Haematology 1B - RBC disorders Flashcards
what do haematopoietic stem cells differentiate into
differentiate + mature to form different blood cell lines
what is erythropoiesis
process which produces RBCs
how is erythropoiesis controlled
negative feedback
what can be the stimulus for starting the negative feedback loop for erythropoiesis
- ↓ O2 (hypoxia)
- high altitude
- ↑ exercise
- lots lung tissue in emphysema
what are 3 reasons why hypoxia can be caused + therefore starts negative feedback loop for erythropoiesis
↓ RBC count,
↓ O2 available to blood ,
↑ tissue demands for O2
Describe the negative feedback loop for erythropoiesis
- stimuli causes reduced O2 level in blood
- kidney (+ liver) release erythropoietin hormone
- erythropoietin stimulates red bone marrow
- enhanced erythropoiesis ↑RBC count
- ↑ O2 carrying ability of blood
- normal blood O2 levels
how are erythrocytes recycled in the body
-RBC death + phagocytosis in spleen, liver or red bone marrow
- RBCs broken down into Globin + Heme group
- globin broken into AA – can be used for protein synthesis
- Heme broken into bilirubin – goes to liver and helps with bile for digestion
- bilirubin excreted in small intestine + part in urine
Heme group broken into ion and converted into ferritin in liver + if needed go to red bone marrow + used for new RBC
what are the 2 categories of red cell disorders
anaemia
polycythaemia
what is anaemia + why it happens
Hb below the normal bc of
- ↓ RBC, ↓ Hb level or defective Hb
- ↓ oxygen carrying capacity of blood
what is polycythaemia + why it happens + what can it lead to
over production of RBCs
- ↑ blood viscosity + BP
- ↓ flow rate of blood + ↓ O2 delivery
- lead to embolism, stroke, heart failure
what is primary polycythaemia
cancer of erythropoietic cell line in red bone marrow
what is secondary polycythaemia
underlying conditions
from dehydration, emphysema, high latitude
what are main causes of anaemia
- ↓ RBCs + Hb production
- increased destruction of RBC
- increased destruction of RBCs (haemolytic)
- miscellaneous
what are the deficiency states that can cause anaemia
iron
folic acid
vitamin b12
coeliac/crohn’s disease (malabsorption of above)
what are main causes of ↓ RBCs + Hb production causing anaemia
- deficiency states
- - bone marrow aplasia
what 4 diseases can cause haemolytic anaemia
sickle cell anaemia
thalassemia major/minor
glucose-6-phosphate dehydrogenase deficiency
hereditary spherocytosis
what is haemolytic anaemia
increased destruction of RBCs
what 4 type of miscellaneous things can cause anaemia
anaemia of chronic disease
acute blood loss
chronic renal failure associated anaemia
malignancy related
what are 3 categories anaemia is classified by
morphology (MCV) was -micro/macro cytic
Hb conc (colour) (MCH) hypo/hyper chromic
etiology
how do you classify microcytic, hypochromic anaemia
↓ MCV (<80) , ↓ MCH
how do you classify normocytic, normochromic anaemia
= MCV (80-100) , = MCH
how do you classify macrocytic, hyperchromic anaemia
↑ MCV, (>100) ↑ MCH
what are 4 ways anaemia can be classified by underlying etiology
- impaired erythropoiesis
- RBC depletion/hemolysis
- loss of RBCs (acute/chronic blood loss)
- impaired RBC distribution
what can caused the impaired erythropoiesis when classifying anaemia
lack of vit B12 + folic acid
bone marrow diseases
disturbed Fe+ absorption
what is iron deficiency anaemia + who is it common in
predominant in women of child bearing age
can be bc acute/chronic blood loss
menorrhagia, GI bleeding, vegans, ↑ aspirin intake, NSAIDs
what are clinical features seen in those with iron deficiency anaemia
early - symptomless
late - tired, tachycardia, palpitations, cold intolerance, tingling + numbness extremities
Koilonychia, Patterson-Brown-Kelly syndrome
what are dental aspects associated with iron deficiency anaemia
- sore tongue
- atrophic glossitis
- candidiasis
- angular stomatitis
- apthous like ulcerations
- pallor of oral mucosa
how would you treat a patient with iron deficiency anaemia
oral iron supplements
treat underlying cause
what is B12 deficiency + clinical features of it
older women (55-60) initial complaint - burning of tongue patients thought to be psychosomatic + neurological symptoms
what are 4 causes of B12 deficiency anaemia
- pernicious anaemia (autoantibody to gastric parietal cells)
- partial gastrectomy (↓ intrinsic factors)
- crohn’s/coeliac disease (malabsorption of B12)
- nitrous oxide abuse
what are dental aspects associated with B12 deficiency anaemia
- depapillated + beefy red tongue
- angular chelitis
- recurrent oral ulcers
- circumoral + peripheral tingling, numbness
- LA is safe
- conscious sedation can be given if Hb slightly low
what special investigations can be done if you suspect they have B12 deficiency
- Serum Vit B12 levels
- IF ABs/ have high specificity (less likely to give you false positive)
how would you treat someone with B12 deficiency
monthly IM injection of Vit B12
what are main causes of folate deficiency
poor food intake - poverty, diet, chronic alcoholism
malabsorption
drug induced - phenytoxin, cytoxic drugs, HIV/AIDS
what are clinical features of folate deficiency
-Initial complaint: ~burning of the tongue with no obvious abnormality on examination
what are dental aspects associated with folate deficiency anaemia
soreness of tongue - without depapillation/colour change
atrophic glossitis
angular stomatitis
how would you treat someone with folate deficien
daily oral intake of folic acid tablets
what is sickle cell anaemia + how is it caused
autosomal recessive inheritance
- Abnormal Hb: HbS and HbC
-Different states: • SS – sickle cell anaemia • AS – sickle cell trait (carrier) • SC (milder form of SS) – sickle-Hb disease -
what other anaemia can sickle cell disease cause + how
↓O2 tension causes sickling –> sig RBC breakdown (haemolysis ) –> haemolytic anaemia
what are the 7 clinical features of sickle cell anaemia
- small capillaries obstructed, restricted blood flow to organ
o Ischaemia, necrosis, organ damage - Painful crises (due to infarcts of bone, CNS, spleen, lungs)
- Haematological crises (aplastic); parvovirus
-Chronic anaemia (reticulocytosis, Hb levels as low as 5-9g/dl
o Body tries to compensate -> ↑ rbcs produced + stale immature reticulocytes
- Chronic hyperbilirubinaemia; bc breakdown of haem -> bilirubin -> circulate around the body -> jaundice/gall stones
-Susceptible to infections (meningitis , pneumonia )
o Treated with Penicillin V (phenoxymethylpenicillin)
-Sequestration syndrome (lungs – chest syndrome, spleen – septicaemia)
what are the 4 orofacial manifestation of sickle cell anaemia
o Painful infarcts in jaw or osteomyelitis
o Hypercementosis
o Excessive overjet & overbite (because of enlarged haematopoietic maxilla)
o Hypomineralised teeth
what are other dental aspects associated with sickle cell anaemia other than orofacial manifestations
- should Prevent infections, hypoxia, acidosis or dehydration
- Early management of infection
- Patient at risk must be investigated prior to GA
- Safe analgesics to be used e.g. paracetamol and codeine
what is aplastic anaemia + what can it cause
non-functioning bone marrow
cause pancytopenia, leukopenia, thrombocytopenia, + anaemia
what are 3 main causes of aplastic anaemia
- idiopathic - exposure to benzene, viral infections(hepatitis)
- autoimmune disorders
- drugs ( NSAIDs, anticonvulsants, cytotoxic drugs, allopurinol)
what are clinical features of aplastic anaemia
- purpura is often 1st manifestation
- anaemia features (tired, pale)
- Susceptibility to infection
- bleeding
what treatment modifications should be considered when treating patient with aplastic anaemia
conscious sedation + GA avoided
haemorrhagic tendencies
Susceptibility to infections
what oral manifestations can appear due to aplastic anaemia
ulcerative lesions of oral mucosa , spontaneous gingival bleeding
gingival swelling if cicloporin used
what are 4 other red cell related conditions
- Thalassaemia
- G6P dehydrogenase deficiency: RBC metabolic disorder -> Hb denature -> haemolysis
o X-linked recessive - Hereditary spherocytosis: Spherical RBCs -> haemolysis
o Autosomal Dominant - Polycythaemia vera: ↑viscosity of blood ∴ ↑ risk of thrombosis
what histories should be taken with anaemic patients
- History of presenting complaint: severity of signs and symptoms of anaemia
- Past medical history: any existing medical problems/prev surgery, could be part of the bowel that could affect absorption
- Dietary history: are they vegans? Nutritional deficiency, iron deficiency anaemia
- Family history: hereditary pattern? Type of anaemia present in family?
- Social history: chronic alcoholics, folate deficiency, pregnancy, puberty
what are key investigations that can be done if anaemic
- FBC of Hb, MCV, MCH, red cell distribution width
- Blood film (would give you an idea of what shape the rbc is)
- Sickledex (solution turns cloudy if given)
- Hb electrophoresis; measures different types of Hb
- Serum B12 - Serum folate
- Serum iron studies: iron, ferritin and TIBC
how to manage anaemia
• Eliminate underlying disease
• Replacement therapy
o Iron; ferrous sulphate, ferrous fumerate
o Folate
o IM B12 monthly!
• Blood transfusion (acute haemolysis/blood loss)
• Erythropoietin (chronic renal failure & anaemia of chronic disease)
o Epo is a HORMONE that stimulates bone marrow to release blood cells
