Can any nephrologist help with my question? how many uti's before you have to worry about kidney damage?

Three in one year: Three uti's in one year prompts most md's to refer the patient to a urologist for a workup which may include cystoscopy or other studies looking for obstructive causes and abnormalities. If the uti"s are untreated and result in a full blown pyelonephritis then one major infection of that type can cause kidney damage.

UTI kidney damage: It is relevant whether a UTI stays within one's bladder or ascends into the kidney. It takes about 3-4 days for an untreated UTI to ascend to the kidney. Once in the kidney, resolution is more difficult. Old data indicate that 3 or 4 true kidney infections will leave residual damage. It matters if the ureters reflux and if there is a stone in the kidney. Then damage is more likely.