Stage 4 CKD patient life expectancy

The life expectancy of stage 4 CKD is very difficult to say .And in other hand

There is no way to know how long a person will survive with any stage of kidney failure. My son was born with only 10% kidney function (back then they did not measure in stages). With surgery, medication and a special diet, he made it to 10 months old before needing to start dialysis.
Is your Dad able to have dialysis? There are two types, hemo dialysis and peritoneal dialysis. They both have pros and cons, but people can survive for YEARS on either of them or a combination of them. My son was on peritoneal dialysis for just over 4 years. He was on hemo dialysis for 3 weeks child he was healing from an abdominal surgery. He did AMAZINGLY well on both.
He was able to have a kidney transplant when he was 5 and I was lucky enough to be his donor. He will turn 21 years old next month and even though most pediatric kidney transplants last about 10 years (or less), he still has that first kidney and it's still going strong (it will be 16 years in June).
If he has other medical conditions that makes it impossible for him to receive dialysis or a transplant, then they can manage for quite some time with medication and modified diet.
I have personally met people who are 35 years or MORE post transplant and they have only been doing them with any success since 1954! You can also have more than one kidney transplant in your life (it gets more complicated and harder to find a good donor, but it happens all the time).
If his BUN gets too high, he will become more and more lethargic and can eventually go into a coma if not treated. Other problems with kidney failure can be high blood pressure, high potassium (can cause heart problems, even cause the heart to stop)....many things. But MANY can be treated with medication and modified diet up to a certain point. Also each person's body can handle the levels differently. One child (most of my experience is with children) might feel totally fine with a BUN over 100 and a creatinine of 8 or higher. Another child the same age and size might become lethargic when their BUN is at 50 or 60 and creatinine only at 2!

Email me my email address is chinesemedicinekidney@hotmail.com if you think I can help with more questions! I will submit a few good kidney related sites in the source section.