A quick google suggests that this is harmonisation of the "normal" low and high levels for all the components of blood, urine, and other tests, and thus flagging of out-of-range results should be comparing against the same "normal" ranges everywhere.
I don't think this will change the calculation of the PSA, but it might mean everyone uses the same PSA ranges to flag up high levels that need investigating in the case of tests taken prior to any treatment.
It's probably irrelevant for PSA measurements taken after treatment starts, but just a bit of boiler plate text that appears on all test results.