I gave myself CKD at the age of ten. Since then the general trend in eGFR has been down, presently at about 40. My eGFR has been down to 5, but that was a reaction to an antibiotic given for pancreatitis. The e in eGFR stands for estimated, because it can give a result very different from the actual GFR for a large number of reasons (dehydration, caffeine, infection, immune system etc.). You can get an actual GFR lab test, but it's more complicated and hence more expensive.