Red Blood Cell Parameters

Question 1

What is PVC/haematocrit

Answer 1

Ratio of volume occupied by packed red blood cells to the volume of the whole blood

Question 2

What is MCV

Answer 2

Mean corpuscular volume
The average volume of the red cells

Question 3

What is MCHC

Answer 3

Mean corpuscular haemoglobin concentration
The average concentration of haemoglobin in the cells relative to the size/volume of the cell

Question 4

What parameters are important for red blood cells

Answer 4

Red cell mass- PCV/Hct, RBCC, Hgb
Evidence for effective and appropriate erythropoiesis- size and colout (MCV, MCHC), reticulocyte count
Red cells size and variation (MCV,RDW
Red cell haemoglobinisation (colour)- MCHC
Red cell shapes and inclusions- smear

Question 5

What is RBCC

Answer 5

Red Blood Cell Count

Question 6

What is RDW

Answer 6

Red blood cell distribution width
Measure of variation of size of red blood cells

Question 7

What is the erythron

Answer 7

the circulating erythrocytes in the blood, their precursors, and all the body elements concerned in their production

Question 8

Types of anaemia

Answer 8

Normocytic, normochromic, hypochromic, macrocytic

Question 9

-chromic anaemia

Answer 9

Refers to haemoglobin content

Question 10

-cytic anaemia

Answer 10

refers to cell size

Question 11

What is polycythaemia

Answer 11

Increase in PCV, hgb conc and RBC count
Can be relative (dehydration) or absolute

Question 12

3 factors affected by haemoconcentration

Answer 12

PCV, RBCC and HgB

Question 13

What can cause a misleading MCV

Answer 13

Cell shrinkage or swelling in transport
Tube filling
osmotic effects in machine
Will have an impact on PCV

Question 14

What does high MCHC mean

Answer 14

Misleading- cannot put any more Hb into red cells than they will take
Result of haemolysis (sample handling or intravascular)
Lipemia- interferes with detection system

Question 15

Rule of three error check

Answer 15

look at MCHC

Hct (%) approx. = Hgb (g/dL) x3 (+/- 3%).

Question 16

what is normocytic normochromic anaemia

Answer 16

Often anaemia of illness or pre-regeneration oroccasionally non-regenerative

Question 17

what is macrocytic hypochromic anaemia

Answer 17

Classic highly regenerative
Can be due to swelling on transport

Question 18

What is microcytic hypochromic anaemia

Answer 18

Classic iron deficient- chronic external blood loss
Without anaemia-> portosystemic shunt

Question 19

Cause of absolute polycythaemia

Answer 19

Increased RBC production/release

Question 20

What is polychomasia

Answer 20

high number of immature red blood cells in circulation
as a result of being prematurely released from the bone marrow during blood formation

Question 21

Causes of relative polycythaemia

Answer 21

Dehydration (water or acellular fluid loss)- e.g. vomiting, diarrhoea, polyuria, extensive burns, adipsia, water deprivation
Exercise, fear, excitement, stress
- adrenalin secretion -> splenic contraction and transient redistribution of RBC from spleen to the circulation
Resolved after rehydration or once trigger is removed

Question 22

What is primary polycythaemia

Answer 22

Absolute polycythaemia
Bone marrow tumour
Rare myeloproliferative disorder
Abnormal response of RBC precursors
Normal EPO levels

Question 23

What is secondary polycythemia

Answer 23

absolute polycythaemia
Increased EPO
Chronic tissue hypoxia of renal tissues (low arterial pO2) due to- heart/ling disease, high altitude, thrombosis, constriction of renal vessels
Renal tumour or cysts

Question 24

What are reticulocytes

Answer 24

Young (immature, non-nucleated) erthrocytes prematurely released to blood from the bone marrow in regenerative anaemias
Bigger but contain less haemoglobin than mature rbcs

Question 25

How to visualise reticulocytes

Answer 25

New methylene blue (NMB) recipitation demonstrates RNA-protein complexes (ribosomal RNA & mitochondria)
Can be counted manually or by haematological analysed (automated)

Question 26

When is it clinically important to be able to visualise reticulocytes

Answer 26

To evaluate erythropoiesis in bone marrow
Differentiation of regenerative and non-regenerative anaemia

Question 27

Reticulocytes in dogs

Answer 27

Low number of reticulocytes (<1%)
Expect at least (>60x106/L) in regenerative anaemias

Question 28

Reticulocytes in cats

Answer 28

Low number of reticulocytes (0.2-1.6%)
Cats have two morphological types of reticulocytes:
‘aggregate’ blue stained coarse clumping (0.5% of erythrocytes)
‘punctate’ small, blue stained dots (1-10%).
Kinetics of Aggregate vs Punctate means we only consider Aggregate in assessment of regeneration
Expect at least (>50x109/L) in regenerative anaemia

Question 29

reticulocytes in ruminants and horses

Answer 29

Virtually no reticulocytes in normal blood;
Reticulocytes may not appear even in very severe anaemias in horses;
In cattle peak production 7-14 days post acute blood loss

Question 30

Red blood morphology variations within dog breeds

Answer 30

Macrocytosis in some poodles
Akitas have unusually small erythrocytes & particularly high potassium content
Greyhounds have high PCVs (0.55-0.6 L/L)

Question 31

What is poikilocytosis

Answer 31

Alteration in cell shape
due to:
abnormal erythropoiesis
specific organ dysfunction

Question 32

What is rouleux formation

Answer 32

Clustering, sticky, piling of RBCs
Normal finding in horses
Indicates inflammation in small animals
Related to increased ‘stickiness’ of plasma with increased globulin content

Question 33

What is agglutination on red blood cells

Answer 33

Immune-mediated haemolytic anaemia
Mismatched blood transfusion