Overview of Anaemias Flashcards
Define anaemia.
Reduced blood haemoglobin concentration in relation to age, gender, physiological state, altitude.
What are the NZ reference ranges for female and male.
Female: 115 - 155 g/L
Male: 130 -175 g/L
Name the different types and values associated to each anaemia.
Mild: > 100g/L
Moderate: 70 - 100 g/L
Severe: < 70 g/L
List the patient symptoms of anaemia.
Mild - often none Weakness, fatigue Short of breath Heart racing, palpitations Pounding in head/headache Pallor of mucus membranes Feel cold If vascular disease is present - angina (ischaemic heart muscle pain, claudication - ischaemic leg pain)
List the clinical examination symptoms of anaemia.
Pallor of mucus membranes
Increased pulse rate
Severe anaemia - pulse rate increased, retinal haemorrhages, heart failure
Severe anaemia with co-existing vascular disease - myocardial ischaemia in ECG/exercise test, confusion - brain failure due to inadequate oxygen delivery
When examining blood screen data, what morphological changes need to be looked at?
Hb normal/reduced/raised? (normal/anaemia/polycythaemia)
Cell size normal? (microcytic/normocytic/macrocytic)
Hb content of red cells normal?
(hypochromic/normochromic)
Name the 3 patterns that are recognized as common forms of anaemia.
Hypochromic, microcytic
Normochromic, normocytic
Normochromic, macrocytic
Name the two patterns that do not commonly occur, but may occur as variants of hypochromic microcytic and normochromic normocytic anaemias.
Normochromic microcytic
Hypochromic normocytic
Name the classification of causes of anaemia.
Blood loss, followed by haemodilution - acute trauma, surgery
Impaired red cell production - disturbance of maturation of erythroblasts
- deficiencies of iron, folate, vitamin B12
- globin abnormalities
- disturbances of bone marrow/stem cell proliferation
Haemolysis - increased rate of RBC breakdown
- inherited: cell membrane, cell enzymes, some Hb abnormalities
- acquired (heterogenous) - antibodies (auto or allo), chemical damage, parasites (malaria), burns, chemical/drug etc
What forms the haem of haemoglobin?
Iron + Protoporyhyrin
What forms haemoglobin?
Haem + 2 alpha + 2 beta globin peptides
What causes erythroid hypoplasia?
Marrow failure, reduced erythropoietin e.g. renal failure, reticulocytes low
What causes haemolytic anaemia?
Shortened cell survival with secondary erythroid hyperplasia i.e. reticulocytes increased
What causes ineffective erythropoiesis?
Megaloblastic anaemia, reticulocytes, usually normal or mildly increased; many erythroblasts destroyed in marrow due to metabolic abnormalities arising in erythropoiesis
What are the causes of microcytic hypochromic anaemias?
Iron deficiency
- unable to make normal amounts of Hb
- reduced concenentration of Hb in red cells
- small, red cells that only have a low concentration of Hb
Thalassemias
- reduced production of alpha/beta globin peptide
- reduced concentration of Hb in red cells
- small red cells
Other causes are rare
Discuss the causes of macrocytic anaemias.
Megaloblastic anaemia
- delayed & abnormal maturation of all cells in the bone marrow & other tissues
- caused by deficiency of vitamins needed for nucleic acid metabolism
- folic acid & vit B12 are needed for thymidine synthesis
- many dividing cells die due to DNA copying errors during mitosis - caused by lack of nucleotides
- deficiency affects all tissues but blood abnormalities are the usual means for diagnosis
- megaloblastic marrow maturation due to folic acid or vit B12 deficiency
Discuss the causes of macrocytic anaemias. (megaloblastic)
Megaloblastic anaemia
- delayed & abnormal maturation of all cells in the bone marrow & other tissues
- caused by deficiency of vitamins needed for nucleic acid metabolism
- folic acid & vit B12 are needed for thymidine synthesis
- many dividing cells die due to DNA copying errors during mitosis - caused by lack of nucleotides
- deficiency affects all tissues but blood abnormalities are the usual means for diagnosis
- megaloblastic marrow maturation due to folic acid or vit B12 deficiency
Discuss the causes of macrocytic anaemias (non-megaloblastic)
Liver disease
- Increased cholesterol in red cell membrane - cells become larger
Marked increased in red cell production
- Haemolytic anaemias
- Younger red cells are larger, as red cells age they lose cell membrane and become smaller
- average cell size increases
Others
- Myelodysplasia - a premalignant condition that is common in the elderly
- others = uncommon
Discuss the causes of normochromic normocytic anaemia.
A large & heterogenous collection of anaemias
- Blood loss followed by haemodilution
- Anaemia of chronic disease (ACD) = secondary feature of an underlying disorder - chronic inflammation or cancer
- Anaemia of renal failure
- Anaemia in liver disease
- Haemoglobinopathies
- Haemolytic anaemias
Discuss anaemia after haemorrhage.
Bleeding causes a reduced blood volume.
- blood pressure in venules (and capillaries) falls
- net movement of fluid into vessels from tissues
- normally a balance exists across blood vessels wall
IV infusion of fluids and kidneys retain salt and water over several days
- replaces fluid in tissues
Outcome: fall in Hb concentration
- time: most occurs in first 24hrs, completed by 72 hours
Describe anaemia of chronic disease.
Normocytic normochromic
Tendency to microcytosis
- Mild to moderate anaemia: Hb above 90g/L
Main cause: Change in iron availability - low serum iron
- caused by liver release of a peptide - hepcidin
- reduced release of iron from stores: liver cells and macrophages of marrow, liver and spleen
- does not respond to iron therapy
- anaemia resolves if underlying condition settles
Frequency: very common
