Blood & Bleeding Disorders

Question 1

Summarise the haematopoietic origins of RBCs, platelets and neutrophils

Answer 1

Made in bone marrow

Megakaryocyte –> platelet

Question 2

List the main physiological factors which influence rate of red cell production

Answer 2

Hypoxia

Question 3

State the approximate intravascular life span of red cells, neutrophils and platelets

Answer 3

RBCs - 120 days
Neutrophils - 5 days
Platelets - 8-9 days

Question 4

List the common causes of an increased neutrophil, eosinophil or lymphocyte count and of reduced neutrophil

Answer 4

Neutrophilia - infection, tissue damage, acute inflammation, acute haemorrhage
Eosinophilia - allergic diseases (asthma, eczema, urticaria, hay fever, aspergillosis), drug hypersensitivity, parasitic infection, skin disease, myeloproliferative conditions
Lymphocytosis - viral/bacterial infections, stress, splenectomy

Question 5

Describe the common causes of thrombocytopenia and explain the differences between it being caused by marrow failure and peripheral destruction

Answer 5

Decreased production - dehydration, vitamin B12/folate deficiency, leukaemia, aplastic anaemia, liver failure, sepsis, systemic viral/bacterial infection, dengue fever
Increased destruction - ITP, DIC, SLE, hypersplenism, dengue fever
Medication induced - valproic acid, methotrexate, interferon, PPIs

Question 6

Describe the critical steps in the clotting cascade

Answer 6

Intrinsic damage –> 12 –> 11 –> 9 –> 10
Extrinsic trauma –> 7 –> 8 –> 10
Prothrombin -10, 5-> thrombin –> fibrin –> cross linked fibrin clot

Question 7

Explain the tests in a coagulation screen

Answer 7

Platelet count
Bleeding time for platelet function
Prothrombin ratio (extrinsic pathway)
Activated partial thromboplastin time (intrinsic pathway)
Thrombin time

Question 8

Explain the mode of inheritance, basic clinical and laboratory abnormalities of patients with haemophilia and von-Willebrand’s disease

Answer 8

Haemophilia - X-linked recessive, deficiency in factor 8 (A) or 9 (B), lower clotting factor level, spontaneous bleeding, internal bleeding
Von-Willebrand’s disease - autosomal dominant (type 1,2) or autosomal recessive (type 3), abnormality of platelet adhesion, deficiency in factor 8, easy bruising, nosebleeds, bleeding gums, heavy periods, heavy blood loss during childbirth

Question 9

Describe the coagulopathy associated with liver disease, renal disease, massive blood loss, DIC

Answer 9

Liver/renal disease - decreased clotting factor/platelet synthesis
DIC - used up all clotting factors

Question 10

Describe the functions of platelets

Answer 10

Adhesion - to vessel wall at site of injury
Secretion - of ADP, thromboxane, fibrinogen
Aggregation - at site of vascular injury (platelet plug), fuse together
Activation - site for coagulation factor activation

Question 11

Describe the process of fibrinolysis

Answer 11

Natural anti-coagulants - protein C, S, anti-thrombin

Question 12

State briefly the functions of red cells, neutrophils, platelets, monocytes, eosinophils, basophils

Answer 12

RBC - oxygen delivery, CO2 removal
Neutrophils - fight infection
Platelets - stop bleeding
Monocyte - fight infection, respond to inflammation and antigens (–> macrophages)
Eosinophil - mediate hypersensitivity reactions, asthma, skin inflammation, phagocytosis of antigen-antibody complexes
Basophil - active in allergic reactions and inflammatory conditions –> mast cells