Hello, yes due to high blood pressure kidneys can take some damage and as you have, they can shrink in size and their functioning also decreases. I suppose your doctor must have put you on antihypertensive medications. For your condition not to worsen, few things are very important. First is taking medications regularly. You should not skip any medication given for high BP or delay the timings. Second thing is taking proper diet, low salt diet, less oily food, low cholesterol food will keep your blood pressure and blood cholesterol in control which is essential. Third and important thing is exercise. With regular medications and proper diet, regular exercise is also equally important as it keeps your heart functioning well and keeps your blood pressure under check. All this things will help you in long run and also keep other vital organs like kidney, heart healthy. Thank you