It is useful to divide the causes of anaemia up on the average size of the red blood cell (the mean corpuscular volume):
This can be remembered using the mnemonic
: Foetus (pregnancy), Alcohol, Thyroid, Reticulocytosis, B12/Folate, Cirrhosis.
Acute blood loss, anaemia of chronic disease, marrow infiltration, haemolysis
"Find Those Small Cells"
is useful: Fe deficiency, Thalassaemia, Sideroblastic anaemia, Chronic disease.
Iron Deficiency Anaemia
The absorption of iron daily is 1g. The total body iron is 4mg, 3mg of
which is stored in haemoglobin, and 1mg of which is stored in
Common causes of iron deficiency anaemia include:
Physiological: growth, pregnancy
Blood loss: peptic ulcer, fibroids
Malabsorption: eg celiac
The general clinical features of anaemia include: fatigue, dizziness,
shortness of breath, palpitations, angina. The specific features of
iron deficiency anaemia are: angular stomatitis (sores and cracks
around mouth), glossitis (smooth red sore tongue), koilonychia (spoon
Microcytic hypochromic anaemia.
Low serum ferritin (Fe store in liver proportional to Fe in body) and low Fe
Increased serum transferrin and total binding capacity.
Decreased transferrin saturation.
Absence of Fe stores on bone marrow smear
If the patient is a man, or a post-menopausal woman, then an endoscopy
may be indicated to exclude gastrointestinal blood loss
Pale, small red cells
If no cause is found then the treatment is replacement with oral iron.
Anaemia of chronic Disease
This causes a mild to moderate anaemia and has a multifactorial
aetiology. It is thought that the main process is a failure to
transport iron from reticuloendothelial cells to red blood cells. On
investigation it is distinguished from iron deficiency anaemia by a
normal or raised serum ferritin. Causes include chronic
infection/inflammation, malignancy, uraemia and endocrine disorders.
Treatment is of the underlying cause. Eryothropoetin is also sometimes
This occurs when
there is marrow infiltration, meaning that insufficient haemopoiesis of
red blood cells is possible. An example is myelofibrosis. Immature
cells (myelocytes and normoblasts) seen on the peripheral blood film.
Immature (nucleated) red blood cell, and immature white blood cell
This is a deficiency of B12 or folate, both which are needed for DNA synthesis .
B12 is absorbed by combining to Intrinsic Factor, which is secreted by
gastric parietal cells. Thus if there is a lack of either B12 or
Intrinsic factor then anaemia will result. Common causes:
Intrinsic Factor deficiency
Pernicious anaemia (antibodies to parietal cells in the stomach), gastrectomy, congenital deficiency
Diseases of terminal ileum (eg Crohns), blind loops (post surgery),
small bowel diverticulae (if colonised then bacteria eat up B12)
Presentation is with anaemia (which can be very low in pernicious anaemia). A peripheral neuropathy termed
subacute combined degeneration of the spinal cord
can result, resulting in weakness. This does not occur with folate deficiency, and a way to remember it is: B12 - Brain.
Low serum B12.
Blood film: megaloblastic changes.
Pernicious anaemia: parietal cell antibodies, IF antibodies.
Schilling test, to distinguish between whether the B12 deficiency is
due to lack of Intrinsic Factor. Oral radiolabelled B12 is given with
intramuscular non-radiolabelled B12. The intramuscular B12 saturates
B12 binding proteins in the
plasma promoting urinary excretion of radiolabelled B12. Next urine is
collected after 24h (anything in urine has been absorbed). If there is
less than 10% oral B12 excreted (ii.e. present in the urine), then
absorption is impaired. The test is repeated once Intrinsic Factor has
been given. If the deficiency due to lack of IF then B12 absorption
will be high
More than 7 lobes on a neutrophil
Folic Acid Deficiency
Presentation is very similar to B12 but there is no neurological involvement. Investigation is serum folate.
Diet: Common in old, institutions, alcoholics (malabsorption, malnutrition)
Utilisation (ie DNA synthesis): Pregnancy, malignancy, haem disorders
Malabsorption: eg coeliac
Drugs: OCP, anticonvulsants
Excessive loss: eg dialysis