Question about Blood found from Urinalysis

Hello,

During our yearly check up, my vet took a urine sample from each of our cats. We also did X'rays and blood work. One of my cats has one kidney normal sized and one kidney half the size. His blood work came back normal, however his creatinine level was 2.3, normal range but higher normal for his age my vet said. The urine sample she said was somewhat cloudy and once tested revealed the presence of red blood cells and a few white blood cells. She sent it to be cultured, but it came back negative.

She called today to tell me all this, he has no other symptoms that we have noticed. Not straining to pee, not going outside the liter box, no excessive thirst and we haven't noticed blood in his urine, though I'm not sure if you would be able to tell once its mixed with litter?

She wants me to try to get another urine sample, at home, to test it again for blood. He gets very very stressed going to the vets, he was shaking the whole time there and during his examination plus since to get the sample the need to insert a sterile needle into the bladder to draw the urine which can sometimes add blood, but she doesnt think that was it just due to the amount and that the process went very smoothly for him.

If there is still blood she wants to do a ultra sound to check the integrity of his bladder, she saw no stones on the xray but can check if there are any, if the bladder wall is thicker etc.

I've done some research too and found something called Cystitis that is mostly harmless and would explain the blood especially since he is can get stressed easily.

I'm writing this to try to get some other thoughts, im still quite worried about it and not having an answer is stressful. She also wants to start him a prescription diet for kidney issues just in case he might have kidney problems, more as a precaution than anything at this point.

He could actually get a little blood in his urine from stress.  It could also have something to do with the kidney that is the wrong size.  In the absence of clinical signs, if it were my cat, I would just make sure he was on a diet that supports urinary health (does not need to be a prescription diet but should be mostly meat protein and fat, with very few carbohydrates, which is what the cat's natural diet would be.  He should not be on dry food at all.

Do a search at the top of this page (right under the brown bar) for things like "cystitis" or "FLUTD" or :Blood in urine" and read some of the other threads and especially the advice from the experienced people who have written in.  One thin to know (and this from a good cat vet) is that before giving a cat ANY antibiotic for suspected cystitis, a bacterial culture AND antibiotic sensitivity should be done.  In most cases, cats under 10 year old do NOT have a bacterial cause of their cystitis, and it can be cured by a change in diet and reducing stress levels. 

Don't allow yourself to be caught up in a lot of worrying because of a finding on a lab test when the cat appears perfectly fine and is happy and enjoying life.  You can get pulled into a whole lot of medical drama which can harm your cat in the long run just because of the stress!  Read a lot and be informed, an always keep the cat's quality of life (not quantity) at the forefront of your decision making.