Thrombopoietin receptor agonists (Romiplostim and Eltrombopag)

What is the primary role of folic acid supplementation?

To prevent folic acid deficiency in high-risk patients

What is the source of recombinant human erythropoietin (rHuEPO, epoetin alfa)?

Mammalian cell expression system

Which of the following is a clinical manifestation of iron deficiency anemia?

Microcytic hypochromic anemia

What do hematopoietic growth factors regulate in the body?

Proliferation and differentiation of hematopoietic progenitor cells

Which hematopoietic growth factor is used more frequently than G-CSF due to better tolerance?

Erythropoietin

Which condition is associated with a high risk of hemorrhage?

Thrombocytopenia

What is the primary role of folic acid supplementation?

Preventing megaloblastic anemia

What is responsible for binding and internalizing the transferrin-iron complex in proliferating erythroid cells?

Transferrin receptor complex

True or False: Folate deficiency results in a megaloblastic anemia that is microscopically indistinguishable from the anemia caused by vitamin B12 deficiency.

True

Which of the following is a common clinical manifestation of iron deficiency anemia?

Pallor

Inadequate supply of which essential nutrient can result in a deficiency of functional blood cells?

Iron

Which of the following is a treatment for iron deficiency anemia?

Ferrous sulfate

Which hematopoietic growth factor is primarily responsible for regulating the proliferation and differentiation of hematopoietic cells?

Erythropoietin

Which condition is associated with a genetic alteration in the hemoglobin molecule and is not easily treated?

Sickle cell anemia

What is a potential consequence of iron toxicity in young children?

Necrotizing gastroenteritis and metabolic acidosis

Which of the following is NOT a condition that may require parenteral iron therapy?

Hemolytic anemia caused by G6PD deficiency

Which form of iron therapy is associated with serious dose dependent toxicity?

Iron dextran

What symptoms are commonly observed in children poisoned with oral iron?

Vomiting, abdominal pain, and shock

In which patients is treatment with erythropoietin (EPO) typically required?

Patients undergoing chemotherapy-induced myelosuppression

What is the process by which the transferrin-iron complex is internalized by proliferating erythroid cells?

Receptor-mediated endocytosis

What is the specific protein responsible for binding and internalizing the transferrin-iron complex in proliferating erythroid cells?

Transferrin receptors

What is the fate of the transferrin receptor complex after the release of ferric iron in endosomes?

It is recycled to the cell membrane

What type of iron is transported into the cytoplasm for hemoglobin synthesis or storage as ferritin after being released from endosomes?

Ferrous iron

Which plasma protein is responsible for transporting iron bound to it?

Transferrin

Which growth factors are used to support patients who have received allogeneic bone marrow transplantation for treatment of hematologic malignancies or bone marrow failure states?

G-CSF and GM-CSF

What is the primary clinical indication for the use of iron preparations?

Treatment of iron deficiency anemia

What is the main role of myeloid growth factors in transplantation?

Mobilization of PBSCs

What is the source of recombinant human erythropoietin (rHuEPO, epoetin alfa)?

Genetically engineered cell lines

Which agent is approved for the therapy of patients with chronic immune thrombocytopenia who have had an inadequate response to other therapies?

Thrombopoietin (TPO)

What is responsible for binding and internalizing the transferrin-iron complex in proliferating erythroid cells?

Transferrin receptor complex

Which growth factors speed the recovery from neutropenia without increasing the incidence of acute graft versus-host disease?

G-CSF and GM-CSF

What are the common traditional forms of parenteral iron?

(Iron dextran) and (iron sucrose)

What symptoms are associated with children poisoned with oral iron?

(Nausea, vomiting, diarrhea), and abdominal pain

What is the manifestation of inadequate iron absorption after gastrectomy or severe small bowel disease?

Deficiency in oxygen-carrying erythrocytes

What is a potential consequence of a high iron requirement in patients with advanced chronic kidney disease undergoing hemodialysis?

Hemochromatosis

What is the most severe clinical manifestation of acute iron toxicity in young children?

Coma and death

What is the classic clinical presentation of children who are poisoned with oral iron?

Vomiting, abdominal pain, and bloody diarrhea followed by shock, lethargy, and dyspnea

Which of the following is a characteristic feature of inorganic free ferric iron toxicity?

Neurological symptoms

What is the treatment of choice for acute iron toxicity in young children?

Chelation therapy with deferoxamine

What is the primary site of iron absorption in the body?

Duodenum & jejunum

Which protein is primarily responsible for storage of iron in intestinal mucosal cells?

Ferritin

Which organ primarily produces the iron-regulatory hormone hepcidin?

Liver

Which compound can be given intravenously to bind and promote excretion of iron that has already been absorbed?

Deferoxamine

What term is used to describe 'chronic iron toxicity' or 'iron overload'?

Hemochromatosis

What is the primary mechanism for excretion of iron from the body?

No mechanism for excretion of iron

What is the primary role of hepcidin in the regulation of iron balance?

Inhibits iron release from storage sites

What is the main function of ferritin in serum?

Estimating total body iron store

Which cells primarily store iron as ferritin in the body?

Macrophages in the liver

Why is regulation of iron balance achieved by changing intestinal absorption and storage of iron?

Because of limited ability to excrete iron

What is the primary cause of folic acid deficiency?

Inadequate dietary intake of folates

What enzyme is responsible for hydrolyzing the polyglutamate forms of dietary folates?

Conjugase

How long does it typically take for folic acid deficiency and megaloblastic anemia to develop after the intake of folic acid stops?

3-6 months

What is the consequence of folate deficiency?

Megaloblastic anemia indistinguishable from vitamin B12 deficiency

What forms the primary constituent of dietary folates?

Polyglutamate N5 -methyltetrahydrofolate

Which growth factor is an alternative to G-CSF for prevention of chemotherapy-induced febrile neutropenia and can be administered once per chemotherapy cycle?

Pegfilgrastim

What is the primary function of G-CSF and GM-CSF in the treatment of neutropenia associated with various disorders?

Reducing the duration of neutropenia

Which hematopoietic growth factor is sometimes combined with other growth factors for the treatment of pancytopenia, as it does not stimulate the formation of erythrocytes and platelets?

GM-CSF

In addition to neutropenia associated with cancer chemotherapy, which condition has G-CSF and GM-CSF proved to be effective in treating?

Myelodysplasia

For which group of patients have G-CSF and GM-CSF been found to result in a decrease in the frequency of infections due to a prompt increase in neutrophil count?

Patients with congenital neutropenia

Which specialized proteins are used by the body to control concentrations based on the demand for hemoglobin synthesis and adequate iron stores?

Ferroreductase and ferroxidase

What is the most common cause of chronic anemia, clinically presenting as pallor, fatigue, dizziness, exertional dyspnea, and other generalized symptoms of tissue hypoxia?

Iron deficiency

Which factor makes women susceptible to iron deficiency anemias, leading to a greater need for iron supplementation?

Greater iron content in men

What does iron from the nucleus of the iron-porphyrin heme ring together with globin chains form?

Hemoglobin

Comparing the average 80-kg male and female, which statement is true?

The iron content in men is stored greater than that in women

What is the primary function of hepcidin in the body?

Regulating the release of iron from storage in the body

What is the main source of iron used to support hematopoiesis in the body?

Recycled iron from damaged erythrocytes

In which population is there an increased requirement for iron, according to the text?

Pregnant women

What happens to the iron content in damaged erythrocytes?

It is reabsorbed by the body

What is the normal daily loss of iron from the body?

Negligible loss through excretion

Which statement accurately describes dietary iron requirements?

Dietary requirements for iron are easily met by a variety of foods

What is the typical fate of the iron content in damaged or senescent erythrocytes?

Reabsorption by the body

What role does hepcidin play in individuals with increased iron requirements?

Suppressing iron absorption from dietary sources

Why does hepcidin play a crucial role in regulating iron levels in the body?

To prevent excessive storage of iron leading to toxicity

How does hepcidin contribute to preventing excessive iron uptake in individuals with special requirements?

By suppressing excessive absorption from dietary sources

This quiz covers the storage of excess iron in intestinal epithelial cells as ferritin, the transportation of iron in the plasma bound to transferrin, and the role of transferrin receptors in binding and internalizing the transferrin-iron complex. Test your knowledge of iron metabolism and storage with this quiz.

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