Most docs like a PCP, an endocrinologist, a cardiologist, and various others use the common method of eGFR to measure creatinine serum in your blood. That creatine level is calculated to show your eGFR in numerical terms, and further into stages of kidney disease. Many researchers say that this is accurate, perhaps 77% - 85% of the time. It is a measurement of kidney function.
Another kidney diagnostic method that is accurate 90% of the time is called Cystatin C. It is more common to see this used with diabetics with kidney disease. However, if there is a question regarding your eGFR, this test will confirm or validate your eGFR result.
Lastly, another sign and test of kidney disease is protein in the urine. Someone could have a eGFR of 60. for example, but have no protein in the urine which may/may not indicate kidney damage.
So being tested often, six to twelve weeks, establishes a relevant trend for those who wish to keep track of these values. For me, my labs are done within and outside of Mayo, so I keep track of the labs by date of service. You may wish to keep track of creatinine, eGFR and Cystatin C to establish your personal trend of values for each. It is that trend that guides us for the long term.
In 1988 I was diagnosed with Systemic Lupus. Even at the beginning, there were massive amounts of protein in my urine. It was always attributed to the lupus, not kidney disease, and even now I wonder what might have happened if my knowledge base had been better at that time. Kidney disease was formally diagnosed in my chart about 2006, but the cause was still given as the lupus. It wasn't until 2014 that an astute nephrologist followed through and did more diagnostic testing. The result was diagnosis of an ultra-rare autoimmune kidney condition. All this is to say, knowledge is power. And yes, there is still the large amount of protein, as related to that kidney condition, not related to lupus nor my blood cancer,
Keeping track of testing, of different health conditions that may affect another, being ready to question what is not clear. Sometimes we are the best person to put the pieces together. It is not for the weak-hearted, nor for those who want to take an easy way out. But it is for our best health.
Ginger