FBC Flashcards
What are the 3 cell lines of haematopoiesis?
-Red cells (carry oxygen)
=Produced under the influence of erythropoietin from the kidneys
-Platelets (haemostasis)
=Thrombopoietin from liver
-White cells (immune system)
=Granulocyte Colony Stimulating Factor (GCSF) creates neutrophils. Also immune cells: monocytes, eosinophils and basophils (all myeloid cells) and lymphocytes (lymphoid)
Where does blood come from?
- Bone marrow
- Stem cells (stem cell= blast primitive daughter cell= more mature= mature cell)
What are the names of the red blood cell during haematopoiesis?
- Pronormoblast
- Basophilic normoblasts
- Polychromatophilic normoblast
- Orthochromic normoblast
- —Reticulocyte
- RBC
What happens to a lymphocyte when it leaves the bone marrow?
- T-cells (helper CD4 and cytotoxic CD8) or B-cells in lymphatic system
- Proliferates when target antigen found
- T-cells final effector cells
- B cells return to marrow to be plasma cells to secrete antibody
Where to blood cells die?
-Liver and spleen
=Reticuloendothelial system
-Macrophages destroy
What is FBC and how is it measured?
- Count all cells
- Cells through beam of light
What are the normal values for FBC?
- Haemoglobin= 130-180g/L (females) OR 115-160g/L (males)
- Mean Cell Volume= 78-98 fL
- White cell count= 4-11 x 10*9/L
- Platelets= 150-400 x10*9/L
Plasma vs serum
-Plasma - Blood minus cells, but with clotting proteins present. Centrifuge anticoagulated blood and extract the clear fraction. Used for coagulation tests.
-Serum – Plasma minus clotting proteins. Centrifuge clotted blood and remove clear fraction. Used for most biochemical tests and non-coagulant proteins e.g. albumin
What is a blood group?
RBCs are “grouped” based on the antigens on their cell membrane. The most important systems are ABO and RhD. Group is determined by the presence/absence of the A and B and RhD antigens. You have natural antibodies against A or B antigens that you lack
What is an antibody screen?
If you are exposed to antigens that you lack (e.g. by transfusion or pregnancy) you may develop allo-antibodies against them: this is sensitisation. Screening detects these antibodies: we avoid choosing blood that you would react against. RhD is the most important example
What is group and save?
consists of three steps:
(i)blood grouping
(ii) antibody screening and
(iii) saving appropriate blood for the patient. Saved blood is group compatible and appropriate to the patient’s antibodies. This process is mostly done electronically with automated analysers.
What is cross-matching?
this final test ensures compatibility of the donor blood cells with the recipient’s serum. Donor cells and patient serum are mixed to look for reactions. This excludes most serious in compatibilities
What is a coagulation screen?
screening test which measures the prothrombin time (PT), the activated partial thromboplastin time(aPTT) and, typically, fibrinogen concentration. PT and aPTT are not influenced by platelet count since a platelet substitute is added as a reagent in the test
Describe primary and secondary homeostasis
1ohaemostasis is the interaction between vessel wall and platelets to form the platelet plug. Failure causes mucocutaneous bleeding pattern.
2o haemostasis involves the coagulation “cascade” forming the fibrin mesh. Failure causes soft tissue bleeds e.g. muscle haematoma or haemarthrosis.
Auto vs allo
In immunology, Auto refers to ‘self’ tissue and ‘allo’ to ‘non-self’ tissue e.g. auto/ allo antibodies, auto/allo stem cell transplant etc. Alloimmunity is an immune response to non-self antigens (from the same species) e.g. in the process of sensitisation in transfusion(above). Autoimmunity is an immune response to self antigens e.g in autoimmune haemolysis
Macrocytic vs megaloblastic
Macrocytic refers to RBCs with a high MCV. There are many causes, but one is the presence of megaloblasts – defective red cell precursors in the marrow. This happens in haematinic deficiency, and some other cases of defective DNA synthesis
What is Polycythaemia?
Increased concentration of red cells. Haematocrit (HCT) is raised.*
-Absolute (increased red cell mass)
=Primary – Polycythaemia Rubra Vera (myeloproliferative condition)
=Secondary – Increased EPO – Chronic hypoxia (COPD, altitude), renal tumours
-Relative (reduced plasma volume)*
=Acute dehydration, alcohol
Causes of microcytic hypochromic anaemia
-Iron deficiency
-Thalassaemia
-Lead poisoning
-Some cases of chronic disease
Causes of normocytic normochromic anaemia
-Chronic disease
-Bone marrow failure
-Acute blood loss
-Haemolytic anaemia
-Mixed iron/ B12/ folate deficiency
Causes of macrocytic anaemia
-B12/ folate deficiency
-Reticulocytosis/ haemolysis
-Liver disease
-Pregnancy
-Alcohol
-Myelodysplasia
Causes of iron deficiency anaemia
-Chronic blood loss – menstrual, GI
-Reduced intake – diet, gastrectomy, coeliac disease
-Increased demand – growth in children, pregnancy
Causes of folate deficiency
-Reduced intake – diet, alcohol, malabsorption (coeliac disease, gastrectomy etc)
-Increased requirements – pregnancy
-Drugs – methotrexate, phenytoin
Causes of B12 deficiency
Reduced intake – dietary, malabsorption (pernicious anaemia, gastrectomy, terminal ileal disease
Causes of haemolytic anaemia
-Inherited
=Haemoglobinopathies – Sickle cell disease, thalassaemia
=Membrane defects – Hereditary spherocytosis or elliptocytosis
=Enzyme defects – G6PD
-Acquired
=Immune-mediated – Autoimmune haemolytic anaemia
=Non-immune mediated – Microangiopathic haemolytic anaemia (MAHA) (e.g. DIC, TTP), valve haemolysis, infection (e.g. malaria)
