Full Blood Count Parameters Flashcards
What does an FBC Analyser count?
~Total number of RBCs, WBCs, & platelets
~RBC: Plasma - haematocrit or packed cell volume
~WBC differential
~Haemoglobin levels - average Hb levels in cells - Mean Cell Haemoglobin & Mean Cell Haemoglobin Concentration
~Average size of RBC - Mean Cell Volume
Elevated RBCs in PCV
Dehydration & Polycythemia(RBCs unable to bend & block capillaries - pain), haemochromatosis
Lowered RBC & Haemoglobin
Anaemia - iron deficiency, blood loss, chronic illnesses, kidney disease (decreased erythropoietin)
Elevated RBC & Haemoglobin
Polycythemia vera, kidney disease, chronic lung disease, physiological changes due to living at high altitude
Decreased RBC in PCV
Anaemia
Decreased WBC
Leucopenia - viral infection, bone marrow disease, exposure to chemo/radiotherapy
Increased WBC
Leucocytosis - bacterial infection, inflammatory disease, bone marrow disease, leukaemia
Decreased platelets
Thrombocytopenia - medications, viral infections, bone marrow disorders, autoimmune disorder, liver disease
Increased platelets
Thrombocytosis - bone marrow disease, inflammatory condition
Packed Cell Volume(PCV)/Haematocrit (HCT) Formula
(MCVxRBC)/10
What is PCV?
The proportion of RBCs as a % to volume of whole blood when anticoagulated blood has been centrifuged at a constant speed
What is Haematocrit?
Volume of red cells found on analyser by multiplying red cell count by MCV
What are the components of a sample of blood that has been centrifuged with an anticoagulant?
Plasma(water, proteins, nutrients, hormones), buffy coat (WBCs & platelets), & haematocrit (RBCs)
Reference ranges for PCV-HCT
~Male: 40-50% (0.40-0.50L/L)
~Female: 36-46% (0.36-0.46L/L)
~Children (2-6): 33-40% (.33-0.40L/L)
~Infants: 45-65% (0.45-0.65L/L)
What causes microcytic hypochromic anaemia?
Iron deficiency
What causes megaloblastic anaemia?
Vitamin B12/Folate deficiency
What causes haemolytic anaemia?
Destruction of RBC - microbial infection, Malaria, red cell membrane defects, enzyme defects. RBC antibodies, sickle cell anaemia
Mean Cell Volume (MCV) formula
PCV/RBC
What is MCV?
Average size of individual RBCs in femtolitres (10^-15L)
What is the reference range for MCV?
Normocytic: 76-96fL
Macrocytic: >96fL
Microcytic:<76fL
Mean Cell Hameoglobin (MCH) Formula
Hb(g/L)/RBC(L)
What is MCH?
Average amount in weight (picograms = 10^-12g)haemoglobin in an individual’s RBC
Reference ranges for MCH
Normochromic: 27-32pg
Hypochromic: <27pg
Hyperchromic: >32pg
What is the relationship between MCV & MCH?
Haemoglobin content of RBCs are determined by the volume of cell -direct link between MCV & MCH
e.g. Hypochromic cells (low MCH) tend to be microcytic (low MCV)
Mean Cell Harmoglobin Concentration (MCHC) Formula
Hb(g/dL)/PCV
What is MCHC?
Average concentration of haemoglobin in an individual’s RBCs in g/dL (can be g/L if Hb is used in g/L)
Reference range for MCHC
Normal: 32-36g/dL
Spherocytosis: >36g/dL
Hypochromia: <32g/dL
What does an elevated MCV mean?
Megaloblastic anaemia - B12/Folate deficiency
What does a low MCH mean?
Microcytic hypochromic anaemia - iron deficiency
What does a decreased MCHC mean?
Microcytic hypochromic anaemia - iron deficiency
What does an elevated MCHC mean?
Hereditary spherocytosis - high number of spherocytes
What is Red Cell Distribution Width (RDW)?
Shows variation of cell volume (degree of anisocytosis) - standard deviation in fL or ad a CV% of RBC volume
What can RDW tell?
Distinguish between iron deficiency anaemia (high RDW) and Beta Thalassemia Trait (normal RDW) - abdnormal production of beta globin chain
