Fundamentals of Medicine: Haematology Beth Harrison Consultant Haematologist University Hospitals Coventry and Warwickshire

What is Haematology about? What is in the blood? What do Haematologists do? What do red cells do? The outside of red cells Why does blood clot?

Plasma: Cellular components: 55% of total blood volume 91% water 7% blood proteins: fibrinogen, coagulation factors, albumin, globulins 2% other: nutrients – amino acids, sugars, lipids hormones – Epo, Insulin electrolytes – Na+ K+ Ca++ etc Cellular components: White cell count=8x109/L Platelet count=270x109/L Red cell count=4.5x1012/L

Haematologists are: Pathologist: Clinician: Investigate anaemia caused by inherited defects of Haemoglobin Diagnose and treat leukaemia and other blood and lymph node cancers Manage patients with bleeding disorders Count cellular components in the blood Monitor blood thinning therapies Care for patients with inherited anaemias Advise on use of blood products Microscopic interpretation of blood and bone marrow smears Measure coagulation using functional tests Investigate and treat anaemia Investigate bone marrow problems; diagnose leukaemia or myeloma from marrow Crossmatch blood for transfusion Advise on use of blood thinning medicines to prevent and treat blood clots Investigate and treat bone marrow failure

What do red cells do?

What do red cells do? Haemoglobin Haem O2 O2 Globin O2 O2 Hb=13.0 g/dL

Counting Red Cells

Counting Red Cells Haematocrit Haemoglobin concentration Red cell count Mean cell volume

How do you know that I am anaemic? Normal range Normal range

The Outside of the Red Cell The sugars expressed on these cell surface proteins determine the Blood Group ABO Blood Groups Being Blood Group A or B describes having one of the enzymes able to change the sugar patterns on the membrane proteins Being Blood Group O describes having neither; Blood Group AB have both

The Outside of the Red Cell All humans naturally form antibodies in childhood against ABO Blood Group Antigens we do not possess. Blood for transfusion must be selected to be suitable by ABO Blood Group

How does blood clot? Haemostasis: normal maintenance of integrity of blood vessels and prevention / limiting of blood loss Thrombosis: blood clot, may be pathological Clots in arteries and veins form by different mechanisms

How does blood clot? Venous Thrombosis RBCs and clotting factors Warfarin Arterial Thrombosis Damaged vessel and platelets Antiplatelet agents: aspirin Mediators of clot formation: Drugs to prevent / treat thrombosis:

Why does blood clot: Virchow’s Triad Vascular injury / trauma Previous deep vein thrombosis Atherosclerosis Indwelling vascular catheter Phlebitis Abnormal heart valve Bed rest, paralysis Venous obstruction Poor cardiac function Perioperative period Old age Obesity Trauma Severe illness Vessel wall injury Abnormal blood flow Thrombosis Increased coagulability Cancer Pregnancy Oral contraceptive pill / other oestrogens Thrombophilia: abnormalities of normal anticoagulant systems Sickle cell disease Smoking Hyperviscosity conditions