Diagnostic Approach to Anaemia Flashcards
What is anaemia?
Low haemoglobin which is:
Men <13.5g/dl
Women <11.5g/dl
Symptoms of anaemia
Fatigue Dyspnoea Faint Palpitations Headache Tinnitus
Normally symptoms are due to cause more than anaemia
Outline the diagnostic approach to anaemia
FBC to confirm anaemia
MCV to categorise anaemia
Microcytic: iron panel
Normocytic: reticulocyte count to assess bone marrow
Macrocytic:
Peripheral blood smear to decide if megaloblastic or non-megaloblastic
Classifications of anaemia based on MCV
MCV <80fL: microcytic
MCV 80-100fL: normocytic
MCV >96: macrocytic
Causes of microcytic anaemia
IRON LAST
Iron deficiency Lead poisoning Anaemia of chronic disease Sideroblastic anaemia Thalassaemia
What is the most common cause of microcytic anaemia?
Iron deficiency
Investigation results seen in iron deficiency anaemia
Low serum iron
Low ferritin
High transferrin
High TIBC
Low TIBC SATURATION
Blood films can show poikilocytosis, target and pencil cells
Clinical features of iron deficiency anaemia
Fatigue SOB Palpitations Pallor Hair loss Atrophic glossitis Angular stomatis
What tests might you consider doing in someone with iron deficiency anaemia?
Occult blood tests, haemoglobin electrophoresis, anti-TTG
endoscopy/colonoscopy
Men of any age with a Hb under 110g/L should be referred under 2WW
Patients >60 should be referred for colonoscopy
Management of iron deficiency anaemia
Ferrous sulfate oral TDG 200mg.
Reticulocyte count will improve in 7 days and treatment should carry on for 5-6 months
What is sideroblastic anaemia?
Iron granules form a ring around the nucleus in developing erythroblasts due to a defect in haem synthesis
What type of anaemia does sideroblastic anaemia cause?
Hypochromic microcytic picture
Investigation findings in sideroblastic anaemia
Low TIBC
Raised serum iron
Hypochromic RBC’s
Ringed sideroblasts
Management of sideroblastic anaemia
Regular transfusions and iron chelation
What is the effect of haemolysis on reticulocyte count?
Increased as more RBC’s are produced by the bone marrow to try and compensate
Causes of normocytic anaemia
Anaemia of chronic disease
CKD/RA
Pregnancy (due to increased plasma volume)
Acute blood loss
Aplastic anaemia
Haemolytic anaemias
What is aplastic anaemia?
Bone marrow failure causes a normocytic anaemia, leukopenia and thrombocytopenia
Causes of aplastic anaemia
Phenytoin
Sulphonamides
Chloramphenicol
ALL
AML
Parvovirus
Hepatitis
Congenital is X linked recessive
Investigation findings in aplastic anaemia
Low reticulocyte count (as bone marrow can’t produce new RBC’s)
Neutropenia
Investigation for aplastic anaemia
Bone marrow biopsy
What are types of haemolytic anaemia?
Intrinsic defects: Haemoglobinopathies (sickle cell, HbC) Enzyme deficiencies (pyruvate kinase deficiency, G6PD deficiency) Membrane defects (paroxysmal nocturnal haemoglobinuria, hereditary spherocytosis)
Extrinsic defects: Autoimmune haemolytic anaemia Microangiopathic haemolytic anaemia Infections Mechanical destruction
What are the two categories of macrocytic anaemia?
Megaloblastic vs non megaloblastic
Megaloblastic:
Have large and immature nuclei due to delayed nuclear maturation with defective DNA synthesis
Non-megaloblastic:
Normal DNA synthesis and no hypersegmented neutrophils
Causes of megaloblastic macrocytic anaemia
Vitamin B12 deficiency
Folate deficiency
Myelodysplasia
What is the neurological consequence of vitamin B12 deficiency?
Subacute combined degeneration of the spinal cord
Affects the pyramidal and dorsal columns
Symmetrical polyneuropathy
Causes of vitamin B12 deficiency
Inadequate intake:
Poor diet
Vit B12 comes from animal sources mainly milk, eggs etc
Malapsorption:
Perncious anaemia
Gastrectomy
Congenital intrinsic factor deficiency
Intestinal causes:
Bacterial colonisation
Ileal resection
Crohn’s disease
What is pernicious anaemia?
Autoimmune gastritis and reduced secretion of intrinsic factor and acid
Often have antibodies to intrinsic factor and parietal cells
What investigations can you consider for someone with vitamin B12 deficiency?
Intrinsic factor antibody
Parietal cell antibodies
Serum gastrin levels
Upper GI endoscopy
Management of vitamin B12 deficiency
1mg IM hydroxocobalamin
*if folate AND B12 deficient, treat the B12 first to prevent neuropathy
What is the most common cause of vitamin B12 deficiency?
Pernicious anaemia
How much folate acid does the body store?
4 months worth
Why does pernicious anaemia lead to vitamin B12 defiency?
You have intrinsic factor antibodies which bind to intrinsic factor preventing vitamin B12 binding
You have gastric parietal cell antibodies which mean reduced acid production and atrophic gastritis
This leads to less intrinsic factor being produced and therefore less vitamin B12 absorption
What is vitamin B12 important for?
Production of blood cells
Myelination of nerves
What antibody test is most specific for pernicious anaemia?
Anti-intrinsic factor antibodies is highly specific
Anti-gastric parietal cell antibodies are sensitive but have low specificity
Causes of folate deficiency
Nutritional: old age, poverty and famine
Malabsorption: gluten induced enteropathy, dermatitis herpetiformis
Increased use: pregnancy, lactation, haemolytic anaemia, carcinoma, lymphoma, myeloma, Crohn’s, RA, malaria.
Excess urinary loss: congestive heart failure and chronic dialysis
Drugs: anticonvulsants and sulfasalazine
Mixed: liver disease and alcoholism
Causes of non-megaloblastic macrocytic anaemia
Pregnancy
Alcohol excess
Liver disease
Hypothyroid
Myeloma
Reticulocytosis
What are the associations of Plummer Vinson syndrome?
Iron deficient anaemia
Dysphagia (post cricoid)
Oesophageal webs
Causes of macroytosis
Alcohol
Aplastic anaemia
Cytotoxic drugs
Myeloma
Liver disease
Myxoedema
Pregnancy
Newborn
