A urine test (urinalysis) uses a sample of urine to diagnose diseases of the urinary system and other body systems. Urinalysis may be ordered to check for early signs of a disease or disorder, or it may be used to monitor conditions such as diabetes or kidney diseases.

For individuals with diabetes, urinalysis serves a number of purposes. It can be used to:

• Estimate glucose (blood sugar) readings when blood testing is impossible
  
  
• Monitor or detect the presence of substances in urine that indicate a potentially life-threatening complication of diabetes, including:
  
  
• • Ketones to diagnose ketoacidosis
    
    
  • Proteins (microalbuminuria or proteinuria) to diagnose or monitor diabetic nephropathy and indicate cardiovascular disease
    
    
  • Creatinine to diagnose kidney damage
    
    
• Help diagnose urinary tract infections, musculoskeletal conditions such as gout and osteomalacia (weakened bones), and autoimmune diseases such as lupus and scleroderma

Urinalysis is also used with many other conditions, including certain cancers (e.g., bladder, prostate, kidney, pancreas), sexually transmitted diseases and prostatitis. Urine tests can also detect pregnancy.

Urine testing is a simple and easy method of detecting potentially serious conditions early. This allows for treatments that may delay or prevent the onset of more serious complications.

Samples of urine may be taken in several ways:

• Spot sample (also called dipstick method). A single urine sample.
  
  
• 24-hour urine sample. A collection of all urine for a 24-hour period.
  
  
• Overnight urine sample. A collection of all urine formed between going to sleep at night and waking up in the morning.
  
  
• Timed urine sample. A collection of all urine voided in a specific period, such as four hours.

Spot samples provided in a physician’s office should be tested within 15 minutes of collection. Immediately after the sample is taken, the cup is labeled with the date and the patient’s name. Timed and 24-hour samples need to be refrigerated throughout the day and are tested once turned over to the physician’s office or lab. The 24-hour sample is the most accurate way of testing conditions such as microalbuminuria, but because of its inconvenience, a physician may recommend an overnight or timed sample instead.

Different urine tests may require different methods of analysis. Urinalysis may include:

• Visual examination. Tester visually examines the color and clearness of the urine sample. Blood may make the urine appear red or brown. An infection may cause the sample to appear cloudy.
  
  
• Test strip examination. Tester uses a chemically coated test strip to measure the amount of certain substances in the urine including blood, glucose, creatinine, protein, pH, nitrite, ketones and bilirubin. The test strip is dipped into the urine sample. A chemically coated test pad on the strip will react with the urine and change color accordingly. The test pad is then compared to a color chart of possible results. Test times vary, but most test strips provide results in less than a minute.
  
  
• Microscopic examination. The tester examines a small amount of urine under a microscope. Cells, bacteria, casts (protein substances that can indicate kidney disorders), crystals and other matter are counted and reported as either the number observed or as estimates (e.g., few, moderate or many).
  
  
• Culture. When the presence of bacteria is suspected in the urine, a urine culture may be ordered. A sample of urine is streaked across the surface of one or more lab dishes (Petri dish). The sample is then placed in an incubator that keeps the urine at body temperature. Bacteria will be allowed to grow in the dish so the type of bacteria can be determined. If there is no growth on the dish at the end of 24 hours, the test is considered negative for infection. If yeast or bacteria are present, the organisms are identified and counted. Further testing is then done to determine what antibiotics are likely to be effective in treating the infection.

Although urine tests often measure or detect the same substances as blood tests, they do not always provide similar information. For instance, a blood glucose test indicates the level of glucose circulating in the body at the moment of the test. Glucose found in urine (glucosuria) is an average value of what glucose levels were several hours ago. Blood glucose monitoring with a glucose meter is thus more accurate and appropriate for the daily evaluation of glucose levels.