false serum creatinine test

my GFR was decreasing from 89 to82 to 73 in the last 9months. i took the test again last week, but this time i drank 2 gallons of water 3 hrs before the test. the result was my GFR went up back to 82. I was happy, but could this be a false reading because i drank so much water?

[Kaneda2112]

This is what the National Kidney Foundation says about GFR numbers -

"Glomerular Filtration Rate (GFR): Your GFR tells how much kidney function you have. It may be estimated from your blood level of creatinine. If your GFR falls below 30 you will need to see a kidney disease specialist (called a nephrologist), Your kidney doctor will speak to you about treatments for kidney failure like dialysis or kidney transplant. A GFR below 15 indicates that you need to start one of these treatments."

and from elsewhere on the web - "Levels below 60 mL/min for 3 or more months are a sign of chronic kidney disease. Those with GFR results below 15 mL/min are a sign of kidney failure."