Haematology RBC Disorders Flashcards
1. Illustrate the haematopoietic system 2. Knowledge of red cell disorders 3. Categorise anaemia 4. Knowledge of signs and symptoms of RBC disorders 5. Interpret haematological data for RBC disorders 6. Knowledge of indices used to analyse RBC disorders 7. Elucidate dental aspects of common RBC disorders
What is a haematopioetic stem cell
Cell that differentiates and matures to form different blood cell lines
What is erythropoiesis
Production of RBCs in bone marrow
What can reticulocyte count be used for
As an estimation of erythropoiesis rate
What are the requirements of erythropoiesis
- Healthy bone marrow to produce RBCs
- Healthy kidneys to produce erythropoietin
- Healthy liver for iron and B12 storage
- Healthy small intestine for vitamin absorption
What are the different Hb types in adults
- HbA; 2 alpha and 2 beta chains
- HbA2; 2 alpha 2 delta chains
- HbF; 2 alpha and 2 gamma chains
What increases erythropoiesis
It is controlled by negative feedback so EPO production increases when;
- altitude increases
- hypoxia
- exercise
- cardiac/pulmonary disease
How long do RBCs circulate in the blood
120 days before kupffer cells (macrophages) engulf them
What is anaemia
When the Hb count is below the normal for a given age, gender and ethnicity
There are fewer RBCs which makes Hb low and so the blood carries less oxygen
Outline the four aetiological factors for anaemia
- Deficiency states; iron, folic acid, B12, coeliac/chrons (malabsorption)
- Bone marrow aplasia
- Increased destruction (haemolytic anaemia)
- sickle cell = inherited
- thalassemia = inherited
- G6P dehydrogenase deficiency = inherited
- hereditary spherocytosis = inherited - Miscellaneous; chronic diseases, acute blood loss, real failure, malignancy thus bone marrow infiltration
What is polycythaemia
The opposite of anaemia; RBC overproduction
This causes increased viscosity and blood pressure and so reduces the blood flow rate - this decreases oxygen delivery = Hyper-viscosity syndrome which increases thrombosis risk
Outline the aetiological factors for polycythaemia
Primary = cancer of erythropoietic cell line
Secondary = dehydration, emphysema, altitude
What does polycythaemia lead to
- embolism
- heart failure
- stroke
What are the morphological classifications of anaemia
- Microcytic
- Normocytic
- Macrocytic
What are the Hb concentration (colour) classifications for anaemia
- Hypochromic
- Normochromic
- Hyperchromic
What are the aetiological classifications for anaemia
- Impaired erythropoiesis
- RBC depletion/haemolysis
- Loss of RBCs due to chronic/acute bleeding
- Impaired RBC distribution causing hypersplenism
What are the causes of iron deficiency anaemia
This is the most common, and typically in women of childbearing age
- acute/chronic blood loss
- menorrhagia, GIT bleeding
- aspirin and NSAIDS
- vegans
Describe the clinical presentations of iron deficiency anaemia
Early stage = symptomless
Late = tiredness, dyspnoea (laboured breath)
- cold intolerance, tingling and numbness
- koilonychia (nail deformity)
- Patterson-Brown-Kelly syndrome making it hard to swallow
What is the relevance of iron deficiency anaemia for dentistry (SPACAA)
- Sore tongue
- Atrophic glossitis (dorsally); there are no filiform/fungiform papillae
- Angular stomatitis; maceration of skin by angle of mouth
- Candidiasis; creamy white lesions
- Aphthous ulcerations (round)
- Pallor of oral mucosa
What are the causes of B12 deficiency anaemia
Common in 55-60 year olds
- pernicious anaemia = antibody to parietal cells (gastric)
- partial gastrectomy = low levels of IF
- crohn’s/coeliac disease = B12 malabsorption
- nitrous oxide abuse
Describe the clinical presentations of B12 deficiency anaemia (same for folate deficiency)
Burning of the tongue
Patients are psychosomatic and can have neurological symptoms (pins + needles at extremities and visual disturbances)
What tests are used to diagnose B12 deficiency anaemia
- Schillings test; IM B12 given and urinary excretion is tested (no longer used)
- Serum B12 test
- Intrinsic factor antibodies = highly specific so there is rarely false positives
- Gastric anti-parietal cell antibody = low specificity
How is B12 deficiency anaemia treated
Monthly IM B12 injections
What is the relevance of B12 deficiency anaemia in dentistry (TUNAB)
Presents depapillated and beefy red tongue
Angular chelitis (inflamed corners of mouth)
Circumoral and peripheral tingling numbness
Recurrent oral ulcers
Neurological symptoms
LA is safe and conscious sedation can be given if Hb is slightly low
What is folate needed for
DNA/RNA synthesis; the body cannot store folate
What does folate deficiency cause during pregnancy
Cleft palate in the child
What are the causes of folate deficiency
Poor intake, chronic alcoholism, malabsorption and it can be drug induced (phenytoin, cytotoxic drugs, HIV/AIDS drugs)
What treatments are given for folate deficiency anaemia
Daily oral intake of folic acid tablets
What causes haemolytic anaemia
Abnormalities in…
- Hb formation
- sickle cell disease where 2 abnormal HbS copies inherited (most common presentation)
- thalassemia; no alpha/beta globulin chain - Erythrocyte structure (presenting as sickle cell anaemia)
- spherocytosis = broken down
- elliptocytosis = oval shaped
- G6P dehydrogenase deficiency causes premature RBC metabolism
- RBC damage by malaria and drugs
What causes sickle cell anaemia
Abnormal HbS + HbC which is common in African + Afro-caribbeans
This reduces oxygen tension causing sickling; this leads to haemolysis and so haemolytic anaemia
SS
Sickle cell anaemia
AS
Sickle cell trait = carrier
SC
Sickle Hb disease (milder SS)
Describe the clinical presentation of sickle cell anaemia
- Obstruction of small capillaries so restricted BF to organs causing ischaemia, necrosis and damage
- Painful crises due to infracts of bone, CNS, spleen + lungs as small vessels are occluded
- Haematological crisis (aplastic); paravirus - cessation of erythropoiesis causes severe anaemia
- Chronic anaemia (reticulocytosis where the body compensated and overproduces stale immature RBC reticulocytes)
- Chronic hyperbilirubinaemia; due to heam breakdown giving bilirubin which circulates in the body causing jaundice and gall stones
- Increased susceptibility to infections; meningitis and pneumonia = treated with penicillin
- Sequestration syndrome; chest and septicaemia (spleen)
What is the relevance of sickle cell anaemia in dentistry
Orofacial manifestations present:
- painful infarcts in jaw/osteomyelitis
- hypercementosis
- XS overjet/overbite due to enlarged haematopoietic maxilla
- hypo mineralised teeth
Patients with SS should always be investigated before GA and given early infection management
- Prevent infections, hypoxia, acidosis and dehydration and these precipitate crisis
- Manage infection early
Give examples of safe analgesics to use for someone with sickle cell anaemia
- paracetamol
- codeine
What is aplastic anaemia
A rare condition where the bone marrow is non-functional; Pancytopenia (leukopenia, thrombocytopenia and anaemia)
What causes aplastic anaemia
Pancytopenia; leukopenia, thrombocytopenia + anaemia
Ideopathic causes; benzene, irradiation, hepatitis
Autoimmune disorders
Drugs = NSAIDs, allopurinol, anticonvulsants, cytotoxic drugs
Describe the clinical presentation of aplastic anaemia
Anaemia, bleeding, increases susceptibility to infection, purpura is the first manifestation
How is aplastic anaemia treated
Similar treatment to that of leukaemia
Who is more at risk of thalassaemia and what is this
Asians, meditaranians and middle easterns - this is a disorder in globing chain reduction = autosomal recessive
What does G6P dehydrogenase deficiency cause
RBC metabolic disorder causing Hb to denature by haemolysis and this is X-linked recessive
What does hereditary spherocytosis cause
Spherical RBCs which undergo haemolysis; this is autosomal dominant
What is polycythaemia vera
Where blood viscosity is increased which increases risk of thrombosis
What key investigations are taken for patients queried anaemia
- FBC pf Hb, MCV, MCH, red cell distribution width
- Blood film which shows RBC shape
- Sickledex
- Hb electrophoresis which measures different Hb types
- Serum B12/folate/iron studies
Outline management for RBC disorders
- eliminate underlying disease
- replacement therapy; folate, IM B12, ferrous sulphate/ fumerate
- blood transfusion
- erythropoietin
What is erythropoietin
EPO hormone; stimulates bone marrow to release RBCs
How is erythropoiesis increased
Reduced O2 is detected in the kidneys (and liver) to release erythropoietin which stimulates red bone marrow to increase the RBC count
What are the special investigations and treatments for iron deficiency anaemia
- FBC
- Iron studies
Oral iron supplements and treatment of the underlying cause
List the dental aspects of folate deficiency
- Soreness of the tongue without depapilation/colour change
- Atrophic glossitis
- Angular stomatitis
Describe oral manifestations of aplastic anaemia (PUBS)
Similar to leukaemia :
- ulcerative lesions of oral mucosa
- oral petechiae
- spontaneous gingival bleeding
- gingival swelling if cyclosporin given
