What is glomerular filtration rate - mine has come up as >90ml/min on blood test?

Glomerular Filtration Rate (GFR) is to check how well your kidneys are working. A level over (>) 90ml/min is normal so your test results are fine. Levels below 60 ml/min for 3 months or more is a sign of chronic kidney disease and below 15 ml/min is a sign of kidney failure.