Haematology Flashcards
Types of macrocytic anaemia
Megaloblastic and non-megaloblastic
Definition of macrocytic anaemia
Anaemia associated with a high MCV of erythrocytes (>100fl in adults)
Causes of megaloblastic macrocytic anaemia
Vitamin b12 deficiency
Folate deficiency
Drugs: methotrexate, hydroxyurea, azathioprine, zidovudine
Causes of non-megaloblastic macrocytic anaemia
Alcohol excess Liver disease Myelodysplasia Multiple myeloma Hypothyroidism Haemolysis (reticulocytosis) Drugs: tyrosine kinase inhibitors: imatinib, sunitinib
Causes of vitamin b12 deficiency
Decreased absorption:
- post gastrectomy
- pernicious anaemia
- terminal ilealresection or disease (crohns, bacterial overgrowth, pancreatic insufficiency, fish tapeworm, metformin, omeprazole)
Decreased intake (vegans)
Abnormal metabolism
- congenital tanscobalamin II deficiency
- inactivation of b12 by nitrous oxide
Causes of folate deficiency
Decreased intake
- alcoholics
- elderly
- anorexia
Increased demand
- pregnancy
- lactation
- malignancy
- chronic inflammation.
- chronic haemolysis
- exfoliative dermatitis
Decreased absorption
- jejunal disease (coeliac disease)
- tropical sprue
Drugs
- phenytoin
- trimethoprim
- methotrexate
Examination signs of anaemia
Pallor
Tachycardia
May be signs of cause: e.g. Malnutrition, jaundice, hypothyroid appearance
Signs of pernicious anaemia
Lemon-tinted skin (mild jaundice)
Glossitis (red sore tongue)
Angular stomatitis (cheilitis)
Weight loss
Signs of vitamin b12 deficiency
Peripheral neuropathy Ataxia Subacute combined degeneration of the spinal cord Optic atrophy Dementia
What is subacute combined degeneration of the spinal cord?
= degeneration of dorsal and lateral columns of the spinal cord causing loss of joint and position sense, ataxia and UMN weakness.
Partially or completely relieved by restoring vitamin b12 levels.
What is pernicious anaemia?
Autoimmune damage to gastric parietal cells causing atrophic gastritis and consequent decreased production of intrinsic factor needed for b12 absorption in the terminal ileum.
Pernicious anaemia can be associated with other autoimmune diseases (e.g. Vitiligo, hypothyroidism)
Management of pernicious anaemia
IM hydroxycobalamin (3x wkly for 2 weeks, then every 3 months for life)
Complications of pernicious anaemia
Increased risk of gastric cancer
Definition of aplastic anaemia
Characterised by diminished haematopoietic precursors in the bone marrow and deficiency of all blood cell elements (pancytopaenia)
Causes of aplastic anaemia
- Idiopathic (>40%) - may be due to destruction or suppression of the stem cell by autoimmune mechanisms
- Acquired
- Drugs (chloramphenicol, gold, alkylating agents, antiepileptics, sulphonamides, methotrexate, nifedipine)
- Chemicals (DDT, benzene)
- Radiation
- Viral infection (B19 parvovirus, HIV, EBV)
- paroxysmal nocturnal haemoglobinuria - Inherited
- Fanconi’s anaemia
- Dyskeratosis congenita (associated with reticulated hyperpigmented rash, nail dystrophy and mucosa leukoplakia)