Haematology Flashcards
What are the functions of blood?
- transport: oxygen, nutrients, hormones, waste
- immune system support - WBCs
- coagulation
What is the blood made up from?
List some components of each:
Where are cells mainly produced?
Composed of plasma and cells
Plasma: proteins, lipids, nutrients, hormones, electrolytes, water
- red blood cells: oxygen and CO2 transport via haemoglobin
- white blood cells - immune system
- platelets - clotting
Cells are mainly produced in bone marrow
A full blood count (FBC) tests the following aspects of blood. What do they mean?
- WBC
- RBC
- Hb
- Hct
- MCV
- MCH
- Plts
- Neut
- Lymph
- WBC - white blood cell count
- RBC - red blood cell count
- Hb - haemoglobin (indicates whether pt is anaemic or not)
- Hct - haematocrit (ratio of colume of red cells to the volume of whole blood - whether pt is bleeding/overproducing RBCs)
- MCV - mean corpuscular volume (size of RBC)
- MCH - mean cellular haemoglobin (density of Hg in given RBC)
- Plts - platelet count
- Neut - neutrophils
- Lymph - lymphocytes
What is contained within RBCs?
What is the function of this molecule?
Lack of this causes?
What does MCV show?
What are they termed if too big?
Too small?
Haemoglobin: reflects quantity and quality of RBCs
Lack of haemoglobin = anaemia
MCV - size of red blood cells
Too big = macrocytic
Too small = microcytic
What is WCC?
Too many?
Too little?
What is a differential count?
What is the condition associated with too little platelets?
Too many?
Which is less common?
Total quantity of WBCs - WCC
Too many = leukocytosis
Too little = leukopaenia
Differential count - number of particular types of white cells e.g. neutrophils, lymphocytes, basophils, eosinophils, monocytes
Too little platelets = thrombocytopaenia
Too many = thrombocythaemia (less common)
What is a blood film?
An acute infection will look like what on a blood smear?
Blood film: a smear of blood cells examined under a microscope
An acute infection results in higher numbers of neutrophils e.g. Neutrophilia
What does this blood film show?
Malaria: infectious disease caused by Plasmodium parasites, abnormality of RBC form - lost central pale area and more rounded, edges becoming more rough and rugged
When would you sample bone marrow and where from?
List some coagulation tests and what they are used for:
Bone marrow sample - if platelet levels, WBC or RBCs are too high or too low, a sample of bone marrow is taken from sternum or iliac crest
Coagulation Tests:
- activated partial thromboplastin time (APTT): intrinsic pathway of coagulation
- prothrombin time(PT)/international normalised ratio (INR): functioning of extrinsic pathway to see how certain factors in our blood are working to clot properly
INR - ratio rather than time incase pt takes meds such as warfarin, hence not actual time
Normal time for PT = 12-13 seconds
What is anaemia?
Causes?
What is the normal RBC life in circulation?
Haemoglobon deficiency due to lack of cells or lack of haemoglobin itself
Causes:
- lack of raw materials - iron deficency anaemia, hookwork (ongoing blood loss)
- production problem
- longevity problem e.g. overactive spleen, turnover time will drop hence you lose more of this
Normal RBC life in circulation = 120 days
When anaemia is due to lack of raw materials, give examples of these materials and how they are lacking:
What does a blood film of anaemia look like?
Iron and folic acid - usually dietary, rarely malabsorption
- more likely when increased demand i.e. pregnancy
Vitamin B12 - pernicious anaemia
- autoimmune disease affects absorption of B12
Iron deficiency anaemia blood film will be paler than normal (hypochromic) and smaller than normal (microcytic)
A production problem causes anaemia, which chemical causes this?
Lack of erythropoietin due to renal failure
- can be abused in sport as can increase oxygen carrying capacity
Bone marrow failure
- aplastic anaemia - complete failure of bone marrow to produce RBCs
- chemotherapy/immunosuppressants
- haematological malignancy
- anaemia of chronic disease: any chronic inflammatory process e.g. rheumatoid arthritis
How can anaemia be caused by losses from circulation?
What disease does this blood film show?
Blood loss - most common cause of anaemia
- bowel (majority)
- menstruation
- trauma/post operative
- bleeding from other organs (unusual)
Haemolysis - destruction of cells in circulation
- autoimmunity (antibodies against red blood cells and destroy them)
- sickle cell anaemia
- thalassaemia
Blood film = sickle cell anaemia
How does anaemia influence cell size (MCV)?
- microcytic (small cells): iron deficiency
- macrocytic (large cells): B12/folate deficiency, autoimmune
- normocytic: marrow, renal failure
List some signs and symptoms of anaemia:
Symptoms:
- tired and weak
- breathless
- dizzy
- palpitations
- specific to cause i.e. blood loss
Signs:
- pale
- rapid pulse
- may be oral features, dependant on type e.g. gingiva more pale
How is anaemia managed?
How is it treated?
- history and examination
- establish type of anaemia: FBC, blood film, haematinics (iron, B12, folate levels)
- establish cause - identify source of bleeding, cause of haemolysis
Treatment:
- replace whats missing (iron sulphate, folic acid, vit B12, erythropoietin, blood transfusion)
- address underlying cause
List some dental aspects of anaemia:
- characteristic oral abnormalities
- general anaesthesia: O2 capacity affected in anaemia, need to verify sickle cell status in all patients of black african or caribbean descent before GA
What is neutropenia and its causes?
Clinical features?
Neutropenia - most important white cell deficiency
- bone marrow failure
- autoimmune i.e. viral infection
Clinical features:
Infection in mouth or throat:
- candida, viral i.e. herpes simplex, commensal bacteria
Risk of life threatening disseminated infection
- from oral infection or other source
List some dental aspects of neutropenia:
- high risk of serious disseminated infection
- be aware of who is at risk
- urgent referral required
- avoid invasive treatment when suspected i.e. pts on chemotherapy, clinical suspicion
What are haematological malignancies mainly due to?
What are the two main types?
Majority due to uncontrolled proliferation of white cells
- Leukaemia: proliferation of immature cells in blood and bone marrow
- Lymphoma: proliferation of cells within lymphoreticular system - nodes, liver, spleen, bone marrow
What is leukaemia and their two forms of manifestation?
Leukaemia: proliferation of primitive blood cells
- acute - presents within weeks/days (most common malignancy in children)
- chronic - months to present
How does acute leukaemia present?
Survival rate?
What does the blood film of acute leukaemia look like?
Presentation:
- marrow failure: anaemia, infection, bleeding
- lymphadenopathy
- soft tissue infiltration
- chance finding
5 year survival for 50% overall, best in children
Blood film: immature white blood cells and low RBCs
How does chronic leukaemia present?
What does the blood film look like?
- anaemia
- lymphadenopathy
Presents in adults, may transform to acute
Blood film: shows lymphocytes in blood which should not be present
What are the two main types of lymphoma?
What is the presentation of each and survival rate?
Hodgkin’s Lymphoma
- mainly young adults esp. males
- lymphadenopathy (cervical)
- fever, weight loss, night sweats, itch, anaemia
Prognosis - 5 year survival 80%
Non-Hodgkin’s Lymphoma
- older adults
- lymphadenopathy
- fever, weight loss
Prognosis: variable, 50% 5 year survival
How are haematological malignancies treated?
- supportive: transfusions, infection management
- chemotherapy - kill off abnormal cell line developing
- radiotherapy - kill off all bone marrow and need a transplant
- bone marrow transplant (autologous - own stem cell, allogeneic - donor stem cell)
- novel therapies
What are some dental aspects of haematological malignancies:
Primary presentation to dentist:
- atypical infections
- bleeding
- lymphadenopathy
- gum infiltration
Coagulation depends upon what?
What happens at site of bleeding?
What aims to achieve a clot formation?
Platelets:
- number and function
Vessel injury:
- vasoconstriction
- platelet aggregation
- coagulation cascade
Clot formation from coagulation cascade and platelet aggregation
List some platelet problems:
What is a common platelet aggregation problem and management?
Coagulation cascade problems:
- deficiency: B12, folate
- production problem: bone marrow failure
- destruction: immune mediated or portal hypertension
Platelet aggregation problems:
- function impaired due to medical therapy: aspirin/clopidogrel
Management:
- treat underlying cause
- platelet transfusions may be necessary
Coagulation cascade problems:
generalised deficiency
- protein deficiency (most clotting factors)
Due to liver disease or severe malnutrition
Coagulation cascade problems:
Coagulation cascade problems:
Generalised deficiency
- protein deficiency (most clotting factors)
Due to liver disease or severe malnutrition
Specific deficiency
- congenital: haemophilia, von willebrands disease
- drugs: warfarin and heparin, NOACs
What is haemophilia A and B?
Which factors are affected?
What is von willebrands disease?
Haemophilia A and B: X-linked genetic disorder (males only)
- absent/low clotting factors
A - factor VIII
B - factor IX
Von Willebrands Disease: autosomal sominant (males and females affected)
- platelet/factor VIII function problem
How is haemophilia/von willebrands disease treated?
Factor replacement:
- early or prophylactic
DDAVP (desmopressin) for haemophilia A and von willebrands: increases factor VIII levels
Tranexamic acid - inhibits clot breakdown
Dental considerations for Haemophilia/Von Willebrand’s Disease?
Risk management:
- trauma avoidance
- preparation for expected bleeding i.e. operations
Associated conditions secondary to treatment with unscreened blood products
- HIV
- Hepatitis
How can bleeding problems manifest?
- cutaneous bleeding
- mucosal surface bleeding: intraoral, GI, ecess menstrual bleeding (menorrhagia), urinary tract bleeding (haematuria)
- traumatic bleeding: post-operative, after minor trauma, joints (haemarthroses)
What are the dental aspects of coagulation:
Identify in history - specific diseases, drugs, symptoms (post-op bleeding, mucosal bleeds)
- suspected undiagnosed bleeding disorder: do not proceed, refer to GP
- known bleeding disorder: may need to liase woth GP/haematologist, specific guidelines for anticoagulants
