Quote Originally Posted by IamN2pot


Step 1. 4-12 hours before the test take 4 aspirin (not Tylenol or Advil). This step may be repeated every 4-6 hours up until 4 hours before the test.
This step can be skipped.

Back when the Guidelines were compiled, aspirin was used as an interferant for only one type of test: the first-generation EMIT screen. Since then, a second-gen EMIT (aka EMIT II ) was introduced to counter the interference issues caused by aspirin. As a result, the first-gen EMIT is seldom used by the labs anymore (if, at all).

Mechanism and elimination of aspirin-induced interference in Emit II d.a.u. assays -- Linder and Valdes 40 (8): 1512 -- Clinical Chemistry