CLINICAL BIOCHEMISTRY DEPARTMENT

LATEX ALLERGY TESTING GUIDELINES

Introduction

Three types of reaction to latex may be seen:

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Non-allergic irritation, caused by chemicals used in the manufacturing process, which is localised and usually reversible.

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Delayed hypersensitivity (Type IV, T-cell mediated) occurring a few hours to a few days after contact.  This is the most common type of latex allergy, is usually against chemicals added to the latex, and is localised.

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Immediate hypersensitivity (Type I, IgE mediated) is an allergy to natural latex rubber proteins. It occurs within minutes of contact, it may be localised but may also cause a systemic reaction, and potentially anaphylactic shock. 

Risk

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A crude estimate is that 1.5 to 2 million people in the UK may be at risk.  In the general population, prevalence is probably less than 1%.  Suggested prevalence varies widely between different studies.

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Risk increases to about 7% in individuals with a history of allergies, more if fruit allergies - especially banana, avocado, chestnut, and kiwi - are present.

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A history of exposure to latex gives a risk of allergy in the range 3 - 17%.  This includes people involved in the manufacture or use of latex.  Healthcare workers are a large group who, with the increase in ‘universal precautions’, have an increased risk.  Patients with history of repeated surgery are high risk; the highest rates quoted are 18 - 68% in those with spina bifida.

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Sensitisation may be from contact, or inhalation of latex proteins on glove powder, and different supplies of latex vary in their protein content.  Combinations of risk factors - e.g. an atopic healthcare worker - increase the risk.

Screening

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A full medical history is the most important tool in screening for latex allergy.  If this shows an increased risk, allergen testing should be considered.

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Serum specific allergen assays (“RAST”) are safe, and current assays are sensitive.  However, turnaround times are about two weeks, and patients may demonstrate antibodies that do not react in vivo.

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Skin prick testing (using commercial allergen preparations, or pricking through a piece of latex glove) gives an immediate result.  It carries a theoretical risk of anaphylaxis, so latex-free resuscitation equipment must be available.  It is less suitable for patients with skin problems, or who are on medication that may suppress the immune reaction. 

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Patch testing will detect delayed (Type IV) reactions.

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Provocation tests have been used - the patient wears one latex glove and one vinyl glove for 15 minutes - again there is a theoretical risk of anaphylaxis.

References

1.

American Academy of Allergy, Asthma and Immunology: www.theallergyreport.org/reportindex.html

2.

American Association of Nurse Anesthetists: www.aana.com/crna/prof/latex.asp

3.

Bandolier EBM: www.jr2.ox.ac.uk/bandolier/bandopubs/NHSSlatex.html

4.

Bowyer R. (1999).  Latex allergy: how to identify it and the people at risk.  Journal of Clinical Nursing 8(2): 144-149

5. Deacon S. (2002). Latex allergy. CPD Bulletin Allergy and Immunology 2(1): 8-11

Reviewed by: John Surrey, Principal Biochemist
Last edited 16/04/14