XLA/blood stuff Flashcards
Signs and symptoms of anaemia
Palor, fatigue, nausea, hypo-tension when standing up, dizziness, palpitations, glottitis, angular stomatitis, heart murmurs,
Tests to determine what type of anemia
MCV, FBC, APTT, PT, Hb, WBC
Microcytic anaemia and how to treat
Due to less iron (malabsorption, diet, extra demand, blood loss) or thalassaemia (hereditary). Treat with ferrous sulphate. Iron only affects the blood cells
Macrocyctic anaemia causes and symptoms.
B12 or B9 deficiency - diet or malabsorption e.g. lack of intrinsic factor for absorbtion of B12 at terminal ilium. Affects WBC, platelets, nerves.
Treatment for macrocytic anaemia
Treat with B12 injections or parenteral hydroxocobalamin and oral folate.
Pernicious anaemia
Autoimmune disorder where body produces Ig that attack the intrinsic factor so not enough B12 absorbed. Treat by giving B12 injections.
Haemolytic anaemia
Hereditary e.g. sickle cell where RBC/Hb defect or abnormal metabolism or acquired e.g. immune problem or infection.
Normal haemostasis
Vasoconstriction, platelet adhesion and aggregation and fibrin formation via coagulation cascade forming a plug/clot and then repair.
Thrombocytopenia definition
reduced platelet count
Thrombocytosis definition
Increased platelet count
Haemostatic problems
Primary = involves platelets and VWF and vessel walls and leads to excessive bleeding and bruising.
Secondary involves coagulation cascade and shows as bleeding in joints but no bruising.
Types of inherited bleeding disorders
Haemophilia A and B, VWF disorder, Ehlers-Danos syndrome.
Haemophilia A and B
A = factor 8, B = factor 9 deficiency. Sex X-linked inherited. Secondary homeostatic problem e.g. bleeding in joints but normal bruising.
Causes a prolonged APTT
Treatment of haemophilia A or B
Give missing factor or DDAVP if mild haemophilia A.
VWF disease
Reduced clotting factor and platelet problems = excessive bleeding and bruising. Also protects against factor 8 break down normally so give DDAVP bc less VWF = less factor 8. Prolongs APTT
Types of thrombosis
Blood coagulation in vessels. Arterial or venous.
Arterial thrombosis
High pressure system, lots of platelets so treat with anti-platelet drugs. No inherited risk factors but acquired risk factors e.g. diet, smoking, obesity.
Venous thrombosis
Low pressure, lots of fibrin so treat with anti-coagulants. Inherited and acquired risk factors e.g. cancer, obesity, age.
Causes of thrombocytopenia
acquired
. Enlarged spleen storing more of the platelets.
. Increased breakdown of platelets e.g. ITP or DIC.
. Failure of platelet production e.g. if have leukemia or B12/9 deficiency.
ITP
acquired
Inherited thrombocytopenia. Autoimmune condition that destroys platelets. Treat using immunoglobulins or remove spleen or steroids.
DIC
acquired
Dissemination Intravascular coagulation. Break down of haemostatic balance, thrombosis and bleeding at the same time.
Acquired anti-platelet function abnormalities
Due to anti-platelet drugs, kidney or liver failure.
How does vitamin K deficiency affect bleeding
Less clotting factors so prolonged prothrombin time.
Drugs that can cause bleeding disorders
Anti-platelets
Anticoagulants
Steroids
Drugs that affect liver, kidneys and bone marrow.
Effects of heparin and how to monitor
Inhibits coagulation cascade. Increases anti-thrombin activity so indirect thrombin inhibitor. Monitor with APTT.
Effects of Warfirin and how to monitor
Inhibits vitamin K dependent clotting factors by blocking vitamin K epoxin reductase which is needed to activate vitamin K. Monitor with PT/INR.
Direct oral anticoagulants and pro/cons
Inhibit factor 2a and 10a.
Limited interaction with other drugs and substances, don’t need monitoring, faster action, fixed dose.
But no specific antidotes and removed by kidneys.
How to measure coagulation after you’ve drawn blood
Add citrate to chelate the Ca2+ and clotting factor and stop clotting. In lab, add Ca2+ and factor needed to initiate intrinsic or extrinsic pathway and measure time.
Intrinsic pathway activated by and measured by ..?
Phospholipids released from cell membranes after trauma and factor 9 activate it. Measured by APTT.
Extrinsic pathway measured by and activated by ..?
Activated by tissue factor and measured using PT (prothrombin time)
Clotting factors involved in intrinsic pathway
8, 9, 10, 2
Clotting factors involved in extrinsic pathway
7, 9, 10, 2
INR
International normalised ration is patient’s PT compared to average PT. But 2 doesn’t mean 2x as slow because these are specific lab conditions and don’t take into account intrinsic pathway or platelets.
Final common pathway
After intrinsic/extrinsic pathway and converts fibrinogen -> fibrin.
Acquired bleeding disorders
Due to drugs, cancer, liver or kidney failure,
How do liver problems affect bleeding
Liver makes all the vitamin k dependent coagulation factors and some other coagulation factors so without them coagulation cascade won’t happen = bleeding problems and prolonged PT time.
How are the kidneys involved in bleeding
They regulate platelet function and calcium homeostasis so disease = more bleeding and coagulation problems.
How does cancer affect bleeding
Can lead to myelosuppression so bone marrow is suppressed and less platelets made.
Examples of blood thinners
Warfarin, heparin, aspirin, clopidogrel, NOACs.
How do NOACs act
Inhibit factors 2 or 10 which are involved in the final common pathway for coagulation cascade.
How does Asparin act
Binds to COX on platelets and stops them functioning. Lasts the life-cycle of the platelet. Blocking COX = blocks production of thromboxane A2 from platelets, needed for platelet aggregation.
What is arachidonic acid metabolized into
- Leukotrienes to attract WBC.
- Prostoglandins cause pain and regulate gastric acidity.
- Thromboxane A2, released from platelets and causes platelet aggregation. Needs COX.
How does Warfarin act
Blocks vitamin K epoxide reductase so Vit K epoxide not converted back to Vit K so not enough Vit K to make the active forms to activate the Vit K dependent coagulation factors.
How does Heparin act
Activates antithrombin 3 which blocks factors 2 and 10 needed in final common pathway to make fibrin.
How does clopidogrel act
Inhibits the P2Y12 receptor on platelets needed for platelet aggregation and forming fibrin meshwork.
How can the effects of warfarin be reversed
Give an excess of vitamin K
How can the effects of heparin be reversed
Give protamine sulphate (salmon semen)
How to manage patients on blood thinners.
Check INR for warfarin (<4 is okay), or give factors 8/9/DDAVP or stop using medication on day of surgery for the others.
Types of bleeding after surgery/XLA
Primary at the time.
Reactionary is up till 48h after due to clot falling out etc.
Secondary is a week later bc of infection.
Ways to stop bleeding after XLA
Check haemostasis before sending patient off. Compress site by biting on gauze or applying pressure. Compress socket. Use haemostatic packs to absorb the blood. Pack using sponges and suture stops pack falling out and compresses blood vessels.
What to use for ongoing bleeding after XLA
tranexamic acid or reverse the anticoagulant e.g. vitamin K or protamine sulphate.
What information needs to be included on a prescription
Name, age, address, DoB, name of medication, amount, frequency, form, route, duration. Signature of dentist and stamp of practice and date.
What is the haematocrit
Solid constituents of the blood. Should make up less than half for good viscosity.
Haematopoiesis
Blood cells made in the bone marrow. Stem cells can differentiate into themselves or into mature cells. Controlled by hormones.
RBC function and structure
Convert glucose to pyruvate and send it to the liver. Hb binds to O2 and transports it around the body. Biconcave circular disc shape makes them flexible so they can move through narrow capillaries.
Polycythaemia
Making too many RBC. Means that the blood is more viscous so harder to pump around the body so can increase the risk of heart attack and stroke. Can be useful e.g. if have bad lungs than extra RBC made to increase 02 carrying capacity.
Plasma proteins
Albumin to keep fluid in the vessels.
Carrier proteins for hormones, nutrients.
Ig and platelets - inactive form normally.
What antigens need to be matched up before a blood transfusion?
ABO and Rhesus D+/-
ABO antigen
ABO sugars on RBCs need the genes for them. The body makes Ab for the other blood types after exposure to food and bacteria e.g. don’t need to be infected. Blood groups don’t go through the placenta so baby is safe.
Rhesus antigen
D + or -
Blood group passes through the placenta so mothers are given anti D to stop their body’s Ab attacking the baby.
What can a myeloblast differentiate into
Basophils, eosinophils, neutrophils, macrophages.
Neutrophil functions
Cytotoxins cause inflammation and symptoms. Phagocytosis.
Lymphocyte functions
B-cells make plasma cells and Ig.
T-cells can be helper cells to make the Ig or cytotoxic cells to stop cellular invasion.