Urine tests

A urine test looks at a sample of your urine. A routine test (urinalysis) checks the colour and clarity, uses a dipstick to look for chemicals such as sugar, ketones and protein, and may look at the urine under a microscope for cells and germs. A urine culture is different: the lab tries to grow any germs in the sample, to name the germ causing an infection and see which antibiotics will work.

A doctor may ask for a urine test as part of a routine check, to look for signs of diabetes or kidney disease, to follow their treatment, to find out why there is blood in the urine, or to look for a urinary tract infection. A culture is asked for when there are symptoms such as pain or burning on passing urine, and sometimes after treatment to check that the germs have gone.

You usually need no special preparation. The lab gives you a clean container.

A clean catch sample is collected like this:

1. Clean the area around the opening where urine comes out with the wipe you are given. Women wipe from front to back. Men pull back the foreskin first, if they have one.
2. Let the first part of the stream go into the toilet.
3. Collect urine in the container until it is about half full.
4. Finish passing urine in the toilet, then screw the lid on tightly.
5. Hand the container to the lab. If you collected it at home, keep it in a plastic bag in the fridge until you can take it.

For a baby, urine is collected in a sticky bag. Sometimes staff pass a thin tube (catheter) into the bladder. A 24-hour test collects all your urine for a day.

You can carry on as normal. Ask when and how you will get the report. A culture takes 24 to 48 hours in the lab. Home test strips can miss an infection, so you may still need a lab test.

Passing urine into a container carries no known risks. If a catheter is needed, it can cause a feeling of pressure, and a numbing gel is used. Rarely, a catheter can make a hole in the urethra or bladder.

The report prints the lab's own normal range, which can differ from one lab to another, so go through it with the doctor. Sugar, ketones, protein, bilirubin, blood cells and nitrites are not normally found.

A result outside the normal range does not always mean disease. Protein can rise for a short time after hard exercise or when you are short of water, so the test is often repeated. Nitrites suggest an infection, but an infection can be present without them.

What the tests cannot show: a routine test cannot name the germ, but a culture can. Bacteria or yeast growing in a culture usually means a urinary tract infection, and normal growth means no infection. Protein, blood or sugar in the urine needs more tests to find the cause.