My Husband (69yrs) Noticed Small White Flakes In His Urine.

my husband (69yrs) noticed small white flakes in his urine. he just started yesterday to have frequent need to urinate. had bladder infection bout 2 yrs ago..was told his prostate was enlarged (benign)..put on Tamsulosin..symptoms improved, so he stopped med.Has no pain/discomfort except for when he first starts to urinate..What are these flakes made of? thank you..