Understanding urine tests

When you go to the toilet and pee, urine leaves your body. That is very important for various bodily functions. It regulates the balance of water in the body, for example, and also gets rid of substances that are produced during metabolic processes and are no longer needed. These include toxic substances in foods or medicines. Urine tests can help to detect diseases of the urinary system as well as metabolic diseases like diabetes or liver disease.

The color, odor (smell) and amount of urine can already indicate whether something is wrong. If, for instance, someone passes only a little very dark urine, it could be a sign that they haven’t had enough to drink – or that their kidneys are no longer working properly. Cloudy urine could be a sign of a urinary tract infection (UTI) like cystitis. If the urine is reddish in color, there might be blood in it. To find out more, the urine needs to be tested using a test strip or in a lab.

Five standard urine tests can be used to examine the different components of urine. Two of them can also be done at home, whereas the other three can only be done in a lab.

Before collecting a sample, it’s a good idea to cleanse your genital area with water (no soap). Otherwise, the urine may be contaminated with bacteria, cells or other substances. To get an accurate result and avoid bacterial contamination, “clean” midstream urine is used. You take a sample of midstream urine by stopping the flow of urine after a few seconds and then collecting the middle part of the urine stream in a cup. Your doctor will let you know if there is anything else you should pay attention to for your specific test.

A rapid urine test is the quickest way to test urine. This involves dipping a test strip with small square colored fields on it into the urine sample for a few seconds. After that you have to wait a little for the result to appear. Depending on the concentration of the particular substance you are testing for, the fields on the test strip change color. Then the resulting colors of the fields are compared with a color table. The color table can be found on the urine test package. It shows which colors indicate normal and abnormal values.

Rapid urine tests are usually done as part of routine examinations – for example, at a family doctor’s office, during routine appointments in pregnancy, when being admitted to a hospital, or before surgery. They are also used in people who have acute symptoms like lower abdominal pain, belly ache or back pain, frequent painful urination, or blood in their urine. Some people who have diabetes use this kind of test to check their sugar levels.

Rapid urine tests can be done at doctor’s offices, in hospital, or at home. The test strips are available without a prescription at the pharmacy or on the internet. But they are not intended for self-diagnosis purposes, and should be used in consultation with a doctor.

Many substances are usually found in specific “normal” amounts in urine, so higher or lower levels indicate that something is abnormal.

The following substances can be checked using a rapid urine test:

• pH value (the acidity of urine. Normal values range from about 5 to 7, depending on your diet. A pH under 5 is too acidic, and a pH over 7 is not acidic enough.)
• Protein (not usually found in urine)
• Sugar (glucose, not usually found in urine)
• Nitrite (not usually found in urine)
• Ketone (a metabolic product, not usually found in urine)
• Bilirubin (breakdown product of hemoglobin, not usually found in urine)
• Urobilinogen (breakdown product of bilirubin, not usually found in urine)
• Red blood cells (erythrocytes, not usually found in urine)
• White blood cells (leukocytes, not usually found in urine)

You can see whether the results are within the normal range by looking at the package insert or the color chart on the package. The pH value, for example, can be used to find out whether there is an increased risk of developing urinary stones. This is the case if the pH is too acidic (if the value is below 5). A pH value over 7 may be a sign of a bacterial urinary tract infection like cystitis. Tests measuring other things can help to detect other problems:

• High protein levels may be a sign of nephritis (a kidney inflammation).
• Ketones and sugar in urine are signs of high blood sugar.
• Leukocytes or nitrite may be a sign of a bacterial infection.

If the test results are abnormal, you should see a doctor. As with all tests, the results of rapid urine tests are not always reliable. For this reason, it might be a good idea to have a more detailed test done in a lab.

Urinalysis is an initial basic test of the main features of the urine. It is often part of a routine examination and is frequently performed when people are admitted to hospital and before surgery. It can also be used to check abnormal results from a rapid urine test.

Complete urinalysis is done in a laboratory. It usually involves three steps:

1. Assessment of the color, cloudiness and concentration of the urine
2. Examination of the chemical composition of the urine using a test strip
3. Examination of the urine under a microscope to look for bacteria, cells and parts of cells

Urinalysis is used to find the cause of – or monitor – urinary tract infections (UTIs) like cystitis, bleeding in the urinary system, or kidney or liver disease. It can also be used for diabetes, some diseases of the blood, and urinary stones.

In addition to the substances that can be detected using a rapid test, urinalysis can also test for the following:

• Creatinine (breakdown product of muscle metabolism, an indicator of kidney function)
• Bacteria (not usually found in urine)
• Urinary casts (cylindrical stuck-together structures that form in the kidney, not usually found in urine)
• Crystals (found if there are high concentrations of certain substances in the urine, not usually found in urine)
• Epithelial cells (cells that line the ureter, bladder and urethra)

With the help of these results, laboratories can also detect signs of other problems:

• Cholesterol crystals can be caused by high levels of cholesterol in the urine, for example.
• Urinary casts are usually a sign of kidney disease, such as an inflammation of the renal pelvis.

Abnormal results can be discussed with a doctor and may be followed by more precise tests, such as a blood test.

A urine culture is a test done in a laboratory to see whether urine has germs in it. A sample of midstream urine is poured into a flat, round container called a Petri dish. Then a round, jelly-like plate is put into the urine sample and the container is closed tightly. The plate has a special substance in it that allows germs to grow. The container is placed in an incubator for one to two days. If there are bacteria or fungi in the urine, visible colonies can grow.

Urine cultures can be done to see whether there are bacteria or fungi in urine. If there are, you can often already see what type of bacteria or fungi they are based on the size, form and color of the colonies.

Urine cultures are usually done to detect bacteria and fungi in urine when testing for a urinary tract infection (UTI) like cystitis. If bacteria are found during laboratory testing, then the type of antibiotic needed is usually determined at the same time.

This test involves collecting urine over a period of 24 hours: The first load of urine (when you first go to the toilet after waking up) is not used, but the time is noted. From then on, for the next 24 hours every single drop of urine is collected in a container. Once the 24 hours are up, you pee one last time and the urine is added to the sample already collected. Your doctor will give you the container for the urine sample. The container usually already has a substance in it to prevent bacteria from growing while the urine is still being collected. The urine should be kept in a fridge for the entire 24-hour period. It is then tested in a laboratory.

24-hour urine samples can be used to find out what amounts of certain substances (such as proteins, hormones, salts and metabolic products) are released from the body.

The test results can tell us things like how much protein and creatinine are in the urine. If too little of the metabolic product creatinine is being filtered out of the blood by the kidneys, the kidneys may not be working properly. High levels of protein in urine, known as proteinuria, can be caused by conditions such as heart failure, diabetes, inflammation of the renal pelvis, urinary tract infections, kidney disease or kidney cancer.

Some disorders of the endocrine (hormone) system increase the amount of hormones and their metabolic products in the urine. In order to detect those disorders, urine is often collected over a 24-hour period on several days and then tested.

If your menstrual period is late, there are different tests available to find out whether you are pregnant. Although they are not absolutely reliable, most tests can already determine whether a woman is pregnant with some certainty from the first day after her period was due. They are usually done like rapid urine tests, using a urine sample in the morning after getting up. You can find exact instructions in the package insert. Pregnancy tests can be bought in pharmacies, drugstores, department stores and on the internet.

The urine of pregnant women contains a special hormone known as human chorionic gonadotropin (hCG). The test detects this hormone.

Many women who would like to find out whether they are pregnant will first do a pregnancy test. The results might be false if a woman does the test too soon, is taking certain kinds of medicine or drinks a lot of fluids before doing the test. Doctors and midwives can also do a pregnancy test to see whether you are pregnant. You will usually have to pay for this test yourself, too.

Drugs can be detected in urine for a while after being used. Depending on the type of test, cannabis can be detected up to several weeks afterwards. Drugs like cocaine, ecstasy or heroin can show up in test results for up to five days. Various types of tests can be used here: Rapid tests help to give police fast results on site, while other drug tests need to be sent to a laboratory. Some urine tests can find out whether athletes have used performance-enhancing substances that are banned (doping).