Haematology Flashcards
what is anaemia
- low haemoglobin concentration, may be due either to a low red cell mass or increased plasma volume
- reduced production or increased loss of RBCs
symptoms of anaemia
- Fatigue
- Dyspnoea
- Faintness
- Palpitations
- Headache
- Tinnitus
- Anorexia
what are the ranges for anaemia in men and women
Low Hb is <135g/L for men and <115g/L for women
signs of anaemia
- May be absent
- Pallor
- Hyperdynamic circulation e.g. tachycardia, flow murmurs and cardiac enlargement
consequences of anaemia
-Reduced O2 transport
-Tissue hypoxia
-Compensatory changes:
>Increase tissue perfusion
>Increase O2 transfer to tissues
>Increase red cell production
pathological consequences of anaemia
- Myocardial fatty change
- Fatty change in liver
- Aggravate angina/ claudication
- Skin and nail atrophic changes
- CNS cell death (cortex and basal ganglia)
what is MCV and how does it separate the types of anaemia
- mean cell volume
- normal = 76-96 femtolitres
- low MCV = microcytic anaemia
- normal = normocytic
- high = macrocytic
what are the 3 causes of microcytic anaemia
- Iron-deficiency anaemia – most common cause
- Thalassaemia
- Sideroblastic anaemia – very rare
- anaemia of chronic disease is an example
what are 7 causes of normocytic anaemia
- Acute blood loss
- Anaemia of chronic disease
- Bone marrow failure
- Renal failure
- Hypothyroidism
- Haemolysis
- Pregnancy
examples of normocytic anaemia
- Aplastic anaemia
- Haemolytic – thalassaemia, sickle cell disease, G6PD
- Infections – malaria
- Haemorrhage
8 causes of macrocytic anaemia
- B12 or folate deficiency
- Alcohol excess – or liver disease
- Reticulocytosis
- Cytotoxics
- Myelodysplastic syndromes
- Marrow infiltration
- Hypothyroidism
- Antifolate drugs
examples of macrocytic anaemia
Megaloblastic
B12/folate deficiency
Pernicious anaemia
what can haemolytic anaemias be
- normocytic or macrocytic
investigations for anaemia
- FBC and film, reticulocyte count, U&E, LFT, TSH, B12, folate, ferritin
- B12 deficiency = intrinsic factor Abs, Shilling test, coeliac Abs, B12 replacement
causes of iron deficiency anaemia (IDA)
- blood loss (haemorrhage, GI bleeding, menorrhagia)
- poor diet or poverty
- malabsorption ( coeliac disease)
- hook worm causes GI blood loss in tropics
pathology of IDA
- inadequate iron supply so interrupts the final step in haem synthesis
signs of IDA
- Tiredness
- Often asymptomatic
- Rare – koilonychias, angular cheilosis and glossitis
tests for IDA
- Blood film: microcytic, hypochromic anaemia
- Decreased MCV, MCH and MCHC
- Low ferritin
treatment for IDA
- treat cause
- ferrous sulfate = oral iron = can cause nausea and diarrhoea
- use for at least 3 months
what is anaemia of chronic disease
- microcytic/normocytic
- Reduced Hb related to chronic inflammatory disorders, chronic infections and malignancy
pathology of anaemia of chronic disease
- inflammatory cytokines = reduce sensitivity of bone marrow to erythropoietin and lead to failed incorporation of iron into developing red cells
- arise from 3 problems = poor use of iron in erythropoiesis, cytokines shorten RBC survival, decreased production and response to erythropoietin)
causes of anaemia of chronic disease
- Chronic infection, chronic inflammatory disease or malignancy
- Vasculitis
- Autoimmune disorders - Rheumatoid
- Renal failure
tests for anaemia of chronic disease
- ferritin normal
- B12, folate, TSH and tests for haemolysis
treatment for anaemia of CD
-Treat underlying disease
-Erythropoietin (raise Hb levels)
Side effects: flu-like symptoms, hypertension, mild rise in platelet count
-IV iron (overcome functional iron deficiency)
what is sideroblastic anaemia
- bone marrow produces ringed sideroblasts rather than healthy red blood cells
- ineffective erythropoiesis, leading to increased iron absorption and iron loading in marrow
- enough iron but can’t incorporate it
causes of sideroblastic anaemia
- Congenital – rare X-linked
- Chemotherapy
- Anti-TB drugs
- Alcohol excess
tests for sideroblastic anaemia
- Increased ferritin
- Hypochromic blood film
- Disease-defining sideroblasts in the marrow
treatment for sideroblastic anaemia
Remove the cause
Pyridoxine (vit B6)
Repeated transfusions for severe anaemia
megaloblastic causes of macrocytic anaemia
- a megaloblast is a cell in which nuclear maturation is delayed compared with the cytoplasm.
- B12 and folate deficiency: both are required for DNA synthesis
non-megaloblastic causes of macrocytic anaemia
alcohol excess, reticulocytosis, liver disease, hypothyroidism.
other haematological causes of macrocytic anaemia
myelodysplasia, myeloma, myeloproliferative disorders, aplastic anaemia
tests for macrocytic anaemia
- B12 and folate deficiency
- blood film = hyper segmented neutrophils in B12 and serum folate
- bone marrow biopsy = megaloblastic or normoblastic marrow, abnormal or increase erythropoiesis
what is folate and folate deficiency
- in green vegetables, nuts, yeast, and liver; it is synthesised by gut bacteria.
- Maternal folate deficiency causes foetal neural tube defects.
causes of folate deficiency
- Poor diet
- Increased demand e.g. pregnancy or increased cell turnover
- Malabsorption e.g. coeliac disease
- Alcohol
- Drugs: anti-epileptics, methotrexate
tests for folate deficiency
- Blood film – anisocytosis and poikilocytosis with large oval macrocytes
- Serum and red cell folate assay
treatment for folate deficiency
- underlying cause
- folic acid 5mg/day for 4 months
- pregnancy = prophylactic doses of 400mcg/day given until 12 weeks (prevents spina bifida)
what is pernicious anaemia
- autoimmune condition in which atrophic gastritis leads to a lack of IF secretion from the parietal cells of the stomach.
- Dietary B12 therefore remains unbound and consequently cannot be absorbed by the terminal ileum
causes of B12 deficiency
- Dietary
- Malabsorption during digestion
- Congenital metabolic errors
pathology of pernicious anaemia
- Autoimmune gastritis affecting the fundus.
- Parietal and chief cells are replaced with mucin-secreting cells = no IF secretion = B12 deficiency
- B12 and folate needed for DNA synthesis so red cell development stops = remain as megaloblasts
differential diagnoses for pernicious anaemia
- other autoimmune diseases
clinical presentation of pernicious anaemia/ B12 deficiency
-Symptoms of anaemia
-Mild jaundice due to haemolysis
-B12 deficiency causes:
>Neurological – paraesthesia, peripheral neuropathy, subacute combined degeneration of spinal cord
> irritability, depression, psychosis and dementia
tests for pernicious anaemia/ B12 deficiency
- FBC = decreased Hb, increased MCV, WCC and platelets low
- reticulocytes may be low
- megaloblasts in bone marrow
- parietal cell Abs, IF Abs
treatment for pernicious anaemia/ B12 deficiency
- treat cause
- malabsorption = hydroxocobalamin to replenish B12 stores
- oral B12
what is haemolytic anaemia
- due to haemolysis = abnormal breakdown of RBCs
immune mediated acquired haemolytic anaemia
- direct antiglobulin test +ve
- Drug-induced: binding to RBC membranes or production of immune complexes.
- Autoimmune haemolytic anaemia: autoantibodies causing extravascular haemolysis and spherocytosis.
- Paroxysmal cold haemoglobinuria: seen with viruses/syphilis
- Isoimmune: acute transfusion reaction
direct antiglobulin acquired haemolytic anaemia
- Coombs -ve
- Autoimmune hepatitis; hepatitis B and C; post flu and other vaccinations, drugs
microangiopathic haemolytic anaemia
intravascular haemolysis and schistocytes
infection acquired haemolytic anaemia
- from malaria = RBC lysis and haemoglobinuria
hereditary haemolytic anaemia
- enzyme defect = G6PD and pyruvate kinase deficiency
- membrane defects = spherocytosis, elliptocytosis
- haemoglobinopathy = sickle cell, thalassaemia
what is aplastic anaemia
- bone marrow failure
- defined as pancytopenia with hypoplastic marrow (stops making cells)
- pancytopenia = reduced numbers of all major cell lines
- reduction in pluripotent stem cells
causes of aplastic anaemia
Autoimmune Drugs Viruses – parvovirus, hepatitis Irradiation Inherited – Fanconi anaemia
symptoms of aplastic anaemia
- bruising, blood blisters in mouth
what is polycythaemia vera
- abnormal increase in the number of circulating RBCs
- malignant proliferation of a clone (haematopoietic myeloid stem cells) derived from somatic mutation of one pluripotent stem cell
clinical manifestations of polycythaemia vera
- vague symptoms due to hyper viscosity
- characteristic = Itching after a hot bath, Erythromelalgia, Burning sensation in fingers and toes
- splenomegaly
- gout
- facial plethora
investigations for polycythaemia vera
- increased: RCC, Hb, PCV, WBC, platelets, HCT
- JAK2 testing (present in most)
- marrow = hyper cellularity, erythroid hyperplasia
management of polycythaemia vera
- aim to keep haematocrit (HCT) < 0.45 to decrease risk of thrombosis
- low dose aspirin
- complications = ay progress to acute myeloid leukaemia
sickle cell disease pathology
- inherited AR
- abnormal Hb results in vaso-occlusive crises
- amino acid substitution in gene coding for beta Hb chain = production of HbS instead of HbA
- HbS is 50x less soluble and under low O2 conditions it polymerises into rods causing sickle shape
genetics of sickle cell disease
- HbS from mutation in beta globin gene on chromosome 4
- homozygotes (SS) = SICKLE CELL ANAEMIA
- heterozygotes (AS)= sickle cell trait (protects against malaria)
clinical presentation of sickle cell disease
- Asymptomatic
- Asthenia (abnormal weakness/ lack of energy)
- Jaundice
- Ulcers around the ankles
- Bone deformities
- Infections
painful vaso-occlusive crises in sickle cell
- microvascular occlusion
- ribs, spine, pelvis, tummy, legs and arms and hands/feet (particularly in children).
- Affects the marrow, causing severe pain, triggered by cold, dehydration, infection or hypoxia