Can elevated creatinine and low eGFR be due to one's exercise intensity?
I exercise 5 days a week for 60 to 75 minutes (spinning class and then resistance training). I am 50. The last three years my creatinine level is slightly high and eGFRis slightly low. When I work out, I always sweat a lot and the smell is ammonia like. My blood pressure is normal; always less than 120/80.
I would suggest that you go see your doctor.
If your doctor sees no other issues at play here then you may need to take into account your nutrition component- are you eating a high-protein diet? If so, the ammonia-like smell may be caused by burning amino acids instead of sugars during your aerobic exercise. Breaking down protein as a fuel source leaves a by-product of excess nitrogen in the bloodstream which is translated into ammonia in the urine. Dehydration could also be a potential cause of these issues.
Over-exercising is the other possibility that comes to mind (which means damaged muscles). Remember that the American College of Sports Medicine recommends strength training the same muscle group up to 3 times per week. If your 5 day per week regimen includes the same strength training exercises every day you may want to skip the resistance training for 2 of them or mix up the muscle groups you're working.
You and your doctor should discuss all possibilities and see if there's any need for further interventions or tests. Also, strictly out of curiosity, are you a diabetic and were these changes to blood levels of creatinine? (Don't answer if you're not comfortable with that information being made public.) Please keep us posted if you determine the cause of the change or a solution!