NEW: Diagnosed with CRF advice and suggestions appreciated deeply

[Diana US]

Hi all,

My 16 years old, Rainbow, has been drinking, peeping frequently and I also notice vomiting from time to time and often see him sit up instead of lying down when he is not sleeping. We had blood and urine test/analysis on him this past Monday showing high BUN 58 plus T4 in the grey 2.2. He has decent appetite, wanting to eat. My vet recommends k/d food, I think (He will be going over the test results with me in person), but I am concerned with all the negative things about it so I would love to have some inputs, advice and personal experience of how others do, given the understanding that each individual is different. Also, should I avoid to exercise him now?

Some background if helps. I have fed them (I have two of them, brothers, I caught them on school campus) exclusively dry food twice a day about 10 years ago when I first realized they were way overweight and reluctant to move, and would throw food for them to chase for exercise purpose when time permitted. Lately, I have given them homemade chicken broth as I noticed the frequent drinking, thought it might be better than water (maybe not??). Yesterday, I switched them on wellness canned food with added water (so the water would be retained if having with food).

I use reference from Tanya's comprehensive guide US Canned cat food data. From pure number perspective, Organic Turkey & Chicken by Nature looks pretty good low phosphorus .68%, low Sodium .23% with protein of 45.45% and high in fat 36.36% (fat is good I think I read somewhere). I looked up ingredents and did see any corn or rice or by-product on the list from By Nature's website, but I am not used to read any labels human or pet food :-(

Here is blood test results:
BUN - Result: 58 Reference Range: 15 - 34 mg/dL
creatinine - Result: 1.6 Reference Range: 0.8 - 2.3 mg/dL
Calcium - Result: 8.6 Reference Range: 8.2 - 11.8 mg/dL
Phosphorus - Result: 3.7 Reference Range: 3.0 - 7.0 mg/dL
TCO2 (BICARBONATE) - Result: 13 Reference Range: 13 - 25 mEq/L
Chloride - Result: 126 Reference Range: 111 -125 mEq/L
Potassium - Result: 4.2 Reference Range: 3.9 - 5.3 mEq/L
total protein - Result: 6.8 Reference Range: 5.9 - 8.5 g/dL
T4 - Result: 2.2 Reference Range: 2.3 - 4.7 Grey zone in old or symptomatic cats

Urine results:
pH 6.5
LEU 25 Leu/uL
PRO trace
S.G 1.020

The vet told me that he didn't see any protein or blood nor infection in his urine. Though he does say he is slightly dehydrated and has heart murmurs :-(

Many thanks in advice!

Diana/Rainbow