FBC Interpretation

Question 1

What is the appropriate volume of blood for a blood sample?

Answer 1

2.5 ml

Question 2

State the pre-analytical issues of FBC interpretation?

Answer 2

1. Adequate volume of blood?
2. Sample from correct patient and adequately labeled?
3. Sensible clinical details given on request form
4. Timely arrival in laboratory?
5. Book into computer system and allocate unique laboratory number
6. Check for clots
7. Analyse

Question 3

The role of automated analysers?

Answer 3

1. Lyse red cells and incubate with cyanide reagents – estimate haemoglobin concentration by light absorbance at 540nm
2. RBC, WBC (plus differential) and platelet counting by electrical impedence and/or light scatter
   Note: RBC, MCV and RDW are directly measured – all other red cell parameters are derived

Question 4

State the red cell parameters?

Answer 4

1. Haemoglobin:
   - Men 13.5 – 17.5g/dL
   - Women 11.5 – 15.5g/dL
2. Mean cell volume: 80 – 95fl
3. Mean cell haemoglobin: 27 - 34pg
4. Reticulocyte count: 50-100x109/L (0.5-2.5%)

Question 5

State the white cell line normal values?

Answer 5

1. White cell count: 4.0 - 11x109/L
2. Neutrophils: 2.5 – 7.5x109/L (40-80%)
3. Lymphocytes: 1.5 – 3.5x109/L (20-40%)
4. Monocytes: 0.2 – 0.8
5. Eosinophils: 0.04 – 0.44
6. Basophils: 0.01 – 0.1

Question 6

Platelet count normal values?

Answer 6

Platelet count: 150-400x109/L

Question 7

Abnormalities that can be potentially seen in each cell line are?

Answer 7

1. white cell line
   - Leucopenia/leucocytosis/leukaemia
2. red cell line
   - Anemia/ Polycythemia
3. Platelet cell line
   - Thrombocytopenia/thrombocytosis/thrombocythemia

Question 8

Abnormalities can be?

Answer 8

1. Single line
2. Bicytopenia
3. Pancytopenia

Question 9

Anemia classifiation?

Answer 9

1. microcytic
2. normocytic
3. macrocytic

Question 10

Describe microcytic anemia and its causes?

Answer 10

MCV <80 fi
MCH <27pg
causes:
1. iron deficiency
2. thalassemia
3. lead poisoning ‘
4. sideroblastic anemia

Question 11

Describe normocytic anemia and its causes?

Answer 11

MCV 80-95 fl
MCH>26pg
causes
1. many hemolytic anemias
2. anemia of chronic disease
3. anemia of inflammation
4. after acute blood loss
5. renal disease
6. bone marrow failure
7. post chemotherapy

Question 12

Describe macrocytic anemia and its causes?

Answer 12

MCV>95fl
causes
1. megaloblastic
- vitamin B12 or folate deficiency
2. non-megaloblastic
- alcohol
- liver disease
- myelodysplasia
- aplastic anemia

Question 13

What is the corrected reticulocyte count?
What does it mean?

Answer 13

(Retic count x Hb)/ normal Hb for the age
- When the CRC is >2% then the Bone Marrow is producing RBCs at an accelerated phase

Question 14

High reticulocyte count indicates?

Answer 14

1. hemolysis
2. chronic blood loss

Question 15

Normal or low reticulocyte count indicates?

Answer 15

impaired red blood cell formation

Question 16

What is red cell distribution width?

Answer 16

is a measure of the range of variation of red blood cell volume

Question 17

What does red cell distribution width indicate?

Answer 17

Indication of dimorphic red cell population e.g. mixed haematinic deficiency

Question 18

RCDW and microcytic anemia?

Answer 18

iron deficiency is associated with increased RDW whereas thalassaemia isn’t

Question 19

RCDW and macrocytic anemia?

Answer 19

B12 / Folate deficiency is associated with an increased RDW whereas most other causes aren’t

Question 20

What is important to note about white blood cells?

Answer 20

1. important to take note of the differential count and the total count
2. leukemias can cause both leukocytosis or leukopenia

Question 21

Neutrophil increases are commonly associated with which kind of infections?

Answer 21

bacterial

Question 22

Causes of neutrophil increases?

Answer 22

1. inflammation and tissue necrosis
2. metabolic disorders e.g. uremia, eclampsia, gout
3. corticosteroid therapy
4. myeloproliferative disease
5. chronic myeloid leukemia
6. treatment with growth factors e.g. G-CSF
7. fever - cytokine release

Question 23

Neutropenia classification?

Answer 23

1. normal - 1.5
2. mild to moderate - >0.5
3. severe - <0.5

Question 24

Consequences of neutropenia?

Answer 24

high risk of infections of the mouth, throat, anus and skin

Question 25

Common organisms seen in neutropenia?

Answer 25

commensals and gram negative organisms

Question 26

Management of neutropenia?

Answer 26

1. prophylactic antibiotics e.g. ciprofloxacin, augmentin, anti-fungals, anti-viral agents 2. granulocyte colony stimulating factor e.g. neupogen

Question 27

High platelet counts?

Answer 27

1. thrombocytosis - can be reactive e.g. inflammation, bleed 2. thrombocythemia - has no secondary cause - risk of blood clots and strokes

Question 28

Consequences of thrombocytopenia?

Answer 28

1. determines surgical procedures 2. risk of bleeding Note: severe if less than 20,000

Question 29

Clinical features of thrombocytopenia?

Answer 29

1. purpura 2. mucosal hemorrhage 3. prolonged bleeding after trauma

Question 30

Classification of causes of thrombocytopenia?

Answer 30

1. failure of platelets production 2. increased consumption of platelets 3. abnormal distribution of platelets

Question 31

What causes failure of platelet production?

Answer 31

1. drugs, chemicals and viral infections 2. radiotherapy and chemotherapy 3. aplastic anemaia 4. HIV infection 5. marrow infiltration 6. leukemia

Question 32

What causes increased consumption of platelets?

Answer 32

1. autoimmune e.g. idiopathic thrombocytopenic purpura 2. drug induced e.g. heparin 3. DIC 4. thrombotic thrombocytopenic purpura

Question 33

What causes abnormal distribution of platelets?

Answer 33

splenomegaly

Question 34

Indications for platelet transfusion?

Answer 34

1. thrombocytopenia with bleeding or invasive procedures 2. thrombocytopenia below 10

Question 35

Contraindications of transfusion in thrombocytopenia?

Answer 35

autoimmune thrombocytopenia 1. ITP 2. TTP 3. heaprin induced thrombocytopenia 4. hemolytic uremic syndrome