If blood is mainly at the end of the stream, it is usually from the urinary bladder. Blood
in urine at the beginning is from urethra, and mid stream blood
is generally from kidney, bladder and ureter.
Gross hematuria visible to naked eye is seen in kidney and bladder stones, cancer of kidney, bladder endometriosis, low platelet count, bladder injury and bladder infections. Apart from urine examination, you would need some other blood tests and imaging tests and maybe cystoscopy.