General Lab Flashcards
MCV
Mean Corpuscular Volume
Average volume of RBC
Femtolitres
MCV = Hct (%) x 10 / RBC (x10^12). = fL
Normal = 83-100.
MCH
Mean Corpuscular Haemoglobin
= average weight of Hb in RBC
picograms
MCH = Hb (g/L) /RBC
MCHC
Mean Corpuscular Haemoglobin Concentration
= Average concentration of Hb in a given volume of blood
g/L
MCHC = Hb x100 / Hct (%).
Haematocrit
Hct aka PCV (Packed cell volume)
= proportion of blood made up of RBCs
%.
Measured using centrifugation of blood sample in a capillary tube and read using Hct reader.
High MCHC report from automated analyser can indicate…
- Possible cold agglutinins in blood (causes RBCs to clump -> low RBC count of v. dense cells)
-> Remix EDTA tube
-> Warm blood to 37C - Possible auto-antibodies present
-> Direct antiglobulin test - Hereditary Spherocytosis
-> check slide for spherocytes.
Lab investigation of Anaemia assays + sample acceptance criteria.
1st line assay = FBC
- Hb + Red cell indices
Sample acceptance criteria = EDTA + <24hrs old.
2nd line assay = Blood film morphological exam
Sample acceptance criteria = EDTA + <8hrs old.
MCV - Microcytic suggests which anaemia? (4)
- Iron Deficiency Anaemia (IDA)
- Haemoglobinopathies (Thalassaemia)
- Anaemia of chronic disease (RA, Renal failure)
- Sideroblastic Anaemia.
MCV = Normocytic RBCs suggests what? (5)
- Acute bleed
- Bone marrow disorders
- Increased destruction e.g. haemolytic anaemia
- Anaemia of chronic disease
- Early IDA.
MCV = Macrocytic RBCs suggests what? (5)
- Megaloblastic Anaemia
- Liver disease/alcohol injury
- Metabolic disorder
- Bone marrow disorder
- Increased destruction - haemolytic anaemia.
RDW
Red Cell Distribution Width
= measurement of variation in RBC size and shape in a sample
- measures Anisocytosis (variation in size) and Poikilocytosis (variation in shape).
Low MCV + High RDW suggests
Iron Deficiency Anaemia
Low MCV and normal RDW suggests
Haemoglobinopathies specifically Thalassaemia
or
Anaemia of Chronic Disease
% Reticulocyte count procedure
Count # mature RBCs in small square (at least 112 x 9 = 1000)
Count # reticulocytes in big square.
#retic/#mature RBCs x100 = __%.
What age group has high reticulocyte count
Babies (2-5%)
Absolute Reticulocyte count (ARC) formula
(%Reticulocyte /100) x RBC (x10^12)
= ___x10^9 /L
- % Retic is in (x10^9) so change RBC to (x10^9) by x1000!!!
High ARC could be due to (10)
= Bone marrow is increasing erythropoietic activity to recover low mature RBC numbers
1. Thalassaemia
2. Sideroblastic anaemia
3. Blood loss
4. Haemolytic anaemia
5. Pregnancy
8. Medications.
9. Leukaemia
10. Sickle cell anaemia
Low ARC could be due to (10)
= When anaemia is hypoproliferative and erothropoietic activity is low
1. Aplastic anaemia
2. Radiation therapy/chemotherapy
3. Chronic disease
4. Megaloblastic anaemia
5. IDA
6. Vit B12/folate deficiency
7. Bone marrow failure
8. Infection
9. Liver disease
10. Pernicious anaemia
Thalassaemia ARC and RDW
High reticulocyte count
Normal RDW.
IDA retic and RDW
Low retic
High RDW
Anaemia of Chronic disease retic count and RDW
Low reticulocytes
Normal RDW
FBC can reveal conditions incl… (6)
- Anaemia
- Erythocytosis (high)
- Leucocytosis
- Leukopenia (low)
- Thrombocytosis (high)
- Thrombocytopenia (low)
What is Polychromasia ? What does it indicate?
Variation in the colour of RBCs - indicates high presence of immature RBCs in sample.
Due to residual RNA in cells.
What disorders are target cells seen? (4)
IDA
Liver disease
Thalassaemia
Post splenectomy.
Laboratory tests to perform in the diagnosis of anaemia (4)
- Full Blood Count
Including
RBC Count (Hb, Hct)
RBC Indices (MCV, MCH, MCHC, RDW)
WBC count
Platelet count
Cell Morphology - Reticulocyte count
% Retic count, ARC - Iron supply studies
Serum iron, total iron-binding capacity,
serum ferrition - Marrow examination
Aspirate + biopsy.
What is ESR? and purpose?
Erythrocyte sedimentation rate
Non-specific test used to report presence of inflammation.
Used for diagnosis of specific inflammatory disease + monitor disease activity + response to therapy.
What diseases does ERS help diagnose?
temporal arthritis, systemic vasculitis, polymyalgia rheumatica
Infectious mononucleosis characteristics
Presence of lymphocytosis - 10% atypical lymphocytes (large, irregular nuclei) on blood film.
Symptoms = pharyngitis , fever, swollen lymph nodes.
Blood film staining principle
Wright stain (Ronanowsky stain) used.
= polychromatic stain consisting of buffered solutions of methylene blue dye and eosin.
Acidic structures (DNA) take us methylene blue -> blue.
Basic proteins (Hb) take up acid eosin dye -> pink.
WBC differential count method
- Count 100 WBCs in total
- Count number of each different WBC
- Neutrophil
- Lymphocyte
- Monocyte
- Eosinophil
- Basophil
