differences in Marker levels), the APMU  shall update the APMU Report  indicating “Suspicion of Urine Exchange”;  • If the APMU  suspects urine exchange, an investigation shall be launched by the Passport Custodian,  with support from the APMU , using a combination of actions such as Sample  storage, confirmation of the steroid profiles of relevant Samples , collection of additional Samples , and/or DNA analysis, as applicable.