3 Red cell disorders Flashcards
Define anaemia
It is a reduced level of haemoglobin
- common clinical conditions
List the symptoms of anaemia (depend on severity)
- Shortness of breath
- Weakness/Lethargy
- Tachycardia
[Skin colour is not a reliable sign - as this is determined by blood flow] - Nail bed and conjunctiva may be pale
Severe anaemia in elderly subjects may cause angina
- Glossitis (pain red tongue) + angular cheilitis (fissures at the corner of mouth)
- DPG may be elevated in RBC’s so O2 is more readily given up to tissues
Describe Iron deficiency anaemia
(Fe is needed for haemoglobin)
Fe deficient anaemia is a Form of Microcytic anaemia:
- decreased mean corpuscular volume
List some causes of Iron-deficiency anaemia
Causes:
(normally diet = need AND input = output)
BUT;
- If input reduced - poor diet, surgical removal of the stomach
- OR output increased:
> menstruation, GI bleeding (ulcers from use of NSAIDs), colon cancer (50% seen with anaemia)
- OR demand increased (pregnancy):
> There may be iron deficiency, when bone marrow + macrophage Fe stores depleted, then anaemia occurs (or folate deficiency - macrocytic anaemia)
Explain how chronic inflammation may lead to chronic disease anaemia
If there is an inflammatory condition of the bowel -
- The inflammation causes the release of cytokine IL-1 and IL-6
- This affects the production of the enzyme hepcidin, which regulates the uptake of iron
This is another form of microcytic anaemia
How can Fe-deficient anaemia be differentiated from chronic disease anaemia?
Doing a blood test:
- The iron storage is measured in the bloodstream by ferritin (levels)
- Microcytic anaemia and low ferritin levels mean = Fe deficient anaemia
- Microcytic anaemia and normal ferritin levels mean = Chronic disease anaemia
Describe the differences between acute and chronic bleeds
Acute - rapid blood loss e.g. haemorrhage
- Severe loss of blood
- BP falls
- Over time there is haemodilution
Chronic - long term bleeding e.g. gastric bleeding/excessive menstruation
- Regular basis - does not drop BP
- V rarely causes haemodilution
As chronic bleed gives the body time to adapt (due to longer time)
- In acute blood loss - lose a bit of everything
- So chronic - compensate with the loss of volume
Give some treatments of iron deficiency
- Find and treat the underlying cause (e.g. find the cause of GI bleed + stop etc.)
- Replace lost Fe - lost oral administration in form of FeSO4 (ferrous sulfate)
> GI tract is the normal entry for FE entry in diet
> Guarantee longer time for efficacy
> If px is intolerant to Iron tablets, administer IV Fe - Prophylaxis in pregnancy - oral Fe with Folic Acid widely used
- Very rarely - transfusion needed
> If Fe deficiency is not diagnosed for a long time, and anaemia is long term
Describe Renal Anaemia
The kidney responds to the level of RBC, so if RBC is low, the kidney releases more EPO (erythropoietin)
- BUT if the kidney is affected by a condition where its function is impaired
- The EPO level will drop
- Leading to the development of renal anaemia - ‘Normocytic anaemia’
Treatment
- with Fe and EPO (leads to the stimulation of the bone marrow to produce RBCs)
Discuss pregnancy and anaemia
There could be a potential Fe and Folate deficiency
- Maybe normocytic anaemia as:
> Pregnancy increases MCV
> BUT iron deficiency decrease MCV
Describe megaloblastic anaemia
It is an abnormal RBC maturation due to defective DNA synthesis, that is out of step with cytoplasmic development: bone marrow megaloblasts (v large cells)
Describe macrocytic anaemia
It is due to Vit. B12 or Folate deficiency
- Increased incidence of alcohol abuse
It gives rise to anaemia, jaundice (excess breakdown of Hb due to ineffective erythropoiesis)
Explain the significance of Vit. B12
Vitamin B12 is an essential cofactor for purine and pyrimidine synthesis (cell division).
- Comes from animal products
- Requires (Castle’s) intrinsic factor for absorption (absent after gastrectomy)
Explain the significance of folate, and its uses
Folate (folic acid) - essential for thymidylate synthesis
- (a rate-limiting step in DNA synthesis, as thymidine, is a pyrimidine base)
- It is found in most food (especially the liver, greens, yeast, marmite)
Drugs that can affect this process:
- Methotrexate - inhibits dihydrofolate reductase (therefore folate regeneration is impaired - treat with folinic acid)
Vit B12 and Folate come from diet
- if there is a poor diet, replace B12 or Fe orally (intake problem)
- BUT if malabsorption) - IV, intramuscular
Describe haemolytic anaemia
It is an increased rate of RBC destruction
Potential causes:
- Spherocytosis - genetic; abnormal reduction in RBC membrane protein (spectrin) - cells become fragile
- Acquired - hemolytic transfusion reaction, malaria, drug-induced
- Jaundice and enlarged spleen
