Generality
The presence of leukocytes in the urine is a sign of a probable urinary tract infection . It can therefore be visually signaled by the turbid appearance of urine, due to the presence, not only of leukocytes, but also of mucus, pus, blood and flaking cells.
Among all the white blood cells, most of the leukocytes present in the urine belong to the category of neutrophils, easily identifiable under the microscope due to their rounded shape and the lobulated appearance of the nucleus; they are also larger than any erythrocytes present in the urine.
What's this
White blood cells or white blood cells are blood cells responsible for the body's immune defenses .
These "elements" are rarely present inside our urine (normally, their concentration is quite negligible, being less than 5-10 units per milliliter of urine). If everything works properly, the kidneys do not allow the passage of leukocytes into the urine, except in small quantities.
However, following infection or inflammation of one of the organs of the urinary tract, the number of leukocytes expelled by urine can increase considerably.
The simple identification of the presence of white blood cells in the urine does not uniquely characterize a specific problem. For this reason, it is essential to undergo a thorough examination and resort to the specific therapies indicated by the doctor.
To remember
Behind the presence of leukocytes in the urine, important health problems can also hide that, if neglected, could develop into wider problems.
Why do you measure
White blood cells or leukocytes are cells of the immune system responsible for defense against attacks by viruses, bacteria and other microorganisms, or foreign bodies that penetrate the body. As a result, their presence in the urine may be a sign of various types of inflammatory processes, primarily in the urinary tract.
In most cases, the increase of leukocytes in the urine is the expression of an inflammation or infection of the urinary tract. However, this sign may depend on several other causes.
The leukocytes present in the urine with values higher than those normally considered can be identified by microscopic observation . This exam can give an idea of the seriousness of the situation, but it cannot establish the type of infection in progress, nor the area subject to the disorder.
Therefore, the excess of white blood cells in the sample must then be deepened with urine culture and the antibiogram, to identify which type of bacterium is responsible for the possible infection and to understand which is the most effective antibiotic.
Normal values
Usually, there are less than 5-10 leukocytes per milliliter of urine .
In most cases, in normal conditions the report reads: traces . However, if the quantity is expressed, this should not exceed 10 per millimeter of urine.
Urine leukocytes - Causes
An increase in the leukocytes in the urine is a generic signal of a urinary tract infection, but it can also depend on trauma received in the area, inflammation of the prostate or polycystic kidney.
In some cases, the presence of white blood cells in the urine may indicate the presence of more serious diseases, such as diabetes mellitus and kidney cancer.
The most common causes
The presence of leukocytes in the urine is used to assess the presence of nephropathies and is a non-specific sign of urinary tract infection .
A moderate increase may indicate:
- Acute or chronic cystitis (most common cause of the presence of white blood cells in the urine);
- glomerulonephritis;
- Renal calculosis;
- Chronic pyelonephritis;
- Bladder cancer;
- Prostatitis;
- Prostate hypertrophy;
- urethritis;
- Balanitis (inflammation of the glans);
- Polycystic kidney disease;
- Trauma;
- Systemic lupus erythematosus (SLE).
A massive increase in leukocytes is generally indicative of an acute infection. This phenomenon can be linked to a number of different factors (the infectious process could originate, for example, from the kidneys) and particular states (such as pregnancy).
The presence of proteins and white blood cells in the urine during pregnancy is quite common. This depends above all on the qualitative worsening of urination following the loss of bladder tone, which creates the ideal conditions for the proliferation of bacteria.
Possible associated symptoms
Before the urine analysis, there are no symptoms that can make the presence of leukocytes evident. These manifestations vary, then, according to the type of disorder.
Depending on the cause, the following can occur:
- Fever, chills, vomiting and general malaise;
- Frequent feeling of having to urinate, accompanied by a sense of incomplete emptying of the bladder;
- Excessive urine emission during the night;
- Pain and strong burning during urination;
- Smelly urine with a cloudy or pinkish appearance due to the presence of blood (hematuria);
- Urethral secretions;
- Lower abdominal pain.
However, considering that other types of problems can lead to the presence of high leukocytes in the urine, it is advisable not to consider the list of symptoms indicated above as absolute.
How to measure it
The dosage of leukocytes in urine is carried out by collecting a sample of the first morning urination (or at least 3 hours after the last urination). In fact, morning urine is more concentrated and can provide more useful indications for diagnosis.
The search for leukocytes in urine is carried out under a microscope, or by using recently introduced automated methods (flow cytometry); the presence of 1-2 leukocytes per microscopic field (40x) is considered normal, while one speaks of leucocituria (excessive presence of leukocytes in the urine) when at least 10 leukocytes are detected per microscopic field (this number varies, according to the sources consulted, from 5 to 20). If instead a cytofluorimeter is used, the reference values correspond to the limits provided by the instrument (for example, more than 20 leukocytes per microliter of urine can be an index of leukocyturia).
Microscopic counting can be influenced by various factors that alter the concentration of urine; moreover, the error can be introduced by the variation of the quantity of liquid that is placed on the slide.
In addition to the methods mentioned, there is a further examination, which can also be performed at home, which evaluates the esterasic activity of the leukocytes; it is a rapid test based on the use of reactive strips to be immersed in urine, which change color and color intensity based on the presence and concentration of leukocytes. Even in this case, however, there is a risk of false positives and false negatives.
Preparation
Urine should be collected in a sterile disposable container. This should be carefully closed immediately afterwards and should be taken to the laboratory within two hours.
Before taking the sample, it is a good idea to wash your hands thoroughly with soap and water, and to clean the genitals, as the bacteria and cells that surround them can contaminate the sample and interfere with the interpretation of the test results.
In the case of women, menstrual flow and vaginal secretions can also cause alterations. From a practical point of view, the first jet of urine is excluded, and then the sample is collected immediately afterwards, until the test tube or glass is filled.
Interpretation of Results
In most cases, the detection of leukocytes in the urine is a non-specific sign of a urinary tract infection (kidneys, ureters, bladder or urethra); the non-specific term emphasizes how white blood cells simply inform of an ongoing infection, without specifying the type or location. However, the amount of leukocytes in the urine may provide some additional clues; for example, we know that a massive increase in white blood cells in urine is generally indicative of an acute infection.
For all these reasons, the finding of significant concentrations of leukocytes in the urine requires subsequent investigations to ascertain the origin of the problem. The first indications can derive from the interpretation of the associated symptoms, even if these are generally non-specific, because they are common to various conditions. Moreover, in chronic or mild infectious forms, leucocituria is modest and the symptoms can be very blurred or even absent.
- If the presence of leukocytes in the urine is due to urethritis, the typically associated symptomatology includes urethral secretions with the presence of pus, associated with burning during urination; in some cases the patient may be asymptomatic or complain of minor ailments. Very often urethritis is of infectious origin; bad personal hygiene and risky sexual relations are therefore the main causative agents.
- If the presence of leukocytes in the urine is associated with cystitis, there are generally disturbed urination, such as difficulty in urinating, pain and burning during the emission of urine and frequent need to urinate, accompanied by a sense of incomplete emptying of the bladder. Sometimes hematuria (blood) and pyuria (pus) are present, which give the urine the characteristic turbidity, with reddish hues due to the presence of hemoglobin.
- If the detection of leukocytes in the urine is associated with renal lithiasis (calculi), the patient may complain of symptoms such as frequent need to urinate and burning and pain on urination; urine may appear cloudy, sometimes with blood and odor. Furthermore, the urinary jet can be reduced in intensity, with the appearance of slight pains in the side up to the actual renal colic.
- When the presence of leukocytes in urine is associated with prostatitis, disorders and pains associated with ejaculation and urination (intermittent flow of urine, pain or burning while peeing, frequent and urgent need to urinate, and excessive emission of urine) can coexist. overnight). In bacterial infections these symptoms are often associated with high fever, chills, malaise, hematuria and vomiting; you can also notice the leakage of secretions from the penis, favored by squeezing the glans. A more or less intense painful symptomatology can affect the prostate, the lower back or the groin. All these symptoms are more violent in acute prostatitis, while in the chronic forms they are milder and with a recurrent course.
- If the presence of leukocytes in the urine is accompanied by balanitis, the glans (terminal part of the penis) appears red, itchy, painful and swollen. Urethral secretions are often present, while the causes of origin must be sought above all in sexually transmitted diseases.
- When the presence of leukocytes in the urine is associated with inflammation of the kidney (pyelonephritis), the patient may complain of pain in the side corresponding to the anatomical site of the affected organ; moreover, there may be fever with chills, accompanied by the "inevitable" urination disorders. These kidney infections are more frequent in people with a weak immune system or who need to use the urinary catheter for a long time.
- If the presence of leukocytes in the urine is accompanied by bladder cancer, the symptoms may be completely absent. The most common symptom is the presence of blood in the urine, which represents the onset in 80% of cases; often, bleeding is visible to the naked eye, while in a more advanced stage urination disorders are common.
- If the presence of leukocytes in the urine is accompanied by polycystic kidney disease, the condition can be asymptomatic or associated with abdominal pain, the presence of blood in the urine and renal insufficiency, with more or less early onset depending on the form (dominant or recessive).
