This should be a simple question to answer… right? About a year ago I was listening to a podcast by Tim Ferris where his guest Dr. Peter Attia was detailing how creatinine is a poor test creatinine to assess kidney function. He stated it was always wrong, either too high or low depending on body type. He recommended Cystatin C as the superior blood marker. Maybe not surprisingly I take copious notes from these podcasts and this was one of them. 

Fast forward to this May before my diagnosis and we are trying to find out what is going on, I convince my primary care doctor to test my Cystatin C level which showed normal kidney function whereas my Creatinine has always been slightly elevated. I start taking the chemo pill and my Creatinine spiked to a very concerning level and has remained there to this day; naturally all the doctors and I became very worried about kidney damage. I convinced my oncologist to test my Cystatin C level last week and it was almost identical to my May test… stating my kidney’s were totally fine.

I then began a quest to understand which test is the true indicator of my kidney function. I reached out to the physicians I previously saw at 2 centers of excellence.  One physician stated they had never even heard of the Cystatin C market and just to trust the Creatinine measure.  The other punted and said go talk to a nephrologist.  I was dumbfounded.  If you are treating cancer, shouldn’t you have some knowledge of the different tests to assess health of impacted organs?

My wife and I then went deep into research mode and found the following:

1.     The US National Kidney association acknowledges creatinine is cheaper and more widely available but recommends a transition to Cystatin C

2.     The UK’s National Institute for Health and Care Excellence recommends Cystatin C

Had I not listened to the podcast and then did follow-up research, would still be wondering/debating about potential trade-off of dialysis vs. no cancer drug… 

As Dr. Reed Tuckson wrote in his book “The Doctor in the Mirror”, we need to own our own health and not abdicate it to anyone else.