Erythroid Flashcards
List the components of blood
- Fluid (plasma/serum)
- Ions
- Proteins (albumin, globulin, hormones, mediators, clotting factors, nutrients)
- Lipids
- Carbohydrates
- Gas
- Cells
List the functions of blood
- Transport: nutrients, oxygen, waste removal, hormones and other mediators
- Fluid/electrolyte haemostasis
- coagulation
- thermoregulation
What are reticulocytes?
Immature non-nucleated erythrocytes prematurely release to blood from bone marrow in regenerative anaemias. Names based on stain used - DiffQuik = polychromatophils, NMB = reticulocytes
Describe the appearance of reticulocytes
- Romanowsky stains: Polychromatic, blue-pink mixed colour due to staining of ribosomes and haemoglobin
- Using new methylene blue stain: precipitation demonstrates RNA protein complexes
What is the clinical relevance of reticulocytes?
- Evaluation of erythropoiesis in bone marrow
- Differentiation of regenerative and non-regenerative anaemia
What is the absolute reticulocyte count?
The observed percentage of reticulocytes x RBC and is independent of variation of RBC numbers, ggiven as x10^9/l
What are the methods for the assessment of reticulocyte production?
- Reticulocyte count (gives percentage)
- Absolute reticulocyte count
- Reticulocyte production index (sometimes used in dogs, going out of favour)
What are the 2 patterns of reticulocyte staining in cats?
- Aggregate
- Punctate
Describe the dog-specific reticulocyte response (normal vs regerenative anaemia)
- Low number of reticulocyte (<1%) in a healthy animal
- Little regerenation of RBCs needed (live for ~100 days)
- > 60x10^9/l in regenerative anaemia (>10 polychromatic cells per oil immersion field)
Describe the cat specific reticulocyte response (normal vs regenerative anaemia)
- Low numbers normally ().2-1.6%)
- Aggregate = 0.5% of erythrocytes, punctate = 1-10%
- .50x10^9/l in regenerative anaemia
Which type of reticulocyte is considered in cats in the assessment of regeneration?
Aggregate
Compare the appearance of aggregate and punctate reticulocytes
- Aggregate: blue stained, coarse clumping
- Punctate: small, blue stained dots
Describe the ruminant and hose specific reticulocyte response (normal and anaemia)
- Virtually no reticulcytes in normal blood, can regenerate when have anaemia but generally do not release these into blood in normal animal
- Reticulocytes may not appear even in very severe anaemias in horses
- In cattle, peak production 7-14 days post acute blood loss
Compare the platelet size in dogs and cats
Platelet vs RBC size differs more in dog than cat
Outline some haematological variations within dog breeds
- Macrocytosis in some poodles
- Akitas have unusually small erythrocytes and particularly high potassium content
- Greyhounds have high PCVs (0.55-0.6l/L)
What is red blood cell size measured by?
MCV (fL) = mean corpuscular volume = PCV (L/L) x1000/RBC count (10^12/L)
What conditions are indicated by macrocytosis of RBCs?
- Regenerative anaemia
- FeLV infection
- Myeloproliferative disease
- Normal in poodles
What does hypochromic macrocytosis indicate?
Regenerative anaemia haemorrhage, haemolysis)
What does normochromic macrocytosis indicate?
Non-regenerative anaemia, assocaited with FeLV usubgroup A in kittens and myeloproliferative disorders in dogs and cats
What does hypochromic microcytosis indicate?
- With anaemia: classic iron deficinecy, chronic external blood loss
- Without anaemia: portosystemic shunts
What is the most common cause of iron deficiency in dogs?
Occult loss from GIT
Explain how microcytosis occurs as a result of iron deficiency
- At a certain haemoglobin concentration this triggers the cell to stop dividing
- Where this takes longer to reach due to deficiency,t he cell will continue to get smaller until the correct concentration is reached
What conditions may cause microcytosis?
- Iron deficiency
- Altered iron metabolism
- Dogs/cats with portosystemic shunts
- Normal in Akitas
What is Red Cell distribution Width?
A numeric representation of the variability in RBC size, more sensitive than MCV