PATCH TESTING FOR SKIN DISEASE|
Some skin diseases are caused by allergies
There are many types of skin disease and one of the most difficult to cure is eczema, which is also known as dermatitis. There are many things that flare dermatitis, such as stress, "nerves", dry skin, genetic factors and skin allergies. Sometimes we are unable to find the cause of the dermatitis; therefore, we simply have to treat the symptoms. The ideal situation, however, is to try to find the cause of the problem and figure out a way to remedy the problem by removing the cause.
Patch testing helps us diagnose skin allergies
Often we may suspect that a person's dermatitis is caused by an allergy to something that comes in contact with the skin. A person may come in contact with the substance (called an allergen) at work, in taking care of the home, or just in the course of day-to-day living. In industry, for example, machine tool operators may become allergic to certain cutting oils. In the home, skin care products, i.e., cosmetics, lotions and soaps, as well as other items that we touch every day like rubber and metal, are all common causes of allergic dermatitis. The first step in determining the cause of an individual's dermatitis is to try to identify any possible substances that the person is exposed to and is likely to be allergic to. Then we can perform patch testing to look for a reaction.
How patch testing is done
Patch testing is a simple, painless procedure. Certain chemicals and other substances are placed on a small aluminum disc, which is attached to a piece of special tape. The discs are taped on the back and left in place for 2 days.
The patches are removed in the office and any allergic reaction will be visible on the skin. When we first remove the tape, we are usually unable to be totally certain about whether the reaction is positive or not and therefore we will need to have the patient return in 2 to 5 more days for one final checkup. During this time there are no further patches placed on the back and the patient can go back to normal activities. During the time that the patient wears the patches, the back must be kept dry. This includes bathing and also perspiration. Therefore, during these 2 days the patient will need to avoid sporting activities or strenuous exercise, and if the patient is in a work situation where perspiration is common, he or she may need to be placed on light duty. We will discuss this with the individual at the time of testing.
The chemicals or substances used in patch testing depend on the type and location of the patient's dermatitis. We keep hundreds of materials in our office for testing that are common causes of skin allergy. In addition, we ask that the patient bring in samples of any substance, either from the home or the work place, that he or she is suspicious may be contributing to the dermatitis.
Limitation of patch testing
Like any medical test, patch testing is not 100% accurate. There is a small chance of a false-negative or false-positive reaction. For this reason, it is essential to correlate the patch test results with a thorough history and examination of the skin. Only then can we be sure that the reaction is significant.
Cost of patch testing
Certainly in these times it is important to be conscious of the cost of medical care. Currently our charges range from $800 to $1200 for most testing procedures. The procedure takes a lot of time, both by the nursing staff and the doctor, in preparing the test and interpreting the results. After the testing is completed, a letter will be sent to the patient giving detailed information on the items the patient is allergic to. In addition, letters will be sent to any referring physician.
Because of the expense and time required to prepare testing prior to the patient's arrival in the office, it is essential, if an appointment must be cancelled, that we receive 48 hours notice of any cancellation. Failure to do this will result in a $50.00 "No Show" fee.
Insurance, including Medicare, usually pays most of the cost of testing. If there are questions regarding this beforehand, please call our Insurance Department at 502.583.7546.
Do you need to be tested
If you suspect that your skin problem may be caused by an allergy, then patch testing should be done. In addition, many cases of dermatitis or eczema without an obvious cause may turn out to be due to an unsuspected allergy. This is particularly frequent with hand eczema.
Please feel free to discuss the need for patch testing with us at any time.
How to schedule a patch test
When you call the office, please tell the receptionist you are scheduling a patch test. Because of the complexity of the procedure we need to do our testing on certain days. We usually apply the patches on Monday and then have the patient return on Wednesday for removal of the patches and readings. Then the patient will need to return on the following Friday or Monday. Plan on 30 - 60 minutes in the office on both the Monday and Wednesday, with a shorter amount of time required for the third visit. If you are coming from out of town, we will be glad to recommend a local hotel facility.
There are several things that are very important that the patient should remember when scheduling patch testing:
- We usually need to wait at least four weeks after a person has been given a cortisone (Kenalog) shot. If the patient was given a lesser strength shot, we may be able to do the testing after a shorter period of time.
- If the patient is on Prednisone or other oral cortisone-type medications, then he or she should be off the medications at least three or four days before testing.
- The back must be free of any active dermatitis at the time of testing.
- Topical cortisone-type creams or lotions should not be used on the back for one week before testing. They may be used elsewhere on the body, however.
- The patient should not have any sun exposure to the back for at least one week prior to testing.
- Usually antihistamines and other medications do not interfere with testing, so these can continue to be taken before and during patch testing.
- Please wear a shirt that is dark colored or "old" on Wednesday when the patches are removed. We mark the back with ink that occasionally rubs off on clothing.
If there are any questions regarding the procedure, please call and ask to speak to one of Dr. Fowler or Dr. Perryman's nurses at 502.583.7546.