WBC Esterase: 8 Uses and Its Clinical significance

WBC Esterase is also known Leukocyte esterase test. Do you know why wbc esterase test is used? Let’s find out from this article.

What are leukocytes?

WBCs are also known as Leukocytes, WBCs protect the body from foreign organisms which include Bacteria, Fungi, and Viruses etc. There are two types of WBCs phagocytes and lymphocytes. Both have a different mechanism to fight external organisms and substances.

  • Phagocytes: Phagocytes work by engulfing the external substances.
  • Lymphocytes: Lymphocytes fight against the foreign substances by recognising the foreign substances based on the previous infection and preparing the body against them. They also work by producing antibodies which stick to the surface of foreign substances making it easier for recognition.

Presence of a higher number of WBCs in the urine denotes that there are foreign particles in the body and there is a risk to the healthy state.

Higher Leukocytes/WBCs in Urine:

wbc esterase test
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Leukocytes in urine are an indicator that body is fighting some infection. It also denotes that there is a possible infection or inflammation in liver or kidney. It also means that the body is trying to fight an infection in urinary tract.

Consistently high levels of WBCs in urine could also mean possible damage to the kidney and its associated organs. A higher WBC count in urine could also mean that the body is fighting some infection.

Normal WBC range in using is 0-5 WBC/HPF. The size of the urethra is smaller in females. Therefore, a higher number of WBCs is found in case of females. A higher number of WBCs is also found during pregnancy. There could be various disease states responsible for a higher WBC count in urine:

Some of the causes of higher WBCs in urine include:

Pregnancy: During pregnancy, there is a sudden rise in the number of WBCs

Renal Infection: Kidney problems can cause an increase in the number of leukocytes in the urine

Kidney Stones: There could be an obstruction to the flow of urine due to stones. As a result, an increasing content of WBCs in urine

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Sexual intercourse: Sexual intercourse also leads to the movement of bacteria to the urinary tract resulting in an increase in WBC count

Delayed urination: In many cases when there is an incomplete emptying of the urine, the urine in the bladder acts a source of bacteria to thrive on, resulting in leukocytes in the urine

Urinary tract obstruction: Due to the damage to the urinary system due to one or the other reasons like stones, pelvic hypertrophy. This leads to the appearance of leukocytes in the urine.

Some of the major signs and symptoms of urinary infections include:

Some of the general symptoms include frequent urination, pain in the lower Urinary tract, an urgency to urinate, blood in urine or cloudy urine

Other symptoms include fever, chills, nausea, vomiting etc.

Diagnosis of urinary infection:

For a person having any of the symptoms, it is important to test the urine or blood for the presence of WBCs. Once the test comes positive for bacteria, it is important to find the type of bacteria causing the infection which is done by taking a culture of urine. Some of the urinary tests performed for diagnosis of infection include:

Microscopic examination of urine:

This test is done to check if there is any pus formation in the urine. Pus formation is prevalent among women; hence the test is mostly done on women.

Microscopic examination of bacteria:

Once the presence of bacteria is confirmed, it is important to search for the type of bacteria. A gram stain of a urine sample is used to identify the type of bacteria.

Another preferred approach used for diagnosis is called WBC Esterase:

This test is also called as Leukocyte esterase test. Kidneys help to eliminate the wastes from the blood. Kidneys help to regulate the water in the body and also help to regulate the electrolytes in the blood.

Usually, the colour of urine is yellow and is clear. However, in certain disease states the colour of the urine changes. Some of the disease states which demand the test are:

  • Back Pain
  • During pregnancy
  • Abdominal pain
  • Before any major surgery
  • Painful or frequent urination
  • Sometimes the test is also done as a preventive measure as well.

The test is an indicative test for the presence of WBCs and the associated signs of WBCs in the urine.

How the WBC esterase test is performed:

The test uses the urine sample; the sample collected in this case is done by clean catch method. The method uses a clean catch kit and wipes.

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The purpose of using this is to get a sterile and uninfected sample of urine. It is usually recommended to urinate after 3 hours of stored urine in the urinary bladder. The process involves cleaning the area;

Women should give the urine after spreading the labia and cleaning the portion from front to back. Similarly, Men should first clean the penis and with a cleansing solution or a wipe and then provide the urine without catching any infection.

The lab technician will carry the test right away to avoid any contamination to the urine.

The lab technician will use a dipstick and a colour sensitive plate. The change in the colour of the plate will tell the presence of WBCs. The test is an indicative test for the presence of WBCs and does not give any confirmation.

In case the test is negative then you are normal, but if the WBC esterase test is positive, you need to undergo a further test to find the type of bacterial infection.

There could be a slight variance in the results of the WBC esterase test between different labs. Healthcare practitioner is a better person to interpret the results of the WBC esterase test.

The WBC esterase test can also give a false reading in case the person is suffering from certain infection:

  • Trichomonas infection
  • Vaginal discretions

In such cases, false negative tests results happen due to the presence of high level of protein or Vitamin C.

To prevent any falsified results a person needs to follow the instructions given below:

  • The doctor might ask you to fast for some time before the test
  • Any medications or supplement taken should also be discussed with the doctor so that the results of the test are not hampered.

WBC esterase test checks the following:

WBC esterase tests check the following characteristics of the urine in detail:

Acidity (pH):

The tests checks for the pH level of the urine. Abnormal pH indicates some disorder which could be due to kidney or urinary tract infection

Concentration:

WBC esterase test also tests for the concentration or specific gravity of the tests. This helps to detect the concentration of the particles in urine. A higher concentration of urine may denote a lesser intake of water by the person.

Protein:

Small amount of proteins are usual to appear in the urine. There could be slight variations to the normal level. It is one there are very high levels of proteins in the urine which may indicate a kidney problem.

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Sugar:

WBC esterase test is also used to detect the presence of glucose in urine. Usually the levels of glucose in urine are negligible; however, the higher amount of glucose in the urine is a possibility of diabetes and requires further tests.

Ketones:

WBC esterase is also tested for the presence of ketones in the urine. Similar to glucose, ketones is negligible in the urine; any amount of ketones is a sign of diabetes and requires further testing.

Bilirubin:

Bilirubin is formed because of the breakdown of red blood cells. Breakage of red blood cells happens in the liver which breaks the red blood cells into bilirubin which passes into the bile. Presence of bilirubin the urine indicates a problem with a liver because of which Red blood cells are not able to break.

Urinary Tract Infection:

The presence of WBC esterase trace in urine is a result of urinary tract infection. WBC esterase 1 or Leukocyte esterase 1 is a by-product of WBC.

Blood:

Some time small lumps in the blood are seen. Blood can be observed through WBC esterase; however, this requires additional tests to find the reason for the presence of blood. There could be multiple reasons for it like kidney damage, an infection, kidney stones, Blood cancer or some sort of blood disorders.

WBC esterase test can also be used as a screening test for urethritis among adolescent males.

The normal range of the WBC esterase is >100kU/l for both males and females.

WBC esterase is a good indicative test but is usually followed by microscopic tests to confirm WBC esterase abnormal and count cells, bacteria, crystals, mucous and other substances in urine. The microscope tests are used for following:

  • Red blood cells: Presence of this could detect a kidney problem, urinary infection or trauma etc.
  • White blood cells: A higher number of white blood cells indicates inflammation of the kidneys or urinary tract
  • Epithelial cells: the presence of this in the urine denotes urinary tract infection
  • Tests are also performed for the presence of casts, bacteria or crystals in the urine.
References:
  1. https://www.lybrate.com/lab-test/leukocyte-esterase
  2. http://pennstatehershey.adam.com/content.aspx?productId=117&pid=1&gid=003584
  3. https://www.scripps.org/articles/3181-leukocyte-esterase-urine-test
  4. https://www.hopkinslupus.org/lupus-tests/screening-laboratory-tests/urinalysis/
  5. https://www.ncbi.nlm.nih.gov/pubmed/2509742
  6. https://www.mayoclinic.org/tests-procedures/urinalysis/about/pac-20384907
  7. https://www.findatopdoc.com/Healthy-Living/leukocytes-in-urine
  8. https://medlineplus.gov/ency/article/003584.htm

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