Microcytic Anaemia Flashcards
.. anaemia describes the presence of a reduced haemoglobin concentration and a reduction in the mean corpuscular volume (MCV).
Microcytic anaemia describes the presence of a reduced haemoglobin concentration and a reduction in the mean corpuscular volume (MCV).
There are numerous causes of a microcytic anaemia:
Iron-deficiency anaemia (IDA)
Anaemia of chronic disease
Thalassaemias (e.g. alpha / beta)
Iron-deficiency anaemia
IDA is commonly seen in women of child-bearing age and children across the world. Premenopausal females are particularly at risk because of the loss of iron during menstruation and pregnancy.
In the developed world, it is estimated that 2-5% of adult men and postmenopausal women suffer from IDA.
Dietary deficiency of iron is uncommon in the developed world because of adequate access to dietary components such as meat. Where meat is not a core component of the diet, the prevalence of IDA is … greater.
Dietary deficiency of iron is uncommon in the developed world because of adequate access to dietary components such as meat. Where meat is not a core component of the diet, the prevalence of IDA is 6-8 times greater.
The total iron content within our body is approximately 3-4 grams, which is distributed among different structures:
Hb: 2-3 grams
Plasma iron (e.g. bound to transferrin): 3-7 mg
Iron-containing proteins (e.g. myoglobin): 300-400 mg
Stored iron (e.g. ferritin, haemosiderin): 1 gram
The major causes of IDA can be grouped into three categories:
Increased requirements (e.g. pregnancy, lactation) Increased loss (e.g. gastrointestinal bleeding) Decreased uptake (e.g. dietary deficiency, malabsorption)
Classical signs of IDA include …
Classical signs of IDA include glossitis, koilonychia (spoon-shaped nails), angular stomatitis, and conjunctival pallor.
Interestingly, some children with IDA may be found to have peculiar dietary cravings (..) for materials such as soil, clay, or chalk. Whether this is a cause or consequence of IDA is not fully understood.
Interestingly, some children with IDA may be found to have peculiar dietary cravings (pica) for materials such as soil, clay, or chalk. Whether this is a cause or consequence of IDA is not fully understood.
Iron studies include: ..
Iron studies include: serum iron, ferritin, and iron-binding globulin (transferrin).
Serum iron, ferritin, and transferrin levels are essential in the diagnosis of..
Serum iron, ferritin, and transferrin levels are essential in the diagnosis of IDA.
Management of IDA should involve investigation into the underlying cause & replacement of iron.
Male and postmenopausal female patients with unexplained IDA should be investigated for suspected gastrointestinal malignancy (or indeed benign GI pathology). The upper gastrointestinal tract is more commonly the site of pathology than the lower gastrointestinal tract.
Oral replacement of iron in the form of ferrous fumarate or ferrous sulfate are common pharmacotherapies. Follow-up blood tests should always be completed to assess for response to treatment and patients should be warned about side-effects. These may include constipation, black stools, diarrhoea, nausea, and dyspepsia/epigastric discomfort.
Oral replacement of iron in the form of…
Oral replacement of iron in the form of ferrous fumarate or ferrous sulfate are common pharmacotherapies.
Anaemia of chronic disease
Anaemia of chronic disease (ACD) is a complex and multi-factorial condition due to a chronic inflammatory process from underlying infection, malignancy or systemic disease.
ACD is the second most common cause of anaemia worldwide, and commonly seen among hospitalised patients.
Aetiology & pathophysiology
Anaemia of chronic disease
ACD is classically described as a normocytic, normochromic anaemia secondary to systemic diseases, infection or malignancy.
Hepcidin
Hepcidin is the normal regulator of iron absorption from enterocytes and the tissue distribution of iron. It is an acute phase protein that usually works to reduce the availability of iron from infecting microorganisms.
Chronic inflammation mediated by IL-6 can lead to a …-induced block of iron absorption and iron release from macrophages. This reduction in the availability of iron for the production of erythrocytes as part of erythropoiesis can lead to a microcytic anaemia. However, this is only seen in 25% of cases.
Chronic inflammation mediated by IL-6 can lead to a hepcidin-induced block of iron absorption and iron release from macrophages. This reduction in the availability of iron for the production of erythrocytes as part of erythropoiesis can lead to a microcytic anaemia. However, this is only seen in 25% of cases.
The clinical presentation of ACD is generally that of the underlying disorder, and unless the haemoglobin concentration is severely reduced, patients may be asymptomatic.
If present, clinical features are typical of all anaemias including fatigue, headache and dizziness. If severely symptomatic, patients may develop palpitations, angina or dyspnoea.
Key investigations in ACD include the FBC, CRP, haematinics, iron studies and blood film.
The FBC may show a normocytic normochromic anaemia (approx. 75%) or the development of a microcytic anaemia (approx. 25%). In ACD, the MCV is rarely below 70 fL.
Similar to IDA, serum iron, ferritin and transferrin are vital for the diagnosis of ACD.
The beta-thalassaemias are a heterogenous group of conditions that result from a reduced or absent production of beta-globin chains.
The prevalence of the beta-thalassaemias varies widely depending on the ethnic population. Beta-thalassaemia is seen more commonly in African, Mediterranean and South-east Asian populations.
Clinical features tend to reflect the severity of beta-thalassaemia. Patients with beta-thalassaemia major tend to have marked extramedullary haematopoiesis and complications secondary to iron overload from repeated transfusions.
Extramedullary haematopoiesis Hepatomegaly Splenomegaly Skeletal abnormalities Iron overload Hypogonadism Growth failure Diabetes mellitus Hypothyroidism
The diagnosis of beta-thalassaemia is confirmed with haemoglobin …
The diagnosis of beta-thalassaemia is confirmed with haemoglobin electrophoresis.
Patients with beta-thalassaemia major will require ..
Patients with beta-thalassaemia major will require early, frequent blood transfusions. Other management options include splenectomy and hematopoietic stem cell transplantation. Patients receiving recurrent transfusions may suffer with iron overload and require iron chelation therapy.
Other causes of microcytic anaemia include sideroblastic anaemia, lead poisoning and other haemoglobinopathies.
Sideroblastic anaemia can be congenital (X-linked recessive) or acquired. It results in the inclusion of a perinuclear ring of coarse iron-containing granules (‘ring-sideroblasts’) within erythrocyte progenitors.
Acquired causes may be seen in myelodysplastic syndromes or following the use of pharmaceuticals such as isoniazid or chloramphenicol.
Lead poisoning is an uncommon cause of microcytic anaemia that can cause a reduction in the synthesis of haem and a reduced lifespan of erythrocytes.
… poisoning is an uncommon cause of microcytic anaemia that can cause a reduction in the synthesis of haem and a reduced lifespan of erythrocytes.
Lead poisoning is an uncommon cause of microcytic anaemia that can cause a reduction in the synthesis of haem and a reduced lifespan of erythrocytes.
… anaemia can be congenital (X-linked recessive) or acquired. It results in the inclusion of a perinuclear ring of coarse iron-containing granules (‘ring-sideroblasts’) within erythrocyte progenitors.
Sideroblastic anaemia can be congenital (X-linked recessive) or acquired. It results in the inclusion of a perinuclear ring of coarse iron-containing granules (‘ring-sideroblasts’) within erythrocyte progenitors.
