My 12 year old CKD cat's creatinine levels dropped out of nowhere. Anyone with a similar experience?

[u/misguid3d-ghost]

​I have a 12 year old CKD cat with significant kidney stones (they're actually in her ureter since July, one each side). She had blood clots in her urine two days ago and I took her to the vet to see if the stones moved.

​They detected that the left ureter and the left kidney had signs of inflammation and I got her home with the usual prescription (corticoid, antibiotics, her usual medicine to relax the ureter, pain meds). Nothing new for us, except for the clots.

​The surprise came when I received her test results. Like I said, she's CKD for almost four years now and her last creatinine level was around 4 and BUN was always a lot higher than what's expected for a cat without CKD.

​In this week's tests, her creatinine was 1.3 and the margin for a healthy result is up to 1.6. Her BUN was only slightly higher than the normal levels, compared to what it was before.

​I texted her vet to check if they switched her tests with another cat or if they double checked the result and she confirmed the result. She had done subq the day before the test, but it doesn't explain how her levels got so low. The vet said that a possible explanation is that they put some product in the syringe and that could interfere in the results, but it never happened before.

​Anyone ever had a similar experience?