Provocationneutralisation test

This method is used particularly by clinical ecologists in the diagnosis of idiopathic environmental intolerances, also referred to as allergic toxaemia or tension fatigue syndrome. This diagnosis is given to people with a wide range of symptoms involving many areas and systems of the body. The 'causes' listed are many, ranging from reactions to synthetic products, naturally occurring foods, viruses, fungi and even some endogenous hormones such as progesterone. There is no evidence of inflammation or organ dysfunction to support the causal model of immunological hypersensitivity. None of the other non-immunological models are supported by experimental or controlled clinical studies. None of the various laboratory tests used to support the diagnosis have been found to be consistently abnormal.

The provocation-neutralisation test is the main tool used in this area. It has been criticised for the lack of a standard protocol. It involves the exposure of patients to fivefold dilutions of subcutaneously or intracutaneously injected allergen or chemical extract. Occasionally these extracts are given sublingually. For the 10 minutes after each injection the patient records their symptoms. Serially higher doses are administered until the appearance of symptoms is elicited. A progressive series of lower concentrations are then administered until a dose is reached at which the patient experiences no symptoms. This is termed the 'neutralising dose' and is used to determine future treatment doses.

The main criticisms of this test are the lack of theoretical background to support it as a diagnostic procedure and the inconsistency of the pathophysio-logical explanations with an understanding of immunology. There is also little allowance for spontaneously occurring symptoms and no negative controls. The issue of safety is not addressed. There is a potential danger of anaphylaxis when applying sublingual preparations to patients with a known or unknown potentially serious IgE sensitivity to an allergen.

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