What can be detected in a urine test?

A urinalysis is a common urine test that can be done as part of a routine physical examination or in an effort to monitor or diagnose a wide range of medical conditions, from urinary tract infections to kidney disease. A urinalysis is a quick and painless way for your healthcare provider to obtain valuable information about your health.

Read on to learn more about what a urinalysis is, what it tests for, and how to prepare for it, as well as what your urinalysis results mean. 

What is a urinalysis?

A urinalysis is a urine test that can be used to screen or monitor a variety of health conditions. During a urinalysis, a sample of urine is collected and then sent to the lab to be analyzed based on the physical appearance, microscopic findings, and chemical makeup of the sample. 

Results of the urinalysis are generally available within 24-48 hours. However, this will depend on the specific lab and what your healthcare provider is testing for. Based on the results, your healthcare provider may order additional testing, such as a urine culture, to help with the diagnosis. 

Why do I need urinalysis?

“A urinalysis provides a window into the functioning of some of the most important organs of the human body,” says Arnold Shoulder, MD, co-founder and board member of Moonstone Nutrition and former chief of the division of urology at St. Clair Hospital in Pittsburgh.

Urinalysis tests are commonly used as part of routine medical exams, such as prenatal checkups and pre-operative testing. “Abnormal findings on a routine urinalysis, even in an asymptomatic patient, may be the first evidence of an underlying medical issue,” says Derek Larson, MD, FASN, a nephrology specialist at St. Louis Kidney Consultants in Missouri.  

However, your healthcare provider may also order a urinalysis to help monitor or diagnose a variety of medical conditions, including: 

• Urinary tract infections (UTIs) 
• Diabetes mellitus
• Kidney stones
• Kidney or liver disease

In many cases, urinalysis screenings are done in conjunction with other tests, such as a blood test or imaging studies, to help identify the underlying cause of a patient’s symptoms.

What does a urinalysis test for?

Depending on the patient’s symptoms, there are various tests that can be requested by a healthcare provider to be included in a urinalysis.

The lab will evaluate the urine sample using three methods, including:  

• Visual examination
• Chemical dipstick 
• Microscopic examination

Together, the results of these three methods will give healthcare providers a clearer picture of what is going on inside the body, making it easier for them to identify the next steps and whether further testing will be needed.

Visual examination

One of the first things a healthcare professional will do when conducting a urinalysis is visually examine the urine. Normal urine is generally clear, pale to light yellow, and relatively odorless. However, changes to the appearance or odor of the urine could indicate a health issue.

For example, red urine may indicate that there is blood in the urine. This could be due to a number of conditions such as kidney disease, urinary tract infection, or cancer. Similarly, foamy urine may be a sign of kidney disease. Dark brown urine may be a sign of liver disease, as excess bilirubin in the blood can spill into the urine and cause this discoloration.

However, there are many factors that can alter the appearance of urine, including diet and medications. While the physical appearance of urine can give important clues about a person’s health, it’s not always conclusive. For more comprehensive results, healthcare providers will also conduct a chemical dipstick test and a microscopic exam.

Chemical dipstick 

During the chemical dipstick test, a plastic test strip with pads or strips of chemicals on it is placed in the urine specimen. These chemical strips change colors when they come in contact with certain substances in the urine. The lab technician then compares the color of the strip to a color chart to determine which, if any, substances are present in the urine. The depth of the color change on the strip can also give clues about the concentration of a substance in the urine.

There are many different tests that can be conducted using a chemical dipstick, including:

• Urine protein test: A small amount of protein in the urine is normal. However, higher levels of protein in the urine may indicate a kidney problem, such as glomerulonephritis. Glomerulonephritis is a type of kidney inflammation that can damage the kidneys and cause them to leak protein into the urine.
• Urine pH level test: Urine is normally slightly acidic, with a pH level of 4.5 to 7.5. A higher-than-normal pH level may indicate a kidney condition, such as kidney stones or infection. A lower-than-normal pH level may indicate metabolic acidosis, a condition that occurs when the body produces too much acid or doesn’t get rid of enough acid.
• Ketones test: A ketones urine test measures ketones—a type of acid that is produced when the body breaks down fat for energy—in the urine. A high level of ketones in the urine may indicate diabetic ketoacidosis (diabetes with sky-high blood sugars). Starvation can also cause this to occur.
• Glucose test: A small amount of glucose in the urine is normal. However, high levels of glucose in the urine may indicate poorly controlled diabetes.
• Bilirubin test: Bilirubin is a yellow pigment that is produced when the liver breaks down red blood cells. A small amount of bilirubin in the urine is normal. However, high levels of bilirubin in the urine may indicate liver disease, such as hepatitis or cirrhosis.
• Urine specific gravity test: Urine specific gravity is a measure of the density of the substances in urine. A high specific gravity means that there are more particles in the urine, while a low specific gravity means that there are fewer particles. The specific gravity of urine can be affected by many factors, including hydration status and diet (dehydration will cause the specific gravity to be high, while drinking a lot of water will cause it to be low).
• Nitrite urine test: The nitrite urine test detects the presence of nitrites in the urine, which are produced when bacteria break down nitrogen in the body. A positive nitrite test result may indicate a UTI.
• Leukocyte esterase urine test: Leukocyte esterase is an enzyme that is produced by white blood cells. A high level of leukocyte esterase in the urine may indicate a bacterial infection in your urinary tract, such as a UTI.

Your healthcare provider will decide which tests to conduct based on your symptoms and medical history.

Microscopic exam

In preparation for the microscopic exam, a portion of the urine will first be put into a centrifuge (a machine that spins down the sample at very high speeds) to concentrate the solids. The concentrated urine sample will then be examined under a microscope, which will help identify any abnormal cells or substances that may be present, such as: 

• Red blood cells (RBCs)
• White blood cells (WBCs)
• Crystals
• Bacteria
• Parasites
• Urinary casts
• Epithelial cells

How do I prepare for a urinalysis? 

While there is generally minimal preparation that needs to be done prior to a urinalysis, it’s important to inform your healthcare provider of any medications or supplements you are taking. 

“Certain medications can affect the interpretation of a urinalysis, so a patient should make sure their physician has an accurate medication list,” Dr. Larson explains. “For instance, vitamin C supplements can cause a false-negative result in the detection of blood on a urine dipstick.”

Certain foods or dyes can also discolor the urine “For example, if a patient consumes a large number of beets the night before, the urine sample could appear to have blood in it,” Dr. Shoulder says. “This would be important to tell a healthcare practitioner if the urine appears discolored.”

Your healthcare provider will then describe the steps you should follow to collect your urine sample without contamination. This process is known as the “clean catch” method.

The “clean catch” method involves the following steps: 

1. Wash your hands with soap and water.
2. Write your name on the sample cup (if requested) and remove the lid. 
3. Clean the area around the urethra (the opening where urine exits the body) with a wipe provided by your healthcare provider.
4. Start to urinate into the toilet, but stop the urine flow midstream.
5. Position the sample cup near your body and begin to urinate again, filling the sample cup about half full. 
6. Stop again, remove the cup, and finish urinating into the toilet. 
7. Place the lid on the sample cup and return the urine collection to your healthcare provider or laboratory where you picked it up. If you are unable to deliver your sample within one hour after collection, talk to your healthcare provider about proper storage guidelines.

“The idea of the ‘clean catch’ method is to examine the urine from the bladder once a small amount of urine has already been passed, to decrease the chance of urethral or vaginal contamination,” Dr. Shoulder explains. 

Following the directions of your healthcare provider will help ensure that your results are not contaminated. “Proper collection is important to reliably interpret the findings of a urinalysis,” says Dr. Larson.

How to read a urinalysis

Results of a urinalysis will vary based on the specific tests that were performed by your healthcare provider. In most cases, the urinalysis report will include the following:

• The name of all of the specific urine tests performed on the specimen
• Your result for those tests
• The normal range for each test 

Some results, however, will simply be reported as “positive” or “negative,” to indicate whether there was evidence of the specific substance being tested for. A negative result would indicate  that the substance was not found, while a positive result would indicate that it was.

A healthcare provider will interpret your test results and compare them to what is considered normal. He or she will then follow up with you to discuss any abnormalities, as well as the next steps based on your results.

When should I call my doctor?

While slight changes to the color, such as clear to dark yellow, or odor of your urine may be normal, there are other changes that may indicate a problem. Contact your healthcare provider if you experience any of the following:

• A severe change in urine color (such as red, brown, or black)
• Any unusual particles or sediment
• Foamy or bubbly urine, unless you’ve recently had a catheter
• Strong or severe change in odor
• Pain during urination that does not go away

They will likely order a urinalysis to help determine the cause of your symptoms. Fortunately, in most cases, this can be done quickly in your healthcare providers office.