Page 468 - Medicine and Surgery

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464 Chapter 12: Haematology and clinical immunology

Bleeding disorders may result from abnormalities of immature cells. It occurs in severe infections, tuber-

blood vessels platelets and coagulation: culosis or malignant infiltration of the bone marrow.
1 Vascular/platelet disorders are suggested by bruis- Aleucoerythroblastic anaemia occurs when nucleated
ing, purpura and petechiae. redcells and immature white cells are released into the
2 Inherited coagulation disorders are associated with circulation. This may result from marrow infiltration or
haemarthroses(bleedingintothejoints)andmuscle myelofibrosis.
haematomas. Aneutropeniamayoccurinviralinfectionsandsevere
bacterial infections. It occurs with any cause of pancy-
Investigations topenia, in association with rheumatoid arthritis (Felty’s
Full blood count and blood film to examine the num- syndrome). There is a recognised racial neutropaenia in

ber and morphology of platelets. Afro-Carribbeans.
Platelet aggregation times (spontaneous and stim-

ulated) can be used to assess the function of Lymphocytes
platelets. Alymphocytosis is seen in viral infections particularly
A full coagulation screen isperformed comprising a Epstein Barr virus and cytomegalovirus. Chronic in-

prothrombin time (PT), thrombin time (TT) and ac- flammation including tuberculosis and toxoplasma may
tivated partial thromboplastin time (APTT), see page
cause a rise in lymphocytes. Malignant proliferation may
465.
result from leukaemias and lymphomas.
Bleeding time is a measure of platelet function.

Ablood pressure cuff is applied and inflated to
Monocytes
40 mmHg. An incision is made that is 1-cm long and
Monocytes are the blood and bone marrow located pre-
1-mm deep. The time taken for bleeding to stop is
cursors of tissue macrophages (including liver Kupffer
measured. The bleeding time is prolonged in quanti-
cells, pulmonary alveolar macrophages and Langerhan
tative and qualitative platelet disorders.
cellsin the skin) and dendritic antigen presenting cells.
Factor assays can be used to measure the levels of any

They are phagocytic and are involved in antigen process-
components of the coagulation cascade.
ing and presentation.
Amonocytosis may be seen in viral infections such as
Investigations and procedures glandularfeverandinchronicbacterialinfectionssuchas
endocarditis, tuberculosis and myelodysplasia. In cycli-
Full blood count cal neutropenia the monocytes rise as the neutrophil
count falls.
The full blood count is the most commonly performed
investigation in medicine. It measures the five types of
white blood cell (neutrophil, lymphocyte, monocyte, Eosinophils
eosinophil and basophil), the red blood cells and the Eosinophils are phagocytic, with a particular affinity for
platelets. The mean cell volume (MCV), packed cell vol- antigen–antibody complexes and are involved in allergic
ume(PCV),meancellhaemoglobincontent(MCH)and reactions and parasitic infections.
the mean cell haemoglobin concentration (MCHC) are An eosinophilia may arise in parasitic infections, al-
also either measured or calculated. Further details about lergic disorders (hay fever, hypersensitivity), skin disor-
cellular morphology can be obtained by examining the ders (urticaria, eczema), pulmonary disorders (asthma,
blood film. allergic aspergillosis, Churg Strauss syndrome) and in
hypereosinophilic syndrome.
Neutrophils
Aneutrophilia is seen in bacterial infections, tissue Basophils
necrosis, inflammation, myeloproliferative diseases and Basophils are thought to be the circulating equivalent
corticosteroid therapy. A leukaemoid reaction is when of tissue mast cells, the granules contain proteoglycans,
overproduction of white cells leads to the release of heparin, histamine. They have surface IgE receptors and