What could cause blood in my urine?

Bright red ?cystitis: If u have symptoms of burning on urination & frequency of urination. Bright red with no other symptoms could be a small vascular malformation (like vascular nevus) of kidney. Brown urine with proteinuria suggests kidney disease. Unusual for kidney or bladder tumor at your age. Microscopic hematuria could be caused by a kidney stone. Microscopic hematuria often benign. Needs work-up & ? Cystoscopy.