anaemia Flashcards
what is anaemia?
anaemia is a reduction in haemoglobin in the blood
What are reasons for haemoglobin issues?
inability to make haem (iron deficiency) to inability to make correct globing chains (sickle cell anaemia/thalassemia)
What are the causes of anaemia?
- reduced production of haemoglobin
- increased losses of haemoglobin
- increased demand for haemoglobin (due to increase in tissue or increase tissue metabolism rate)
What may indicate the cause of anaemia?
size of RBCs (MCV)
Give 2 examples of haemoglobinopathies.
thalassemia and sickle cell disease
what does autosomal recessive mean? Give an example of an autosomal recessive disease.
- the disease only occurs if maternal and paternal pass on the defect gene
- sickle cell anaemia
what mutation causes sickle cell anaemia?
point change mutation in beta globing chain
Complications of sickle cell anaemia?
RBCs change shape in reduced oxygen levels preventing them from passing through capillaries. This blocks circulation causing pain, ischaemia and necrosis.
The abnormal haemoglobin chains function normally at standard oxygen levels.
Describe the difference between heterozygous and homozygous in sickle cell anaemia.
Heterozygous means they carry one abnormal allele and do not display symptoms (sickle cell trait)
Homozygous means they carry 2 abnormal alleles, have sickle cell disease and display symptoms.
What are haematinics?
Used to make RBCs, Folic acid, iron and vitamin B12
Give examples of production failure causing anaemia.
Bone marrow failure -> reduced RBC -> not enough RBC to package haemoglobin into
Reduced haemoglobin due to deficiencies in elements needed to make haemoglobin - iron, folic acid, vit B12
Describe non-haem iron?
- iron 2+ or 3+ valency
- can only be absorbed by conversion from 3+ to 2+ first then through specific haem transporter system
- non-haem iron is harder for body to deal with than haem iron
How is iron stored in a cell?
stored as ferritin then passed into blood for circulation and reprocessing
How are RBCs reprocessed?
reprocessed through macrophages and then into bone marrow through the haem reprocessing system to allow new RBCs and haem to be made.
what is achlorhydria?
- disease reducing iron absorption
- lack of stomach acid
- no conversion of non-haem iron
how does coeliac disease reduce iron absorption?
affects intestinal villi and therefore the body’s ability to absorb iron
How can iron loss occur?
- bleeding into GI tract
- bleeding elsewhere in body
- gastric erosions and ulcers
- inflammatory bowel disease (ulcerative colitis and Crohn’s)
- haemorrhoids
- bowel cancer
how is vit b12 absorbed?
- secretion of intrinsic factor by gastric parietal cells
- vit b12 from diet binds to intrinsic factor
- passes to terminal ileum where it is absorbed by specific transporting system
How does vit B12 deficiency occur?
- comes from meat and dairy so lack of intake
- vegans have issue
- lack of intrinsic factor in stomach
- disease of terminal ilium e.g. Crohn’s
- monthly injections to treat
where is folic acid absorbed?
- small bowel (same as iron)
- diseases affecting iron absorption also affect FA absorption