Allergists believe that skin testing, especially if intradermal tests
are used, are more sensitive and specific. The RAST tests measure IgE
levels to an antigen, but may not be clinically significant. My
allergist uses the RAST tests when it is too dangerous to try a skin
test: like if a patient had a life threatening reaction to nuts--he had
a patient almost die with a prick test to nuts.
 Skin testing is best when the allergens/serum used are standardized
and the protein is known to be the one that causes a reaction.
 Also, technique is important. My daughter had tests done at a
prestigous hospital in Boston that literally lacerated her arms. The
allergist/pulmonologist rated them on a 1+. 2+, rather than measure the
induration and erythema relative to the histamine and saline
control--which is the standard. As our local allergist pointed out: he
gave 2+ positives for tests that were 1 mm different from ones he felt
didn't react--and in reality, his nurse did it. Our fingers just aren't
sensitive enough to really distinguish between 1mm induration
(firmness). He also did substandard pulmonary function testing. He lied
about the tests: he didn't document results, and when questioned about
his poor protocols on the pulmonary function testing, refused to adopt
the national standards.
 The sad thing, is that another college student, who wheezes just
walking up a hill, was seen by him and diagnosed with no asthma and no
allergies. So, watch for correct technique.
 When you order blood tests, technique isn't an issue, but cost
is--for insurance companies.
Judy