Why does kidney cancer cause blood in urine?

The kidneys filter blood and make urine. A growth in kidney tissue may contain fragile blood vessels or irritate nearby structures, allowing blood cells to enter the urine. The urine may look pink, red, brown or normal to the eye when blood is present only in a laboratory test. Blood in Urine is a very common presentation of Kidney Cancer. However, blood in urine also has many other possible causes, including infection, stones and some medicines.

Contact a clinician promptly if you see blood in your urine, even if it happens once or stops. They may ask about pain, urinary symptoms, recent exercise, medicines and smoking history. Assessment can include a urine sample, blood tests and imaging of the urinary tract. Do not assume the colour change is harmless or try to diagnose its cause from appearance alone.

Seek urgent care if you cannot pass urine, pass clots, have severe pain in the side or lower abdomen, feel faint, or have fever with urinary symptoms. These features can need prompt treatment regardless of the cause. Keep a note of when the bleeding began and any pain or urinary changes to share with the clinical team.

Ask what tests are needed to identify the source of bleeding, whether a urine infection or stone needs checking, and when you should expect results. Tell the clinician about blood-thinning medicine, previous urinary problems and any family history of kidney disease or cancer.