Mechanisms of Spherocyte Formation

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Questions and Answers

What occurs during intravascular hemolysis?

Spherocytes are formed in the bone marrow

RBCs are removed by the spleen

Bilirubin levels decrease

Cells are destroyed directly in circulation (correct)

What is a clinical feature of hemolytic anemia?

Thrombosis

Reduced heart rate

Increased platelet count

Pallor (correct)

Which disorder results in spherocytes in the blood?

Hereditary elliptocytosis

Hereditary stomatocytosis

Acanthocytosis

Hereditary spherocytosis (correct)

Which of the following is a feature of hereditary elliptocytosis?

Elliptocytes blood picture Signup and view all the answers

Aplastic crises in hemolytic anemia are occasionally caused by what virus?

Parvo-virus B19 Signup and view all the answers

Which type of spherocytes result from acquired conditions such as antibodies on RBCs?

Acquired spherocytes Signup and view all the answers

What is the inheritance pattern of hereditary stomatocytosis?

Autosomal dominant Signup and view all the answers

Pigment stones in patients with hemolytic anemia are primarily a result of what?

Increased bilirubin production Signup and view all the answers

What is the primary characteristic of hemolytic anemias?

Decreased lifespan of red blood cells Signup and view all the answers

What happens to hemoglobin when red blood cells are hemolyzed?

It breaks down to form amino acids and bile pigments Signup and view all the answers

Which component is released into the plasma pool after hemolysis?

Iron Signup and view all the answers

Which of the following is a key pathophysiological change during hemolytic anemia?

Increased circulating reticulocytes Signup and view all the answers

What is the expected result of erythroid hyperplasia in bone marrow during hemolytic anemia?

Frontal bossing and hair on end appearance Signup and view all the answers

How does the body respond to a decrease in circulating red blood cells in hemolytic anemia?

Increase in reticulocyte production Signup and view all the answers

What type of hemolysis is characterized by the destruction of red blood cells in the bloodstream?

Intravascular hemolysis Signup and view all the answers

What abnormality is typically seen in reticulocytes during hemolytic anemia?

Presence of Howell-Jolly bodies Signup and view all the answers

What is the main consequence of a deficiency in Beta Spectrin or Ankyrin in hereditary spherocytosis?

Loss of membrane surface area Signup and view all the answers

Which test shows increased red cell osmotic fragility in hereditary spherocytosis?

Osmotic fragility test Signup and view all the answers

What is typically observed in a complete blood count of a patient with hereditary spherocytosis?

Decreased mean corpuscular volume (MCV) Signup and view all the answers

What characterizes the morphology of blood cells in hereditary spherocytosis?

Presence of spherocytes and microspherocytes Signup and view all the answers

What does a high level of indirect bilirubin in serum indicate in hereditary spherocytosis?

Increased hemolysis of red blood cells Signup and view all the answers

What can partly correct the autohemolysis observed in hereditary spherocytosis?

Addition of glucose Signup and view all the answers

In an osmotic fragility test, which concentration of NaCl is typically associated with the start of hemolysis in normal red blood cells?

0.45% Signup and view all the answers

What is a common clinical manifestation of hereditary spherocytosis?

Hyperbilirubinemia Signup and view all the answers

Study Notes

Direct Coomb's Test

Positive test indicates presence of antibodies on the surface of red blood cells.
Important for diagnosing hemolytic anemias, differentiating between hereditary and acquired causes.

Mechanism of Spherocyte Formation

Caused by cytoskeletal protein abnormalities in red blood cells.
Deficiency of Beta Spectrin or Ankyrin leads to loss of membrane surface area.
Spherocytes are formed as cells become more spherical in the spleen, leading to their destruction (extravascular hemolysis).
Spherocytes are permeable to sodium influx, making cells more fragile.

Clinical Features of Hereditary Spherocytosis (HS)

Common symptoms include jaundice, anemia, and splenomegaly.
Jaundice is due to increased bilirubin production from hemolysis.

Laboratory Tests for HS

Complete blood count reveals lower Hb, lowered hematocrit (PCV), and increased reticulocyte count.
Blood film morphology shows spherocytosis and microspherocytes with polychromasia.
Osmotic fragility test detects increased osmotic fragility in red cells; abnormal hemolysis at higher NaCl concentrations.
Autohemolysis increases, partially corrected by glucose addition.
Serum bilirubin (indirect) levels are elevated.

Types of Hemolysis

Intravascular Hemolysis: Red blood cells destroyed within circulation; complications include hemoglobinuria.
Extravascular Hemolysis: Removal of RBCs by reticuloendothelial system primarily in liver and spleen.

Classification of Hemolytic Anemias

Hemolytic anemias defined as premature destruction of RBCs leading to decreased survival (<120 days).
Increased breakdown of RBCs releases hemoglobin, leading to hyperbilirubinemia and hemolytic jaundice.

Red Cell Membrane Disorders

Hereditary conditions such as Spherocytosis, Elliptocytosis, Stomatocytosis, and Acanthocytosis each exhibit unique cellular morphologies.
Spherocytes indicate hereditary spherocytosis with autosomal dominant inheritance.

Mechanism of Hemolytic Anemia

High breakdown of RBC leads to excess hemoglobin breakdown into bilirubin, causing hyperbilirubinemia.
Increased reticulocyte production in response to decreased circulating RBCs, enhances erythropoietic activity.
Bone marrow demonstrates increased activity with possible extramedullary hematopoiesis in severe cases.

Special Tests for HS

Osmotic fragility test assesses red blood cell stability under osmotic stress.
Indirect bilirubin is high, indicating increased breakdown of red blood cells and subsequent liver processing.

Risk of Aplastic Crises

Occasional occurrences due to infections (e.g., Parvovirus B19) can exacerbate anemia in patients with hereditary spherocytosis.

Summary Definitions

Hemolytic anemia results from a shorter life span of RBCs due to hemolysis, leading to increased erythropoietic activity to compensate for loss.

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Description

This quiz delves into the mechanisms involved in the formation of spherocytes, as well as related topics such as the normal RBC membrane and hereditary spherocytosis. It is aimed at medical students and professionals looking to enhance their understanding of blood cell morphology and pathology. Gain insights into the significance of the positive Direct Coomb's test in this context.