Commone blood tests- Haematology tests Flashcards
Common blood test- Haematology tests
- FBC- full blood count
- Ferritin
- B12/folate
- ESR (erythrocyte sedimentation rate) and CRP
- INR and APTT
Full blood count
- RBC red blood cell coung
- Packed cell volume (PCV)
- Mean cell volume (MCV)
- Hb
- Mean cell Hb concentration (MCH)
- Reticulocytes
- WBC: neutrophils; eosinophils; basophils; lymphocytes; monocytes
- Platelet count
RBC
- Produced in bone marrow (erythropoiesis)
- Make 200 billion dd
- Erythropoietin (kidneys) is major stimulant
- Lifespan of mature RBC is ~120 days- REMEBER THIS
- Low RBC in anaemia –> decreased O2 supply to tissues (why patients with anaemia are tired)
- High RBC (Polycythaemia) indicated increased production as a physiological response to hypoxia (COPD) or malignancy of RBCs (increase in dehydration too)
- Different RI (reference range) in male and female
Packed cell volume PCV
- Also known as haemautocrat
- Different RI in male and females
- Ratio of volume occupied by red blood cells to the total volume of blood
- Low in any form of anaemia in haemorrhage or in haemolysis
- High in polycythaemia (high Hb in blood) and dehydration
Mean cell volume (MCV)
- Avarage volume of a single red blood celll
- Low MCV- microcytic
- High MCV- macrocytic
- Helps to differentiate between different types of anaemia
- Fe deficinent- microcytic
- B12 or folic acid deficiency- macrocytic
- Raised in liver disease, alcholics and myxoedema (severe hypothyroidism(
Hn adm MCH
-Commoly measured to detect anaemia
-Different RI in men and women
-Mean cell Hb (MCH) is in the average weight of Hb in a red cell- dependant on size of cell
-Low (hypochromic) in microcytic anaemia may be raised in macrocutic anaemia
-Reference range for this changes from g/dL to g/L
+Male need 180 g/L
+Female need 168 g/L
Reticulocytes
- Non-nucleated RBC
- Normal 1% of red blood cells, this can form up to 40% in haemorahage and other events
- Increased production (reticulocytosis) seen at times of rapid red cell production such as haemorrhage or haemolysis
- Useful to monitor early response to treatment of anaemia
Blood flim
- The shape of red cells also useful in diagnosis
- Variation in size (anisocytosis)
- Variations in shape (Poikilocytosis)
- NB in Fe deficiency the cells are pencil shape
Ferritin
- An Fe store protein
- Serum ferritin is closely related to body Fe stores
- Decrease in Fe deficiency anaemia (unless renal failure- lack of erythropoietin so no red cells)
- When treating Fe deficiency anaemia, Hb corrects quite quickly (2-3 wks) but need to ensure stores are replenished too
- Increase in Fe overload, in many patients with liver disease and cancer- ferritin will be high
Fe deficiency anaemia
- Microcytic, hypochromic blood film showing anisocytosis and poikilocytosis
- Decrease in: Hb; MCV: MCHC; Serum Fe; Ferritin
- Clinical symptoms depend on how quickly the anaemia has developed
- Acute: shock, with collapse, dyspnoea and tachycardia
- Commonest chronic symptoms: tiredness and lethargy
- If Hb falls below 70 or 80 g/L, compensatory increase in cardiac output due to poor O2 carrying capacity –> worsening of angina, worsening of HF and exacerbation of intermittent claudication (peripheral vascular disease)
- Chronic- physical signs e.g. nails
Folate and Vit B12
- Decrease folate and B 12 in folate deficienct, Vit B12 anaemia and percinious anaemia (lack of intrinsic factor)
- Due to poor diet and malabsorption
- Decrease in chronic alcoholism and liver disease
- Decrease by some drugs- MTX, trimethoprim- hinder folate metabolism: metformin long term use leads to B12 deficiency
- Known as megaloblastic anaemias- macrocytic cells
Differential white cell count
1)Neutrophils
-50-70% total WCC
-Count increased in infection and tissue damage
-Neutropenia (low count) associated with malignancy and drug toxicity
2)BASOPHILS
-0.4-1% total WCC
-Function unknown
-Tissue= mast cells
3)EOSINOPHILS
-1-3% total WCC
-Associated with Ag/Ab reactions
4)MONOCYTES
-4-6% WCC
-Largest cells in normal blood
-Phagocytes in inflammation and 2nd line infection
5)LYMPHOCYTES
-25-35% total WCC
-Primary component of immune system
-B cells and T cells
NB Can increase with infection (check temp) or inflammation (CRP) but not always the case
Common terms
- Leukopenia- abnormal decrease in number of WBC
- Neutropenia- Abnormal decrease in number of neutrophils
- Agranulocytosis- severe reduction of granulocytes (baso; eosino; neutrophils)
Neutropenia
-Neutrophil ref range is 2.5-7.5x 10 (to the)9/L
-Moderate neutropenia- 0.5-1 x 10(9)/L
-Severe neutropenia- <0.5x10(9)/L
-<1x10(9) a patient becomes immunocomprimised and at risk of serious infection
-Remove cause and protect from infection
-If have temperature >38,5C or 2 consecutive readings of >38 1-2 hours apart then start antibiotics
-If severe, give G-CSF (granulocyte growth stimulating factor) to stimulate the bone marrow
-If giving chemo that typically causes severe neutropenia may give antibiotic and G-CSF
prophylactically
-Must have excellent hygiene- particularity the mouth
-WCC will not be raised
Platelets
- Main function to foirm a pliug at sites of damage to vascular endothelium
- In circulation for 8-12 days
- May fall a little in pregnancy and following viral infections
- large decrease due to bone marrow failure (decrease production) or increase destruction (autoimmune)
- Thrombocytopenia *decrease in platelets) –< bleeding
- Increase in malignancy of bone marrow, inflammatory disease and in response to blood lossm, severe infectious illness
