My mother aged 80 has 23 percent kidney functioning left.does she require dialysis at this stage?which food we may prefer to let her take?

No: If 23 is gfr, not likely to need dialysis. Gfr < 15 with symptoms and chronic is likely to need dialysis. First of all need to assess of there is any treatable cause. Eventhough creat. Clearance and GFR are not the same, they are used synonymously. To keep it simple , better to follow egfr which is calculated based on mdrd and ckd-epi.

Dialysis: She does not require dialysis at this stage. Dialysis is typically required at 15 percent or less kidney function. Diet is important. She must avoid high potassium and high phosphate foods. She must take low salt diet. See a dietitian as soon as possible. Food lists are available on AAKP and NKF web sites.