Urine Test

A urine test checks different components of urine, a waste product made by the kidneys. A regular urine test may be done to help find the cause of symptoms. The test can give information about your health and problems you may have.

The kidneys take out waste material, minerals, fluids, and other substances from the blood to be passed in the urine. Urine has hundreds of different body wastes. What you eat, drink, how much you exercise, and how well your kidneys work can affect what is in your urine.

More than 100 different tests can be done on urine. A regular urinalysis often includes the following tests.

• Color. Many things affect urine color, including fluid balance, diet, medicines, and diseases. How dark or light the color is tells you how much water is in it. Vitamin B supplements can turn urine bright yellow. Some medicines, blackberries, beets, rhubarb, or blood in the urine can turn urine red-brown.
• Clarity. Urine is normally clear. Bacteria, blood, sperm, crystals, or mucus can make urine look cloudy.
• Odor. Urine does not smell very strong, but has a slightly "nutty" odor. Some diseases cause a change in the odor of urine. For example, an infection with E. coli bacteria can cause a bad odor, while diabetes or starvation can cause a sweet, fruity odor.
• Specific gravity. This checks the amount of substances in the urine. It also shows how well the kidneys balance the amount of water in urine. The higher the specific gravity, the more solid material is in the urine. When you drink a lot of fluid, your kidneys make urine with a high amount of water in it which has a low specific gravity. When you do not drink fluids, your kidneys make urine with a small amount of water in it which has a high specific gravity.
• pH. The pH is a measure of how acidic or alkaline (basic) the urine is. A urine pH of 4 is strongly acidic, 7 is neutral (neither acidic nor alkaline), and 9 is strongly alkaline. Sometimes the pH of urine is affected by certain treatments. For example, your doctor may instruct you how to keep your urine either acidic or alkaline to prevent some types of kidney stones from forming.
• Protein. Protein is normally not found in the urine. Fever, hard exercise, pregnancy, and some diseases, especially kidney disease, may cause protein to be in the urine.
• Glucose. Glucose is the type of sugar found in blood. Normally there is very little or no glucose in urine. When the blood sugar level is very high, as in uncontrolled diabetes, the sugar spills over into the urine. Glucose can also be found in urine when the kidneys are damaged or diseased.
• Nitrites. Bacteria that cause a urinary tract infection (UTI) make an enzyme that changes urinary nitrates to nitrites. Nitrites in urine show a UTI is present.
• Leukocyte esterase (WBC esterase). Leukocyte esterase shows leukocytes (white blood cells [WBCs]) in the urine. WBCs in the urine may mean a UTI is present.
• Ketones. When fat is broken down for energy, the body makes substances called ketones (or ketone bodies). These are passed in the urine. Large amounts of ketones in the urine may mean a very serious condition, diabetic ketoacidosis, is present. A diet low in sugars and starches (carbohydrates), starvation, or severe vomiting may also cause ketones to be in the urine.
• Microscopic analysis. In this test, urine is spun in a special machine (centrifuge) so the solid materials (sediment) settle at the bottom. The sediment is spread on a slide and looked at under a microscope. Things that may be seen on the slide include:
  • Red or white blood cells. Blood cells are not found in urine normally. Inflammation, disease, or injury to the kidneys, ureters, bladder, or urethra can cause blood in urine. Strenuous exercise, such as running a marathon, can also cause blood in the urine. White blood cells may be a sign of infection or kidney disease.
  • Casts. Some types of kidney disease can cause plugs of material (called casts) to form in tiny tubes in the kidneys. The casts then get flushed out in the urine. Casts can be made of red or white blood cells, waxy or fatty substances, or protein. The type of cast in the urine can help show what type of kidney disease may be present.
  • Crystals. Healthy people often have only a few crystals in their urine. A large number of crystals, or certain types of crystals, may mean kidney stones are present or there is a problem with how the body is using food (metabolism).
  • Bacteria, yeast cells, or parasites. There are no bacteria, yeast cells, or parasites in urine normally. If these are present, it can mean you have an infection.

A urine test may be done:

• To check for a disease or infection of the urinary tract. Symptoms of a urine infection may include colored or bad-smelling urine, pain when urinating, hard to urinate, flank pain, blood in the urine (hematuria), or fever.
• To check the treatment of conditions such as diabetes, kidney stones, a urinary tract infection (UTI), high blood pressure (hypertension), or some kidney or liver diseases.
• As part of a regular physical examination.

Do not eat foods that can color the urine, such as blackberries, beets, and rhubarb, before the test. Do not exercise strenuously before the test.

Tell your health professional if you are menstruating or close to starting your menstrual period. Your health professional may want to wait to do the test.

Your health professional may ask you to stop taking certain medicines that color the urine. These include vitamin B, phenazopyridine (Pyridium), rifampin, and phenytoin (Dilantin). Be sure to tell your health professional if you are taking diuretics, which may affect the test results.

Talk to your health professional about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form (What is a PDF document?).

A routine urine test can be done in your health professional's office, clinic, or lab. You may also be asked to collect a urine sample at home and bring it with you to the office or lab for testing.

Clean-catch midstream one-time urine collection

• Wash your hands to make sure they are clean before collecting the urine.
• If the collection cup has a lid, remove it carefully and set it down with the inner surface up. Do not touch the inside of the cup with your fingers.
• Clean the area around your genitals.
  • A man should retract the foreskin, if present, and clean the head of his penis with medicated towelettes or swabs.
  • A woman should spread open the genital folds of skin with one hand. Then use her other hand to clean the area around the urethra with medicated towelettes or swabs. She should wipe the area from front to back so bacteria from the anus is not wiped across the urethra.
• Begin urinating into the toilet or urinal. A woman should hold apart the genital folds of skin while she urinates.
• After the urine has flowed for several seconds, place the collection cup into the urine stream and collect about 2 fl oz (59 mL) of this “midstream” urine without stopping your flow of urine.
• Do not touch the rim of the cup to your genital area. Do not get toilet paper, pubic hair, stool (feces), menstrual blood, or anything else in the urine sample.
• Finish urinating into the toilet or urinal.
• Carefully replace and tighten the lid on the cup then return it to the lab. If you are collecting the urine at home and cannot get it to the lab in an hour, refrigerate it.

Double-voided urine sample collection

This method collects the urine your body is making right now.

• Urinate into the toilet or urinal. Do not collect any of this urine.
• Drink a large glass of water and wait about 30 to 40 minutes.
• Then get a urine sample. Follow the instructions above for collecting a clean-catch urine sample.

Return the urine sample to the lab. If you are collecting the urine at home and cannot get it to the lab in an hour, refrigerate it.

There is no discomfort in collecting a one-time urine sample.

There is no chance for problems in collecting a one-time urine sample.

A urine test checks different components of urine, a waste product made by the kidneys. Normal results may vary from lab to lab.

Reasons you may not be able to have the test or why the results may not be helpful include:

• If you are having your menstrual period.
• Taking medicines, such as diuretics, erythromycin, trimethoprim (Trimpex), or high doses of vitamin C (ascorbic acid) taken with an antibiotic, such as tetracycline.
• Having an X-ray test with contrast material in the past 3 days.
• Not getting urine sample to lab in 1 hour.

• Some urine tests can be done using a home test kit. For more information, see the medical test Ketones or Home Test for Urinary Tract Infections.
• In some cases, the amount of urine you make in 24 hours may be measured. Most adults make about 1 qt (1 L) to 2 qt (2 L) per day. Children make about 0.3 qt (0.3 L) to 1.6 qt (1.5 L) per day.
• Other substances that may be checked during a urine test include:
  • Bilirubin. This is a substance formed by the breakdown of red blood cells. It is passed from the body in stool. Bilirubin is not found in urine. If it is present, it often means the liver is damaged or that the flow of bile from the gallbladder is blocked. For more information, see the medical test Bilirubin.
  • Urobilinogen. This is a substance formed by the breakdown of bilirubin. It is also passed from the body in stool. Only small amounts of urobilinogen are found in urine. Urobilinogen in urine can be a sign of liver disease (cirrhosis, hepatitis) that the flow of bile from the gallbladder is blocked.
  • Bence Jones protein. This is an abnormal protein found in the urine of about 50% of people with a rare type of cancer called multiple myeloma. A urine test is often done when multiple myeloma is suspected. The protein test done during a regular urine test does not check for Bence Jones protein.
• Collecting a urine sample from a small child or baby is done by using a special plastic bag with tape around its opening. The bag is placed around the child's genitals until he or she urinates. Then you carefully removed the bag. To collect a urine sample from a very sick baby, a health professional may use a urinary catheter through the urethra or a needle through the baby's belly directly into the bladder (suprapubic tap).
• To lower the chance of contaminating the urine sample with bacteria, a health professional may collect a urine sample by using a urinary catheter. A catheter may be used to collect urine from a person in the hospital who is very ill or who cannot give a clean-catch sample. Using a catheter allows a clean sample to be collected.
• If an abnormal result is found during a urine test, more tests may be done, such as a urine culture, X-ray of the kidneys (intravenous pyelogram [IVP]), or cystoscopy. For more information, see the medical tests Urine Culture, Intravenous Pyelogram (IVP), and Cystoscopy.

Other Works Consulted

• Pagana KD, Pagana TJ (2006). Mosby’s Manual of Diagnostic and Laboratory Tests, 3rd ed. St. Louis: Mosby.