What Is a Urinalysis?

What to expect when undergoing this test

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A urinalysis is a common test used to analyze the content and chemical makeup of your urine. While it is standardly performed before surgery to identify any kidney problems, a urinalysis may be used at a doctor's office if a kidney infection, urinary tract infection, or other urinary-related disorder is suspected. 

A urinalysis should not be confused with a urine drug screening, used to check for recent illicit drug use, or a home pregnancy test, used to detect the pregnancy hormone hCG in urine.

Purpose of Test

The urinary tract is composed of the kidneys, ureter, bladder, and urethra. Its primary role is to filter waste and regulate the balance of water, electrolytes, proteins, acids, and other substances in the body. If any part of this system is damaged or impaired, it will alter the chemical composition and/or volume of urine.

The urinalysis is a direct means of assessing these changes. While a urinalysis is not diagnostic (meaning that it cannot determine the cause of a disease), it can suggest the nature of a problem and may be used to support a diagnosis.

A urinalysis can also be used to monitor and manage a wide range of disorders, most specifically kidney (renal) disorders. Among its applications, a urinalysis may be used to:

A urinalysis may even be included as part of a general annual physical exam. 

Types

When we refer to a urinalysis, we typically assume that to mean peeing in a cup at your doctor's office. In truth, that is just one of the ways urinalysis is performed in clinical practice.

A urinalysis may refer to:

  • A complete urinalysis performed in a lab to assess the physical, chemical, and microscopic characteristics of your urine
  • A rapid urinalysis performed at your doctor's office using test strips to routinely check for common renal abnormalities
  • A 24-hour urine collection in which urine is collected over 24 hours to provide your doctor a clearer picture of your overall renal function, including output and composition

While a urine culture (in which a urine sample is placed in a growth medium to check for bacteria or fungi) is not technically a form of urinalysis, it may be an extension of the test if a UTI is suspected. It can even be performed using the same urine sample.

Risks and Contraindications

A urinalysis is considered a safe and non-invasive form of testing. The only risk it may pose is for those who require catheterization to obtain a urine sample. A Foley catheter, a flexible tube inserted into the urethra to drain the bladder, is the most common type used in people with urinary retention, urinary incontinence, or other conditions that interfere with normal urination. 

The risks of urinary catheterization include infection, bleeding, pain, and bladder damage.

Before the Test

While the preparations for a urinalysis are minimal, there are a few things you should know before delivering a sample.

Timing

An optimal urine sample is usually obtained in the early morning when the concentration is at its highest. If possible, try to schedule the collection for this time and "hold it in" until you get there if you can. The collection itself only takes a couple of minutes.

For a 24-hour urine collection, you should ideally pick a 24-hour period when you can stay at home so that you don't have to carry the samples with you or miss a collection.

Location

A urinalysis may be performed at your doctor's office, clinic, or lab, or upon admission to hospital. In some instances, you may be provided a sterile plastic cup and lid to collect the sample at home, after which you would deliver the sample to the lab within an hour. (If performing a 24-hour urine collection, as your doctor when samples should be dropped off.)

Food and Drink

Typically, no fasting is required before the collection of a urine sample. The only exception would be if other tests are being performed that do require fasting, such as a cholesterol test or fasting plasma glucose test. Check with your doctor if you are unsure about the dietary restrictions. The test is obviously easier with a full bladder, so some like to drink liquids beforehand.

Medications

Most routine medications can be taken before a urinalysis unless your doctor tells you otherwise. It is important, however, to advise your doctor about any and all drugs you may be taking, whether they be prescription, over-the-counter, traditional, homeopathic, or recreational.

Since the test involves a visual, chemical, and microscopic examination of the collected urine, certain substances may throw off the results. Examples include:

  • Anthraquinone laxatives
  • Azulfidine (sulfasalazine), used to treat ulcerative colitis and rheumatoid arthritis
  • Levodopa (L-Dopa), a Parkinson's disease drug
  • Metronidazole, an antibiotic
  • Nitrofurantoin, an antibiotic
  • Phenazopyridine, used to treat UTIs
  • Robaxin (methocarbamol), a muscle relaxant
  • Vitamin B2 (riboflavin) 
  • Vitamin C supplements

Ask your doctor if you need to stop any of these before taking the test.

Cost and Health Insurance

A urinalysis is a common and relatively inexpensive test. Standard testing panels can range in price from $5 of $30, which may be covered in part or in full by health insurance. If you're enrolled in a plan, check the terms of your policy or speak with a customer service representative at your insurance company for complete details, including your deductible and co-pay costs. 

Taking the Test

On the day of the test, bring identification and your insurance card to register. You may also be asked to fill out a patient information form if it is your first visit, detailing any health problems or medications you may be taking. If you are taking the test as part of a doctor's appointment, this may not be necessary.

Preparation

You will then receive a sterile plastic cup and lid, a sanitary cleansing wipe, and instructions on how to obtain a "midstream clean-catch" sample. The clean-catch technique prevents bacteria or fungus from the penis or vagina from accidentally getting into the urine.

You will collect the sample on your own in a private bathroom. First, clean the area around the urethra:

  • Women should clean around the urethra with the cleansing wipe by spreading the labia and wiping from front to back (toward the anus). The cleaning hand should then be used used to keep the labia spread, while the cup is held with the other hand.
  • Men need to clean the tip of the penis before providing a sample.

Collection

To get the optimal catch, start urinating for few seconds to ensure that any contaminants in the urethra are cleared before placing the cup under the stream. Once you have collected at least 30 to 60 milliliters (mL), or roughly three to five tablespoons, you can stop the collection and empty the rest of your bladder into the toilet.

Completion

Once filled, you can place the lid on the cup, wash your hands, and deliver the sample to the nurse or attendant. Some places may instead have you deposit the cup in a designated area.

If you collected the urine sample at home and cannot bring it to the lab within an hour, you may be able to refrigerate it. Speak with your doctor or lab to ensure this is acceptable.

If it is, you should place the sealed cup in a sealed plastic bag to prevent exposure to anything in the fridge. Generally speaking, a urine sample should not be refrigerated for more than 24 hours and should be kept at temperatures of around 39 degrees. A urine sample should never be frozen or kept on ice.

Interpreting the Results

Though evaluation of a urinalysis involves three separate steps, you will generally get your results in just a few days. Understanding the process used to come to your results can help you better understand them and what they might mean.

Visual Examination

During the visual exam, the lab technician will characterize the color and clarity of the urine. Any variations may be signs of an abnormality.

Urine color is considered normal if it is described as yellow, straw color, or near colorless. Abnormal colors may be the result of a disease, something you've eaten, or something you've taken.

Examples include:

  • Dark yellow urine may be an indication of dehydration.
  • Bright yellow urine is often caused by multivitamin supplements.
  • Red or pink urine may be a sign of bleeding or simply a result of having eaten beets.
  • Brown or greenish-brown urine may be a sign of hepatitis or other liver problems.
  • Green urine is sometimes seen in people who have been on the sedative Diprivan (propofol) for a long period of time.

Urine clarity refers to now clear the urine is. Under normal circumstances, urine is expected to be relatively clear or only slightly cloudy. Overt cloudiness is often caused by abnormal or excessive substances in the urine, such as:

  • Bacteria, including sexually transmitted bacteria
  • Calcium crystals, a possible sign of kidney stones
  • Excess protein (proteinuria)
  • Fungus, including yeast (Candida)
  • Pus, a sign of infection
  • Prostate fluid
  • Semen, a sign of retrograde ejaculation
  • Red blood cells (RBCs), a possible sign of bleeding
  • White blood cells (WBCs), a possible sign of infection
  • Uric acid crystals, a possible sign of gout

Chemical Examination

To perform the chemical exam, the lab uses commercially prepared test strips (called reagent strips) impregnated with reactive chemicals. The technician dips each strip into the urine. Any abnormality in the urine composition triggers a color change within seconds or minutes. There are also machines able to do this all at once and deliver an automated result within minutes. 

The 10 most commonly performed reagent tests are:

  • Bilirubin, a yellowish pigment associated liver problems
  • Erythrocytes (red blood cells), a sign of bleeding 
  • Glucose, elevations that suggest diabetes
  • Ketones, elevations that also suggest diabetes
  • Leukocytes (white blood cells), a sign of infection
  • Nitrites, suggestive of a bacterial infection
  • pH, which measures how acidic the urine is
  • Protein, elevations that suggest kidney impairment
  • Specific gravity (SG), which measures urine concentration 
  • Urobilinogen, seen with hepatitis and liver disease

Vitamin C (ascorbic acid) reagent strips are sometimes used to see if any abnormality in the results is caused by disease or a vitamin supplement you may have taken.

Microscopic Examination

A microscopic exam may or may not be performed if the results of the visual and chemical exams are normal. If it is used, the urine sample is prepared by placing it in a centrifuge and spinning it at a rapid speed so that all of the contents are sedimented on the bottom of the tube.

A drop or two of the sediment is then placed on a slide under the microscope. Cells, crystals, and other substances are counted and reported as either "per low power field" (LPF) or "per high power field" (HPF). Other, smaller substances may be reported as "few," "moderate," or "many."

Some of the substances found either abnormally or in abnormal quantities may include:

  • Bacteria, fungi, or parasites
  • Crystals (calcium, uric acid, etc.)
  • Epithelial cells, possibly due to an infection or malignancy
  • RBCs or WBCs
  • Urinary casts, multicolored particles produced by the kidney in response to disease

Reference Ranges

Your doctor should review the results with you. The lab values can be difficult to decipher but are generally evaluated on a scale called a laboratory reference range (RR).

The RR delineates the numeric values between which a test result is considered normal. The RR differs for each substance being tested and is based on the expected value within a specific population. Those values higher than the RR are often marked "H" for high, while values lower than the RR may be marked "L" for low.

In reviewing your results, your doctor will explain which values are normal, borderline, and/or abnormal. Oftentimes, a doctor can explain an abnormality based on your medical history and offer a treatment plan. In other cases, further testing will be needed.

Follow-Up

There will be conditions by which a urinalysis may need to be repeated, either to monitor your response to therapy or the progression of your disease. Two such examples include chronic kidney disease (CKD), in which the amount of protein in urine reveals how rapidly the disease is advancing, and an acute kidney injury (AKI), in which urine test reveals how well the kidneys are recovering.

The same may apply to monitoring gestational diabetes during pregnancy. Routine urinalysis may be ordered to check to see if glucose, not commonly found in urine, is detected. The findings may help direct prenatal treatment and care.

If you have symptoms of a urinary tract infection but the causal agent (pathogen) cannot be identified in the initial urinalysis, a bacterial or fungal culture may be performed along with pathogen-specific blood tests. (Negative urine culture results are sometimes suggestive of a less common viral UTI).

Imaging tests, such as an ultrasound, computed tomography (CT), or magnetic resonance imaging (MRI), may be also be used to determine whether the problem is located before the kidneys (pre-renal), in the kidneys (renal), or after the kidneys (post-renal).

A flexible fiber-optic tool called a cystoscope may be used to check for benign or malignant bladder tumors. The narrow, tube-like device is fed into the bladder through the urethra, providing direct visualization of injuries that other imaging and blood tests sometimes miss.

A Word From Verywell 

A urinalysis with all normal values is generally a strong indication that your kidneys and urinary tract are functioning normally. Beyond that, there are limitations as to what can be interpreted from the test.

What is important to remember is that the absence of abnormal values in a urinalysis is neither the "all clear" sign nor an indication that your symptoms are all in your head. It simply means that the lab has not been able to detect any abnormalities from this one test. 

Similarly, a urinalysis with abnormal values could mean any number of things, both consequential and inconsequential. It is only when used with other tests—such as a complete blood count, liver function, or renal function test—that a urinalysis can provide fuller insights into what is going on. A urinalysis is almost never used as the sole form of diagnosis.

While a urinalysis is an important tool for diagnosis, remember that the values need to be taken in context. Try not to make assumptions until an experienced clinician is able to review your results in their entirety. If an explanation cannot be found, you can seek a second opinion or ask for a referral to a specialist who may have better insights into a possible cause.

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