Leukocytes in urine

Leukocytes in urine, what does it mean?

Urine analysis is a simple study and includes as a basic study the analysis of its physical characteristics (by means of visualization) and its chemical characteristics (by means of a reactive strip to detect the presence of nitrites and also of other substances that indirectly guide the presence of red blood cells -red blood cells or erythrocytes- and white blood cells -leukocytes-).
Urine analysis is a simple study and includes as a basic study the analysis of its physical characteristics (by means of visualization) and its chemical characteristics (by means of a reactive strip to detect the presence of nitrites and also of other substances that indirectly guide the presence of red blood cells -red blood cells or erythrocytes- and white blood cells -leukocytes-).

Sometimes, the study of urine includes knowing its microscopic characteristics (by means of the urine sediment, to see the presence of cells, crystals, cylinders and bacteria) and its culture (urine culture, to identify germs).

Characteristics of urine


Under normal conditions, urine is light yellow in color and depending on its concentration (water content) it can take on a light yellow color (if it is diluted) or dark yellow (if it is concentrated). Normal urine does not usually contain chemicals or abnormal elements (cells, crystals) or only traces of them. Thus, urine may have a cloudy appearance if there are cells (leukocytes, red blood cells) or crystals in it . Or also if certain medications are being taken since the urine could be stained by them.


Various chemical parameters are included in the dipstick urinalysis. Two of them are esterase (or leukocyte esterase) and nitrites. Esterase is a protein found in white blood cells or leukocytes and if these are in the urine, we can detect the presence of esterase with the test strip. The presence of nitrites indicates the presence of bacteria in the urine and, consequently, a probable urinary tract infection. The introduction of a reactive strip in the urine sample causes it to change to a violet color in the presence of esterase and nitrites, putting us on the trail of a urinary infection.


The presence of nitrites and/or esterase in the test strip will indicate the need to carry out a study of the urinary sediment and, sometimes, also of a urine culture. The urinary sediment is investigated for the presence of cells (including white blood cells and red blood cells), crystals, casts, and bacteria. The crystals are due to the crystallization of some substances that are dissolved in the urine, mainly salts. Casts are like imprints of the renal tubules that are created when urinary cells, proteins, or both precipitate in the renal tubules and are eliminated in the urine. The presence of crystals and cylinders can guide us to kidney or urinary tract diseases.

It consists of incubating the urine in specific bacterial growth media to identify the possible cause of the infection.

Urine culture (uroculture)

The results of all these studies (dipstick, sediment and urine culture) are usually ready in a few minutes (the dipstick) or a few hours (the sediment) or a few days (the urine culture). However, some types of bacteria reproduce slowly and results may take several days or even weeks.

How should urine collection be?

It is important to obtain a urine sample in the best possible conditions. Depending on the study that we are going to carry out, we will need one type of urine sample or another. In the case at hand, and for a simple test strip, it could be a random sample, that is, a urine sample taken at random at any time , although it would be preferable to collect the urine after several hours after the last test. urination. In the case of taking a sample to make a sediment and to make a culture, it is preferable to take extreme measures to collect urine.

  • Before collecting the urine, it is essential to wash the external genitalia with warm soapy water and then rinse with plenty of water and dry well.
  • The urine must be collected in a container that is clean or sterile (usually this container is wrapped in a small plastic bag that maintains cleanliness) and with an airtight seal.
  • The container should not be uncovered until it is ready and urine collection is to begin. It is better to ignore the first stream and collect the middle portion of the urine stream “on the fly,” without stopping urination.
  • If there will be some time between collection and delivery to the laboratory, it is best to keep it in a cool place (for example, the refrigerator); you don’t have to freeze it. Then it will have to be transported to the laboratory trying to alter it as little as possible (basically that the container is in a vertical position, well covered and without being subjected to high temperatures), and quickly bring the sample to the laboratory.
  • It is also important that the container where the urine sample is collected is well labeled with our name and some other information that allows correct identification.


What do we mean by leukocytes in urine?

The presence in the urine sediment of an excessive number of erythrocytes (or erythrocytes or red blood cells) is called “ hematuria ”. And the presence of an excessive number of leukocytes (or white blood cells) is called “leukocyturia”.

If in the urine, in addition to leukocytes, erythrocytes are detected and both are in the same or similar proportion as they are in the blood, we cannot speak of leukocyturia but of simple hematuria.

What number of leukocytes is normal?

The presence of a few white blood cells (up to 5 leukocytes per high-resolution field, 400x field) when the urine is examined under a light microscope may be normal. When the values ​​are equal to or greater than 5 leukocytes, we speak of leukocyturia.

The laboratory result can also be expressed in other units: thus, the presence of up to 10 leukocytes per microliter (mcL) or 10,000 cells per milliliter (mL) is considered normal.

Significance of the presence of leukocytes

The presence of high leukocytes in the urine does not mean , from the outset, that we should be alarmed . And, in most cases, the cause is going to be a minor health problem. The results of the urinalysis must always be correlated with the person’s health status (current symptoms, previous history of any disease, taking medication for another reason, etc.).

Why can leukocytes appear?

The possible causes of the presence of leukocytes in the urine are many, but from the outset you should always think of a urine infection as the first option.

Urine infection

It is the most common cause, especially in women . It can correspond to cystitis (the usual) or pyelonephritis, and is caused by bacteria. Symptoms of cystitis include burning or itching when urinating, painful urination, frequent urination, cloudy color and bad smell of urine, and sometimes weakness, tiredness, and fever.

The symptoms are of sudden appearance and with variable intensity. Pyelonephritis (kidney infection) is a more serious infection and manifests with pain and frequent urination accompanied by high fever, chills, rapid heart rate, and vomiting. There is a higher chance of developing a kidney infection if a person is immunosuppressed (has a weak immune system) or has been using a urinary catheter for some time. In the urine analysis we will find , in addition to numerous leukocytes, the presence of bacteria and nitrites .

Urine infection without bacteria:

It is possible to have leukocytes in the urine and with symptoms of bacterial infection, but without evidence of such an infection (there are no bacteria in the sediment or in the culture). It’s called sterile leukocyturia. This occurs in a urinary tract infection that has been “decapitated” by antibiotic treatment or not finished or with partial resistance of the germ to the antibiotic used. There are also some sexually transmitted diseases, viral or fungal infections or even tuberculosis that can cause this. In these cases (except in the case of viruses, which we can study better in blood tests) a special culture must be done to demonstrate these germs.

Bacteria in urine without symptoms:

It is the presence of bacteria in the urinalysis (confirmed in the sediment and in the urine culture) but without symptoms . It is called asymptomatic bacteriuria. Since there are no symptoms, the urinalysis may have been done for another reason. This entity is not usually treated with antibiotics , and this treatment is only reserved when the person has an increased risk if a urinary tract infection is produced by not treating it.

Acute and chronic prostatitis:

This entity only occurs in men . The acute form is characterized by the presence of pain when urinating, difficulty urinating, frequent urination , especially at night, fever and chills. There may also be pain in the abdomen, pelvis, or lower back. Chronic prostatitis is rare and usually occurs with repeated episodes as if it were an acute infection (increased frequency, urgency and burning when urinating) and between episodes there may be no symptoms or you may present a sustained clinic of pain in the lower abdomen or pelvis.

Lithiasis (stones) or grit in the kidney or urinary tract:

Typical symptoms are lower back pain, difficulty urinating, decreased amount of urine, nausea, vomiting, chills, and fever. In the urinalysis we find leukocytes, erythrocytes and crystals, but there should be no bacteria.

Glomerulonephritis (Noninfectious Nephritis):

It is an acute inflammation of the kidney (renal glomeruli), either as the onset of the disease or as exacerbation outbreaks of a previously known disease. Symptoms can be varied: decreased urine output, shortness of breath, headache, tiredness, pale skin, swelling… The number of leukocytes in urine is usually much lower than in the case of an infection and leukocytes of the urine may be eosinophils. In addition, there is usually protein in the urine and there may be erythrocytes. There are no bacteria. In the blood test kidney function is affected.

Systemic lupus erythematosus:

It is an autoimmune disease , that is, it is a disease in which the cells of the immune system act against the body itself, producing inflammation in the joints, skin, eyes and kidneys. In the urine test, a large number of leukocytes can be observed ; In addition, we can also find proteins and erythrocytes .

Interstitial cystitis:

It is a long-term disorder and the cause is often unknown. The symptoms are discomfort or pain, pressure and increased sensitivity in the region of the bladder, in the lower abdomen and in the pelvic area. Symptoms vary from person to person, and can be mild or severe. But they are generally very disabling and impair the quality of life of the person who suffers from them.

Urinary retention:

If urine accumulates in the bladder, the presence of bacteria increases the risk of infection. This can raise the levels of leukocytes in the urine.

Use of some medications:

Some medications, such as antibiotics, aspirin, corticosteroids and diuretics, for example, can cause leukocytes to appear in the urine. Leukocytes are usually eosinophils.


Tumors in the bladder, prostate and kidneys can give leukocytes in the urine, since in these situations the immune system is weakened. These leukocytes may be eosinophils. In addition, the presence of leukocytes can occur as a consequence of the treatment carried out against the tumors.

When to go to the doctor?

Generally, the urinalysis will have been requested by a doctor who has seen the patient and given the symptoms that the patient can explain, so that at the control visit and with the results, the doctor will be able to explain to the person the meaning of the urine test. presence of leukocytes and if further studies are necessary or if treatment is to be started.

In the event that the analysis has been done without a doctor’s indication, going to it should be done as long as altered values ​​and/or symptoms appear , as explained in this text. In general, you can go to the Primary Care doctor. And if the symptoms are intense or are not controlled with the medication started or new symptoms appear, you can go to an emergency room for evaluation.


The detection of elevated values ​​of leukocytes in the urinalysis will allow their presence to be quantified, in addition to detecting other alterations (presence of cylinders, erythrocytes, glucose or sugar, proteins, etc.) that guide us to their origin.


Treatment is based on treating the cause that causes leukocyturia . Therefore, only a correct diagnosis will allow us an adequate treatment.

In most cases, either there is no need to treat leukocyturia , or antibiotics will be administered in case of infection or the corresponding treatment for each disease.

The Primary Care doctor will be able to adequately treat most situations. If there is suspicion of stones in the kidney or urinary tract, or if there is suspicion of non-infectious inflammatory processes or atypical infections, a specialist should be consulted.

For bacterial infections that may be more serious or those that do not resolve easily with the antibiotic given, more complex medical treatment may be needed. In some cases, hospitalization may be necessary.

Prevention to avoid urine infections

Lifestyle changes can help reduce bacterial urine infections. These include:

      • Drink more water regularly; enough water should be taken so that the urine is clear.
      • Urinate when you feel like it and not hold your urine.
      • Prevent constipation and do not postpone the evacuation, so that germs do not colonize the areas near the urinary tract.
      • Keep your genital area clean .
      • Wipe the genital and anal area from front to back after using the bathroom
      • Clean the genital and anal areas before and after sexual activity .
      • Urinate before and after sexual activity.

What you should know…

  • The presence of an excessive number of leukocytes (or white blood cells) in the urine is called “leukocyturia”.
  • The possible causes of the presence of leukocytes in the urine are many, but it should not alarm us and, from the outset, we should always think of a urine infection as the first option.
  • In most cases, either there is no need to treat leukocyturia, or antibiotics will be administered in case of infection or the corresponding treatment for each disease.
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