>Does the RAST test have an "age limit"
>so to speak?

My son's allergist conducted RAST testing from ages 1-5 years--telling
us it was more sensitive for younger children.  We just went back for
re-testing (he'll now be 7 years old this week) and the doctor
suggested skin prick.  He said it was more sensitive than RAST (I
followed up with literature from FAN and this was confirmed).
However, skin testing can show a false negative (but not false
positives). Daniel did react to many environmental allergens and a few
more foods (he's anaphylactic to milk and was NOT tested for milk). He
didn't react to beef which we strongly suspected (perhaps a false
negative?) so the doctor ordered a new beef standard for the test and
we are going back in this week for testing with the new beef standard.
 If this shows up as negative again, the doc suggested that we may
want to run a RAST.
BTW-the skin prick test was much LESS stressful than the blood draw
for the RAST.  The nurses were great and three nurses did 30 pricks (5
in each hand) simulataneously so we only had about 3 seconds of
trauma.  Fortunately, we have a world class pediatric institution
(Stanford Packer Hospital) in our neighborhood.

Kathy