Semi-feral cat with kidney failure

Question
Hi, Long story short: One of the ferals I take care of lost a lot of weight suddenly.  Took her to the vet and she was in kidney failure.  Her creatine was over 5 and the bun (i think that's it) was 158.  She was on iv fluids for a week and I just brought her home last night. Her creatine was down to 3.4 and bun was 63.  She is very thin but eating normally.  Because she is an outdoor cat I cannot give her fluid injections.  I have the special food for cats with kidney disease.  I'm having her blood levels tested one week from now and if they are going back up I'm pretty resigned to euthanizing her which breaks my heart because she is only four years old.  But, I'm fearful of her getting sicker and then going off to hide somewhere and dying a horrible death alone which is why I think euthansia is probably her best option.  Having said all of that, is there anything else you think I could do to save her?  She will not stay indoors (nor could I keep her indoors) and is friendly with me but fearful of most people. She has been an outdoor cat all her life and I think it's where she loves to be. Plus she has a brother and sister outdoors with her as well.  She does have shelter (I have heated cat boxes.)  Your thoughts and/or suggestions would be welcome.  Thanks so much for taking the time to answer.  

Answer
Fluids are really the main thing for a kidney patient.  If it wouldn't be possible to bring her in just to get fluids a few times a week, there isn't anything I know of besides diet that might help, and I think your plan is the best you can do.  If a week from now her levels haven't changed much, then I would keep her kidney levels monitored.  Most importantly, keep her appetite monitored.  If her appetite begins to suffer, you can try offering her different foods - making sure a kidney patient eats is more important than WHAT she eats.  If she turns her nose up at most anything, then I believe the time has come to put her to sleep.  

I just put a kidney patient to sleep who was given 4 months to live with treatment.  He lived another year and a half without any treatment.  Yet I have a kidney patient now, who was diagnosed with milder kidney failure.  She receives fluids and a special diet, and she does not look as if she will survive as long.  This is why I recommend to pay the appetite more attention than the blood tests.  It's all about quality of life, and science can't measure that.