What happens if a man urinates blood?

Lupus

nephritis is due to abnormal immune system produced immune complex, resulting in kidney damage bleeding, blood into the ureter

and urine together with the excretion of the body, resulting

3. Bladder cancer

If a man has bladder cancer, cancer cells will damage bladder tissue and bleeding, blood and urine inside the bladder combined, resulting in urine blood when excreted.