This is a common medical problem, which may present with mild symptoms but in certain cases can become severe and life threatening (Anaphylaxis).
Allergy can be defined as the response of the body’s own immune system to certain usually harmless substances called allergens, some of the common allergens include pollens, house dust mites, cats and dogs, certain insect venoms such as bees and wasp stings, medications especially antibiotics like Penicillin, certain foods including eggs, nuts and rubber or latex used in making surgical gloves.
When the body comes in contact with a known allergen it produces certain proteins called ANTIBODIES or Immunoglobulin E (IgE). The antibodies are stored in the body, a process is called SENSITISATION and does not give rise to an allergic reaction. If however, the body is re-exposed to the allergen it reacts with the stored antibodies and this results in an allergic reaction which may be mild but in some cases become very severe and life threatening (called ANAPHYLAXIS).
Allergic reaction may be limited to the skin or it may be more generalised and may involve several organs and tissues in the body.
The common symptoms of an allergic reaction include the following:
- Skin rash or urticaria or ‘nettle rash’ which is itchy may be localised or generalised.
- Runny or blocked nose and sneezing (as in the case of hay fever).
- Watery, itchy eyes (common in hay fever).
- Swelling of the lips, tongue, throat and eyelids, sometimes resulting in difficulty swallowing.
- Tightness in the chest, difficulty breathing, wheezing due to swelling of the wind pipe/airways – usually the upper airways.
- In very severe cases may cause sudden fall in the blood pressure, loss of consciousness, cardiac arrest and death (theend result in the very severe form of allergic reaction with no prompt or appropriate treatment).
Allergic reactions must be differentiated from Food Intolerance, through detailed history of the presenting symptoms including past medical, family and drug history.
Some common Food intolerance conditions include Lactose, Sucrose and Gluten intolerance. In food intolerance the body is unable to deal with certain substances in the food or diet and patients may present with diarrhoea, abdominal cramps, bloating and malabsorption (problem absorbing nutrients from the diet).
The Gold standard test for diagnosing food intolerance is by the method called “elimination and challenge diet” which involves stopping the suspected food in the diet and then re-introducing the diet and taking note of the response in a diary.
Due to the lack of the enzyme lactase an enzyme in the small intestine (gut) that digests the sugar found in cow’s milk called lactose. The lack of this enzyme results in inability to digest the lactose in the Cow’s milk.
Occurs following excessive intake of sweetened fruit juices, which results in an inability of the sucrose-digesting enzyme to digest the sucrose in the sweetened juice. This can be diagnosed by carrying out a special test on the liquid stools that measures the amount of reducing sugars in the liquid stools or can be diagnosed through another special test called the “hydrogen breath test.”
Gluten Intolerance / Coeliac Disease
Gluten is a form of protein present in wheat this can lead to damage of the lining of the gut or small intestine. Patients with certain medical conditions, including Down’s syndrome, diabetics on insulin and those who are deficient in the Immunoglobulin called IgA should be screened routinely for gluten intolerance. This can be diagnosed by doing a blood test initially and if this comes back positive they are referred for biopsy of the small intestine (gut) to confirm the diagnosis.
The blood test involves measuring the IgA antibodies to intestinal wall proteins such as the endomysium or the tissue transglutaminase.
Common Allergy Tests that we use or can arrange include:
- Skin Prick.
- Blood Test – Radioallergosorbent Test (RAST).
- Patch Test.
- Food Challenge Tests.
BLOOD TESTS – RAST
This measures the amount of immunoglobulin E (IgE) antibodies in the blood. IgE causes histamine release from the mast cells in response to exposure to allergens. This test unlike the patch or skin prick test can be carried out while patient is receiving anti-histamine treatment. The result of the test is graded 0 to 6 and zero result indicates a negative test suggesting no allergy and 6 indicates strong positive result. The grading depends on the amount of IgE antibodies in the blood.
The disadvantage of this test is that not all allergens can be tested by this method for example RAST cannot test for preservatives and colouring in foods or allergic reaction to certain medications including Aspirin.
RAST is commonly used for respiratory allergy screenings including house dust mites, pets including cats, dogs, pollens and mould spores, may also be used for screening food allergy including cow’s milk, eggs, wheat, fish soy and peanuts.
Allergy Treatment Options
Allergy treatment can be broadly divided into 3 main groups including:
- Prevention. Avoiding exposure to the known allergens.
- Use of medication. Mostly anti-histamines but including the use of vaccines in certain cases.
- Immunotherapy (also called desensitisation). In this we administer a small amount of the allergen either by injection or sublingual and gradually increase the dose until the patient is able to develop tolerance. This form of treatment is particularly good for treating allergy due to pollens and insect venoms such as bees or wasp stings but less so effective for cats, dogs and house dust mites. The injectable form of immunotherapy is best done under supervision of the Specialist in a Hospital environment.
If you would like to discuss any aspect of your allergy problems including hay fever, and the management options available please complete our booking form with details of your medical history and current medications or send an e-mail to firstname.lastname@example.org.