Anaemia Flashcards
What is anaemia?
reduced total red cell mass, Hb is a surrogate marker for this
How can anaemia be measured?
using Hb concentration or haematocrit (ratio of the whole blood that is red cells if the sample was left to settle)
Anaemias can be classified by MCV (mean cell volume) as ________
normocytic, (hypo chromic) microcytic or macrocytic
Hypochromic microcytic anaemia is due to _________
deficient Hb synthesis, a cytoplasmic defect, defects in Hb result in small cells, the cells keep dividing as they try to accumulate Hb
What is the most common cause of microcytic anaemia?
iron deficiency anaemia
What is the second most common cause of microcytic anaemia worldwide?
thalassaemia
List all the main causes of microcytic anaemia?
TAILS
thalassaemia, anaemia of chronic disease, iron deficiency, lead, sideroblastic anaemia
What are the potential causes of iron deficiency anaemia?
diet, malabsorption or chronic blood loss
What are some causes of chronic blood loss?
menorrhagia, GI bleeding, haematuria
Macrocytic anaemia is due to a problem with ______
maturation
Macrocytic anaemia can be ____________
megaloblastic or non-megaloblastic
What is a megaloblast?
an abnormally large nucleated red cell precursor with an immature nucleus
What are megaloblastic anaemias characterised by?
a lack of red cells due to predominant defects in DNA synthesis and nuclear maturation in developing precursors in the bone marrow
Explain how megaloblasts cause a macrocytic anaemia?
the megaloblast cytoplasm still develops and they accumulate Hb, once Hb level in the cell is optimal the nucleus is extruded leaving a bigger than normal red cell i.e. a macrocyte
Why do megaloblasts cause an anaemia?
compared to normal precursors megaloblasts have reduced division and increased apoptosis which is what causes the anaemia
The larger cell size in megaloblastic anaemia is due to what?
failure of precursors to get smaller NOT an increase in size
What are the two major causes of megaloblastic macrocytic anaemia?
B12 or folate deficiency
Explain the role of B12 and folate?
they are essential cofactors in linked biochemical reactions regulating
1) DNA synthesis and nuclear maturation (this is what causes the blood cell effect)
2) DNA modification and gene activity (what causes the nervous system effect)
What are dietary sources of B12?
animal products e.g. meat, fish, milk, cheese, eggs
What are dietary sources of folate?
liver, leafy veg and some fortified cereals
___1_____ secreted by gastric parietal cells is what allows B12 to be absorbed
B12 is absorbed in the _____2_____
1) intrinsic factor
2) ileum
Folate is absorbed in the ___________
duodenum and jejunum
Body stores of B12 last ___1_____
Body stores of folate last __2_____
1) 2-4 years
2) 4 months
Why do symptoms of B12 deficiency take longer to manifest than folate?
Body stores of B12 are longer (2-4 years vs 4 months) so can have to be deficient for several years before stores can no longer meet demand
How can you assess for B12 or folate deficiency?
measure serum folate or B12
List some causes of B12 deficiency?
diet (vegan)
pernicious anaemia
surgical resection of the small bowel
gastrectomy
List some causes of folate deficiency?
diet, malabsorption in coeliacs or crohns, excess utilisation when stores are low (e.g. haemolysis, exfoliating dermatitis, pregnancy, some malignancies), certain drugs such as AEDs can cause folate deficiency too
What is the most common cause of B12 deficiency in adults?
pernicious anaemia
What is pernicious anaemia?
an autoimmune condition causing destruction of the gastric parietal cells resulting in intrinsic factor deficiency so malabsorption of B12
What is pernicious anaemia associated with?
personal or family history of other autoimmune diseases e.g. atrophic gastritis, vitiligo, addisons and hypothyroid
Is diet more likely to be an issue in folate or B12 deficiency?
folate- because body stores are lower
Who does folate deficiency often occur in?
alcoholics
What can you check for in pernicious anaemia?
anti-gastric parietal cell and anti-intrinsic factor
What are the causes of non-megaloblastic macrocytic anaemia?
alcohol, liver disease, hypothyroidism - these are not always associated with an anaemia and can cause macrocytosis on own
marrow failure is another cause and this will always be associated with an anaemia
When can spurious anaemias occur?
when there are increases/ decreases in plasma volume which affect the Hb conc relative to the plasma
What can cause a spurious macrocytosis?
acute blood loss or haemolysis- there are increased reticulocytes which may raise MCV
cold agglutinins- abnormal proteins produced in infection or cancer cause clumping of cells when not at body temperature
Symptoms of anaemia?
can be asymptomatic
fatigue, headaches, faintness
breathlessness
anaemia can exacerbate cardiorespiratory symptoms in the elderly causing angina, palpitations and intermittent claudication
Signs of anaemia?
pallor
tachycardia
systolic flow murmur
cardiac failure
Specific signs of iron deficiency?
brittle nails koilonychia (spoon nails) atrophy of the papillae of the tongue angular stomatitis brittle hair
Specific signs and symptoms of B12 and folate deficiency?
weight loss diarrhoea infertility glossitis pre-hepatic jaundice developmental problems with B12 only: posterior dorsal column abnormalities, neuropathy, dementia, psychiatric manifestations (these neurological manifestations can be irreversible)
Treatment of iron deficiency anaemia?
treat underlying cause
oral ferrous sulfate 200 mg tablets 2-3 a day
can experience GI side effects e.g. nausea, diarrhoea or constipation
monitor Hb and once returned to normal continue for a further 3 months
sodium feredetate is a liquid solution used in children
Treatment of B12 deficiency?
IM B12 injections can be given, at first get several over a couple of weeks and then move to every 3 months lifelong
Treatment of folate deficiency?
5mg folic acid daily, should be taken for 4 months to replace body stores, any underlying cause should be treated
List some causes of normocytic anaemia?
acute blood loss, anaemia of chronic disease, CKD, autoimmune RA, marrow infiltration/ fibrosis, endocrine disease, haemolytic disease
Alpha like genes are on chromosome ________ and their are ______ per chromosome meaning ________
16
2 genes
4 overall
Beta like genes are present on chromosome ______ and there _______ per chromosome meaning _______
11
1 gene
2 overall
Only _____ chains are present in both adult and fetal Hb
alpha
Adult levels of HbA are reached by ___________ and this explains why _______
6-12 months of age
beta chain problems dont manifest until this point
What are the haemoglobinopathies?
hereditary conditions affecting globin chain synthesis
hundreds of mutations
behave as autosomal recessive disorders
thalassaemias: decreased rate of globin chain synthesis (normal chains though)
structural Hb variants: normal production of abnormal globin chains e.g. HbS