Hematology Quiz on Anemia and Hemostasis

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Questions and Answers

What hemoglobin levels indicate sustained absolute erythrocytosis in men?

15.0 g/dL

16.5 g/dL

18.5 g/dL (correct)

17.0 g/dL

Which therapy is indicated for patients who cannot tolerate or fail phlebotomy?

Blood transfusion

Hydroxyurea (correct)

Vitamin K supplementation

Low-dose aspirin

What finding can only be detected by performing a bone marrow biopsy?

Pancytopenia

Initial myelofibrosis (correct)

Asymptomatic thrombocytosis

Sustained absolute erythrocytosis

Which globin chains are present in fetal hemoglobin?

2 alpha and 2 gamma Signup and view all the answers

What is a common therapy used to decrease thromboembolic events in patients with polycythemia vera?

Anagrelide Signup and view all the answers

What stimulates the formation and maturation of megakaryocytes?

Thrombopoietin produced in the liver Signup and view all the answers

Approximately what percentage of adult hemoglobin is represented by Hemoglobin A?

90% Signup and view all the answers

How long do platelets typically circulate in the bloodstream before being destroyed?

8-10 days Signup and view all the answers

Which of the following factors could lead to dysfunction in hemostasis?

Improper function of platelets Signup and view all the answers

What is the most common type of anemia worldwide?

Iron deficiency anemia Signup and view all the answers

In the classification of anemia by Mean Corpuscular Volume (MCV), what does a low MCV typically indicate?

Iron deficiency anemia Signup and view all the answers

What component of blood is localized to the area of tissue damage during hemostasis?

Platelets Signup and view all the answers

Which of the following is NOT a cause of anemia?

Excessive iron absorption Signup and view all the answers

What is the primary function of red blood cells in the circulatory system?

Transport oxygen from the lungs to the tissues Signup and view all the answers

Which statement regarding the location of hematopoiesis in adults is correct?

Restricted to the red marrow of specific bones Signup and view all the answers

What percentage of total marrow cells are pluripotent hematopoietic stem cells?

0.01% Signup and view all the answers

During which developmental phase does hematopoiesis initially occur in the human body?

In the yolk sac Signup and view all the answers

Which of the following components is NOT part of the blood's cellular composition?

Collagen Signup and view all the answers

What role do platelets primarily serve in the circulatory system?

Maintain vascular integrity and prevent bleeding Signup and view all the answers

How do progenitor cells derived from hematopoietic stem cells differ from pluripotent stem cells?

Progenitor cells are lineage-committed Signup and view all the answers

Which condition can primarily lead to increased hematopoiesis in the body?

Infection or bleeding Signup and view all the answers

What is the primary role of CFU-GM cells in hematopoiesis?

To generate granulocytic and monocytic cell lines Signup and view all the answers

Which growth factor is primarily involved in the stimulation of red cell precursor differentiation?

Erythropoietin (Epo) Signup and view all the answers

In what condition is granulocyte-colony-stimulating factor (G-CSF) particularly utilized?

To promote neutrophil recovery post-chemotherapy Signup and view all the answers

What does the first non-nucleated red cell, known as a reticulocyte, contain?

Residual ribosomal material Signup and view all the answers

Which of the following growth factors specifically influences the differentiation of megakaryocytes?

Thrombopoietin (Tpo) Signup and view all the answers

The process of increased erythropoiesis can be indicated by the presence of which cell type?

Reticulocytes Signup and view all the answers

What structural characteristic distinguishes the haemoglobin molecule?

It contains iron within a porphyrin ring Signup and view all the answers

Which cell type is specifically produced by CFU-E progenitor cells?

Erythroid cells Signup and view all the answers

Which statement correctly differentiates between true and relative polycythaemia?

True polycythaemia involves an increase in red blood cells due to a primary marrow increase. Signup and view all the answers

What is a common complication associated with Polycythemia Vera?

Increased risk of thrombotic events such as stroke. Signup and view all the answers

Which factor is NOT typically associated with apparent erythrocytosis?

Low dietary iron intake. Signup and view all the answers

How is Polycythemia Vera primarily classified?

As a clonal multipotent hematopoietic stem cell defect. Signup and view all the answers

Which symptom is least likely to be reported by a patient with Polycythemia Vera?

Increased fatigue. Signup and view all the answers

What is considered a major diagnostic criterion for Polycythemia Vera?

Presence of myeloproliferative neoplasm. Signup and view all the answers

Which of the following drugs is known to cause hemolysis?

Sulphonamides. Signup and view all the answers

What characterizes the Hct levels in apparent erythrocytosis?

High Hct with normal red cell mass and reduced plasma volume. Signup and view all the answers

Study Notes

Hematological Disorders

Hematological disorders encompass a range of conditions affecting blood cells, the process of blood cell formation (hematopoiesis), and coagulation.
These disorders can originate from diseases in the blood system itself or affect other body systems, impacting blood cell function.
Clinical assessment includes a thorough medical history and physical examination, along with investigations for irregularities in red blood cells, white blood cells, platelets, blood clotting mechanisms, lymph nodes, and lymphoreticular tissues.

Functional Anatomy and Physiology of Blood

Blood, circulating through the vascular system, contains several crucial components.
Red blood cells carry oxygen from the lungs to tissues.
White blood cells defend against infections.
Platelets help maintain blood vessel integrity and prevent bleeding by contributing to the clotting process.
Plasma contains proteins responsible for numerous functions, including antibodies and coagulation factors.

Hematopoiesis

Hematopoiesis is a dynamic process crucial for maintaining normal blood cell counts and responding efficiently to demands like bleeding or infection.
During development, hematopoiesis occurs in the yolk sac, liver, and spleen. Later, red bone marrow in the medullary cavity of most bones becomes the primary site.
In adults, hematopoiesis is primarily confined to specific bones: vertebrae, pelvis, sternum, ribs, clavicles, skull, upper humerus, and proximal femur.
Bone marrow can expand in response to increased demands for blood cells.

Structural Organization of Normal Bone Marrow

Bone marrow displays a complex structure with diverse cell types.
Major cellular components include megakaryocytes, fat cells, bony trabeculae, neutrophils, erythroid nests, and lymphocytes.
Vascular sinusoids permeate the marrow, supporting cell circulation.

Stem Cells

All blood cells originate from pluripotent hematopoietic stem cells.
These cells constitute only a small percentage (~0.01%) of bone marrow cells.
They can self-renew and differentiate into various committed progenitor cells, each specializing to produce specific blood cell types.
Progenitor cells are categorized based on the types of cells they differentiate or which cell lines they generate (e.g., CFU-GM, CFU-E).

Growth Factors

Growth factors, produced in bone marrow stromal cells, regulate the survival, proliferation, and differentiation of blood cells and their precursors.
Examples include interleukins (IL-3), stem cell factor (SCF), granulocyte-macrophage colony-stimulating factor (GM-CSF), erythropoietin (EPO), granulocyte colony-stimulating factor (G-CSF), and thrombopoietin (TPO).
Various growth factors are now produced using recombinant DNA technology and used therapeutically (e.g., EPO for renal anemia, G-CSF for chemo recovery).

Blood Cell Development

Blood cell development follows a hierarchical lineage system, with hematopoietic stem cells differentiating into committed progenitor cells.
These progenitor cells differentiate further into various types of blood cells.
Key stages in red blood cell, granulocyte, and platelet development are visually represented in maturation pathways.

Clinical Examination in Blood Disorders

Clinical evaluation of blood disorders often involves assessing physical attributes of various body systems like conjunctiva, mouth, pulse, hands, lymph nodes, skin, abdomen, joints, and feet, to glean insight into underlying conditions.

Haemostasis

Haemostasis is the body's localized response to vascular injury, preventing excessive bleeding and facilitating tissue repair.
This process relies on complex interactions between the vascular endothelium, platelets, coagulation factors, natural anticoagulants, and fibrinolytic enzymes.
Dysfunction in any component can lead to haemorrhage or thrombosis.

Red Blood Cells

Red blood cells originate in the bone marrow from erythroid progenitor cells (erythroblasts).
These cells mature, acquiring hemoglobin, which colors the cytoplasm, and losing their nuclei.
Reticulocytes, the first non-nucleated red blood cells, contain ribosomal material, giving them a bluish tinge.
Erythropoietin, a polypeptide hormone produced in the kidneys, primarily regulates red blood cell production, reacting to low oxygen.

Haemoglobin

Haemoglobin is a protein critical for oxygen transport within the blood.
It comprises four globin chains encircling the porphyrin pigment molecule heme.
Iron (Fe²⁺) within heme reversibly binds oxygen, and this process's affinity strength increases with added oxygen molecules.
Haemoglobin type A (HbA) is the main adult form; hemoglobin F (HbF) is predominant in the fetus.

Platelets

Platelets are formed in the bone marrow from megakaryocytes.
Mature megakaryocytes fragment, releasing platelets into the bloodstream.
Thrombopoietin, produced in the liver, is the main regulator of megakaryocyte development and platelet production.
Platelets circulate for about 8-10 days before being removed from circulation.

Anemia

Anemia represents a deficiency or insufficient number of red blood cells or a reduction in hemoglobin content.
Reduced red blood cell production, accelerated red blood cell destruction, or both can lead to anemia.
Decreased or ineffective marrow production, increased cellular destruction (e.g., blood loss or haemolysis), or some disease processes can cause anemia.
Signs and symptoms include tiredness, lightheadedness, and breathlessness.

Clinical Assessment of Anemia

Assessing the patient's iron intake and folate levels, past medical history (including chronic kidney disease or prior surgery), and family history (including haemolytic disorders) are important for evaluating the cause of anemia.
Drugs (including aspirin and certain anti-inflammatory drugs) are known potential causes of blood loss or aplasia.

Regulation of Iron Absorption, Uptake, and Distribution

Iron absorption, uptake, and distribution are regulated processes within the body; it plays a crucial role in various bodily functions.
The body's control ensures sufficient iron availability while safeguarding against excess iron buildup, supporting the oxygen-carrying capacities of cells.

Reduction in EPO Production (Chronic Kidney Disease)

Reduced erythropoietin (EPO) production in the kidneys, a common finding in patients with chronic kidney disease (CKD), leads to reduced red blood cell production. This is a well-known cause of anemia.
Injured renal tubules and proliferation of myofibroblasts contribute to reduced EPO production.

Investigations for Anemia

Common investigations for anemia involve analyzing the characteristics of red cells, specifically the mean corpuscular volume (MCV).
MCV measurements categorize anemia as normocytic (in cases of acute blood loss or chronic inflammation), microcytic (usually associated with iron deficiency anemia), or macrocytic (often linked with B12 or folate deficiencies) through their respective sizes.

Overview of Differential Diagnoses of Anemia

This diagnostic overview for various types of anemia includes several factors like bleeding, autoimmune conditions, and other disease processes.

Peripheral Blood Smears in Anemia

Microscopy of blood smears can detect various abnormalities in red blood cells including morphology of red blood cell defects, and reticulocytes in autoimmune hemolytic anemia, teardrop cells in myelofibrosis, and target cell features in situations like liver disease.

Hemolytic Anemia

Hemolytic anemia describes accelerated red blood cell destruction, exceeding the bone marrow's capacity to compensate.
The processes underlying hemolytic anemia trigger excessive breakdown of red blood cells.
Compensation for excessive red blood cell destruction includes increasing the rate of red blood cell production as well as decreasing the lifespan of red blood cells.
Symptoms often include increased bilirubin, elevated urinary excretion of urobilinogen, and increased serum levels of lactate dehydrogenase (LDH).

High Hemoglobin

High hemoglobin (or erythrocytosis) can occur from elevated red blood cell counts, either due to primary causes such as polycythemia vera, increased erythropoietin levels due to abnormal secretion or secondary to hypoxic states or inappropriate erythropoietin levels.
This can also be due to relative increases from reduced plasma volume.
Conditions such as high altitude, cardiovascular disease, and certain medications can present as causes of high hemoglobin counts

Classification and Causes of Erythrocytosis

Erythrocytosis can be categorized as absolute or relative (low-volume).
Absolute erythrocytosis has increased red blood cells with normal plasma volume.
Relative erythrocytosis involves an increase in red blood cells due to a decrease in plasma volume (e.g., dehydration, diuretics).
Underlying causes include primary (e.g., polycythemia vera), secondary (e.g., hypoxia), or drug-related erythrocytosis.

Polycythemia Vera (Definition and Epidemiology)

Polycythemia vera (PV) is a clonal disorder stemming from a hematopoietic stem cell defect.
Characterized by elevated red blood cell counts.
A relatively infrequent blood disorder.

Polycythemia Vera (Clinical Presentation)

The clinical presentation of polycythemia vera often presents with headache, visual issues, mental impairment, itching, and occlusive vascular events like strokes or myocardial ischemia.
This disorder can affect organ systems through thrombosis in pulmonary, deep vein, hepatic, or portal venous systems.
Certain hemorrhagic events might result, with abnormal platelet function playing a role in this presentation.

Diagnostic Criteria for Polycythemia Vera

A definitive diagnosis of polycythemia vera requires meeting criteria on blood tests or bone marrow samples (especially in cases of persistently elevated red blood cell counts).
Major criteria include elevated hemoglobin or hematocrit levels.
Minor criteria include low serum erythropoietin levels and specific genetic mutations. Bone marrow biopsies are important in ambiguous cases or for detecting early myelofibrosis.

Treatment for Polycythemia Vera

Treatment options vary depending on factors like age or presence of thrombotic complications.
Low-dose aspirin and treating any asymptomatic thrombocytosis can lessen thromboembolic events.
Patients with cardiovascular risk factors or significant splenomegaly might benefit from cytoreductive therapies including hydroxyurea, interferon α, or anagrelide. (note: specific therapy protocols depend on patient factors, and this is a summary)

Haemoglobinopathies

Haemoglobinopathies stem from mutations affecting globin chain genes, leading to abnormal hemoglobin.
Alpha-thalassemia arises from disruptions in the alpha globin chain genes.
In beta-thalassemia, mutations result in decreased or absent beta globin chain production.

Sickle Cell Disease

Sickle cell disease results from a substitution of glutamic acid for valine.
Homozygotes (SS) develop sickle cell disease with abnormal, rigid red blood cells.
Heterozygotes (AS) have sickle cell trait, with some potential for abnormal red blood cell aggregation under certain conditions.

Clinical and Laboratory Features of Sickle Cell Disease

Clinical presentation often features anemia, organ damage (esp cardiovascular or CNS), infections, and painful crises.
Laboratory findings may show the presence of sickled red blood cells and characteristic changes in hemoglobin.

Treatment for Sickle Cell Disease

Treatment usually involves managing symptoms, preventing crises, and sometimes, specific treatments like chronic transfusions, or potentially curative allogenic stem cell transplants (for young patients).

Thalassemias

Thalassemias are inherited blood disorders characterized by decreased or absent hemoglobin production either due to reduced or absent alpha or beta chains.
Beta-thalassemia major presents with severe anemia, requiring frequent transfusions and/or bone marrow transplants.
Beta-thalassemia minor is a milder form, characterized by some abnormal hemoglobin but no critical anemia or complications.

Thalassemias Major Diagnostic Features (and Treatment)

Diagnostic indicators include anemia, evidence of red blood cell dysplasia, or reduced production of healthy hemoglobin A, often accompanied by elevated F (fetal hemoglobin).
Management often involves transfusions to maintain hemoglobin levels, iron chelation treatments, allogeneic hematopoietic stem cell transplants or splenectomy in some cases (depending on comorbidities).

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Description

This quiz covers key concepts related to hemoglobin levels, types of anemia, and hemostasis. Answer questions about erythrocytosis, therapies for polycythemia vera, and the role of platelets in blood clotting. Ideal for students and professionals in the medical field.