A urinalysis is a group of tests that measures several substances in your urine, including tiny traces of blood that you can't see. Some substances in your urine are expected, as they're simply by-products of your body working normally.

The main purpose of your urinalysis is to check for blood that's invisible to the naked eye. Small amounts of blood can be caused by everyday things like recent hard exercise or your period. It can also come from an infection, kidney stones, kidney problems or an enlarged prostate. Less often, it can be an early sign of cancer of the kidney, bladder or prostate. That's why your results will tell you if blood is found and whether you should speak to your GP.

As well as checking for blood, your sample is tested for:

• Protein
• pH
• Glucose
• Ketones
• Urobilinogen
• White blood cells
• Red blood cells
• Casts
• Epithelial cells
• Crystals