Urinalysis: Purposes, Types, Results

A urinalysis, or urine test, is a common medical test in which the urine is examined to diagnose and monitor various illnesses.

During a urinalysis, a clean urine sample is collected into a specimen cup and analyzed with a visual exam, a dipstick test, and a microscopic exam. The presence of cells, bacteria, and other chemicals is detected and measured in a urinalysis.

Why Is a Urinalysis Conducted?

Urinalyses are typically conducted when someone is admitted to the hospital or before they have surgery. Your doctor may also order a urinalysis if you experience symptoms such as: (1)

• Blood in urine
• Back or abdominal pain
• Painful urination
• Frequent urination
• Cloudy urine

Urinalyses are useful because they can often detect medical problems before additional symptoms arise. They are most often performed to monitor overall health, to diagnose a medical problem, or to monitor a medical condition, including: (2)

• Urinary tract infections
• Diabetes
• Kidney problems
• Liver problems
• Pregnancy

How Is a Urine Sample Collected for a Urinalysis?

Most urinalyses simply involve the patient urinating into a specimen cup, either at home or at a doctor’s office. Sometimes a sample is requested first thing in the morning, as more concentrated urine provides easier-to-read results. (3)

You do not have to do anything to prepare for a urinalysis, and you can eat and drink beforehand. Inform your doctor if you take any medications or vitamins, as these can impact the results of a urinalysis. (3)

For many urinalyses, doctors will recommend that patients collect a “clean catch” sample, meaning that urine cannot touch the skin of the penis or tissues of the vagina, which contain additional bacteria. Occasionally, a clean sample may be obtained via urinary catheter. (4)

The Mayo Clinic recommends taking the following steps to obtain a clean sample of urine: (3)

• Clean the urinary opening with a sterile wipe to remove bacteria. Men should wipe the tip of the penis. Women can clean their labia from front to back.
• Start to urinate into the toilet. Do not collect the initial urine stream.
• In midstream, begin to collect urine into the sample container.
• Make sure that you collect at least 1 to 2 ounces.
• Finish urinating in the toilet.

Getting a clean sample from a child may be difficult. Parents or the child can clean the skin surrounding the urinary opening. To get a “midstream” urine sample, which has the least amount of bacteria, a child is encouraged to stop urinating momentarily (if possible) and then urinate again into the sample container. (5)

What Does a Urinalysis Measure, and What Do the Results Mean?

A typical urinalysis involves a visual exam, a dipstick test, and a microscopic exam.

Visual Exam For the visual exam, the urine will be examined for its color and clarity. Dark urine, abnormal colors, blood in urine, cloudy urine, or foamy urine can indicate kidney problems, dehydration, or other medical problems. Normal urine should range in color from clear to dark yellow. (6)

Dipstick Test Chemical testing usually involves inserting a thin strip of plastic known as a dipstick into the urine sample. Chemicals on the stick react with urine and change color to measure the following: (7)

• Urine acidity (pH) level may indicate kidney stones or urinary infections. The level of acidity can be affected by diet, chemical imbalances, and certain metabolic disorders.
• Concentration is a measure of the concentration of various molecules in urine. Highly concentrated urine can be a sign of dehydration.
• Nitrites in urine can indicate a bacterial infection such as a urinary tract infection.
• Proteins in urine can indicate kidney disease or kidney damage. They may also be present in urine after strenuous exercise and when dehydrated.
• Ketones in urine emerge when the body begins to break down fat as a source of energy. Ketones may be a sign of uncontrolled diabetes, starvation, alcohol abuse, or a condition known as diabetic ketoacidosis.
• Glucose (sugar) in urine can indicate diabetes or high blood sugar.
• Bilirubin in urine is a type of waste produced when old red blood cells break down. Bilirubin can indicate liver disease.

Sometimes small amounts of certain substances, such as proteins, can be found in urine and do not indicate a medical problem. Talk to your doctor about your urinalysis results, as the criteria for abnormal values can vary depending on age, gender, medical history, and other factors.

Microscopic Exam: What Test Results Can Reveal

Before examining under a microscope, technicians spin the urine in a centrifuge in order to concentrate the solid particles and make them easy to examine. A microscopic examination might reveal the following: (3,8)

• White blood cells may indicate infection or inflammation.
• Red blood cells may indicate kidney disease, a blood disorder, or bladder cancer.
• Bacteria can indicate infection.
• Skin cells can indicate infection or kidney disease.
• Crystals may be a sign of kidney stones.
• Casts, or tube-shaped proteins, may be a sign of a kidney disorder.
• Parasites can indicate parasitic disease in various parts of the body.

Sometimes a healthcare provider will also order a urine culture to be performed with a urinalysis. A urine culture is used to grow bacteria found in the urine sample in order to diagnose an infection. (4)

It usually takes several hours to get the results of a urinalysis test, and one to three days for a urine culture to be complete.