Urinalysis

What is being analysed?
Urinalysis is a group of tests that detect or semi-quantitatively measure various components eliminated in the urine, including normal and abnormal products of metabolism as well as cells, bacteria and cell fragments. Urine is produced by the kidneys, located on either side of the spine at the back of the abdomen. The kidneys filter waste and metabolic products from the blood, help regulate the amount of water in the body, and conserve proteins, electrolytes and other components that the body reuses. Everything
that is not needed is excreted in the urine, which passes from the kidneys to the bladder and, through the urethra, out of the body. Urine is generally yellow and fairly clear, but depending on the time of day it is passed, its colour, quantity, concentration and content will vary somewhat as its components change.
Many disorders can be diagnosed at an early stage by looking for abnormalities in the urine, such as glucose, protein, bilirubin, red blood cells, white blood cells, crystals and bacteria. These may be present because there are high concentrations of the substances in the blood and the body is trying to lower them by “offloading” them into the urine, because kidney disease has impaired the kidneys’ filtering capacity or, in the case of bacteria, because of an infection.

A complete urinalysis consists of three separate steps:

physical examination, which assesses colour, clarity and specific gravity;
chemical examination, which tests chemically for 9 substances that provide information on health and disease;
microscopic examination, which identifies and counts the types of cells, casts, crystals and other components (bacteria, mucus) that may be present in the urine.

A routine urinalysis usually includes the chemical and physical examination. These two steps can be completed in a few minutes, even in the family doctor’s surgery. Microscopic examination is carried out if the chemical and physical examination has given abnormal results, or if the family doctor specifically requests it.

How is the sample collected for testing?
Urine for chemical and physical examination can be collected at any time, but a first-morning sample is much better because, being more concentrated, it is more likely to show any abnormal results. Because of the risk of contaminating the urine with bacteria and cells from the surrounding skin during collection (especially in women), it is important to clean the genitals first. Women should separate the labia and clean them from front to back; men should clean the tip of the penis. When you start passing urine, let the first stream go into the toilet, then collect the urine (10-20 ml) in a suitable container, and then finish passing urine normally

How is it used?
When is it requested?
What does the test result mean?
Is there anything else I should know?

How is it used?
Urinalysis is used for screening and/or diagnosis because it can detect substances or cellular material in the urine in a variety of metabolic and kidney disorders. It is widely and routinely requested to detect any abnormal condition that should be monitored. Substances such as protein or glucose often appear in the urine before patients realise they have a problem. It is used to detect urinary tract infections (UTIs) and other abnormal conditions. In patients with acute or chronic conditions, such as kidney disease, urinalysis may be requested at frequent intervals to help monitor kidney function and the response to treatment.

When is it requested?
A routine urinalysis may be carried out on admission to hospital. It may be part of a check-up, during pregnancy or before surgery, or in the case of abdominal pain, back pain, increased frequency of urination, blood in the urine, or when symptoms of a UTI appear. The test can also be useful for monitoring all these conditions to see whether they are improving or getting worse.

What does the test result mean?
A urinalysis can be interpreted in many ways. It is a warning sign that something is wrong and needs further investigation. In general, the higher the concentration of abnormal substances (such as a significant increase in glucose, protein or red blood cells), the more likely it is that there is a problem that needs to be properly identified. But the results on their own often do not tell the doctor the exact cause of the abnormal result, or whether the situation is temporary or chronic. It should also be stressed that a normal urinalysis does not necessarily rule out disease. Some people do not release large amounts of abnormal substances in the early stages of a disease, and some release them only sporadically during the day (which means the information may be missed if only one urinalysis is done). In very dilute urine, small amounts of abnormal chemicals may not be detected.

Is there anything else I should know?
Urinalysis is a group of screening tests that can give an overall picture of your state of health. Your doctor must compare the results with your symptoms and their own findings, and look for the causes of any urinalysis abnormalities with tests such as a comprehensive metabolic panel, a full blood count or a urine culture (to look for a urinary tract infection). A urine sample is only useful if it has been collected cleanly and taken promptly to the laboratory. If it is expected to take more than an hour after collection to deliver the sample, it should be refrigerated

1. How soon are urinalysis results available?
2. Does the time the sample is collected matter?
3. Are there kits for doing the test at home?

1. How soon are urinalysis results available?
It depends on the laboratory and its equipment. Ideally, once the sample is in the laboratory, the test takes about 30 minutes.

2. Does the time the sample is collected matter?
Since urinalysis is a screening test, the timing is not critical, although a first-morning sample is preferred. Your doctor may ask you to collect a urine sample at a particular time. For example, if they are looking for glucose excretion, it is better to collect the sample after a meal. If they are looking for a small amount of protein in the urine, it is better to collect a concentrated first-morning urine sample.

3. Are there kits for doing the test at home?
No commercial kits are available for this test, because of the equipment and technical expertise required. However, some commercial dipsticks may be available for part of the chemical examination only, such as pH, glucose and ketones.