FBC Interpretation Flashcards
What is the appropriate volume of blood for a blood sample?
2.5 ml
State the pre-analytical issues of FBC interpretation?
- Adequate volume of blood?
- Sample from correct patient and adequately labeled?
- Sensible clinical details given on request form
- Timely arrival in laboratory?
- Book into computer system and allocate unique laboratory number
- Check for clots
- Analyse
The role of automated analysers?
- Lyse red cells and incubate with cyanide reagents – estimate haemoglobin concentration by light absorbance at 540nm
- 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
State the red cell parameters?
- Haemoglobin:
- Men 13.5 – 17.5g/dL
- Women 11.5 – 15.5g/dL - Mean cell volume: 80 – 95fl
- Mean cell haemoglobin: 27 - 34pg
- Reticulocyte count: 50-100x109/L (0.5-2.5%)
State the white cell line normal values?
- White cell count: 4.0 - 11x109/L
- Neutrophils: 2.5 – 7.5x109/L (40-80%)
- Lymphocytes: 1.5 – 3.5x109/L (20-40%)
- Monocytes: 0.2 – 0.8
- Eosinophils: 0.04 – 0.44
- Basophils: 0.01 – 0.1
Platelet count normal values?
Platelet count: 150-400x109/L
Abnormalities that can be potentially seen in each cell line are?
- white cell line
- Leucopenia/leucocytosis/leukaemia - red cell line
- Anemia/ Polycythemia - Platelet cell line
- Thrombocytopenia/thrombocytosis/thrombocythemia
Abnormalities can be?
- Single line
- Bicytopenia
- Pancytopenia
Anemia classifiation?
- microcytic
- normocytic
- macrocytic
Describe microcytic anemia and its causes?
MCV <80 fi
MCH <27pg
causes:
1. iron deficiency
2. thalassemia
3. lead poisoning ‘
4. sideroblastic anemia
Describe normocytic anemia and its causes?
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
Describe macrocytic anemia and its causes?
MCV>95fl
causes
1. megaloblastic
- vitamin B12 or folate deficiency
2. non-megaloblastic
- alcohol
- liver disease
- myelodysplasia
- aplastic anemia
What is the corrected reticulocyte count?
What does it mean?
(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
High reticulocyte count indicates?
- hemolysis
- chronic blood loss
Normal or low reticulocyte count indicates?
impaired red blood cell formation
What is red cell distribution width?
is a measure of the range of variation of red blood cell volume
What does red cell distribution width indicate?
Indication of dimorphic red cell population e.g. mixed haematinic deficiency
RCDW and microcytic anemia?
iron deficiency is associated with increased RDW whereas thalassaemia isn’t
RCDW and macrocytic anemia?
B12 / Folate deficiency is associated with an increased RDW whereas most other causes aren’t
What is important to note about white blood cells?
- important to take note of the differential count and the total count
- leukemias can cause both leukocytosis or leukopenia
Neutrophil increases are commonly associated with which kind of infections?
bacterial
Causes of neutrophil increases?
- inflammation and tissue necrosis
- metabolic disorders e.g. uremia, eclampsia, gout
- corticosteroid therapy
- myeloproliferative disease
- chronic myeloid leukemia
- treatment with growth factors e.g. G-CSF
- fever - cytokine release
Neutropenia classification?
- normal - 1.5
- mild to moderate - >0.5
- severe - <0.5
Consequences of neutropenia?
high risk of infections of the mouth, throat, anus and skin
Common organisms seen in neutropenia?
commensals and gram negative organisms
Management of neutropenia?
- prophylactic antibiotics
e.g. ciprofloxacin, augmentin, anti-fungals, anti-viral agents - granulocyte colony stimulating factor
e.g. neupogen
High platelet counts?
- thrombocytosis
- can be reactive e.g. inflammation, bleed - thrombocythemia
- has no secondary cause
- risk of blood clots and strokes
Consequences of thrombocytopenia?
- determines surgical procedures
- risk of bleeding
Note: severe if less than 20,000
Clinical features of thrombocytopenia?
- purpura
- mucosal hemorrhage
- prolonged bleeding after trauma
Classification of causes of thrombocytopenia?
- failure of platelets production
- increased consumption of platelets
- abnormal distribution of platelets
What causes failure of platelet production?
- drugs, chemicals and viral infections
- radiotherapy and chemotherapy
- aplastic anemaia
- HIV infection
- marrow infiltration
- leukemia
What causes increased consumption of platelets?
- autoimmune e.g. idiopathic thrombocytopenic purpura
- drug induced e.g. heparin
- DIC
- thrombotic thrombocytopenic purpura
What causes abnormal distribution of platelets?
splenomegaly
Indications for platelet transfusion?
- thrombocytopenia with bleeding or invasive procedures
- thrombocytopenia below 10
Contraindications of transfusion in thrombocytopenia?
autoimmune thrombocytopenia
1. ITP
2. TTP
3. heaprin induced thrombocytopenia
4. hemolytic uremic syndrome
