I have been told I have white cells in my urine but no infection can be detected, what could this mean?

WBC. Was a urine culture done ? And how many white cells were found. If the culture was done and was negative then you have sterile pyuria. Search for cause needs you to see a kidney doc. Sometimes abx, herbal medications can cause this as an allergic reaction. Often a repeat urine test with culture is the best next step. Best of luck.