introduction to anaemia Flashcards
what is anaemia?
when the haemoglobin concentration falls below defined level (outside normal range)
what are the units of haemoglobin?
g/L
what are 3 causes of anaemia?
- lowered Hb content
- lowered red blood cell count
- altered Hb does not carry sufficient O2
what is the normal haemoglobin range in children?
110-160g/L
what is the normal haemoglobin range in women?
115-165g/L
what is the normal haemoglobin range in pregnant women?
110-160g/L
what is the normal haemoglobin range in men?
130-180g/L
what are the symptoms of anaemia?
- fatigue
- shortness of breath
- palpitations
- headache
- worse: acute bleed/haemolysis
what are the signs of anaemia?
- skin pallor
- pale conjuncitvae
- tachypnoea
- tachycardia
what are the 2 main causes of anaemia?
- problems of inadequate synthesis
- problems of blood loss or consumption
what causes problems of inadequate synthesis?
- deficiency in necessary components (iron, B12 and folic acid)
- bone marrow dysfunction/infiltration
what causes problems of blood loss of consumption?
- bleeding
- haemolytic (increased red cell destruction or shortened RBC lifespan)
what are the 3 classifications of anaemia?
- size of red blood cell
- acute or chronic
- underlying aetiology
what is the most common type of anaemia?
iron deficiency
what are the causes of iron deficiency?
- bleeding
- nutritional deficiency
- increased requirements
what iron studies do you do to confirm iron deficiency?
- Ferritin
- Serum Fe
- Transferrin
- Transferrin saturation %
what is the serum ferritin diagnostic test?
- storage form of iron
- low = iron deficient
what is the serum iron diagnostic test?
labile in blood, so reflects recent intake of iron
what is the serum transferrin diagnostic test?
- carrier molecule for iron from gut to stores
- homeostatically goes up if iron is deficient
- reflects total iron binding capacity of the blood
what is the % transferrin saturation diagnostic test?
- sensitive measure of iron status
- reflects proportion of transferrin with iron bound
- low TF saturation indicates iron deficiency
what are the 3 causes of iron deficiency in the UK?
- bleeding (GI, menstrual, renal tract)
- inadequate intake
- increased requirements (pregnancy)
what is the mean corpuscular volume?
- this is the size of the red blood cells
- usually about 80-100fL
what are microcytic red blood cells?
- small
- iron deficiency
- inherited disorders of haemoglobin (beta-thalassemia trait)
what are macrocytic red blood cells?
- large
- B12 and folate deficiency
- myelodysplasia (causes defective erythropoiesis)
what are normocytic red blood cells?
- normal
- anaemia of chronic disease
- acute haemorrhage
- renal failure (caused by low erythropoietin levels)
what is a blood film good for and why?
- quick, easy and useful
- microcytic/macrocytic
- hypochromic
- sickled cells
- polychromasia
- white cells, platelets, leukaemic cells
how long do red blood cells circulate in the blood?
100-120
what is a reticulocyte count?
reticulocytes represent newly produced RBC ~1 day old
how can you calculate the reticulocyte count?
- calculated on a blood film using a stain to detect RNA
what is a reticulocyte count used for?
- the rate of production of RBCs by bone marrow
- low during percursor deficiencies
- low if bone marrow is infiltrated
- high in chronic bleeding
- high is haemolysis
- useful to monitor response to treatment
what is red blood cell production driven by?
erythropoietin from kidney
what history do you need to take when anaemia suspected?
- GI symptoms
- menstrual history
- bowel history
- dietary history
- travel history
- ethnic origin
- family history
what is megaloblastic anaemia?
anaemia caused by deficiency of vitamin B12 and folate
what is B12 needed for?
- DNA synthesis
- results in impaired cell division when it lacks
what are hyper-segmented neutrophils?
neutrophils with more than 4 nuclear lobes
what is B12 deficiency caused by (mechanism)?
when the body cannot absorb B12 in terminal ileum where IF receptors are located
how do you treat B12 deficiency?
B12 injections, load initially with 5 doses alternate days then every 3 months
what causes vitamin B12 deficiency?
- pernicious anaemia
- dietary
- malabsorption (coeliac disease and Crohn’s disease)
what causes folate deficiency?
- dietary
- malabsorption
- excess utilisation
- alcohol
- drugs
what are the common causes of anaemia of chronic disease?
- chronic inflammation
- chronic infection
- auto-immune conditions
- cancer
- renal failure
- poor utilisation of iron in the body
- dysregulation of iron homeostasis
- impaired proliferation of erythroid progenitors
what is the most common form of anaemia in hospitalised patients?
anaemia of chronic disease
what does it mean if there is poor utilisation of iron in the body?
- iron is stuck in macrophages of the reticuloendothelial system
- there is poor mobilisation of the iron from the stores into the erythroblasts
what is dysregulation of iron homeostasis?
- decreased transferrin
- increased ferritin
- increased hepcidin
what is impaired proliferation of erythroid progenitors?
- blunted response EPO (erythropoietin)
- iron is functionally unavailable
what is sickle cell anaemia?
point mutation in the beta globin gene causing HbS (sickle Hb)
how does sickle cell anaemia affect the red blood cells?
- increases the turnover of red cells
- survival is approximately 20 days due to haemolysis
what is a sickle cell crisis?
- it is triggered by low blood O2 level
- vaso-occlusive due to sickling in the vessels
- causes ischaemia leading to pain, necrosis and potential organ damage
how do you manage sickle cell anaemia?
analgesics, hydration, transfusion
what type of disease is sickle cell anaemia?
autosomal recessive
what is the mechanism of sickle cell anaemia?
- mutated sickle haemoglobin
- forms long filamentous strands
- insoluble at low O2 tension
- RBCs become inflexible + spiky leading to crisis
what is the sickle cell trait?
- heterozygous
- 50% HbS and 50% HbA
- much lower risk of sickling and crisis
- resistance to malaria infection
what is thalassaemia?
- insufficient production of normal Hb
- imbalance of alpha and beta chains
- inherited autosomal recessive
what are the clinical features of thalassaemia?
- enlarged spleen, liver and heart
- may be misshapen (frontal bossing)
what is beta-thal major?
- homozygous
- requires long-life transfusions
what is beta-thal minor?
- heterozygous
- carrier
- clinically healthy
what are the character indicies of beta-thalassaemia?
- microcytic
- hypochromic
what are the 3 types of bone marrow infiltration?
- leukaemia
- lymphoma
- myeloma
why is bone marrow sample obtained from iliac crest?
- aspirate film for morphology of cells
- trephine biopsy for histological section
how do you treat chronic anaemia?
erythropoietin (EPO) weekly sib-cut injections in patients receiving haemodialysis or with kidney failure
what are the long-term transfusion causes of chronic anaemia?
- iron overload
- allo-antibodies
what is the worldwide impact of anaemia?
- increased risk of morbitiy in children
- impaired physical and cognitive development
- poor pregnancy outcome
- contributes to 20% of all maternal deaths
- reduced work productivity in adults
