Vitamin B12 is required for the maturation of red blood cells. It is absorbed in the body from the lower ileum. This absorption is facilitated by an enzyme known as ‘intrinsic factor’, secreted by the stomach. Animal foodstuffs are the main sources of dietary Vitamin B12.
Deficiency of Vitamin B12 in the body can be either due to inadequate dietary intake or impaired absorption from the ileum because of insufficient ‘intrinsic factor’.
Vitamin B12 deficiency can lead to a condition known as megaloblastic anaemia where most of the red blood cells fail to mature. These immature red blood cells are called megaloblasts and are destroyed easily.
Megaloblastic anaemia primarily due to deficiency of ‘intrinsic factor’ in the stomach is known as pernicious anaemia, also known as Addisonian Pernicious Anaemia.
This deficiency in intrinsic factor is usually due to an auto-immune disease where antibodies develop against the enzyme secreting cells in the stomach.
Features
- Pernicious anaemia is commoner in females than in males.
- Commonly seen between the age of 45 and 65 years,
- Weight loss is common although the patient may seem well nourished.
- Young females often have infertility.
- General features of anaemia like tiredness, easy fatigability, palpitations, visual disturbances, headache and dizziness may be present.
- In addition, there may be occasional soreness of the tongue and intermittent diarrhoea.
Diagnosis of Pernicious Anaemia
- Demonstrable antibodies against the intrinsic factor secreting cells of the stomach in about half of the patients.
- Decrease in the levels of serum Vitamin B12 .
- Blood film often shows a ‘dimorphic’ picture of macrocytic and microcytic anaemia.
- Examination of the bone marrow may show the presence of megaloblasts.
Addisonian Pernicious Anaemia Treatment
- Correction of the Vitamin B12 deficiency by administration of Hydroxocobalamin injections in doses of 1000 micrograms twice during the first week, followed by a weekly injection of 1000 micrograms for a further 4-6 weeks.
- Correction of the iron deficiency by oral iron supplements of 200 mg ferrous sulphate tablets containing 60 mg of elemental iron, to be taken thrice daily.
- Maintenance therapy – injections of 1000 micrograms once every three months for life and regular blood counts to done atleast once every year.
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