Can post-tx creatinine be too low?

[UkrainianTracksuit]

Like the question says.

The highest my creatinine has been since transplant has been mid-50’s μmol/L. It usually hovers around 46 μmol/L. I am splitting hair here as 50 is the norm and 46 is close enough to normal. Creatinine and urea are infamous for being mobile and finding a range is better than exact numbers. But I’m just worried that something could be out of the norm for me? It seems as though those recipients with really good kidneys have numbers a bit hiigher.

[Marilee]

Creatinine is a waste product, so I cannot imagine how it could be considered "too low". It's not like a mineral or electrolyte that the kidney needs to be balancing (i.e., Phosphorus, Potassium, Calcium, Magnesium, Sodium): Those do have a range of minimum - maximum and can cause problems outside those norms.

Since Creatinine is a waste product produced from muscle metabolism and protein consumption, perhaps your low numbers have more to do with lack of exercise or a low protein diet?

Have you talked about it with your Neph?

[PaulBC]

I don't think it is a problem with the kidney. If it's eliminating creatinine from your blood, that's good news.

Could it be a sign of another problem? I.e., you are not producing enough creatinine for some reason. I haven't heard of it before, but it does seem that there are conditions that cause low creatinine. https://www.healthline.com/health/low-creatinine You should talk to your doctor about it.

[UkrainianTracksuit]

Yeah, it's strange, after CKD/ESRD for the majority of my life, I may be well-versed in creatinine but never the concept of it being too low.

I am on a high protein/high calcium diet (fish, poultry, eggs, dairy) so that's not the source. As for exercise, with the blessing of the tx team, I resumed competitive biathlon training. I roller-ski 5 km each day as of now. It's strange.

I talked to my tx neph and my regular neph. They aren’t concerned about it since it is “close enough” to a normal range. Not even close to levels that would peak interest of a problem. Their opinion at the moment is that I could be taking in too much water (around 4 L) and passing it excessively too. So, I have to measure. In the end, they told me I’ve going to go crazy over numbers so let it go. Accept that I got a “really good” kidney and be thankful.