73 y.o. w/m, left kidney hydronephrosis 3 yrs, large cyst 10 yrs, history kidney stones, lumbar stenosis, bilat leg/back pain - nephrologist or urologist?

Bilateral leg/back: Pain could be most related to spinal stenosis, epically if back pain made worse with prolonged standing or walking a reproducible distance relieved by sitting down, in about 5 min.The bilateral location of your pain argues against kidney stone pain( that pain is always unilateral(one kidney or the other.It would be very unusual to have a moving stone in both kidneys simultaneously. C primary care.

Urologist and...: By hx, you may require no urgent attention but a timely follow-up so to define what you would practically need for the above. Seeing a urologist will decide if intervention is needed or not; to me, 10-yr large cyst is benign so leaving it lone; for 3-7 yr left kidney hydronephrosis ; stones, they appear clinically silent and may be just watch them. Regarding l-stenosis ; ...Pain, see neurologist..

Diagnosis: Start with urologist. May need both for optimal care.