During a patch test, very small quantities of potential allergens (including nickel) are applied to your skin and covered with small patches. The patches remain on your skin for two days before the. Patch tests (skin allergy tests). Authoritative facts about the skin from DermNet New Zealand. The patch testing described here is as it is undertaken in Hamilton.
Nickel allergy treatment and symptom information. Nickel allergy commonly develops following ear piercing and the use of metal jewellery. European Union legislation currently limits the amount of nickel released from metals in prolonged contact with the skin and it is hoped that the allergy may become less common in the future. The allergy results in the development of a localized eczema/dermatitis. Pure gold (1. 8 carat or more), solid silver and platinum are usually safe alternatives for jewellery. Other metal objects in prolonged contact with the skin such as jeans studs, watches, buckles, clips in underwear, spectacle frames and mobile phones can also cause dermatitis.
Items in transient contact with the skin such as kitchen utensils, door handles etc. Ideally find a nickel free alternative. Nickel allergy is more common in people with hand dermatitis although the reason for this is not always clear. If you regularly handle money, this may contribute as coins release nickel and exposure to nickel builds up with repeated contact. Orthopaedic pins and plates may result in eczema affecting the overlying skin.
The role of nickel in joint replacements is unclear, although typically if there is concern, a titanium prosthesis can be used. It is uncertain whether nickel in the diet is important, although it is unlikely to be a problem in the majority of nickel allergic individuals.
A spot test that detects the presence of nickel in metals is available which uses the chemical dimethylglyoxime. Last updated: September 2.
Nickel allergy (also referred to as.
Next review date: September 2.
Patch tests are not the same as skin prick tests, which are used to diagnose hay fever allergy (house dust mite, grass pollens and cat dander). Skin prick tests have very limited value for patients with skin rashes. The patch testing described here is as it is undertaken in Hamilton, New Zealand.
There may be slight differences in methods used at other centres - if you are having patch tests done, ask your dermatologist to explain. A range of substances can be used for patch testing. A baseline series such as the European Standard Series of allergens (or similar) is applied to nearly every patient, together with specific tests appropriate to the individual.
Each substance (known as an allergen) has been tested to find the best concentration to demonstrate an allergic reaction without causing irritation to those who are not allergic to the material. Sometimes the results can be inconclusive or misleading. Instead of one or two positive reactions, sometimes nearly all test areas become red and itchy. At other times, there may be little or no apparent reaction to a substance that regularly causes dermatitis in that person (false negative result).
Further testing may be necessary. Patch tests do not always explain the cause of a dermatitis. More images of patch tests .. The appointments. The first appointment will take about half an hour. Tiny quantities of 2. They are kept in place with special hypoallergenic adhesive tape.
The patches stay in place undisturbed for 4. At the second appointment, usually two days later, the patches will be removed. Sometimes further patches are applied. The back is marked with an indelible black felt tip pen or other suitable marker to identify the test sites. These marks must still be visible at the third appointment, usually two days later (4 days after application). The back should be checked and if necessary remarked on several occasions between the 2nd and 3rd appointments. The results. The dermatologist will complete a record form at the second and third appointments (usually 4.
The result for each test site is recorded. The system we use is as follows: Negative (- )Irritant reaction (IR)Equivocal / uncertain (+/- )Weak positive (+)Strong positive (++)Extreme reaction (+++)Irritant reactions include sweat rash, follicular pustules and burn- like reactions. Uncertain reactions refer to a pink area under the test chamber. Weak positives are slightly elevated pink or red plaques. Strong positives are . The relevance depends on the site and type of dermatitis and the specific allergen.
The interpretation of the results requires considerable experience and training. Notes. Do not expose your back to the sun for four weeks before your patch tests.
Wear old clothing; felt tip pen marks can stain clothes. Do not swim, rub, or exercise, as the patches may come off. Keep the back dry, so no baths, showers or unnecessary sweating. Arrange for someone to remark the test sites with indelible felt tip marker. Bring Your Own Materials For Testing. Discuss the particular substances with which you come into contact with your dermatologist; you may be asked to bring materials from home or work.
Provide your dermatologist with data sheets of industrial items with which you are in contact. Bring or send all chemical items for testing at least a week before the first appointment so that they can be prepared for testing if necessary.
Only small quantities are required eg. Shampoo and soap are not usually tested (these are intended to be washed off and may irritate the skin if left on the skin for two days). Bring all prescribed and non- prescribed ointments, creams and lotions that you have used. Relevant clothing including rubber gloves and footwear can be tested; about one centimetre of material is needed, taken from seams or other unimportant areas in contact with the affected skin. Photopatch tests.
Some patients have photopatch tests because their dermatitis develops on skin exposed to the sun (photosensitivity). Two sets of perfumes, antiseptics, plant materials and sunscreens may be applied.
After removal, one set is exposed to a small dose of ultraviolet radiation (UVA). This is not enough to cause a photosensitivity reaction on its own. Adverse reactions to patch tests. Positive patch test results are small areas of active eczema / dermatitis. They will be itchy and may require treatment with topical steroid. Occasionally patch test reactions persist for several weeks. Patch tests may provoke other areas of dermatitis to recur or to appear for the first time.
Although hypoallergenic tape is used, occasionally people react to all areas in contact with the tape. An 'angry back' reaction may arise, particularly in a patient with active dermatitis at the time of testing, or in someone who has multiple positive reactions.