Red Blood Cell Parameters Flashcards
What is PVC/haematocrit
Ratio of volume occupied by packed red blood cells to the volume of the whole blood
What is MCV
Mean corpuscular volume
The average volume of the red cells
What is MCHC
Mean corpuscular haemoglobin concentration
The average concentration of haemoglobin in the cells relative to the size/volume of the cell
What parameters are important for red blood cells
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
What is RBCC
Red Blood Cell Count
What is RDW
Red blood cell distribution width
Measure of variation of size of red blood cells
What is the erythron
the circulating erythrocytes in the blood, their precursors, and all the body elements concerned in their production
Types of anaemia
Normocytic, normochromic, hypochromic, macrocytic
-chromic anaemia
Refers to haemoglobin content
-cytic anaemia
refers to cell size
What is polycythaemia
Increase in PCV, hgb conc and RBC count
Can be relative (dehydration) or absolute
3 factors affected by haemoconcentration
PCV, RBCC and HgB
What can cause a misleading MCV
Cell shrinkage or swelling in transport
Tube filling
osmotic effects in machine
Will have an impact on PCV
What does high MCHC mean
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
Rule of three error check
look at MCHC
Hct (%) approx. = Hgb (g/dL) x3 (+/- 3%).
what is normocytic normochromic anaemia
Often anaemia of illness or pre-regeneration oroccasionally non-regenerative
what is macrocytic hypochromic anaemia
Classic highly regenerative
Can be due to swelling on transport
What is microcytic hypochromic anaemia
Classic iron deficient- chronic external blood loss
Without anaemia-> portosystemic shunt
Cause of absolute polycythaemia
Increased RBC production/release
What is polychomasia
high number of immature red blood cells in circulation
as a result of being prematurely released from the bone marrow during blood formation
Causes of relative polycythaemia
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
What is primary polycythaemia
Absolute polycythaemia
Bone marrow tumour
Rare myeloproliferative disorder
Abnormal response of RBC precursors
Normal EPO levels
What is secondary polycythemia
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
What are reticulocytes
Young (immature, non-nucleated) erthrocytes prematurely released to blood from the bone marrow in regenerative anaemias
Bigger but contain less haemoglobin than mature rbcs
How to visualise reticulocytes
New methylene blue (NMB) recipitation demonstrates RNA-protein complexes (ribosomal RNA & mitochondria)
Can be counted manually or by haematological analysed (automated)
When is it clinically important to be able to visualise reticulocytes
To evaluate erythropoiesis in bone marrow
Differentiation of regenerative and non-regenerative anaemia
Reticulocytes in dogs
Low number of reticulocytes (<1%)
Expect at least (>60x106/L) in regenerative anaemias
Reticulocytes in cats
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
reticulocytes in ruminants and horses
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
Red blood morphology variations within dog breeds
Macrocytosis in some poodles
Akitas have unusually small erythrocytes & particularly high potassium content
Greyhounds have high PCVs (0.55-0.6 L/L)
What is poikilocytosis
Alteration in cell shape
due to:
abnormal erythropoiesis
specific organ dysfunction
What is rouleux formation
Clustering, sticky, piling of RBCs
Normal finding in horses
Indicates inflammation in small animals
Related to increased ‘stickiness’ of plasma with increased globulin content
What is agglutination on red blood cells
Immune-mediated haemolytic anaemia
Mismatched blood transfusion
