Category Archives: Diseases of the blood

The white cell

The five types of leucocytes found in peripheral blood are neutrophils, eosinophils and basophils (which are all called granulocytes) and lymphocytes and monocytes. The development of these cells is shown. NEUTROPHllS The earliest morphologically identifiable precursors of neutrophils in the bone marrow are myeloblasts, which are large cells constituting up to 3.5% of the nucleated cells in the marrow. The nu

Blood, blood components and blood products

Most blood collected from donors is processed into: 1 Blood components, such as red cell and platelet concentrates, fresh frozen plasma (FFP) and cryoprecipitate, are prepared from a single donation of blood by simple separation methods such as centrifugation and transfused without further processing. 2 Blood products, such as coagulation factor concentrates and albumin and immunoglobulin solutions, are prepa

PROCEDURE FOR BLOOD TRANSFUSION

The safety of blood transfusion depends on meticulous attention to detail at each stage leading to and during the transfusion. Prevention of simple errors involving patient and blood sample identification would avoid most serious naemolytic transfusion reactions, almost all of which volve the ABO system. About 50% of fatalities associled with blood transfusion are due to immediate haernovtic transfusion reac

Blood transfusion

The cells and proteins in the blood express antigens which are controlled by polymorphic genes, i.e. a specific antigen may be present in some individuals but not others. A blood transfusion may immunize the recipient against donor antigens that the recipient lacks (alloimmunization); repeated transfusions increase the risk of the occurrence of alloimmunization. Similarly, the transplacental passage of fetal

Splenomegaly

A clinically palpable spleen has many causes including: 1 Infection (a) acute-septicaemia, infective endocarditis, typhoid, infectious mononucleosis (b) chronic- tuberculosis and brucellosis (c) parasitic-malaria, kala-azar and schistosomiasis 2 Inflammation: rheumatoid arthritis, sarcoidosis, SLE 3 Haematological: haemolytic anaemia, haemoglobinopathies and the Ieukaernias, lymphomas and myeloproliferative dis

The spleen

The spleen is the largest lymphoid organ in the body and sitated in the left hypochondrium. There are two anatomical components: 1 The red pulp, consisting of sinuses lined by endothelial macro phages and cords (spaces) 2 The white pulp, which has a structure similar to lymphoid follicles Blood enters via the splenic artery and is delivered to the red and white pulp. During the flow the blood is ‘skimmed

Myelofibrosis (myelosclerosis)

The terms myelosclerosis and myelofibrosis are interchangeable. There is clonal proliferation of stem cells and extramedullary haemopoiesis in the liver and spleen. There is increased fibrosis in the bone marrow caused by hyperplasia of abnormal megakaryocytes which release fibroblast-stimulating factors such as platelet-derived growth factor. In about 25% of cases there is a preceding history of PV. CLINICAL

Polycythaemia

Polycythaemia (or erythrocytosis) is defined as an increase in Hb, PCV and red cell count. PCV is a more reliable indicator of polycythaemia than Hb, which may be disproportionately low in iron deficiency. Polycythaemia can be divided into absolute erythrocytosis where there is a true increase in red cell volume or relative erythrocytosis where the red cell volume is normal but there is a decrease in the pla

Myeloproliferative disorders

In these disorders there is uncontrolled clonal proliferation of one or more of the cell lines in the bone marrow, namely erythroid, myeloid, megakaryocyte lines. Myeloproliferative disorders include polycythaemia vera (Pv), essential thrombocythaemia (ET), myelofibrosis and chronic myeloid leukaemia. These disorders are grouped together as there can be transition from one disease to another, for example PV

DRUG-INDUCED HAEMOLYTIC ANAEMIA

Drugs have been classically thought to cause immune haemolytic anaemia by the following mechanisms: IMMUNE COMPLEX. The formation of drug-antibody immune complexes that become attached to red cells, activating complement and resulting in cell destruction. Example: quinine. MEMBRANE ADSORPTION. An antigenic drug-red cell complex is formed. Production of IgG antibodies results in cell destruction. Example: peni