Hello doctor, I am a 62-year-old very fit male. I lift weights three times a week and use the stair master for 30 minutes five times a week vigorously. I have had this same routine for the past 20 years. I am 5'7" and weigh 160 pounds. My serum creatinine was 1.33 16 years back, and for the past 16 years, it has fluctuated from 1.34 to 1.48. There was one test done last year that came back at 1.2. However, the latest test result was 1.38. All other values are normal. BUN is always around 15 to 20. My spot urine protein was 7 and my spot creatinine was 85. Based on the serum creatinine levels alone my eGFR is low indicating stage 3 CKD. This seems crazy to me. All my blood work is perfect except for the creatinine. My lipids are great, my BP is 120/75, my fasting glucose is 98 to 100, and A1c is always 4.6 to 4.8. I am not on any drugs, I do not take creatine supplements, I do not take any medication. I do not take NSAID. If I had stage 3 CKD, would the urine levels be indicative of disease? Also, how can the creatinine be elevated with normal BUN? If CKD, would the kidneys not functioning increase the BUN at the same time? This makes no sense to me. Since level has held steady for 16 years, is that evidence of no disease? I have been told that higher muscle mass may lead to elevated creatinine, but I do not have huge muscles. Is it possible that the muscle metabolism from exercise is always creating elevated creatinine? Does this sound like stage 3 CKD to you? I have had Gilbert's disease so bilirubin is always elevated at about 2 to 3 for the past 40 years. No other conditions.
Hello. I went through your reports (attachment removed to protect patient identity), see basically beyond 40 years of age, there is 1ml/min/1.73 m2 decline in eGFR per year, and that is a normal physiological response because of an increase in age, same as skin wrinkles, since you have high creatinine, but is static and there is no protein in urine, your chronic kidney disease is very slowly progressing. Differential diagnosis, in this case, is chronic tubulointerstitial disease or benign nephrosclerosis, as you told you are not taking any drugs, NSAIDS, gym supplementation. About confirming the diagnosis, it will need a kidney biopsy to confirm it. But whatever disease it is, it is slowly progressive and mostly probably will behave same way for next 10 to 15 years. What you need to do is restict protein in diet to 0.8 gm/kg/ day, less salt, blood pressure monitoring. Avoiding alcohol, tobacco products, weight management.