Abnormalities of the erythron Flashcards Preview

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Flashcards in Abnormalities of the erythron Deck (35):
1

Function of RBCs?

- haemaglobin oxygen carrying capacity

2

Where are RBCs produced in foetus? In adult?

- liver/spleen in foetus
- bone marrow in neonate
- growing animals = BM of all bones
- red marrow/yellow marrow (femur/humerus) in long bones, flat bones remain active
- liver and spleen maintain erythropoietic capacity, espcially if incresed demand (extramedullary haematopoeisis) as do long bones (reversion to red marrow)

3

Production requirements for haemopoeisis?

- stem cells
- space in marrow
- Growth factors (IL3, GM-CSF, G-CSF, erythropoeitin)
- Iron
- Cholesterol/lipids for membrane (more humans)
- enzyme pathways for construction and maintainance

4

Outline the different cell lines as a RBC matures

- Rubriblast (nucleoli, fine granules in nucleus, dark blue cytoplasm)
- Prorubriocyte
- Basophilicrubricyte
- Polychromatophilic rubricyte
- Metarubricyte
- Reticulocyte

5

What is blue basic dye attracted to?

Acid

6

How long do RBCs live for?

- 100d (Dog)
- 70d cat
- 150d horse and cattle

7

How are RBCs removed when too old normally?

- MAJOR ROUTE: macrophage phagocytoses recycles components
- MINOR ROUTE: intravascular haemolysis

8

What is anaemia? Howo may this be appreciated diagnostically?

> reduction in red cell mass, evidence in decreased:
- [Hgb] conc Haemoglobin
- PCV packed cell volume
- HCT haematocrit
- [RBC] RBC conc

9

How should PCV, HCT, [Hbg] nd [RBC] values change?

All together - if they change independantly suspect something

10

What is HCT?

Haematocrit (= PCV)
- calculated by machine
- Relies on RBC count and cell volume (less accurate)

11

What is [RBC]]

- total red cell numbers

12

What is [Hbg]?

- total oxygen carrying capacity

13

What is PCV?

- packed cell volume = % red cells in a volume of blood
- centrifuged whole blood, red cells red as % of column length

14

What else can be assessed in PCV?

- buffy coat assessment (WBC)
- plasma (clear/straw or pink if hamolysed)
- total protein measurement (put serum into refractometer)
> if bleeding, losing protein, protein v

15

Different classifications of anaemia?

> mild/mod/severe
> regenerative/non-regenerative
> normocytic/microcytic/macrocytic
> normochromic/hypochromic (hyperchromic artefact)
- Haemoglobin
* helps to narrow the cause of anaemia *

16

Define mild anaemia

- normal - 10% decrease PCV
- may not affect animal until excercised
- common in animals with ongstanding dz, endocrine disorders etc.
- will not present for this as main presenting factor

17

Define moderate anameia

- varies between species, depends on normal PCV of each
- weakness or may be well adapted (takes time)
- mm pallor
- fast bounding pulse

18

DDefine severe anameia

- PCV low teens and less
- pale, weak, unable to excercise
- may need O2 stabilisation before dxx
> dont fight with severely anaemic cats!

19

How would hypochromic anaemia appear? Why?

- increased central pallor
- MCHC/MCH (hbg conc)
- decreased in iron deficiency/poor iron incorporation (with microcytosis)

20

When does hyperchromia occour?

Artefact, cells cannot be hyperchromic
- haemolysis

21

What is the MCV?

= mean cell volume
- average volume of a single red cell (micro/normo/macrocytic)

22

Distinguishing features of normocytic

- erythrocytes unremarkable size
- often assoc with mild, non-regnerative anaemia, acute haemmorrhage etc.

23

Distinguishing features of microcytic?

- RBC haemoglobin conc determines when devision stops
- iron deficiency allows oe more division -> smaller RBC
- eg. seen with PSS, Fe deficiency, hepatic failure
- akitas (congenital, normal cells but smaller, NOT path)

24

Distinguishing features of macrocytic?

- in regeneration
- polychromatophils larger than mature RBC
- more purple colour too
- we want these as indicate regenerationi (yay)
- some poodles inherited dz (path)

25

How may macrocytosis affect your dxx?

Can increase PCV as dependant on size of cell as well as number

26

When is macrocytosis also seen?

- FeLV affected cats
- myelodysplasia
- common artefact in stored (usually posted) blood

27

What is regenerative anaemia and what stimulates it?

- body response to a fall in oxygenation
- kidneys release EPO -> BM stimulation
- takes 2-3d and younger red cells (polychromatophils/reticulocytes) increase in circulation.

28

Non regeneratvie

no notes

29

What are the 2 Ddx for regenerative anaemia?

- haemorrhage (loss)
- haemolysis (destroyed)
> if you can control the loss, animal will get better by itself
> allows assessmeent of how well an anmal is resposing

30

What cells do you look for as hallmarks of regenerative anaemia?

> reticulocytes
- RNA precipitates
- new methylene blue
- aggregates/reticulum forms
> polychromatophils
- Diff-Quick/Giemsa
- young immature cells containing ribosomal RNA show as large, blue cells (polychromatophils)
> these are the SAME CELLS

31

How do cat reticulocytes differ?

- cat retics released as aggregate retics, mature to punctate retics over time
- retic counts should record AGGREGATE or BOTH (punctates hang around for a while)

32

How can regenerative v non-regenerative be distignusihed?

- reticulocyte % (1000 red cells counted, retics expressed as %)
- corected % (same no retics will take up more % in a very anaemic animal)
> retic% x patient PCV/normal PCV
[ PCV 45% normal dog, 35% normal cat ]
> regenerative if >1% corrected (Dog) or >0.4% (cat)
> absolute reticulocyte conc may be better ([RBC] x Retic%)

33

What casues decreased red cell mass?

- ^ loss or v production

34

Causes of increased losses of RBC

> haemorrhage (external)
- melena
- UT
- epistaxis
- post-trauma/surgery

35

Shape of RBCs = ? Reason? Exceptions?

- biconcave disk in most species
- central pallor (seenin dogs)
- high surface area to volume ratio -> ^ deformability
> camelids have elliptical RBCs
> anucleate in all animals except birds and reptiles