Welcome to Just Answer and thanks for your question. An estimated GFR of 53 is stage 3 chronic kidney disease with moderately reduced kidney function. Treatment is controlling hypertension and whatever else is contributing to the reduced function. There is an excellent link below that discusses chronic kidney disease including the different causes.
Observe. Control blood pressure
Mildly reduced kidney function.
Control blood pressure. Monitor kidneys closely.
Moderately reduced function,
Continue above. If not already diagnosed, determine why kidneys are failing.
Severely reduced kidney function.
Plan for end stage kidney disease.
End stage kidney failure
GFR is a calculated number based on creatinine, age, sex, and race that is then compared to statistics. A far more accurate method of measuring your kidney function is 24 hour urine collection. No one would diagnose kidney failure based on GFR alone. It is most useful in tracking kidney disease in someone who has been properly diagnosed with kidney failure.
Among the many things besides hypertension that can lead to chronic kidney disease is diabetes, a kidney infection called glomerulonephritis. polycystic kidney disease, reflux nephropathy, kidney stones, and some medications. A creatinine level of 1.1 is quite acceptable and nothing to be concerned about if you aren't having any other problems. Below is an automatic calculator for GFR.