The math here is a little confusing, but that's an exceptionally long lived organ. For reference I received a kidney transplant from my mother at 16. It lasted 19 years after being transplanted. My mother was 68 when I had to return to dialysis.
TFA mentioned this is very exceptional, it says both that it's the longest lasting transplant this hospital has ever done and that a living kidney donation typically lasts 15 to 20 years. Meaning your 19 years is typical.
The transplant itself was done 48 years ago and the mother was 52 at the time (thus the kidney was already 52 yrs old at the time of transplant)
The detail that got me: both on gurneys holding hands, and the mom crying tells him "don't worry about a thing, I've got a Genesis concert and I'm not missing it". They both made it to the concert. He still has the ticket stub
That won't happen. Even though it's still adequate for him it's very likely preforming under what a typical healthy kidney performs at. Long term slow rejection is nearly impossible to eliminate. No kidney transplant is forever and only in truly exceptional cases does it last the lifetime of the recipient.
The transplant itself was done 48 years ago and the mother was 52 at the time (thus the kidney was already 52 yrs old at the time of transplant)