My husband has stage 4 ckd, We just found out few months ago. He only has one kidney functioning. Going on a special diet, and getting some exercise. How long before a patient has to think about dialysis? What is the usual life span for this Stage 4?

I am unable to provide a prognosis without performing a complete history and physical examination.  The best person to provide a prognosis is the nephrologist who has seen and examined your husband.  The decision to start dialysis is a decision that must be made by you, your husband and the nephrologist who is caring for your husband.