Leukocytes in urine

Urine is considered a waste substance of the organism, but the presence of leukocytes can become a tool for diagnosing certain pathologies.

Along with red blood cells (also called erythrocytes) and platelets, leukocytes, better known as white blood cells, are one of the cell types found in the blood. Their task is to protect and maintain good health of the body by putting in place defense mechanisms against germs of various kinds (viruses, bacteria, fungi and parasites) and foreign bodies that have overcome the protective barriers of the body, consisting of the skin and mucous membranes.

Various types of leukocytes are present in the blood: polymorphonuclear granulocytes, divided into neutrophils, eosinophils, basophils, and mononuclear granulocytes, divided into lymphocytes and monocytes, from which macrophages derive.

All these cells are produced by the bone marrow and each of them has a particular activity. Some are involved in the so-called innate immunity, or the first line of defense, non-specific, put in place by the body in the presence of a pathogen. Others (T and B lymphocytes) are instead responsible for a more specific immune response, the adaptive one, which is activated following the recognition of an antigen.

The number and ratio between the various species of leukocytes is controlled with the so-called leukocyte formula, which is part of the blood count, a laboratory test that aims to evaluate the quantities of the main cellular constituents of the blood.

In an adult person, normal values of leukocytes in the blood are between 4,000 and 10,000 per cubic millimeter of blood. The various types of white blood cells are present in different percentages:

Type of leukocytes	Percentage
Neutrophils	54-62%
Eosinophilic	1-6%
Basophils	approx. 1%
Lymphocytes	27-37%
Monocytes	6-9%

In some cases it may happen that their number in the blood changes: in case of increase we speak of leukocytosis, while their deficiency is called leukopenia. In most cases it should be noted that it is not only an increase in leukocytes in the blood that should worry, but an alteration of relationships with other blood cells.

In pathological conditions it is possible to observe the presence of leukocytes not only in the blood, but also in the urine. If everything works properly, when they filter the blood to cleanse it of impurities, the kidneys do not let leukocytes pass into the urine, except in very small percentages. Sometimes, however, following an infection or inflammation, it can happen that the number of leukocytes in the urine can increase until it reaches high levels. This is a sign of a problem that needs to be acted on promptly. In these cases, the doctor will examine the patient and examine the cause.

How they are measured

Knowing the amount of leukocytes “let through” by the kidneys is very simple: just undergo a urine test that consists of observing under a microscope (or by means of a technique called flow cytometry) a urine sample subjected to centrifugation, and then analyzing the contents of the so-called urinary sediment.

This type of examination, called microscopic, also detects the presence of hematia (red blood cells), epithelial cells, crystals, cylinders, bacteria and yeasts. It is always included in the standard urine test together with the physical examination (which describes color, clarity and smell) and the chemical one, (with which they analyze characteristics such as pH and specific gravity and look for the possible presence of nitrites, leukocyte esterase, bilirubin, albumin and other substances).

In the case of leukocytes, the presence of 1-2 of them per microscopic field is considered normal, while we speak of leukocyturia, that is, of excessive presence of leukocytes in the urine, when 10 or more leukocytes are present per microscopic field. The calculation of leukocytes under a microscope can be conditioned by factors that can change the concentration of urine and by the variation in the amount of liquid that is put on the slide.

Leukocytes are rarely present in the urine; In this case their count results in a quantity defined as “negligible”. If the result of the urine test is marked “traces”, it means that their concentration in the urine is slightly higher than normal.

However, there is no need to worry, especially if there are no other signs that may worry, such as the presence of blood or pus.

The urine test, in addition to the leukocyte count, also evaluates its appearance, taking into account two characteristics: color and turbidity. If the color is straw yellow, it means that there is no infection, while if the appearance has a turbid yellow color, due to the presence of mucus, pus, germs or flaking cells (old epithelial cells), it means that there could be an inflammation in progress.

For the measurement of leukocyte levels it is good to collect a urine sample of the first morning urination, as it is more concentrated and more able to provide useful indications. It is, however, important not to collect the first jet of urine, but the next one, until the test tube is filled, closing it well. During the menstrual cycle, it is advisable to use an absorbent swab at the time of sample collection, so as not to run the risk of contaminating it, or postpone the examination for a few days, if possible.

The urine should be collected in a sterile disposable container that can be purchased in pharmacies without a prescription. The urine must be delivered to the laboratory in a short time, so as to avoid contamination by germs capable of modifying some important characteristics of the urine (acidity, clarity, precipitation of substances in the form of crystals).

Before taking the sample, it is advisable to wash your hands with soap and water and clean the genitals to avoid contamination of the sample and alter the result of the examination.

In addition to the laboratory examination, it is also possible to perform an analysis at home, using test strips to be immersed in the urine that you buy in pharmacies without a prescription and that change color and intensity according to the presence and concentration of leukocytes. In case of a positive result, it is advisable to contact your doctor and repeat the analysis in the laboratory for a more reliable and accurate result.

Interpretation of results

The presence of leukocytes in the urine usually indicates a urinary tract infection. If the number of leukocytes detected is very high, it is usually in the presence of an acute infection, while if their number is just above normal, it is often a chronic infection or a poorly treated systemic disorder (such as diabetes).

However, the leukocyte count in the urine does not provide information about the type of infection (for example viral or bacterial) or about the organ of the urinary tract that has been affected (kidney, ureters, bladder or urethra). It will therefore be the task of the doctor to study the report to investigate the presence of any symptoms or to prescribe further analyzes and instrumental examinations (such as urine culture or ultrasound of the lower abdomen).

For example, when the presence of leukocytes in the urine is due to infection of the urethra (urethritis), the other symptoms may be:

• urethral secretions with the presence of pus,
• burning during urination.

Very often urethritis is due to viral or bacterial infections (caused mostly by microorganisms responsible for sexually transmitted diseases such as gonorrhea), poor personal hygiene or unprotected sex; It is treated with antibiotics.

If it is cystitis (an infection of the bladder caused by bacteria such as Escherichia coli, which mainly affects young and sexually active women), the presence of leukocytes in the urine will be accompanied by urination disorders, such as frequent need and difficulty urinating, pain and burning during the emission of urine, sense of incomplete emptying of the bladder. In some cases, blood (hematuria) or pus (pyuria) may be present, which give a cloudy appearance and reddish hues to the urine, but it can generally be treated effectively with short-term antibiotic therapy.

In the case of kidney stones (renal lithiasis), the patient may feel a frequent urge to urinate, burning and pain when urinating; The urine jet can be reduced in intensity, with mild pain in one side until you have a real renal colic. Urine can become cloudy, sometimes with blood and a foul odor.

If the increase in the number of leukocytes in the urine is due to a prostate infection (prostatitis), you may have disorders and pains associated with ejaculation and urination (intermittent urine flow, pain or burning while urinating, need to urinate often and excessive urine output at night). If prostatitis is due to a bacterial infection (i.e. pathogens such as Klebsiella, Proteus and Escherichia coli), these symptoms are often associated with fever, chills, general malaise, blood in the urine and vomiting and are treated through the use of an antibiotic. In some cases, there may also be leakage of secretions from the penis. These disorders are more pronounced in case of acute prostatitis, while they are more modest and appear more frequently in chronic forms.

In men, when the infection is localized at the level of the glans, the penis is reddened, itchy, painful, swollen (balanitis), and urethral secretions are often also present. This condition is mainly caused by sexually transmitted diseases, fungal infections (such as that due to Candida albicans) and to a lesser extent by irritants and allergic forms.

When the presence of leukocytes in the urine is due to pyelonephritis (an inflammation of the kidney caused by the rise of infections along the urinary tract), you may have pain in one side (right or left depending on the affected kidney) and, in more serious cases, fever with chills, also associated with other urination disorders. These infections occur more frequently in individuals who have weak immune systems or who often use a urinary catheter.

In the case of bladder cancer, the most common symptom is the presence of blood in the urine, often visible to the naked eye, while only at a more advanced stage do the classic urinating disorders appear.

Prevention

To prevent infections that can cause the presence of leukocytes in the urine there are several strategies:

– Drink two liters of water between meals. Taking adequate amounts of water allows, in fact, to hydrate the body and, therefore, promote diuresis, an essential physiological process to be able to “clean” the urinary tract and reduce the possibility of infection or stones.

– Cleanse the female genitals with movements from the vagina to the anus, to avoid infecting the urethra with bacteria present in the stool.

– Do not make excessive use of intimate cleansers that can reduce the body’s defenses and alter the bacterial flora of the vagina, facilitating the appearance of infections.

– Promptly treat gynecological infections, even during pregnancy, to avoid the passage of germs from the vagina to the bladder.

– Keep your diet under control: limiting, on the one hand, the consumption of fried foods, cold cuts, spices, alcohol and beer (which can cause prostate and bladder problems); and increasing, on the other hand, that of foods rich in fiber, able to improve intestinal motility and thus reduce the presence of fecal bacteria, often the cause of urinary tract infections.