A urinalysis is a test that examines urine by physical, chemical or microscopic methods. It’s also referred to as a urine test, urine analysis or simply a UA. It can be used to diagnose and monitor a multitude of presenting conditions, and can detect early signs of disease, including those that affect the urinary tract and male reproductive system.
Urinalysis Collection Methods
There are three possible methods of collecting a sample for a urinalysis:
- The patient can collect samples over a 24-hour period under their doctor’s instructions
- A sample can be collected through catheterization and draining the bladder
- The patient can urinate in a cup at the doctor’s office
The most common method of collecting a sample is for the patient to urinate in a cup at the physician's office. Female patients may be asked to clean the genital area with a cleansing wipe, and male patients may be asked to do the same with the tip of the penis. The patient then urinates into a sterile urine sample cup. The sample should be transported to a laboratory within an hour.
In cases where a sample can’t be collected in this manner, a catheter is inserted through the urethra into the bladder. The urine sample is then collected through the catheter as the bladder drains. The urine sample can then be analyzed visually or chemically, or it can be sent to a laboratory for a more detailed analysis. A urinalysis is not to be confused with a drug screening or pregnancy test.
When is a Urinalysis Used?
A urologist will often recommend a urinalysis as part of a routine medical exam to look for early signs of disease, but it may also be used to assess, detect, diagnose and monitor urological conditions, as well as their accompanying symptoms.
Urological conditions that may require a urinalysis, include:
- Bladder stones
- Kidney stones
- Kidney failure
- Urinary tract infection
- Nephritis (inflammation of the kidneys)
- Epididymitis (swelling of the epididymis, the coiled tube that connects the testicle to the vas deferens)
- Injury to the kidney, bladder, urethra, or ureter
- Irritable bladder
- Kidney disease
- Orchitis (inflammation of one or both testicles)
- Prostate cancer
- Prostatitis (irritation of the prostate gland)
- Pyelonephritis (kidney infection)
- Retrograde ejaculation (sperm enters the bladder instead of passing through the urethra during ejaculation)
- Urinary incontinence
- Ureterocele (swelling in the lower region of the ureter)
- Urethral stricture (abnormal narrowing of the urethra)
- Urethritis (inflammation of the urethra)
- Wilms tumor (pediatric cancer that affects the kidneys)
Symptoms that may require a urinalysis, include:
- Painful urination
- Pain in the flanks or abdomen
- Blood in the urine
- Fever
Types of Urinalysis
There are three separate types of urine tests, or methods of analysis. The first and easiest is a macroscopic urinalysis, which is a visual inspection of the urine; the second is a chemical analysis; and the final one is a microscopic analysis.
Macroscopic Analysis
A doctor can tell several things about a person’s health by visually examining a urine sample. A normal sample is usually a clear and light yellowish color. If the urine appears cloudy, it can indicate an infection. Different colors outside the normal range can also indicate problems. For example, reddish urine indicates the presence of blood; orange indicates muscle breakdown; and tea-colored urine can indicate liver trouble. Darker colored urine can be a sign of severe dehydration.
Chemical Analysis
The doctor will submerge a plastic dipstick into the urine sample, which has different colored squares on it. Each square represents a different chemical reaction and will change color if certain things like proteins or sugars are in the urine sample. The chemical urinalysis test can determine things like acidity (pH) of the urine and the presence of proteins, nitrites, bilirubin and other substances. Using the results from the chemical test strip, the doctor can make a diagnosis and begin recommending treatment options. The disadvantages of the dipstick test are that it is time sensitive, and it doesn’t measure quantities of the different substances in the urine. Therefore, it can’t detect just how severe certain problems are, such as liver or kidney disease.
Microscopic Analysis
A microscopic analysis is just what it sounds like. The urine sample is first run through a centrifuge, and then it’s examined under a traditional microscope. The doctor will look for crystals, bacteria and other compounds in the sample. Different cells that are seen under the microscope can indicate different conditions. For example, the presence of some cells can indicate inflammation of the bladder (interstitial cystitis), and other cells can point to an inflammation of the kidneys.
Other Urine Tests
Two of the most common urine tests aside from urinalysis are a drug screening urine test and a pregnancy test. A drug screening is often done as a condition for employment in some areas, or as a part of probation after a person has served a prison sentence. It can detect the presence of illegal narcotics in the person’s system. A pregnancy urine test measures for the presence of beta-HCG, a hormone associated with pregnancy.
References
McPherson RA, & Ben-Ezra J. (2011). Basic examination of urine. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, PA: Elsevier Saunders; chap 28.
Albala DM, Morey AF, Gomella LG, & Stein JP. (2011). Urine examination. Oxford American Handbook of Urology. Oxford, New York: Oxford University Press; pp 36-37.
