Medicine - Haematology Flashcards
Define anaemia
Low RBC’s / reduced O2 carrying capacity of RBC’s -> leads to not enough O2 in the blood to meet the body’s physiological demands
Hb <130g/L (M) or <120g/L (F)
Define the aetiologies of anaemia
- increased cell loss (bleeding, hypersplenism, haemolysis)
- reduced/ineffective production (malignancy, myelodysplasia, folate/B12/ferritin deficiencies, renal failure (low EPO), ACD (high hepcidin))
What is the role of hepcidin?
Produced by the liver
Controls movement of iron from the gut -> blood
What are the two storage forms of iron?
Old RBC’s are eaten by macrophages in the RES and then the iron is stored as
1) ferritin (soluble)
2) haemosiderin (insoluble)
What are signs and symptoms of anaemia?
SOB palpitations chest pain pale cravings faint/dizzy pale mucous membranes koilonychia tachynoea oedema angular stomatitis/glossitis
What investigations should be carried out to investigate anaemia?
- FBC (Hb, RBC, WCC)
- MCV
- Haematinics (B12, plasma ferritin, plasma folate)
- Iron studies: serum iron, Tf saturation, TIBC
Describe iron deficiency anaemia and its causes
Hypochromic microcytic anaemia Tf saturation <15% Causes: - dietary (low iron) - blood loss (menorrhagia, bleeding) - malabsorption (coeliac disease)
What might be seen on the blood film of a patient with iron deficiency anaemia?
Poikilocytes (abnormally shaped RBC’s can be due to low vit B12)
In a patient with iron deficiency anaemia, what abnormalities in the following blood tests might be seen?
- Serum iron
- Serum ferritin
- TIBC
- MCV
- MCH
- low
- low
- high
- low
- low
Define anaemia of chronic disease and its causes:
Normochromic, normocytic anaemia
Failure of iron utilisation, as it is trapped in the RES
? thought to be due to increased hepcidin (as this protein controls iron movement from the gut into the blood)
Causes:
- infection
- renal failure
- malignancy
- inflammatory conditions e.g. arthritis, IBD (the severity of the anaemia correlates with the severity of the disease)
What would a blood film in ACD show?
Rouleux (stacks of RBC’s)
Describe the following blood results in a patient with ACD:
- serum iron
- serum ferritin
- TIBC
- low
- high/normal
- low (bound to ferritin)
Describe the treatment of ACD
Treat the underlying cause (anaemia will not respond to iron replacement)
- ?EPO
- ?hepcidin inhibitors
- .?transfusion (beware of iron overload)
Define sideroblastic anaemia, its causes and how it may present (in addition to normal anaemia symptoms)
- Ineffective erythropoiesis
- Sideroblasts produced
- Causes increased Fe absorption and haemosiderin accumulation -> think of sideroblastic anaemia when microcytic anaemia is not responding to iron
Causes: - congenital
- acquired (chemotherpay, MPD)
Will present with organomegaly (XS RBC destruction) and organ failure as iron accumulates in heart, kidneys, and liver
What would the blood film and bone marrow look like in a patient with sideroblastic anaemia
Film: HYPOCHROMIC micro/normo/macrocytic anaemia
Bone marrow: sideroblasts will be seen (nucleated erythrocytes with iron granules)
What would the following blood results be like in a patient with sideroblastic anaemia?
- Serum iron
- Serum ferritin
- TIBC
- high
- high
3.
How is sideroblastic anaemia treated?
Treat the cause:
- alcohol cessation
- pyridoxine replacement (vit B6)
- transfusions
Describe megaloblastic anaemia and its causes
- megaloblastic anaemias are a group of conditions which are due to folate/B12 deficiencies leading to a reduced no. RBC’s which are very large
- delayed maturation of RBC nucleus relative to cytoplasm
Causes: low B12/ferritin due to -> - deficiencies
- pernicious anaemia (antibodies against IF)
- coeliac disease (malabsorption)
- gastritis (malabsorption)
What would BR and LDH measurements be like in megaloblastic anaemia?
High BR, high LDH
What important questions should you ask a patient with megaloblastic anaemia?
DIET! vegetarian vegan coeliac dietary deficiencies
What would the following blood results be in megaloblastic anaemia?
- MCV
- haematocrit
- reticulocytes
- B12/folate
- anti-parietal cell antibody
- high
- low
- low
- low
- may be present if pernicious anaemia
What would a blood film/smear of megaloblastic anaemia show?
Hypersegmented neutrophils
Megaloblastic (big) RBC’s
When treating megaloblastic anaemia, why should B12 be replaced before folate?
Can cause subacute combined degeneration of the spinal cord
Compare intra/extravascular haemolysis and their features
Intravascular -> in the circulation, raised free Hb in the plasma, may present with red/brown urine (haemoglobinuria)
Extravascular -> in the RES, causes splenomegaly
Describe hereditary spherocytosis
Congenital cause of haemolytic anaemia
AD
Defect on RBC membrane, causes the RBCs to be removed by the spleen leading to spherocytes remaining
S/Sx: gallstones, jaundice, pallor, splenomegaly
Bloods: Low Hb, high reticulocytes, high UCBR
Blood film: reticulocytes and spherocytes
Treatment: transfusions, folic acid supplementation, splenectomy, cholecystectomy
Describe warm and cold type autoimmune haemolytic anaemia and how they present/are investigated
Acquired types of haemolytic anaemia
Intravascular haemolysis
Warm -> IgG
Cold -> IgM
Can be idiopathic or caused by cold/infection/drugs
Antibody coats the RBC membrane and causes them to be destroyted
Produces spherocytes
Presents with: anaemia, high UCBR, reticulocytes, haemoglobinaemia/uria
Describe the treatment for warm and cold type autoimmune haemolytic anaemia
Warm:
- steroids
- transfusions
- folic acid
- splenectomy
Cold:
- keep warm
- Rituximab
- Steroids
- Splenectomy
Describe how the DAT (direct antiglobulin test)/direct Coombs test works
Detects antibody in vivo which is already coating RBC’s
Test by taking a sample of blood from the patient and adding anti-human immunoglobulin to the sample
If agglutination occurs this is a + test result
Describe how the indirect Coombs test works
Used pre-blood transfusion
Detects antibody in the donors serum which could attack the patients RBC’s
Test for by taking a sample of the recipients RBCs and adding some donors blood to it
A positive test result will cause agglutination
Describe isoimmune haemolytic anaemia
Antibodies are produced as a result of antigen from another person e.g. haemolytic disease of the newborn (e.g. mother Rh-, first baby Rh+, then the baby 1 sensitises the mother and means that baby 2 could be attacked during development)
Describe non-immune haemolytic anaemia
E.g. drug induced, which causes formation of RBC antibodies
Describe complications of splenectomy and what patients should be warned of
Complications:
- increased infections with encapsulated organisms (strep. pneumonia, haemophilus influenza, neisseria meningitidis)
Pts should be:
- on long term antibiotic prophylaxis (penicillin V), vaccinated (annual influenza and pneumococcal vaccines), and carry a splenectomy warning card
Define haemoglobinopathies
The term for a group of blood disorders affecting RBC’s
Mutations in the globin genes leads to production of structurally abnormal globin molecules
Describe thalassaemias
Underproduction of globin proteins due to gene mutations
What three types of haemoglobin are normally found in adults
HbA (2 x alpha and 2 x beta genes)
HbF (2 x alpha and 2 x gamma genes)
HbA2 (2 x alpha and 2 x delta genes)
What chromosomes are the alpha globin genes normally found on?
Chr 16
What chromosomes are the beta globin genes normally found on?
Chr 11
What are the three main categories of thalassaemias?
alpha gene thalassaeima
beta gene thalassaeima
sickle cell disease
Describe the types of alpha gene thalassaeima
1) loss of 1/2 genes = not associated with disease
2) loss of 3 alpha genes (HbH) = severe microcytic hypochromic anaemia and splenomegaly
3) loss of all alpha genes (hydrops fetalis) = not compatible with life, as these genes are essential to make fetal haemoglobin
Describe beta thalassaemia minor and major
Common in the meditarranean region
B thalassaemia major -> loss of both B genes, can make foetal Hb but not adult Hb, normal development until 6 months and then require blood transfusions
B thalassaemia minor -> loss of 1 B gene, not as serious as the major forms
Describe sickle cell anaemia
Amino acid substitution in the beta-globin gene
Valine -> glutamine
Results in abnormal haemoglobin production and HbS is made (2 x alpha and 2 x beta-sickle)
HbS is insoluble and forms crystals in the body, causing vaso-occlusion and RBC haemolysis
Define pancytopenia
Reduction in all major cell lines (RBC, WBC, plts)
Define agranulocytosis
Reduction in the production of granulocytes (neutrophils, basophils, eosinophils)
What are the causes of pancytopenia?
1) Reduced marrow production
- aplastic anaemia
- infiltration (cancer)
- megaloblastic anaemia
- myelofibrosis
- megaloblastic anaemia (lack of vit B12/folate)
2) Increased peripheral breakdown
- hypersplenism
What drug commonly causes agranulocytosis?
Carbimazole
Define multiple myeloma
Clonal proliferation of plasma cells in the bone marrow
Monoclonal proliferation of Ig (rather than the normal polyclonal)
What are the S/Sx of multiple myeloma?
Bone pain, pathological fractures
Hypercalcaemia (increased osteoclast activity)
Anaemia (low RBC)
Infections (neutropenia)
Fatigue
Renal impairment (deposition of immunological light chains in kidneys)
Describe the three key laboratory findings in myeloma
1) Paraprotein (monoclonal Ig in the blood, detected by electrophoresis)
2) Free light chains (Bence jones in the urine, or serum free kappa/lambda chains)
3) B2-microglobulin (this protein is raised in myeloma when the serum is measured, and it is a component of all MHC-I cells)