Anaemia Flashcards

1
Q

What are the stages of red blood cell maturation in the bone marrow?

A

Red blood cell maturation in the bone marrow involves several stages. Initially, the erythrocytes are large, nucleated, and have intensely blue-staining cytoplasm. As they mature, they become smaller, lose their nucleus, and contain a higher proportion of hemoglobin, imparting a redder coloration. The penultimate stage is the reticulocyte, which undergoes remodeling of its cell surface before exiting the bone marrow.

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2
Q

Describe the significance of reticulocytes in the bloodstream.

A

Reticulocytes are juvenile red cells that contain varying degrees of residual RNA, which is absent in mature erythrocytes. The presence of reticulocytes in peripheral blood indicates ongoing erythropoiesis, and their volume can indicate accelerated red cell regeneration. In dogs, aggregate reticulocytes are observed, while in cats, there is an additional “teenage” stage called punctate reticulocytes.

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3
Q

Explain the oxygen-hemoglobin dissociation curve and its significance in oxygen transport.

A

The oxygen-hemoglobin dissociation curve illustrates the saturation of hemoglobin with oxygen concerning the partial pressure of oxygen in arterial blood. It demonstrates the cooperative binding of oxygen to hemoglobin. In systemic capillaries, where oxygen levels are low, hemoglobin releases oxygen readily to oxygenate tissues. In the lungs, where oxygen levels are high, hemoglobin binds oxygen rapidly. The curve plateaus when all heme sites are fully oxygenated, and the steep incline represents increased oxygen affinity as successive oxygen molecules bind.

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4
Q

What is the role of 2-3 diphosphoglyceric acid (DPG) in oxygen transport?

A

2-3 DPG is necessary for the release of oxygen when partial pressure is low, such as in the systemic capillaries supplying blood to the tissues. Its levels are important during storage of red cells, as they decrease, making oxygen release less efficient. However, within 24 hours of transfusion, the recipient’s body restores normal 2-3 DPG levels, improving oxygen delivery.

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5
Q

How are senescent erythrocytes cleared from the bloodstream, and what happens to their components?

A

Senescent erythrocytes are primarily phagocytosed by Kupffer cells in the liver and red pulp macrophages in the spleen. During clearance, some red cell components are recycled. Globulin is broken down into amino acids, and heme is separated into iron and biliverdin. Iron can be stored or transported in plasma to be stored in the liver for erythropoiesis. Biliverdin is converted to bilirubin, which is excreted in the feces after conjugation in the liver. (Senescent cells are unique in that they eventually stop multiplying but don’t die off when they should. They instead remain and continue to release chemicals that can trigger inflammation)

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6
Q

What are the main methods used by in-house hematology analyzers to analyze blood components?

A

In-house hematology analyzers use various methods to analyze blood components. These include:

Quantitative Buffy Coat Analysis (QBC): Centrifugation of a dye-coated microhematocrit tube to calculate cell count based on the width and fluorescence of different cell layers.
Impedance Counters: Passing blood cells through an electrical current, with impedance changes used to differentiate cell types based on size.
Laser Flow Cytometry: Cells pass through a laser beam, and interruptions in light help count and characterize cells, with additional staining for more accurate identification.

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7
Q

What components are typically included in the analysis of the erythron by hematology analyzers?

A

The analysis of the erythron by hematology analyzers includes:

Red Cell Mass
Red Cell Indices:
Mean Cell Volume (MCV)
Mean Cell Hemoglobin (MCH)
Mean Cell Hemoglobin Concentration (MCHC)
Red Cell Distribution Width (RDW)
Reticulocyte Count

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8
Q

Explain the significance of Mean Cell Volume (MCV) and Mean Cell Hemoglobin Concentration (MCHC) in red cell analysis.

A

MCV (Mean Cell Volume): It represents the average volume of erythrocytes. An increased MCV indicates larger cells (macrocytes), while a decreased MCV indicates smaller cells (microcytes).
MCHC (Mean Cell Hemoglobin Concentration): It represents the average hemoglobin concentration in erythrocytes. Normal MCHC is termed normochromic, low MCHC is hypochromic, and high MCHC is considered an artifact.

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9
Q

What does an increased Red Cell Distribution Width (RDW) indicate?

A

An increased RDW indicates a greater variation in the size of red cells, a condition known as anisocytosis. This is consistent with a regenerative response, as immature red cells tend to be larger in size.

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10
Q

How can the Dot Plot in graphical results be useful in analyzing blood samples?

A

The Dot Plot in graphical results is created from data about individual red cells. It provides a visual representation of cell fluorescence (RNA volume) on the x-axis and cell size on the y-axis. Changes in the reticulocyte count are often easier to identify on the Dot Plot. Large populations of cells outside the normal area may indicate abnormal cell morphology, prompting further evaluation of a blood smear.

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11
Q

What are some limitations of hematology analyzers?

A

Sample Quality: Poor sample quality, including lipemia, hemolysis, clots, or using aged samples, can affect accuracy.
Cell Clumping: Agglutinated erythrocytes or platelet clumps can reduce cell counts inaccurately.
Standard Cell References: Red cells that deviate from the standard reference range may be misidentified, especially if they are larger, smaller, or nucleated.
Quality Control: Regular maintenance and quality control testing are essential to ensure optimal analyzer performance.

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12
Q

Why is it recommended to evaluate a blood smear even if automated results are available?

A

While automated hematology analyzers provide valuable information, an overreliance on them alone can lead to missing vital erythrocyte information. Evaluating a blood smear is recommended to confirm the accuracy of automated results, especially when abnormalities are suspected based on graphical displays or clinical context.

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13
Q

What are the key steps and precautions in blood sample procurement?

A

Aspirate blood carefully to avoid damage to erythrocytes.
Use veins, not capillaries, to ensure parasite detection.
Fill EDTA tubes to the specified line.
Remove the needle to prevent unintentional cell damage.
Avoid touching the tube’s sides.
Mix the sample thoroughly.
Wear gloves when handling blood samples.
Label tubes properly.

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14
Q

What are the steps involved in making a blood smear?

A

Prepare a flat surface with the frosted side of the slide facing up.
Place a small drop of blood at one end using a plain capillary tube.
Hold a second clean slide at a 30-45 degree angle.
Slowly pull the spreader slide towards the blood drop until it touches.
Allow the blood to spread 75% of the slide’s width.
Quickly and smoothly push the slide away from the drop.
Dry the smear quickly to prevent osmotic changes.
Label the slide with the patient’s name and date.

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15
Q

What are the different regions of a blood smear, and what can be observed in each region?

A

Feathered Edge: Large cells, microfilaria (parasites), and platelet clumps. Morphology and distribution may be abnormal.
Monolayer: Evenly distributed cells, suitable for cell count. Used with an oil immersion lens.
The Body: Examined for rouleaux, agglutination, or other clumps using a low-power lens.
The ‘Dot End’: Morphology may be poor.

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16
Q

Describe the normal characteristics of erythrocytes in terms of shape, color, and size.

A

Shape: Biconcave disc, allowing for easy movement through capillaries.
Color: Red, with a central area of pallor representing the less dense center. Cats may lack a prominent central pallor. Normal coloration is termed normochromic.
Size: Dogs have erythrocytes around 7 microns, while cats have 5.5-6.5 microns. Normal size is termed normocytic.

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17
Q

Explain the abnormalities related to erythrocyte size, including hypochromasia, polychromasia, and macrocytosis

A

Hypochromasia: Erythrocytes lack color, appearing like a bike wheel, indicating iron deficiency and chronic blood loss. Often smaller in size, reported as low MCHC.
Polychromasia: Variation in erythrocyte color, indicating regenerative response with larger, bluer cells. May include reticulocytes, identifiable with stains like New Methylene Blue.
Macrocytosis: Increased number of larger erythrocytes, often associated with early release of immature cells from the bone marrow. May stain bluer.

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18
Q

What are spherocytes, and what pathology are they indicative of?

A

Spherocytes: Small, spherical, intensely staining red blood cells.
Indicative of: Pathognomonic for Immune-Mediated Hemolytic Anemia (IMHA). Formed following a failed phagocytic encounter.

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19
Q

Discuss the importance of reticulocytes in blood smear evaluation.

A

Reticulocytes: Immature red cells indicating active regeneration. Important for assessing bone marrow response in anemic patients.
Types: Aggregate reticulocytes (A) in dogs and cats, punctate reticulocytes (B) in cats.
Staining: Can be identified using new methylene blue stain, showing darker nuclear remnants.
Regenerative Anaemia: Presence of reticulocytes indicates a normal bone marrow response.
Non-regenerative Anaemia: Absence or inadequate number of reticulocytes suggest bone marrow pathology.
Pre-regenerative Anaemia: Bone marrow regeneration underway but not yet evident in peripheral blood.

20
Q

How is anaemia confirmed, and what information can be obtained from automated haematology analysers?

A

Anaemia is confirmed when a deficiency in the number of functional, mature erythrocytes is identified. Automated haematology analysers provide information such as haematocrit (HCT), red blood cells (RBC), red cell distribution width (RDW), reticulocytes, and red cell indices. In cases of anaemia, these values are typically decreased. Additional information can be obtained from blood smears and pack cell volume/total solids (PCV/TS).

21
Q

What are the indicators of a regenerative response in anaemia, and why is it important to identify this?

A

Indicators of a regenerative response in anaemia include increased mean corpuscular volume (MCV), macrocytosis, polychromatophils (larger and bluer immature erythrocytes), increased RDW, punctate reticulocytes (indicating regeneration 7-10 days ago), and aggregate reticulocytes (indicating active regeneration within the previous 24 hours). Identifying a regenerative response is crucial for prognosis and treatment decisions, ruling out bone marrow failure as the cause of anaemia.

22
Q

What are the three mechanisms that can cause anaemia, and how do they contribute to its development?

A

The three mechanisms causing anaemia are:

Blood loss: Severe or prolonged, resulting from surgery, trauma, coagulopathy, bleeding ulcer, neoplasia, or heavy flea burden. A regenerative response usually follows, provided there is no deficiency in key red cell components.
Haemolytic process: Erythrocyte destruction due to conditions like immune-mediated haemolytic anaemia (IMHA), erythrocyte parasite infection, or toxic cell damage. A regenerative response is often observed, assuming no deficiencies in key red cell components.
Hypoplasia or Aplastic process: Reduction or absence of erythropoiesis. More than one blood cell line may be affected, and erythropoiesis may be reduced secondary to other diseases like chronic kidney disease or hypothyroidism. Hypoplastic or aplastic anaemia typically lacks evidence of red cell regeneration.

23
Q

Describe the characteristics of spherocytes and their association with specific conditions.

A

Spherocytes are smaller, densely staining, spherical erythrocytes formed following incomplete phagocytosis. They are pathognomonic for Immune-Mediated Hemolytic Anemia (IMHA).

24
Q

Explain the characteristics and contributing factors of Anaemia of Inflammatory Disease (AID).

A

Anaemia of Inflammatory Disease (AID) is characterized by normocytic, normochromic, non-regenerative anaemia in patients with inflammation but no evidence of infection, neoplasia, or immune-mediated disease. Contributing factors include reduced red cell lifespan, inhibition of iron metabolism (hepcidin release), and impaired bone marrow function due to inflammatory cytokines.

25
Q

What are some contributing factors to hospital-acquired anaemia, and how can it be prevented during phlebotomy?

A

Contributing factors to hospital-acquired anaemia include surgical blood loss, anaemia of inflammatory disease, cumulative phlebotomy volumes, and hemodilution due to intravenous fluids. Prevention measures include grouping tests together, correct sample labeling, using smaller sample tubes, and calculating and monitoring the patient’s total blood volume to reduce unnecessary sampling.

26
Q

How does anaemia manifest differently in dogs and cats?

A

In cats, anaemia develops faster due to a shorter red blood cell (RBC) lifespan and lower blood volume. Cats have different types of haemoglobin, allowing better tolerance to anaemia than dogs. Cats may present with very low packed cell volume (PCV). Additionally, cats are more challenging to read for signs of anaemia, and owners may not notice lethargy.

27
Q

What are the clinical signs of anaemia, and how might these differ in severity?

A

Clinical signs of anaemia include:

Pale mucous membranes
Reduced CRT
Lethargy, weakness, collapse
Reduced demeanour/mentation
Tachypnoea
Tachycardia
Poor peripheral pulse quality
Hypotension
Heart murmur (cats)
Reduced heart and/or lung sounds
The severity of these signs can vary and may include more severe manifestations such as icterus, melena, hemorrhagic diarrhea, splenomegaly, spontaneous hemorrhage (petechiation and ecchymoses), epistaxis, hematemesis, external hemorrhage, abdominal distension, and heavy flea burden.

28
Q

What are the triggers for associative (secondary) IMHA in animals?

A

Neoplasia (lymphoma, haemangiosarcoma), infectious diseases (babesiosis, ehrlichiosis), envenomation, drug therapy.

29
Q

What is the term for the immune response directed at self-erythrocytes in IMHA?

A

Autoantibodies produced by B and T cells.

30
Q

What is the primary difference between extravascular and intravascular haemolysis in IMHA?

A

Extravascular occurs in organs (spleen, liver), more chronic; intravascular occurs in the bloodstream, more acute.

31
Q

What is the significance of a positive Coombs test in diagnosing IMHA?

A

It demonstrates the presence of surface-bound anti-erythrocyte antibodies or complement, supporting a diagnosis of IMHA.

32
Q

What is the primary immunosuppressive drug used in the treatment of IMHA, and what is its mechanism of action?

A

Prednisolone; it inhibits the phagocytic action of macrophages.

33
Q

Why is antithrombotic therapy often recommended in IMHA patients?

A

IMHA patients are often hypercoagulable, and antithrombotics help prevent venous thrombus formation.

34
Q

What nursing considerations are important for managing IMHA patients?

A

Monitor vital signs, urine and serum color, signs of haemolysis, avoid jugular samples, barrier nurse for immunosuppressed patients.

35
Q

What is the purpose of administering oxygen-carrying support, such as packed red blood cell (PRBC) transfusions, in severe IMHA cases?

A

To buy time for medications to take effect by temporarily improving tissue oxygenation.

36
Q

According to the ACVIM consensus statement, what is the recommended age limit for PRBC units in IMHA patients?

A

Less than 7-10 days old.

37
Q

What is the difference between hypoplastic and aplastic conditions in the bone marrow?

A

Hypoplastic involves reduced haematopoietic activity, while aplastic indicates inactive haematopoietic tissue in the bone marrow.

38
Q

Define erythroblast and precursor in the context of erythrocyte development.

A

Erythroblast is the early developmental stage of the erythrocyte line. Precursor, or blast cells, are committed to becoming a specific cell type and represent the first developmental stage.

39
Q

What do normocytic and normochromic refer to in relation to erythrocytes?

A

Normocytic: Erythrocyte of normal size. Normochromic: Erythrocyte of normal color.

40
Q

How would you differentiate between myeloid and cytotoxic terms in the context of bone marrow?

A

Myeloid is related to the bone marrow, while cytotoxic refers to a drug toxic to living cells, causing damage or cell death.

41
Q

What is the significance of a Coombs test in diagnosing conditions like immune-mediated haemolytic anaemia (IMHA)?

A

A positive Coombs test indicates the presence of surface-bound anti-erythrocyte antibodies or complement, supporting a diagnosis of conditions like IMHA.

42
Q

Explain the concept of non-regenerative anaemias and the absence of reticulocytosis.

A

Non-regenerative anaemias lack reticulocytosis despite decreased haemoglobin levels and reduced tissue oxygenation.

43
Q

Describe the impact of infectious agents like Feline Leukaemia Virus (FeLV) on bone marrow.

A

FeLV targets haemopoietic and lymphoid tissues, infecting stem cells and causing conditions like Pure Red Cell Aplasia (PRCA).

44
Q

What are the common origins of primary bone marrow disorders?

A

Primary bone marrow disorders can be infectious, cytotoxic, immune-mediated, neoplastic, or necrotic in origin.

45
Q

How does cytotoxicity contribute to anaemia, and why might cats be more sensitive to cytotoxic drugs?

A

Cytotoxic drugs, while causing transient injury to all progenitor cells, may induce more severe anaemia in cats than in dogs.

46
Q

Briefly outline the bone marrow sampling procedure, including common sites and required equipment.

A

Bone marrow sampling involves using a needle to aspirate or biopsy the marrow, commonly from the proximal humerus, iliac crest, or trochanteric fossa of the femur. Equipment includes sterile gloves, a surgical gown, a needle and syringe with a local anaesthetic, an Illinois or Jamshidi bone marrow needle, and slides for preparing samples.

47
Q
A