Red and yellow and pink and green – your urine can sing a rainbow too. You may be surprised to find out it can be purple and orange and blue. And a myriad of other unusual colours besides.

Urine acts as a medium through which the body can excrete several waste products. This includes nitrogenous waste from the breakdown of protein and muscle (in the form of urea and creatinine), and red blood cells. In addition, many different ingested compounds, including vitamins, medicines, and some from our diet work their way out of the body via urine.

But there are plenty of things that shouldn’t be present in urine, and one important question a doctor should consider is: “What colour is it?” Doing so can help point toward a diagnosis.

Red urine usually signifies bleeding. This can come from anywhere in the urinary tract – from the kidneys to the bladder and the prostate gland, and all the tubing that connects them.

The appearance of blood varies according to volume and freshness and can produce many different colours. In high-volume bleeds, the urine can be so stained that it looks like red wine. Many conditions can cause bleeding, from kidney stones to cancer, to trauma and urinary tract infections.

But red urine can also come from eating too much beetroot.

Of course, we know that the colour of urine in its normal form covers many........

© The Conversation