My father aged 70 creatinine 7 renal cyst disease .no other major symptoms except weight loss .should he undergo dialysis .if yes hemodialysis or peri?

See a kidney doctor: Most likely he would need dialysis. Peri is more convenient for most of people, but it may not as effective as hemo depending on size of kidney cysts.

Start of dialysis: Your father should have a 24 hour urine collection to see what his renal function is. If GFR result is < 10 ml/min, he needs to start some sort of dialysis. He should speak to a nephrologist to learn about the benefits and disadvantages of hemodialyis (h) and peritoneal (p) dialysis. Once these are explained to him, he can make a choice that is best for him. Good luck to him.