What does yellow urates (see pic) in poop indicate? (with lose of appetite)

[Hannah G]

I have a 3 year old Isa Brown and I noticed she was ill 6 weeks ago. Took her to the vet who had no idea. He said she had a sllight temperature but it was a VERY hot day, and she was underweight. Since then she hasn't improved and has gradually been going off her food and now is not perching at night but sleeping in nest box. My other chickens are fine. She won't eat her grain so I'm tempting her as much as possible toast, pasta, tomato, kitten food, boiled egg whites (she seems to like the most) and she is still keen on earwigs and slaters when I take her hunting for insects. But, she isn't eating nearly enough and is SO thin with protruding chest bone.
I've added garlic and a bit of apple cider vinegar to her water and am keeping her warm at night.
Any other suggests?
Do you think I should give her anitbiotics (amoxyclav)?
Do you think she has kidney failure?
See photo showing yellow urates..

 

[Eggcessive]

Yellow urates can be a sign of liver disease. Liver disease can happen with heart failure, cancer, egg yolk peritonitis, and other reproductive problems. Cancer can be common in hens over two. You could try antibiotics just in case.

 

[Hannah G]

Yellow urates can be a sign of liver disease. Liver disease can happen with heart failure, cancer, egg yolk peritonitis, and other reproductive problems. Cancer can be common in hens over two. You could try antibiotics just in case.

Thanks for the reply Eggcessive, I was concerned that if it is a 'gut' problem, that anitbiotics could make it worse by killing the healthy biota. Do you know of any illnesses that can be made worse by using anitbiotics?