Just got Nova back from the vet after having him checked out for his weight loss (as mentioned last time in the currently meme), and... they basically couldn't find anything wrong with him. His thyroid levels were good (which reminds me, I'm overdue to have mine checked). His creatinine levels and white cell counts were outside normal range, but only the eensy-weensiest smidge, so the vet thinks that's probably noise rather than signal, meaning his kidneys are probably fine and he probably doesn't have an infection. They also x-rayed him and didn't see any tumors. Which doesn't necessarily mean there aren't any cleverly hidden ones, but, OK, he probably doesn't have cancer, either. The vet thinks mostly likely it's a gastrointestinal problem, and he's not getting full value out of his food. So they just gave him a vitamin B shot and switched him over to a higher-calorie food. I'm going to keep an eye on his weight -- I actually own a pet scale I originally bought to monitor the fat cat -- and take him back in in a few weeks if he keeps losing weight.
So, for the moment... No news is good news, I guess?