About 4 months ago, I noticed white tissue like particles in my urine. It is very visible and is in my urine EVERYDAY, it's not always present everytime I use the bathroom. I went to have my urine tested and that moment there were no particles present at the time of that urinalysis. I was given a strainer to catch the particles to be analyzed. I was told by the doctor the lab results showed that as protein. They sent me to a urologist and again they did a pee test and there were no particles present, so they want me to do a 24hr test. What can be causing this? I didn't have any pain associated with it. Although, about 2 weeks ago I have started having flank pain on both sides. I am a 28yr old female, with high blood pressure(on medicine and under control right now), I take Yaz, and I am on Synthroid. Both Kidney disease and heart disease run in my family.