Red Cell Parameters Flashcards
What are the parts of a haematology report?
What do we look for when assessing RBCs?
Red cell mass (PCV, RBCC, Hgb)
Evidence of effective and appropriate erythropoiesis - size and colour (MCV, MCHC, reticulocyte count)
Red cell size and variation (MCV, RDW - red cell distribution width)
Red cell haemoglobinisation (colour) (MCHC)
Red cell shapes and inclusions (smear)
What are we assessing when analysing the erythron?
Is there inadequate, adequate or excessive red cell mass to deliver oxygen to tissues?
What is polycythaemia?
Too many RBCs
relative - lowered fluid content e.g., dehydration, stress
absolute - increased RBCs
Which tests measure the Red cell mass and oxygen carrying capacity of blood?
PCV
RBCC (red blood cell count)
Hgb
- all equally affected by haemoconcentration
- increase and decrease in line so interpreted as a block
When might PCV be calculated wrong in an analyser?
RBCs miscounted:
-mistaken for platelets
- aggregated into pairs and triplets
MCV misleading:
- cell shrinkage or swelling (transport, tube filling, osmotic effect of machine)
What does a high MCHC suggest?
Haemolysis or lipaemia
How does an analyser calculate PCV?
MCV (mean corpuscular volume) x RBCC
What is the rule of three?
PCV = Hgb x 3 (+/-3%)
Describe normocytic anaemia
red blood cells that are normal in size but abnormally low in number
Describe normochromic anaemia
having a normal amount of hemoglobin in red blood cells
Describe macrocytic anaemia
larger than normal red blood cells
Describe microcytic anaemia
Smaller than normal RBCs
Describe hypochromic anaemia
red blood cells are paler than normal caused by a lack of haemoglobin
What does normocytic normochromic anaemia suggest?
Often anaemia of illness or pre-regenerative or occasionally non-regenerative
What does macrocytic hypochromic anaemia suggest?
Classic highly regenerative
Sometimes could just be cell swelling of transport
What does microcytic hypochromic anaemia suggest?
Classic iron deficiency
chronic external blood loss
How is polycythaemia identified?
Increase in PCV, Hgb concentration and RBC count
How can relative polycythaemia be caused?
What is primary polycythaemia?
rare myeloproliferative disorder
abnormal response of RBC precursors
Normal EPO levels
What is secondary polycythaemia?
Chronic tissue hypoxia of renal tissues (low arterial pO2) due to:
heart/lung diseases, high altitude, thrombosis, constriction of renal vessels
Renal tumor or cysts [↑intra-capsular pressure]
Increased EPO
What are reticulocytes?
Young (immature/non-nucleated) erythrocytes prematurely released to blood from the bone marrow in regenerative anaemias.
how can erythrocytes be visualised?
New methylene blue (NMB) precipitation demonstrates RNA-protein complexes (ribosomal RNA & mitochondria).
Young red cells including reticulocytes have “polychromatophil” appearance on Romanowsky (routine) stain
What are the clinical applications of reticulocyte observation?
Evaluation of erythropoiesis in bone marrow.
Differentiation of regenerative and non-regenerative anaemia.
