What can i do if i have kidney polysystic? is there any preventative way?

Consistency : Make healthy decisions: low sodium diet, exercise, no tobacco, and be consistent. Take prescribed medications, control blood pressure, avoid all nsaids, if diabetic manage it well, and like everyone it helps to have a little bit of good luck too. Get a nephrologist (kidney doctor) who will look for ways to slow/prevent loss of kidney function, and if needed prepare for end stage kidney disease.