Full blood count

Question 1

abnormal results

Answer 1

• Outside the normal range

Question 2

normal range only includes

Answer 2

• 95% of healthy population
  
  • 2.5% normal values above the range
  • 2.5% normal values below the range

Question 3

results just outside the range may be

Answer 3

normal for that person

Question 4

Significant fall in value

Answer 4

e.g. 160g/L to 115g/l (both in normal ranges- but still worrying)

Question 5

nromal rnage changes with

Answer 5

• Age
• Sex
• Ethnicity
• Co-morbidities

Question 6

If you receive an a result you are not expecting….

Answer 6

repeat test and consider contacting haematologist

Question 7

interpret abnormal haematology results in light of

Answer 7

clnical context and previous FBC

e.g. to spot acute/chronic change

Question 8

sources of error

Answer 8

1. speciment collection error
2. delivery of speicimens to laboratory
3. specimen analysis and result reporting
4. responsive action

Question 9

1) Specimen collection error

Answer 9

• Specimen mixed up
• Wrong blood in tube
• Wrong bottle
• Pooling samples
  
  • Adding blood from another tube to fill one up to the line
• Poor technique- may activate (haemolytic) sample

Question 10

2) Delivery of specimens to laboratory

Answer 10

• Specimen delayed/not delivered
• Wrong delivery method
  
  • Some need to be sent in the dark, on ice, body temp

Question 11

3) Specimen analysis and result reporting

Answer 11

• Specimen mix up
• Incorrect clinical details
• Wrong test requested/performed
• Inherent test variability
• Technical error

Question 12

4) Responsive action

Answer 12

• Results not reviewed
• Reflex tests not carried out
• Right result applied to wrong patient

Question 13

how is the full blood count carried out

Answer 13

Measured using an automated test with a very high level of accuracy that uses an analysing machine that can process thousands of samples every day.

Question 14

essential parameters of the FBC

Answer 14

• Red blood cells
  
  • Indices
  • RCC
  • haemoglobin
• Platelet count
• White blood cells
  
  • Count
  • Full differential

Question 15

FBC ANALYSER TECHNIQUE

Answer 15

uses Flow cytometry

• hydrodynamic focusing
  
  • single file line of cells
  • pass through light beam
  • impedance counting

Question 16

forward scatter=

Answer 16

size

the more scatter= the bigger the cell

Question 17

Spectrophotometry

*

Answer 17

• Amount of light absorbed by the sample proportional to amount of absorbent compound within it e.g. haemoglobin
  
  • Hypotonic solution to lyse cells
  • Use light of appropriate wavelengths
  • Use calibration curve to determine sample conc

Question 18

Flow cytometry differential

Answer 18

• Forward scatter= size
• Side scatter
  
  • Mono/polymorphonuclear
    
    • A type of immune cell that has granules (small particles ) with enzymes that are released during infections, allergic reactions, and asthma
  • Intracellular complexity
    
    • Granules
  • Myeloperoxidase activity

Question 19

what are WBC

Answer 19

also known as leukocytes, WBC are cells of the immune system that are responsible for protecting the body againsdt infections or foreign bodies

Question 20

how are WBCs counted

Answer 20

RBC in a sample of blood are lysed and the majority of remaining cells are WBC.

These are counted automatically as they interrupt a beam of light/ elecrcial current whilst going through a narrow tube in a straight line

Question 21

what causes an increase in WBC

Answer 21

infection, smoking, leucocytosis, immune system disorders

Question 22

what causes a decrease in WBC

Answer 22

damaged bone marrow, antibiotics, chemothrrapy drugs

Question 23

Red blood cells contain

Answer 23

haemoglobin, which gives blood its red colour. The primary role is to transport oxygen and carbon dioxide to and from tissue

Question 24

how are RBCs measured

Answer 24

measured in the same way as WBC Clight beam) but withou the lysis step.

In comparision to BRC there are very few WBC so it does not affect the RBC count signif

Question 25

what causes an increase in RBC

Answer 25

congenital causes, hypoxia, polycythaemia vera

Question 26

what causes an decrease in RBC

Answer 26

anaemia, internal/external bleeding, erythropoietin deficiency

Question 27

what is haematocrit (HCT)

Answer 27

fraction of the whole blood volume that consists of RBC

Question 28

how is haemocrit counted

Answer 28

multiply the mean cell volume by the number of RBC per litre

Question 29

what causes abnormal haemocrit

Answer 29

similar reasons to high/low RBC values

Question 30

what is haemoglobin concnetreation

Answer 30

the amount of haemoglobin the blood (g/L)

Question 31

how is haemoglobin conc measured

Answer 31

after red cells have been lysed froma. blood sample, the Hb is converted to a stable form and measured by a colorimeter

Question 32

what causes an abnormal increase in Hb

Answer 32

living at high altitudes, lung dysfunction (smoking, COPD)

Question 33

what causes an abnormal decrease in Hb

Answer 33

lack of dietary iron, vitamin B2 or folate ,bleeding , anaemia

Question 34

what is mean cell volume (MCV)

Answer 34

the average volume of red cells

Question 35

How is MCV counted

Answer 35

use a beam of light or an electric current, and assess the amount of either that is blocke dby the red cells

Question 36

what causes an abnormal MCV

Answer 36

macrocytic anaemia \>100 fl microcytic anaemia \<80 fl

Question 37

mean cell haemoglobin (MCH)

Answer 37

a erage amount of hb in an individual RBC

Question 38

how is mean cell haemoglobin (MCH) counted

Answer 38

divide Hb conc by the number of red cells in a given volume of blood

Question 39

what causes an abnormal increase in mean cell haemoglobin (MCH)

Answer 39

macrocytic anaemia, insufficient vitamin B12 or folate

Question 40

what causes an abnormal decrease in mean cell haemoglobin (MCH)

Answer 40

microcytic anaemia, low iron levels

Question 41

platelets

Answer 41

a fragment of a megakaryocyte invovled in clottign

Question 42

how are platelets counted

Answer 42

measured the same way as red or white cells. Platelets produce a much smaller signal (due to their smaller size) so can be easily distinguished

Question 43

what causes an increase in platelets

Answer 43

thrombocytosis, bone marrow disorders

Question 44

what causes an decrease in platelets

Answer 44

increased platelt destruction (ITP)

Question 45

reticulocytes

Answer 45

immature red blood celsl

Question 46

how are reticulocytes counted

Answer 46

stains and dyes are used which bind to rRNA (not present in mature cells)

Question 47

what causes an abnormal increase in reticulocytes

Answer 47

high altitudes, hameolytic anaemia, bleeding

Question 48

what causes a decrease in reticulocytess

Answer 48

aplastic anaemia and bone marrow failure

Question 49

what are differential white blood cells

Answer 49

analyses te numebr of didfferent white cells in a blood sample * neutrophils * lymphocytes * monocytes * eosinophils * basophils

Question 50

how are differential white blood cells counted

Answer 50

can use automated blood anaylser- if abnormalities are detected then they will need to be counted manually on a **blood film**

Question 51

what causes abnormal differential white blood cells

Answer 51

infection allergic reactions

Question 52

packed cell volume (PCV)

Answer 52

* Proportion of blood that is made up of RBC * Centrifuged blood allows visualisation

Question 53

what can overestimate Hb results

Answer 53

* Turbidity (is the cloudiness or haziness of a fluid) of plasma can overestimate Hb measurement

Question 54

what can underestimate Hb results

Answer 54

in vitro haemolysis

Question 55

**Red cell distribution width (RDW)**

Answer 55

* Variation in size of the RBC * If increased= **anisocytosis** (patient's red blood cells are of unequal size. This is commonly found in anemia and other blood conditions.)

Question 56

Red cell distribution width (RDW) can be used to assess

Answer 56

anaemia * Increased in iron deficiency * First parameter to rise as iron stores fall * Usually normal in thalassaemia trait * Increased following **transfusion**