Urine Examination (Urinalysis): Examination Procedure

Various methods are available for the examination of urine. Test strips are a quick form of urine examination. Other examinations require analysis of the urine in the laboratory. Sometimes a urine culture must then be obtained. There are also different functional tests for urine examination. In the following, we present the different examination procedures. Urine: This is what the color means

Urine strip rapid test

The urine test with a test strip is a quick, easy-to-perform examination based on a chemical reaction. It can be used to detect the most important substances in urine:

The finger-length test strip is briefly dipped into the urine, so that all test fields are wetted. These are coated with different substances that react with the urine and change color. After a waiting time of 1 to 2 minutes, the discolorations are compared with a special color scale. The urine strip rapid test is also part of the preventive examinations during pregnancy.

Urine test by laboratory diagnostics

Further analysis in the laboratory is performed depending on the findings and suspected diagnosis. Usually, other tests such as blood tests or ultrasound are performed at the same time, and sometimes complementary tests to assess kidney and bladder function. On the one hand, the urine sample is looked at under the microscope, and on the other hand, the presence and amount of certain substances can be determined. If an infection of the kidney or bladder is suspected, a “urine culture” can be made.

  • Admixtures under the microscope: after centrifugation, the solid components accumulate (urine sediment) and can be examined under the microscope. Isolated tissue cells from the mucosa of the urinary tract and a few white and red blood cells or mucus threads are not of concern. However, if larger quantities or protein cylinders, urinary crystals, pus or pathogens are found, a disease of the kidneys or the urinary tract is suspected. Under the microscope can also identify abnormal cells, for example, from a malignant tumor (cytological examination).
  • Urine culture: a coated carrier is immersed in the fresh urine, placed in an associated container and sent to the microbiology laboratory. If germs are present, bacterial colonies show up about 24 hours later; their number is estimated using a comparison table. In the next step, the pathogens can be precisely identified and it can be determined which antibiotics are effective. Germs are not only present in an infection of the kidneys or urinary tract, but can also indicate a tumor.
  • Urinalysis for certain substances: Water-soluble substances are usually excreted with the urine. So can be determined in the urine, for example, electrolytes (such as sodium, potassium, calcium), active drug ingredients, toxins, doping agents or hormones and their degradation products. Their amount then allows conclusions, for example, an enzyme defect (for example, porphyria) or a hormone disorder.

Urine examination by function tests

If kidney or bladder function is suspected to be impaired, a number of specific tests are available.

  • 24-hour collection urine: the patient collects all the urine he or she passes over 24 hours in a special collection vessel. Creatinine can then be determined in it, a substance that allows conclusions to be drawn about the functional performance of the kidney.
  • Specific urine weight: this involves using a specific measuring cylinder to determine the mass of urine per unit volume, which depends on the amount of substances dissolved in the urine. Deviations from the normal value are often signs of kidney failure.
  • Urodynamics: This generic term covers a range of examinations that can be used to test bladder functions.They are used, for example, when patients cannot hold their water (urinary incontinence). Determined, among other things, the amount of urine that flows through the bladder within a certain period of time, the pressure in the bladder and whether there is still urine in it after emptying.

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