Hello.
These are the most challenging cases, especially when family are involved!
I would say the priority is indeed to get the hyperthyroidism under stable control and keep a very close eye on what the kidneys are doing. Despite the increase in SDMA, I would be encouraged by the USG and the creatinine. This should be early in CKD progression, but obviously the hyperthyroidism can have an effect on how this looks from a blood and urine POV.
The main DDX for the haematuria have to be inflammation, infection, uroliths or something structural. Hopefully the imaging has helped rule many of these things out, but there are always subtleties that could be missed. I think the meloxicam idea is a good one and should not be too much of a risk:
https://pubmed.ncbi.nlm.nih.gov/21906984/
It is not that common to get lots of haematuria as a consequence of CKD alone. Other DDX I would consider would be a coagulopathy (assess platelets, PT and aPTT) and possibly idiopathic renal haematuria. Renal haematuria can be really challenging to diagnose in cats as it normally requires cystoscopy.
How has this urine been collected?
Scott 🙂
