Anemia

• Anaemia


  Decrease in the amount of Red blood cells (RBC)/haemoglobin in the blood
• Haemoglobin


  Oxygen carrying molecule in blood
• Full blood count


  Essential screening test to investigate suspected anaemia
• MCV (Mean Corpuscular Volume)


  First step to look at in a full blood count
• Full blood counts are commonly requested as part of a general screen in a patient who is unwell to screen for a variety of disorders – such as anaemia, infection, inflammation, nutritional status and bleeding
• A blood sample is taken from a vein in the arm or a finger-prick or heel prick (newborns) to perform a full blood count
• Haemoglobin


  Four subunits, two alpha and two beta, with iron and haem to bind 4 x O2
• Normal erythropoiesis


  1. Pluripotent stem cell

  2. Erythroid burst forming unit (EPO target)

  3. Erythroid colony forming unit

  4. Erythroblast

  5. Reticulocyte

  6. Erythrocyte
• Underlying causes of anaemia

  • RBC Loss without RBC destruction (Haemorrhage)
  • Deficient RBC production
  • Increased RBC destruction – Haemolytic Anaemias
• Haemorrhage


  RBC loss without RBC destruction due to trauma, disorders, menstrual flow, gynecological disorders, pregnancy, parasitism
• 100mls blood = 40 days Fe intake, in a western diet
• Regulation of Erythropoiesis


  Kidneys monitor blood oxygen, if renal tissue is hypoxic, Erythropoietin is produced by renal peritubular interstitial cells
• Factors necessary for erythropoiesis

  • Erythropoietin
  • Iron
  • Vitamin B12 (cyanocobalamin)
  • Folic Acid (folate)
  • Ascorbic acid (Vitamin C)
  • Pyridoxine (Vitamin B6)
  • Amino acids
• Recombinant Erythropoietin (RhuEPO)


  Used to treat anaemia in Chronic Kidney Disease, AIDS, Transplant, Cancer, Premature children
• EPO is abused by professional cyclists, causes increased blood viscosity, increases Blood pressure, increased heart workload, can lead to heart failure
• Haematocrit


  Percentage of red blood cells in the blood
• Iron deficiency anaemia


  Most common cause of anaemia, results in microcytic hypochromic anaemia
• Common Causes of Iron Deficiency anaemia

  • Lack of Iron in diet
  • Partial gastrectomy due to ulcers
  • Blood loss due to bleeding peptic ulcers, malignancy
  • Malabsorption syndromes like Cystic fibrosis, Coeliac Disease
• Iron Absorption


  Absorbed from the duodenum and upper jejunum, Vitamin C increases absorption by reducing dietary ferric (Fe3+) to ferrous (Fe2+) iron, Caffeine and other xanthines decrease absorption
• Normal iron levels are 12g/dL of blood, takes 40 days to obtain Iron in 100mls blood, Therapy is Ferrous Sulfate 200mg 3 times a day, will take 1-2 weeks to raise by 1g/dL
• Side effects of oral iron preparations

  • Nausea
  • Gastric discomfort
  • Constipation
  • Diarrhoea
  • Darkened stools
• Sideroblastic anaemias


  A group of conditions diagnosed by finding ring sideroblasts in the bone marrow, both Hereditary (rare) and acquired forms, main defect is reduced activity of enzyme 5-aminolevulinate synthase (ALAS) involved in haem synthesis
• Causes of acquired sideroblastic anaemia

  • Associated with other disorders like Myelodysplastic syndromes, Myeloid leukaemia, Myeloma, Collagen disease
  • Drugs and toxins like Alcohol, Isoniazid, Chloramphenicol, Lead poisoning
• Treatment of sideroblastic anaemia

  Main medication is Pyridoxine, if reversible remove offending agent, severe cases require Blood transfusions with iron chelating agent like desferrioxamine
• Megaloblastic (macrocytic) anaemia


  Due to lack of folic acid or vitamin B12, lack of either prevents formation of DNA so RBC production does not occur or occurs abnormally, results in macrocytic cells (large cells)
• Rings


  Also known as ring sideroblasts
• Causes of acquired sideroblastic anaemia

  • Associated with other disorders
  • Myelodysplastic syndromes
  • Myeloid leukaemia
  • Myeloma
  • Collagen disease
  • Drugs and toxins
  • Alcohol (e.g. the metabolite acetaldehyde lowers levels of ALAS and pyridoxal)
  • Isoniazid
  • Chloramphenicol
  • Lead poisoning
• Treatment of sideroblastic anaemia

  1. Main medication - Pyridoxine (may take months to see the benefit)

  2. If reversible (e.g. drugs and toxins) - remove the offending agent

  3. Severe cases - Blood transfusions (However there is a problem with iron overload - so a chelating agent - e.g. desferrioxamine is required)
• Megaloblastic (macrocytic) anaemia


  Due to lack of folic acid or vitamin B12
• Folate (folic acid) interacts with vitamin B12 and is essential for normal blood and nerve function
• Lack of either folate or vitamin B12 prevents formation of DNA so RBC production does not occur or occurs abnormally
• Macrocytic cells


  • Large cells which may have enough Hb, but are not concave and are fewer in number
  • Cannot take up or transport oxygen normally
  • More easily damaged - also contributing to the anaemia
• Pernicious anaemia


  Lack of vitamin B12
• Vitamin B12 absorption


  1. Must combine with intrinsic factor IF produced by the parietal glands of the stomach

  2. The combination enables binding to receptor and phagocytosis of the complex by the distal ileum cells
• Pernicious anaemia is usually a result of an autoimmune disease that destroys the parietal cells of the stomach
• Vitamin B12


  Must be ingested - is not synthesized in body
• Sources of vitamin B12


  • Meat
  • Eggs
  • Dairy products
• Vitamin B12 can also be administered by injection in pernicious anaemia as cyanocobalamin
• Groups at risk of dietary vitamin B12 deficiency

  • Elderly
  • Vegans
  • Alcoholics
• Vitamin B12 treatment


  1. In normal patients - orally

  2. In pernicious anaemia - vitamin B12 can be given via intramuscular injection or parenterally (IV)