Haematology Flashcards
define haematocrit or PCV
percentage of which the cells make up the total volume
40-52%
define mean cell haemoglobin
the amount of haemoglobin in an individual cell
Hb/RCC
define mean cell volume
the size of the cell
PCV/RCC
define mean cell haemoglobin concentration
the concentration of the haemoglobin in the cell
Hb/PCV
define reticulocyte count
a measure of the immature red cells
whether there are young red cells being made and active or increased red cell turnover
what are the findings in microcytic anaemia?
reduced Hb, Hct, RCC, MCH, MCHC
MCV reduced below the normal range
anaemia with small, poorly haemoglobinised red cells
blood film - small, abnormal shape, paler (less Hb), bigger area of central clearing
what is the different between latent iron deficiency and iron deficiency anaemia?
latent iron deficiency - iron stores are cleared, but cells are ok
continued iron deficiency - hypo chromic, microcytic red cells, reduction in MCV, MCH and MCHC
what are the findings in macrocytic anaemia?
reduced Hb, Hct, RCC
normal MCH and MCHC (looking at the amount of Hb in the individual cell)
MCV increased
blood film - less red cells, larger, extra lobes in the white cells (problem with cell division)
what are the causes and treatment of macrocytic anaemia?
vitamin B12 or folic acid deficiency
replacement of deficiency
do not require a blood transfusion unless severely symptomatic
describe neutrophils
2-5 lobed nucleus
Barr body - protrusion from one of the lobes and present in XX
dense nucleus
granules present from promyelocyte stage right through to the mature nucleus
contain myeloperoxidase, phosphatase, acid hydrolases
secondary granules develop from the myelocyte stage and contain collagenase, lactoferrin, lysosome
very fast turner
lifespan of 10 hours
what are the functions of neutrophils?
fighting infection
chemotaxis
phagocytosis
killing of phagocytosed bacteria
describe eosinophils
bilobed nucleus bright pink granules pale blue cytoplasm larger than neutrophils remain longer in the circulation than neutrophils
what are the functions of eosinophils?
fight infection
enter inflammatory exudates
play a role in immediate type hypersensitivity reactions and antibody-dependent parasite damage
high count in allergic reactions or parasites
describe basophils
dark granules
often overlay and obscure the nucleus
larger than neutrophils
move from the circulation into the tissues; mast cells
what are the functions of basophils?
immediate type hypersensitivity reactions
IgE attachment sites
degranulation and histamine release in allergic responses
describe monocytes
large cells bilobed nucleus pale blue cytoplasm granules in the nucleus largest white cells
what are the functions of monocytes?
killing of microorganisms
release of cytokines
rare cells in the circulation; not often seen on routine blood films
describe lymphocytes
similar size as RBC
very little cytoplasm
activated with various infections; on activation can contain large amounts of cytoplasm, sometimes with granules
describe T lymphocytes
originate in the thymus
usually parafollicular in the nodes and periarteriolar in the spleen
make up 80% of the lymphocytes in the blood
have membrane receptors for the T-cell receptor antigen
function - T helper cells, part of antibody production
describe B lymphocytes
originate in the bone marrow
have membrane receptors for immunoglobulin
function - humoral immunty
describe immunoglobulins
produced by plasma cells and B lymphocytes
part of the defence against foreign organisms
what is the treatment of infectious mononucleosis (glandular fever)?
symptomatic
occasionally require corticosteroids
must not get any ampicillin; may gets rashes with this
recovery will be quite slow
describe platelets
cellular fragments involved in clotting and bleeding
produced in the bone marrow from the megakaryocyte (contained in the cytoplasm)
what is the cause of low large platelets?
immune thrombocytopenic purpura
some reason that they are producing an antibody that is destroying their platelets
describe the pathophysiology and treatment of immune thrombocytopenic purpura
platelet turnover increased
large immature platelets released into the circulation
steroids
immunoglobulins
anti-D
splenectomy (Howell-Jolly bodies)
do not benefit greatly from platelet transfusion
not useful unless they have life-threatening bleeding
what is the cause of increased platelets?
essential thrombocythaemia
infection
reactive cause
what is the treatment of essential thrombocythaemia?
aspirin whenever the platelet count >1000
decreased the tendency to thromboembolic phenomenon
may need cytoreduction
describe platelet activation
glycoprotein IIb sticks to the injured vessel wall
this slows the platelet down to go through secondary activation; glycoprotein IIb/IIIa is upregulated/further expressed
this causes more platelets to stick together
releases 5-HT, ADP, thromboxane, fibrinogen
what are the uses of glycoprotein IIb/IIIa inhibitors?
angiography of acute MI
what drugs inhibit the substances released by platelets (causing bruising)?
SSRIs
aspirin
NSAIDs
what is the trigger for the clotting cascade?
tissue factor exposure at the vessel wall site which will activate clotting factor VII
triggers prothrombin cleavage to thrombin
what is the result of the clotting cascade?
fibrin activation with factor XIII
makes a firm clot
which factor is not essential in the clotting cascade?
factor XII
what does warfarin suppress?
protein C and S (vitamin K-dependent anticoagulants)
factor II, VII, IX, X
what is the role of antithrombin?
switches off the activation of factor XI, X, XI§
what does a normal coagulation screen indicate?
normal patient
von Willebrand’s disease (AD)
factor XIII deficiency
platelet disorders
what are the signs of bleeding disorders?
mucocutaneous (epistaxis >30mins) unexplained menorrhagia >80ml per cycle post-dental extraction post-childbirth petechiae, purpura, soft tissue haematoma loss of function
what are the causes of a deranged coagulation screen?
paracetamol overdose
liver disease
stress (shortened APTT, high factor VIII level)
tourniquet placed on the arm for a long time
traumatic venepuncture
taken from an in-dwelling line (often locked with heparin)
transport delay
heating of the bottle
high Hct (citrate acts as a diluting for clotting factors)
what are the causes of prolonged PT?
extrinsic pathway; primary factor VII problem early warfarinisation congenital factor VII deficiency early sepsis early vitamin K deficiency
what are the causes of a prolonged PT and APTT?
common pathway;
vitamin K deficiency (factor II, VII, IX, X)
oral warfarin therapy
oral dabigatran therapy
DIC; septicaemia, meningitis, malignancy (directly activate factor X)
what are the causes of prolonged APTT?
intrinsic pathway; DIC liver disease massive transfusion unfractionated heparin therapy monitoring heparin contamination in line locks oral warfarin therapy lupus anticoagulant (antiphospholipid syndrome) factor VII, IX, XI, XII deficiency
describe an APTT correction study
undertaken whenever the APTT is abnormal
if it corrects when normal plasma is added; clotting factor deficiency (ES liver disease)
if it does not correct; lupus anticoagulant present
describe D-dimer
breakdown product of clot
present in any form of inflammation
positive in >3/4s of those >60 with good health
positive; suspected case of DIC
used to see if thrombolytic therapy is working
how is D-dimer used in suspected venous thromboembolism?
negative predictive value
used with the wells score
what is the cause of bleeding with normal PT, APTT, fibrinogen?
von willebrand’s disease
factor VIII deficiency
platelet dysfunction
what is the cause of bleeding with prolonged PT only?
early warfarin deficiency
factor VI deficiency
what is the cause of bleeding with prolonged APTT only?
factor VIII, IX, XI XII deficiency
lupus anticoagulant
unfractionated heparin present (clinically or due to line contamination)
what is the cause of bleeding with PT and APTT prolonged?
oral warfarin therapy
vitamin K deficiency
oral direct thrombin inhibitor dabigatran
what is the cause of bleeding with PT and APTT prolonged and fibrinogen reduced?
hyperfibrinolysis
severe end stage liver disease
DIC
what is the problem with testing levels of protein C, S and antithrombin at the time the clot is diagnosed?
they are frequently reduced as it is the body’s response that these anticoagulants will be dissolving the clot
what are the causes of a reduced antithrombin level?
low molecular weight heparin
unfractionated heparin