Leukocyturia is the presence of white blood cells ( leukocytes ) in the urine. The white blood cells have no business there. If they appear there, this is considered an indication of the presence of a urinary tract infection with bacteria that the blood cells are trying to contain, or an inflammation in the urinary tract .
How do leukocytes get into the urine?
Normally, white blood cells have no place in the urine. Urine is an ultrafiltrate of blood, with the kidneys passing only small molecules and water. Structures as large as whole cells should therefore not appear in the urine.
If they do it anyway, there is a disorder in the urinary tract. If you find white blood cells, they got into the urine as a result of an inflammatory reaction. This usually happens due to a urinary tract infection .
The leukocytes are the cells of the body’s immune system . As soon as bacteria enter the bladder via the urethra and possibly climb up the ureter into the renal pelvis, the immune system is alarmed. The white blood cells pounce on the invaders and render them harmless before penetrating deeper into the tissues and causing further damage.
Likewise, white blood cells pass into the urine when there is chronic inflammation in the urinary tract. A sure sign of such cystitis or pyelonephritis is the absence of bacteria in the urine.
Leukocyturia – the most important things at a glance!
- Leukocyturia is the presence of white blood cells in the urine.
- Such an appearance is considered an indication of the presence of a urinary tract infection or an acute or chronic inflammation.
- Detection takes place using special urine test strips or in a laboratory.
- Mid-stream urine in the morning is best suited for determination.
- Treatment of the cause of the disease is the focus of treatment.
Where does leukocyturia come from?
Leukocyturia is usually the result of an infection of the urinary tract. The pathogens come almost exclusively from the outside, i.e. bacteria penetrate the urethra into the urogenital tract. Since women have a shorter urethra than men for anatomical reasons, they suffer from urinary tract infections much more frequently.
Depending on the defense status of the immune system and the amount of urine formed (which contributes significantly to flushing), they can continue to rise from the urethra. That’s how it happens
- Inflammation of the urethra (urethritis)
- Bladder infection (cystitis, urocystitis)
- Inflammation of the ureters (ureteritis)
- Inflammation of the kidneys (pyelonephritis).
A corresponding inflammatory reaction can also occur without a persistent bacterial infection. In most cases, this is an acute or chronic cystitis or inflammation of the renal pelvis, for example as a result of tuberculosis, deformation of the renal calyx or autoimmune processes that cause an inflammatory reaction (interstitial cystitis).
How many leukocytes in urine is normal?
A normal value is up to ten leukocytes per microliter (thousandths of a milliliter). If a higher value is found, further determinations must follow on the following days in order to control and secure the finding.
How does the doctor diagnose leukocyturia?
The easiest, cheapest and fastest way to detect white blood cells in urine is to use special urine test strips or U-Stix. To do this, this strip simply has to be dipped into a patient’s urine sample. The test result is available within a few seconds. In addition to the detection of leukocytes, this also includes the determination of nitrite, protein, erythrocytes , glucose and other parameters of the urine status.
For more detailed examinations, the doctor sends a patient’s urine sample to a specialist medical laboratory. Numerous other parameters can be determined there, including the urine concentration, the urine sediment, or in the case of a urinary tract infection, a urine culture can be created to identify the bacteria involved. The leukocytes can also be precisely counted with a microscope.
How does the detection of leukocytes with test strips work?
The commonly used urine test strips contain a field that can be used to detect leukocyturia. This patch contains a dye that is converted to blue indoxyl by an enzyme found in certain white blood cells called granulocytes , an esterase . If this reacts with the diazonium salt also contained in the test strip, the field turns purple.
The advantage over a microscopic determination: Even lysed leukocytes can be detected based on their esterase, which is no longer possible with a microscopic examination.
Which urine is suitable for diagnosing leukocyturia?
In order to be able to detect leukocyturia, it is preferable to use midstream urine, which is collected in the morning after getting up. Due to the long residence time in the bladder, morning urine contains a particularly large number of cells. Midstream urine means that you discard the first milliliters of urine, which are often contaminated with bacteria.
Sources of error in the determination of leukocytes in urine
In the case of fever and high physical stress, the leukocyte value in the urine increases. The same occurs when taking certain medications, especially acetylsalicylic acid (ASA).
What does the doctor do with leukocyturia?
Leukocyturia is not a disease but the result of a bacterial infection and/or an inflammatory reaction. Therefore, the doctor takes care of the infection, usually by prescribing a suitable antibiotic. In the case of autoimmune processes such as interstitial cystitis, special medication must be used.
Sources and further reading
- Overview article on Urinary Training on wikipedia ↑read more
- Willibald Pschyrembel: Clinical Dictionary . 266th edition. Berlin 2014: Walter de Gruyter-Verlag. ISBN-10: 3110339978.
- Wolfgang Piper: Internal medicine. 2nd Edition. Stuttgart 2012: Springer Verlag. ISBN-10: 3642331076.
- Gerd Herold: Internal medicine. Cologne 2016: G. Herold Verlag. ISBN-10: 3981466063.
