Hematuria

[balloonlady]

I'm in my mid-40's and have had microscopic hematuria at least since my early 20's. A work-up (20 years ago) consisted of serial u/a's (all 3+ or 4+) IVP (normal) and finally a cystoscopy = A little inflammation. Final Dx: Probable benign chronic trigonitis.

My current docs are asking for a current work-up because the benign trigonitis isn't an "adequate" diagnosis. My u/a's the past couple years have varied between trace-large for blood.
My BUN has been fine, my creatinine was 1.something but still wnl, but they said my GFR was low.
(I'm s/p hysterectomy, so it is not menstrual contamination.)

1).Why would a GFR be low with a normal creatinine?

2). How often should so-called benign hematuria be worked up?

I'd feel silly going through extensive tests if this is a normal variant.
Thanks for any input you can offer.