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Hemolymphatics > Erythron > Flashcards

Erythron Flashcards

1
Q

What condition is it when hematocrit is INCREASED and total protein is INCREASED?

A

Haemoconcentration

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2
Q

What condition is it when hematocrit is INCREASED but the total protein is NORMAL?

A

Erythrocytosis

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3
Q

What condition is it when hematocrit is DECREASED and total protein is also DECREASED?

A

Haemorrhagic anemia

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4
Q

What condition is it when hematocrit is DECREASED but the total protein is NORMAL?

A

Hemolysis or bone marrow disease

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5
Q

What method is used to determine the amount of hemoglobin in blood I.e the O2 capacity?

A

Cyanmethemoglobin method

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6
Q

Explain how the cyanmethemoglobin method works.

A

A lying agent is added to the sample of diluted blood — releasing the hemoglobin from red cells into the fluid
- the hemoglobin is converted to a form known as cyanmethemoglobin and the concentration is read by a spectrophotometer with wavelengths set at the peak absorbance of cyanmethemoglobin (540 nm)

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7
Q

What measurements are determined by the cyanmethemoglobin method?

A

The MCH and MCHC - red cell indices

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8
Q

What can cause false readings of hemoglobin concentration in a sample?

A

Heinz bodies, hemolysis, lipemia and treatment with oxygen in can cause false readings in hemoglobin concentration

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9
Q

What is the primary value of the RBCC test?

A

Primary value is that it allows for the determination of the MCV and MCH

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10
Q

What does the RBCC measure?

A

It measures the amount of erythrocytes per L of blood — a measure of the O2 carrying capacity

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11
Q

What device is used to be able to count the RBC and WBC within a sample?

A

A Neubauer Haemocytometer

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12
Q

What are the features of a Neubauer Hemocytometer that allow for counting of white and red blood cells?

A
  • H shaped moat
  • 2 cover slips held 0.1 mm above counting chamber
  • Neubauer style rulings
  • Brightly illuminated grid lines
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13
Q

How does the counting work for a Neubauer hemocytometer?

A

Count the WBC in the 4 primary corner squares and multiply by 50 to get cells/ uL
Count the RBC in 5 secondary squares of central primary square and multiply by 10,000 to get cells/ uL

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14
Q

How do impedance counters work?

A
  • they rely on the coulter principle
  • when a particle passes through a narrow orifice, it causes a change in electrical resistance, for which the magnitude corresponds to cells size and the frequency corresponds to cell number
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15
Q

How do laser flow cytometers work?

A

They detect individual cells in microdroplets as they pass through a laser beam. Each cell type scatters light in a characteristic “signature” based on its size, nucleus, and cytoplasmic contents

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16
Q

What is the CHCM used for (cell hemoglobin concentration mean)?

A

It is used to flag inaccuracies in hemoglobin concentration skewed by things like lipemia, or hemolysis - it is measured using laser light scatter and is used to back-calculate a cellular hemoglobin which reflects the hemoglobin content within intact RBCS. Compare to the MCHC to determine accuracy of the MCHC

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17
Q

What could microcytosis indicate with a low MCV?

A
  • Microcytosis can occur in immature animals of most species which have small RBCs
  • Nutritional: copper, iron , and B6 deficiencies (Iron deficiencies are also common in young animals)
  • from portosystemic shunt (esp in dogs)
  • from increased erythropoiesis resulting in depletion of stored iron
  • hepatic lipidosis in cats
  • inhibitors of heme synthesis e.g., lead (Pb), chloramphenicol
  • Genetic defects: thalassemia, band 4.1 deficiency, familial dyserythropoiesis in English Springer Spaniel, Hereditary elliptocytosis
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18
Q

How might hyponatremia result in microcytosis of red blood cells?

A

RBCs adjust to hyponatremia by increasing their cytoplasmic water content but when then placed into a diluent prior to counting, osmosis results in water loss from the RBCs causing cell shrinkage — microcytosis

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19
Q

How does EDTA cause microcytosis?

A

EDTA is hypertonic and therefore when blood is placed in EDTA, water is removed from the RBCs to balance the osmotic pressure resulting in cell shrinkage!

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20
Q

What can cause macrocytosis in small animals?

A
  • regenerative anemia - especially hemolytic anemia
  • non-regenerative anemia in Fe-LV positive cats and some dogs with IMHA
  • myeloproliferative disorders including MDS, EM/EL
  • Hereditary stomacytosis in dogs (Alaskan malamute)
  • hyperthyroidism in some cats (minimal increase)
  • fetal and neonatal animals - fRBCs are macrocytic — macrocytic fRBCs are normally rapidly removed from the blood after birth but in some species (esp foals) they can remain macrocytic immediately after birth
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21
Q

What can cause a false increase in MCV?

A

Erythrocytes agglutination can cause a false increase in the MCV

If the animals has hypernatremia then this causes the RBCs to become dehydrated in vivo so when they are placed in an iso-osmolant diluent for counting, the RBCs swell to maintain the osmotic balance

RBCs also swell with storage - so prolonged storage before assay can result in a falsely increased MCV

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22
Q

What would treatment of horses with heparin do to the value of the MCV?

A

Heparin treatment for acute laminitis, thrombophlebitis or DIC induces agglutination which results in a false increase in the MCV of the horse

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23
Q

What is the RDW?

A

RDW = red cell distribution width

- this is the coefficient of variation of erythrocytes volumes & an electronic measure of anisocytosis

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24
Q

How do you calculate the RDW?

A

RDW = (STD of erythrocyte volumes/ MCV) X 100

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25
Q

What would cause an increased RDW?

A
  • regenerative anemias with increased numbers of reticulocytes
  • Iron deficiency anemia with increased numbers of microcytes
  • Erythrocyte fragmentation
  • After blood transfusion with different sized cells
  • Dyserythropoiesis = defective development of red blood cells
  • it can be spuriously increased with: RBC agglutination or when platelets are counted in erythrocyte histogram of a severely anemic patient
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26
Q

How do you calculate the MCHC?

A

MCHC = [Hb] / PCV

Note that [Hb] is in g/L and the PCV is in L/L which means that the value of the MCHC is g/L

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27
Q

What alterations do we see to the value of the MCHC?

A

Can see either hypochromic or normochromic cells — don’t generally see hyperchromic cells as RBCs have a maximum capacity of hemoglobin to which they normally carry. If the MCHC is above normal, check calculations for an artefact — occasionally can be from a real change like eccentrocytes

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28
Q

What could a high MCHC value indicate?

A

Generally, high MCHC values are from artefact but the MCHC value accounts for both intra and extra-cellular hemoglobin BUT assumes all hemoglobin is intracellular

  • intravascular hemolysis
  • in vitro hemolysis
  • Heinz bodies with erythrocytes
  • Lipemia
  • erythrocyte agglutination in electronic cell counters
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29
Q

What could account for a low MCHC value?

A
  • Regenerative anemia
  • chronic iron deficient anemia
  • hereditary stomatocytosis in dogs
  • spurious in aged samples (RBCs fill with water due to ATP deficiency)
  • spurious in some dogs and cats with persistent hypernatremia
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30
Q

What is MCH measured in ?

A

Picograms (10^-12)

31
Q

What are the two forms of reticulocytes found in cats?

A
  • punctate reticulocytes

- aggregate reticulocytes

32
Q

Explain the use of aggregate vs punctate reticulocytes in cats.

A

Increased aggregate reticulocytes reflect the current bone marrow response to anemia (I.e., increased erythropoiesis or regeneration) whereas..
Punctate reticulocytes are derived from aged aggregate reticulocytes and persist for at least 2 weeks post bone marrow response.
Aggregate reticulocytes are much more useful in measuring the bone marrows response to anemia

33
Q

What is the physical difference between aggregate and punctate reticulocytes in cats

A

Reticulocytes in general are big and blue!
Punctate reticulocytes contain small blue stained dots whereas in aggregate reticulocytes there are larger area of the blue stain being taken up

34
Q

Explain the progression of reticulocytes into erythrocytes in cats

A

Metarubricyte —> aggregate reticulocyte —> punctate reticulocyte —> erythrocyte

The nucleus of the metarubricyte is extruded. The stage at which the reticulocyte leaves the bone marrow is dependent on the demand for RBC production

35
Q

What is the reticulocyte production index in dogs?

A

RPI = corrected reticulocyte count / reticulocyte maturation time

The RPI = the increase in erythrocyte production aka an RPI of 3 is 3X the normal erythrocyte production

36
Q

What does a RPI value >2 tell you ? How about >3?

A

It tells you that there is a regenerative response to anemia as it should normally be ~1. >3 indicates a marked response especially hemolysis

37
Q

How long does it take for reticulocytes that are in the bone marrow to be released in the blood with a case of anemia?

A

Takes 2-3 days for reticulocytes to appear in the blood - release from bone marrow

38
Q

Why is the RPI necessary to use?

A

It is the corrected reticulocyte response as generally the reticulocyte percentage tends to overestimate the % reticulocytes. This is because when larger more immature reticulocytes are released earlier into the blood due to anemia, they persist longer as it takes more time for them to mature —> this results in a higher % of reticulocytes

39
Q

Why might the RPI in an anemic patient be <2 aka not a regenerative response?

A
  • this could suggest that the bone marrow is the source of the anemia indicating a non-regenerative anemia
  • there may be insufficient time for the reticulocytes to be produced in an acute event as it takes 2-3 days for them to be released from the BM
  • may be due to a deficiency in the existing reticulocyte response
  • or may be due to defective erythropoiesis
40
Q

Which form of anemia would have a greater reticulocyte response - hemolytic or hemorrhage? Why?

A

Reticulocytosis is more intense with a hemolytic anemia compared to external hemorrhage. This is because the iron from hemolysed RBCs is more readily available for erythropoiesis compared to iron that is stored as hemosiderin.

41
Q

Why is it important to rapidly air dry your blood smear sample after you have made it?

A

Air drying rapidly prevents cremation (kinocytosis) of cells — if you dry the smear slowly then the fluid concentrates and sucks water out of cells by osmosis causing cell shrinkage and kinocytosis of the cells.

42
Q

What does the term anisocytosis mean?

A

Variation in cell size

43
Q

What does the term poikilocytosis mean?

A

It means that the RBCs are abnormally shaped

- these are typical in goats and young cattle

44
Q

What are Echinocytes?

A

Echinocytes are usually an artefact that is reversible due to RBC dehydration.
- spicules present on the RBC

45
Q

What can cause Echinocytes?

A
  • Echinocytes are usually artefactual
  • can be due to a non-specific change associate with certain diseases like: snake bites, uraemia, post-transfusion, PK deficiency in dogs, neoplasia (dogs), glomerulonephritis, cation depletion (horses)
  • it can be due to RBC dehydration, ATP depletion, increased pH, increased RBC calcium
  • can also be due to fatty acids, bile salts, drugs and lysophosphlipids
46
Q

What are the main causes of IHA in dogs?

A

Mostly idiopathic but can also be neoplasia, infection or toxicity

47
Q

What are the clinical signs associated with IHA in dogs?

A

Lethargy, inappetence, +/- pigmenturia, tachycardia, pale mucous membranes, fever

48
Q

What is used to diagnose IHA in dogs?

A

IHA is diagnosed by:

  • Hct <25-30% (recall normally 35-55%)
  • hemolysis (hemoglobinemia, hemoglobinuria, bilirubinemia -83%)
  • RBC antibodies - agglutination -51%, spherocytosis - 67%, Coombs positive - 60%)
49
Q

What age group and sex is more predisposed to IHA in dogs?

A

Middle aged female dogs

50
Q

What are spherocytes?

A

Normally red blood cells are bi-concave discs but with spherocytes they lose their area of central pallor and have an increased osmotic fragility due to their more circular appearance.
They are about 1/4 to 1/3 smaller than a normal RBC with a reduced surface area to volume ratio

51
Q

How do spherocytes form?

A

In IMHA the antibodies on the RBC surface target the RBC for destruction by splenic macrophages. The macrophages partially phagocytose the RBC causing a loss of surface membrane

These can also occur when Heinz bodies are removed from RBCs by splenic macrophages.

52
Q

What are ghost cells?

A

Ghost cells form with intravascular hemolysis (occurs in IHA in dogs) where cells are depleted of their hemoglobin but there is still enough left to faintly stain the membrane that is left.

53
Q

What is the difference between extravascular and intravascular hemolysis in IHA in dogs?

A
  • IHA is usually extravascular hemolysis by macrophages of the spleen, liver and marrow that phagocytose RBCs that are coated with IgG
  • intravascular hemolysis occurs with IgM coating on RBC causing complement activation — this causes hemogloninemia, hemoglobinuria and ghost cells to appear
54
Q

How does auto-agglutination occur?

A

Auto-agglutination occurs if increased amounts of IgG and IgM coated on RBC and spherocyte surface and cause cross-link, causing true auto-agglutination

55
Q

How do you rule out false positive for RBC agglutination tests?

A

RBCs saline-washed of other protein on the cell that may contribute to agglutination — 3X you add physiologic saline to centrifuged blood after removal of the supernatant — if agglutination persists then it is true

56
Q

What are acanthocytes?

A
  • Acanthocytes form when there is increased membrane cholesterol creating usually 5-10 finger like projections on the red blood cell
57
Q

What clinical disease conditions would you see acanthocytes in?

A

Acanthocytes are seen in liver disease, hemangiosarcoma, DIC and glomerulonephritis

58
Q

What are schistocytes?

A

These are split cells or red blood cell fragments

59
Q

What diseases might you see schistocytes in?

A
  • DIC
  • portosystemic shunts
  • iron deficient anemia
  • glomerulonephritis
  • vasculitis
60
Q

What are elliptocytes? Are they always abnormal?

A

Elliptocytes are red blood cells that have a elongated oval form. These would be considered normal red blood cells in camelidae.

61
Q

In what clinical diseases might you see elliptocytes forming?

A
  • In cats: marrow abnormalities, hepatic lipidosis, portosystemic shunts, doxorubicin toxicity
  • In dogs: myelofibrosis, myelodysplasitic syndrome (MDS), glomerulonephritis, RBC band 4.1 deficiency
62
Q

What are dacrocytes?

A

Dacrocytes are tear drop shaped red blood cells resulting from the inability of the RBC to return to its pre-existing shape after deforming in a blood vessel.

63
Q

In what clinical disease might you see dacrocytes?

A
  • myelofibrosis in people, rarely in dogs
  • glomerulonephritis in dogs
  • Hypersplenism in dogs
  • iron deficient ruminants
  • myeloid metaplasia/ metaplastic neoplasms to BM

Overall from alterations in cytoskeletal proteins causing the formation of dacrocytes

64
Q

What are Howell-Jolly bodies?

A

Howell-jolly bodies are basophilic nuclear remnants within the cytoplasm of RBCs

65
Q

When might you see the formation of Howell-Jolly bodies?

A
  • post splenectomy
  • in accelerated erythropoiesis with regenerative anemia’s
  • with glucocorticoid therapy
  • vincristine therapy in regenerative anemia

Cats and horses have low numbers of these Howell-Jolly bodies normally

66
Q

When you see a nucleated RBC what stage of RBC development is it most likely at?

A

Generally metarubricyte or rubricyte stage

67
Q

In what conditions would you see increased numbers of nucleated RBCs?

A
  • regenerative anemia
  • lead toxicity
  • marrow injury or disease
  • splenic dysfunction (spleen usually removes anything abnormal from in the blood)
  • hereditary dyserythropoiesis (dogs & cattle)
  • cardiovascular disease, inflammation, trauma and hyperadrenocorticism in the dog
68
Q

What is a Heinz body?

A

Heinz bodies are comprised of denatured, precipitated hemoglobin caused by oxidation. It forms a round structure that protrudes from the RBC membrane or appears as a refractive spot in the cytoplasm

69
Q

What conditions cause Heinz body formation in small animals?

A
  • onion ingestion
  • splenectomy in dogs
  • propylene glycol in soft moist foods (cats)
  • zinc toxicity in dogs
  • acetaminophen, methylene blue, methionine phenazopyridine, menadione (Vit K3)
70
Q

What is the normal amount of Heinz bodies to be found in a cat?

A

Cats have up to 5% Heinz bodies in a healthy condition and this increases with some diseases - e.g., diabetes, lymphoma, hyperthyroidism.

Cats are more susceptible to Heinz body formation —> this is because they have a larger number of sulfhydryl groups that increase the susceptibility of hemoglobin to oxidation. As well, the feline spleen is inefficient at removing the Heinz bodies.

71
Q

What conditions cause Heinz body formation in large animals?

A
  • onion ingestion by livestock
  • lush winter rye in Florida cattle
  • selenium deficiency
  • post partum cattle on perennial ryegrass
  • copper toxicity in sheep and goats
  • phenothiazine in horses
72
Q

What stain is required to see Heinz bodies?

A

NMB stain

73
Q

What conditions causes basophilic stippling?

A
  • regenerative anemia primarily in ruminants

- lead toxicity

Hemolymphatics (3 decks)

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