Approach to diagnosing anaemia Flashcards
what is anaemia
reduction in Hb concentration for what is normal to that individual
what tools can be used to diagnose anaemia
History and examination FBC Blood film Reticulocytes Haematinics - B12/folate/ferritin Bone marrow biopsy specialised tests eg HLPC in thalassaemia
how can anaemia be classified according to bone marrow function
measure reticulocytes
what does reticulocytosis in context of anaemia mean for bone marrow
bone marrow is active and trying to compensate for red cell loss or destruction
what does a low reticulocyte count in context of anaemia mean for bone marrow
there is a defect in bone marrow and it cannot compensate
there is reduced red cell production
what are causes of anaemia with reticulocytosis
haemorrhage
haemolysis
how can you differentiate between haemolysis and haemorrhage
haemorrhage = reticulocytosis only haemolysis = reticulocytosis AND breakdown products
what are the 2 main categories that cause anaemia with a low reticulocyte count
hypoproliferative
maturation abnormality
what are causes of maturation abnormality in anaemia
cytoplasmic defect - impaired haemoglobinisation
nuclear defect - impaired DNA synthesis and nuclear maturation
what size are cells with impaired haemoglobinisation
small/low MCV/microcytic
what size are cells with impaired DNA synthesis
large/high MCV/macrocytic
what size are cells that cause hypoproliferative anaemia
normocytic
why are cells with impaired haemoglobinisation microcytic?
Because they cannot make Hb, they dont reach the threshold needed to trigger enucleation.
Therefore, the cells keep dividing meaning they keep getting smaller hence microcytic cells
why are cells with impaired DNA synthesis macrocytic?
Cells have abnormal nuclei and so cell division is abnormal meaning there are fewer divisions resulting in fewer cells that are large. Failure to become smaller cells.
if reticulocytes are low, what is the next step investigation
red cell indices: MCV, MCH
what are causes of microcytic anaemia
insufficient Hb synthesis
Haem or globin
causes of haem deficiency
Fe deficiency: diet, bleeding, malabsorption
Porphyrin deficiency: genetic
causes of globin deficiency
Thalassaemias
alpha: trait, HbH, Hb Barts Hydrops fetalis
beta: trait, intermedia, major
what are causes of macrocytosis
alcohol
liver disease
hypothyroidism
what are causes of megaloblastic macrocytic anaemia
B12/folate deficiency
drugs
inherited
causes of non-megaloblastic macrocytic anaemia
marrow failure:
myelodysplasia - mutation in stem cells
aplastic anaemia
causes of spurious macrocytosis
reticulocytosis
cold agglutins
causes of hypoproliferative normocytic anaemia
marrow failure hypometabolic marrow infiltration renal impairment anaemia of chronic disease
what is renal anaemia
anaemia of chronic disease due to failure of EPO production
is there a single pathological mechanism for anaemia of chronic disease
no, multifactorial
what is the central process behind anaemia of chronic disease
inflammation
what are the mechanisms of anaemia of chronic disease
inflammation activates monocytes and T cells which produce pro inflammatory cytokines:
- increased hepatic synthesis of hepcidin causes degradation of ferroportin and so iron is trapped
- EPO production is reduced
- erythroid proliferation in marrow is inhibited
- haemophagocytosis by macrophages in induced
anaemia of chronic disease can sometimes be microcytic, true or false
true
if the predominant mechanism is increased hepcidin
what will the following results show in iron deficiency anaemia: serum iron transferrin % transferrin saturation ferritin MCV
serum iron - low transferrin - normal/low % transferrin saturation - low ferritin - low MCV - low (can be normal)
what will the following results show in anaemia of chronic disease: serum iron transferrin % transferrin saturation ferritin MCV
serum iron - low transferrin - normal/low % transferrin saturation - low ferritin - high/normal MCV - normal (can be low)
what are the steps to approaching anaemia in blood results
name, age, ethnicity, PC FBC - red cells, Hb, WBC, platelets Red cell indices - MCV, MCH Reticulocytes Blood film Haematinics Special tests / biopsy
