- 23 year old, male, recurrent nose-bleeds, infection after chemotherapy
- Aplastic anaemia
- Presentation of pancytopenia with hypoplastic marrow
- Primary or secondary
- Most common primary is idiopathic acquired aplastic anaemia
- Congenital causes of primary aplastic anaemia are very rare (e.g. Fanconi's anaemia)
- Secondary causes of aplastic anaemia include infection (especially viral, e.g. hepatitis, measles, parvovirus B19) and drugs
- Cytotoxic drugs such as busulphan and doxorubicin are well-recognised causes of secondary aplastic anaemia via a type A (dose-related response)
- Non-cytotoxic drugs such as chloramphenicol and gold have also been reported to cause aplastic via a type B (not dose-related) response
- Rarely, pregnancy is associated with a secondary aplastic anaemia
- 24 year old, Cypriot, male, worsening anaemia and jaundice, Heinz bodies
- Glucose-6-phosphate dehydrogenase deficiency
- G6PDH deficiency
- Most common red blood cell enzyme defect
- These individuals are susceptible to oxidative crises precipitated by fava beans and drugs such as ciprofloxacin and sulphonamides
- G6PDH plays an important role in the hexose monophosphate shunt which provides NADPH (reduced nicotinamide adenine dinucleotide phosphate - the reducing agent)
- NADPH is used to regenerate glutathione
- In the absence of glutathione, red blood cells are exposed to oxidative stress
- Heinz bodies represent oxidised haemoglobin
- 50 year old, male, tiredness, dyspnoea and paraesthesia, on examination extensor plantars, brisk knee jerks, and absent ankle jerks, blood film shows macrocytic anaemia
- Pernicious anaemia
- Most common cause of vitamin B12 deficiency
- Atrophy of gastric mucosa with subsequent failure of intrinsic factor production
- Intrinsic factor is required for vitamin B12 absorption
- Other causes are terminal ileum disease, gastrectomy, and low dietary intake (e.g. vegans)
- Vitamin B12 can just be taken orally in those with lack in diet
- It has to be given intramuscularly in those with pernicious anaemia (intramuscular hydroxocobalamin)
- 23 year old, woman, trimethoprim for recurrent urinary tract infections (UTIs), macrocytic anaemia
- Folate deficiency
- Macrocytosis causes include vitamin B12/folate deficiency, alcohol, liver disease, hypothyroidism, and myelodysplasia
- Trimethoprim is a bacterial dihydrofolate reductase inhibitor, but with prolonged therapy it can act in humans
- It is avoided in pregnancy because interference with folate makes it teratogenic
- Bone marrow biopsy is indicated if the cause of the macrocytosis is not established with blood tests
- 25 year old, woman, SLE, acute anaemia, steroid treated, Direct Coomb's test was strongly positive, direct antiglobulin test was positive with IgG alone
- Autoimmune haemolytic anaemia
- Many causes of anaemia in patient with SLE
- These include iron deficiency anaemia secondary to NSAID use, bone marrow suppression secondary to immunosuppressive drugs such as cyclophosphamide/azathioprine
- AHA is the cause in this patient since the direct Coombs' test demonstrates and confirms the presence of antibody binding to red blood cells
- Other causes of secondary AHA include lymphoma, infections (e.g. EBV, Mycoplasma spp.), carcinoma and other autoimmune conditions
- Drugs may also cause immune haemolysis e.g. methyldopa treatment can induce the formation of red cell autoantibodies
Wednesday, 26 September 2012
Causes of anaemia
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