Dr Wrishi Raphael
Anaemia is regarded as a masquerade because the problem can develop surreptitiously and the patient may present with many seemingly undifferentiated
symptoms before the anaemia is detected. Once identified, a cause must be found .
Clinical features
Patients with anaemia may be asymptomatic. When symptoms develop they are usually nonspecific.
Symptoms can include:
tiredness or fatigue
muscle weakness
headache and itching
lack of concentration
faintness or dizziness
dyspnea on exertion
palpitations
angina on effort
intermittent claudication (condition in which cramping pain in the leg is induced by exercise, typically caused by obstruction of the arteries)
pica or appetite for non food substances like paper, clay etc.
Classification of anaemia
The various types of anaemia are classified in terms of the red cell size-the mean corpuscular volume
(MCV) :
microcytic-MCV ≤ 80 fL
macrocytic-MCV >98 fL
normocytic-MCV 80-98 fL
Iron-deficiency anaemia
Iron deficiency is the most common cause of anaemia worldwide. It is the biggest cause of microcytic anaemia, with the main differential diagnosis of microcytic anaemia being a haemoglobinopathy such as thalassaemia
Haemoglobin E
This haemoglobin variant is common throughout South –East Asia. It has virtually no clinical effects in either the homozygous or heterozygous forms, but these people have microcytosis, which must be distinguished from iron deficiency; moreover, if the HbE gene is combined with the thalassaemia gene, the child may have a lifelong anaemia almost as severe as thalassaemia major. Both genes are well established in the South-East Asian populations in Australia as well as in their own countries.
Thalassaemia
This inherited condition is seen mainly (although not exclusively) in people from the Mediterranean basin, the Middle East, north and central India and South-East
Asia, including south China. The heterozygous form is usually asymptomatic; patients show little if any anaemia and require no treatment. The condition is relatively common in people from these areas. The homozygous form is a very severe congenital anaemia needing lifelong transfusional support but is comparatively rare, even among the populations prone to thalassaemia. Homozygous is a word that refers to a particular gene that has identical alleles on both homologous chromosomes. It is referred to by two capital letters (XX) for a dominant trait, and two lowercase letters (xx) for a recessive trait. A diploid organism is heterozygous at a gene locus when its cells contain two different alleles of a gene. The cell or organism is called a heterozygote specifically for the allele in question, therefore, heterozygosity refers to a specific genotype
Macrocytic anaemia-MCV >98 fL
Drug toxicity
Cytotoxic drugs, anticonvulsants in particular, and various others may cause macrocytosis. This is of little clinical significance and does not need correction unless associated with anaemia or other cytopaenia.
Myelodysplastic syndromes
These conditions have been recognised under a variety of names, such as refractory anaemia' and 'preleukaemia', for a long time, but only relatively recently have they been grouped together. They are quite common in the elderly
but may be seen in any age group.
Vitamin B12 deficiency (pernicious anaemia)
Although well recognised, this is a much less common cause of macrocytosis than the foregoing conditions. It is usually caused by lack of intrinsic factor due to autoimmune atrophic changes and by gastrectomy. Anaemia does not develop for about 3 years after total gastrectomy. Vitamin B 12 deficiency may also be seen together with other deficiencies in some cases of malabsorption and Crohn disease.
Normocytic anaemia (anaemias without change in the MCV)
Acute haemorrhage
This is the most common cause of normocytic anaemia and is usually due to haematemesis and/or melaena.
Chronic disease
Chronic inflammation
Intercellular iron transport within the marrow is suppressed in inflammation so that, despite normal iron stores, the developing red cells are deprived of iron
and erythropoiesis is depressed. If the inflammation is short-lived, the fall in Hb is not noticeable but, if it continues, an anaemia may develop that responds only
when the inflammation subsides.
Malignancy
Anaemia may develop for the same reasons that apply to chronic inflammation.
Kidney failure
This is often associated with anaemia due to failure of erythropoietin secretion and is unresponsive to treatment, other than by alleviating the insufficiency
or until erythropoietin is administered.
The writer can be reached at: [email protected]