Core Haematology - Introduction (34) Flashcards
Haematology
Biology and pathology of cells that normally circulate in the blood
Haemopoiesis
Physiological developmental process that gives rise to cellular components of blood
Haemopoietic stem cell
Differentiation potential for all lineages, high proliferative potential, self renewal, long term activity
2 Haemopoietic lineages
- Myeloid
2. Lymphoid
Myeloid
Granulocytes (WBC), erythrocytes (RBC), platelets
Lymphoid
B and T cells (WBC)
RBC life span
120 days
Neutrophil life span
6-10 hours
What day of embryology does haemopoiesis start?
Day 27
Where does haemopoiesis start?
Aorta gonad mesonephros region (expands rapidly day 35, then disappear day 40 > foetal liver)
Blood cell function
O2 transport, coagulation, immune response to infection/abnormal cells (senescent, malignant)
RBC
Bi-concave discs, 7.5um diameter, contain Hb
Anaemia
Reduced RBC
Polycythaemia
Raised RBC
Relative polycythaemia
Plasma vol is reduced
Function of WBC/leukocytes
Immunity and host defence
Granulocytes
Cytoplasmic granules - neutrophils, eosinophils, basophils
Neutrophils
Phagocytes, most common, live for few hours
Neutrophilia
Increased neutrophils (bacteria infection/inflammation)
Neutropenia
Decreased neutrophils (drug side effect)
Eosinophilia
Increased number (parasitic infection, allergies)
Basophils
Rare, part of primitive immune system
Basophilia
Increased numbers (chronic myeloid leukaemia)
Monocytes
Phagocytic and antigen presenting cells, migrate to cells then are macrophages/histiocytes (Kuppfer cells in liver, Langherhans cells in skin)
Monocytosis
Increased monocytes (TB)
Natural killers
Innate immune system, large granular lymphocytes , recognise ‘non-self’ (viruses)
B-lymphocytes
Adaptive immune system, rearrange Ig genes > antigen specific antibody production, humoral immunity
T-lymphocytes
Adaptive immune system, rearrange T-cell antigen receptor, cell-mediated immunity, cytotoxicity target-specific, interact with B cells and macrophages, regulate immune responses
Lymphocytosis
Increases numbers of lymphocytes (atypical lymphocytes of glandular fever, CLL)
Lymphopenia
Decreased numbers of lymphocytes (post bone marrow transplant)
Plasmacytosis
Increased plasma cells (infection, myeloma)
Platelets derived from
Bone marrow megakaryocytes
Platelets function
Aggregate to plug holes in damaged blood vessels
4 subdivisions of haematology clinical practice
- Coagulation
- Malignant
- Non-malignant
- Transfusion
Diagnostic tests
FBC, Blood film/smear, coagulation screen
FBC
Hb conc, RBC (MCV, MCHb), WCC, Platelet count
Coagulation screen
Time taken for clot to form when plasma is mixed with specific reagents
Coagulation screen types
- Prothrombin time
- Activated partial thromboplastin time
- Thrombin time
Bone marrow aspirate
Local anaesthetic, liquid marrow from posterior iliac crest and a trephine core biopsy taken with hollow needle
Blood specimen
EDTA anticoagulated blood - mixed well, [K2EDTA] = 1.5-2.2 mg ml-1, filled to line
Reference range
Set of values for a given test that incorporate 95% of normal population
Sensitivity
Abnormal results correctly classified by the test, expresses ability to detect a true abnormality
Sensitivity calculation
True positive/(TP + false neg)
Specificity
Normal results, ability to exclude abnormal results in healthy person
Specificity calculation
True negative/(TN + false pos)
Classification of Microcytic hypochromic anaemia
MCV
Causes of Microcytic hypochromic anaemia
Iron deficiency, thalassaemia, anaemia of chronic disease, lead poisoning, sideroblastic anaemia
Classification of Normocytic normochromic anaemia
MCV 80-95 fl and MCH > 27 pg
Causes of Normocytic normochromic anaemia
Many haemolytic anaemias, anaemia of chronic disease, after acute blood loss, renal disease, mixed deficiencies, bone marrow failure (post-chemo infiltration by carcinoma)
Classification of macrocytic anaemia
MCV >95 fl
Causes of megaloblastic macrocytic anaemia
Vit B12/folate deficiency
Classification of non-megaloblastic anaemia
Alcohol, liver disease, myelodysplasia, aplastic anaemia