Some laboratories use the Ictotest® to rule out a false-positive bilirubin dipstick result caused by urine color interference. The test is performed by adding drops of urine to an absorbent test mat, placing the reagent tablet on the absorbed urine on the mat, and adding water to the tablet, allowing it to spill over the tablet onto the mat.
Since the urine is placed on the mat first in the tablet test, this staining is evident before the reaction is performed and can be accounted for. Also, because the reaction product is blue rather than tan or magenta, there are fewer interpretation problems. The Ictotest® employs the same diazotization reaction as the reagent strip but should not give a false-positive result with colored urines.
