Haematology Flashcards
What is APTT?
Activated partial thromboplasmin time
What is haemostasis?
Process whereby haemorrhage following vascular injury is arrested
Tightly regulated by vascular endothelium, platelets, coagulation factors and fibrinolysis
What is activated in injury of the vascular wall?
Tissue factor-> coagulation cascade
Collagen exposure and vWF-> platelet activation
Vasoconstriction-> stable plug
How does the endothelium usually act as an anticoagulant?
Prostacyclin, NO, heparin sulphate
What are platelets derived from?
Megakaryocyte shards
What stimulates platelet production?
Thrombopoetin
How long do platelets circulate for before being destroyed?
6-8 days
Describe the extrinsic pathway in the coagulation cascade
Tissue injury-> tissue factor and phospholipids F7->F7a F8-> F10->F10A Prothrombin-> thrombin Fibrinogen-> fibrin
Describe the extrinsic pathway in the coagulation cascade
-ve surface (collagen/plastic) F12-F12A F11-F11A F9->F9A F10-> F10A Prothrombin-> Thrombin Fibrinogen-> Fibrin
What initiates fibrinolysis?
Coagulation cascade
tPA (tissue plasminogen activator)
urokinase-like plasminogen activator
Plasminogen does what?
Turns into plasmin, degrades factor 5&7
Fibrin-> soluble products
What does a blood count and film show?
Number and morphology of platelets
May show leukaemia
When is PT (prothrombin time) extended?
Abnormal factor II, V, VII, X Liver disease Warfarin Vitamin K deficiency DIC
What is DIC?
Disseminated intravascular coagulation
Seen in septicaemia and post partum haemorrhage
When is APTT prolonged?
Deficiency/inhibition of II, V, VII, IX, X, XI, XII
Unfractionated heparin therapy
Vitamin K deficiency
DIC
What is a correction test?
Add normal plasma to patient’s plasma so its 50:50
See if clotting time corrects
If it does it is a deficiency not an inhibitor
What do you look for in a bleeding disorder examination?
Signs of systemic diseases
Skin, mouth, fundi, joints
Easy bruising?
Purpura, bruising, petechiae
What is scurvy?
Vitamin C deficiency
What are Henoch-Schönlein purpura?
Small vessel vasculitis
Purple nodules that do not disappear on pressing
Intradermal bleeding
Seen in young males
+glomerulonephritis, joint pain, abdo pain
What is haemorrhagic telangiectasia?
Small red/purple clusters if dilated capillaries on skin or surface of organs
What is thrombocytopenia?
Low platelet count Failure of production? Increased consumption? Dilutional? Abnormal distribution?
What would cause a failure in the production of platelets?
Selective megakaryocyte depression Dugs/chemicals/viral infections Part of generalised bone marrow failure Leukaemia, lymphoma, cancer Aplastic anaemia HIV
What would cause an increased consumption of platelets?
Immune/autoimmune
Drug induced (heparin)
Infections
DIC
What would cause dilutional thrombocytonpenia?
Massive blood transfusion
What do you treat congenital disorders if platelet function with?
Tranexamic acid, platelet transfusion
Avoid antiplatelet drugs
Give 2 examples of congenital disorders of platelet function
Bernard-Soulier
Glanzmann’s
What would cause an acquired disorder of platelet function?
Antiplatelet agents (aspirin, NSAIDs) Renal failure Gammaglobulins Cardiopulmonary bypass Myeloproliferative disorders
Name 4 congenital coagulation disorders
Haemophilia A, Hameophilia B, vWF disease, Factor XI deficiency
What is tranexamic acid?
Blocks fibrinolysis
Used in haemophila and platelet function disorders
What stimulates red blood cell production?
Decreased O2 supply
Erythropoetin produced by the kidneys
What can iron be stored as?
Ferritin, haemosiderin
Name 4 symptoms of anaemia
SOB
Lethargy
Headache
Angina
Name 2 haemaglobinopathies
Sickle cell
Thalassaemia
What is pancytopenia?
White cell, red cell and platelet deficiency
What can caused pancytopenia?
Bone marrow failure
Bone marrow infiltration (Myelofibrosis, lymphoma, leukaemia, carcinoma)
Peripheral consumption/destruction (septicaemia, splenomegaly, immune mediated destruction)
What is aplastic anaemia?
Anaemia caused by bone marrow failure/stem cell defect/growth factor defect
Bone marrow is ‘empty’
A version of pancytopenia, defined by a bone marrow biopsy
What anticoagulant is used in a FBC bottle?
EDTA (purple bottle)
What is a blood film used for?
Assess red cell size and shape
White cell appearances
Platelet size and morphology
Parasites
What does iron deficiency anaemia look like?
Low Hb
Hypochromic microcytic red cells
Pencil and target cells
Low ferritin
What does haemolytic anaemia look like?
Low Hb
Increased platelets and reticulocytes
increased bilirubin
Serum haptoglobins low/absent
Types of acute leukaemia
Myeloid (AML)
Lymphoblastic (ALL)
Pathogenesis of acute leukaemia
Alteration of leukaemia stem cells
Development arrested at level of blast
Lack of functionally useful and differentiated cells
What can cause leukaemia?
Ionising radiation Viruses Chemicals Congenital factors (eg Down's) Acquired haematological disorders
Which acute leukaemia occurs in younger patients?
ALL
Signs and symptoms of ALL and AML
Bone marrow failure Anaemia (SOB, tired) Neutropenia (sepsis?) Thrombocytopenia (decreased clotting) Infiltration of gums, skin, retina
What is CML?
Chronic myeloid leukaemia
Clonal proliferation of primitive haematopoietic stem cells
Characterised by chromosomal marker ‘philadelphia chromosome’ translocation (9; 22)
Leads to increased tyrosine kinase activity
Signs and symptoms of CML?
Fatigue, malaise Anorexia, abdo discomfort Gouty arthritis Priapism (persistent painful erection of the penis) Splenomegaly Pallor
What is CLL?
Chronic lymphoblastic leukaemia
Clonal proliferation and accumulation of immune incompetent B-lymphocytes
Insidious onset
Infiltration of spleen, lymph nodes, liver
Most patients are over 50yrs old
Why infection common in advanced CLL?
Neutropenia
Hypogammaglobulinaemia
Impaired immunity
CLL can progress into:
Diffuse lymphoma
Prolymphocytic leukaemia
Treatment of CLL?
Supportive blood products
Treatment of infection (antibiotic, antifungals, antivirals)
Specific combination chemo
Marrow cell transplant
