I am 55 years old and i workout 4 to 5 days a week. i weigh 115 pounds and i dont smoke. bun - 24, bun/creatine - 25, creatinine - .97 and egfr - 59. these are from my latest physical. should i be concerned?

Your kidney function is borderline low for your age even after accounting for a mildly low volume when you had that blood test done. I assume you are not taking any medication because you did not mention. If your blood pressure is normal (less than 120/80) and urine test is negative, you should not worry too much. If not, you can request to be seen by a kidney doctor.