Urine test (urinalysis)
A urine test or urinalysis may be carried out to check for dozens of conditions, including urinary tract infections (UTIs) such as cystitis, pregnancy and diabetes.
Many substances circulating in the blood eventually make their way into the urine, where excess concentrations of protein or sugar may be detected. Urine is normally sterile, but infections with bacteria or yeast may also be found in a urine sample.
Once collected, a urine sample may be tested instantly with a special test strip or sent off to a laboratory for analysis. Sometimes the appearance of the urine, such as cloudiness or colour, or its smell, can give clues about health problems.
Depending on what the urine is being tested for, doctor or nurses may ask for the sample to be collected at a certain time, such as first thing in the morning, or for a whole day's urine to be collected and measured.
A urine test may be just part of steps taken to diagnosis a condition, or it may be all a doctor needs to check a diagnosis.
Some common urine tests include:
Collecting a urine sample
If you are asked for a urine sample, you will usually be given a special labelled container to fill and instructions on when to collect the sample.
Specific instructions may be given, but generally the NHS advises the following to collect a clean urine sample:
- Label the container with your name, date of birth and the date
- Wash your hands
- Men should wash their penis, women should wash their genitals
- Begin to urinate, you may be advised to collect the first or middle part (mid-stream) of the stream
- Collect a sample of urine
- Seal the container securely
If you cannot hand it in within one hour, you can store it hygienically for up to 24 hours in a sealed plastic bag in the fridge.
Urine colour changes
Urine gets its yellow colour from a pigment called urochrome, also called urobilin. That colour normally varies from pale yellow to deep amber, depending on the concentration of the urine. Darker urine is usually a sign that you're not drinking enough fluid.
Pale urine is usually a good thing, as it means that you're drinking enough water, but very pale urine may also result from taking a diuretic - a drug that forces the body to get rid of excess water - or from a rare type of diabetes called diabetes insipidus.
Urine can appear different colours, but this isn't always a reason to be concerned. Certain medications can turn the urine fluorescent green or blue, carrots can tint it orange, some vitamins can give it a yellow hue, and beetroot or food colourings may produce pink urine. Sometimes an unusual colour is due to a medical problem, for example blood in the urine may turn it pink or light brown. Milky or cloudy urine suggests a urinary tract infection, dark brown urine can be a sign of liver disease and port-coloured urine can occur with an inherited disease called porphyria.