Urinalysis

Leukocytes in urine

Urinalysis
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Leukocytes in urine
foto de Fernando Martínez Sáez
Written by

Fernando Martínez Sáez
Medically reviewed by our Medical staff

Last update: 02-12-2021

How else can it be called?

  • White Blood Cells in urine

  • WBCs in urine

  • Leukocyturia

  • Pyuria

  • CIE-10: R82.9

Why leukocytes (WBCs) can be present in urine?

The presence of a high number of leukocytes or white blood cells (WBCs) in a urine test may be a sign of infection or inflammation of the urinary tract.

Normally, there should not be more than a few leukocytes in the urine (4–5 per high-power field) when studying under the microscope the urine sediment. However, higher numbers may be present in urine from females.

Leukocytes or WBCs may come from anywhere in the genitourinary tract.

Why is this test performed?

The presence of a high number of leukocytes in the urine sediment may help to diagnose infection or inflammation of the urinary tract.

There are two groups of leukocytes or WBCs: polymorphonuclear (neutrophils, eosinophils and basophils) and mononuclear (lymphocytes and monocytes).

Most of those present in the urine sample are neutrophils, although eosinophils or mononuclear cells may be elevated in certain situations.

Eosinophils are not normally seen in the urine. The presence of eosinophils is primarily associated with urinary tract infection (UTI). There are other possibilities for a high presence of eosinophils in urine such as a drug-induced interstitial nephritis or a renal transplant rejection. Lymphocytes may be also seen in increased numbers in the early stages of renal transplant rejection.

How is the test performed?

This test is performed along with other urine tests. The patient must collect a sample of the urine in a specific container using a special kit. This sample will be sent to the lab for the analysis. The urine should be collected by a clean-catch midstream to rule out bacterial contamination.

It is important to avoid vaginal discharge because it can contaminate the sample.

To study the presence of WBCs in the urine, it is necessary to obtain previously the urinary sediment. For this matter, the urine sample should be placed at rest for some hours waiting for the different elements of the urine (white and red blood cells, crystals, etc.) precipitate to the bottom. As this process is very slow, the urine is centrifuged for about 5 minutes at 1500 or 2000 revolutions per second to obtain a sample of the sediment in less time.

What is considered a normal result?

It is considered normal to see fewer than five leukocytes per HPF (High Power Field), when examining under the microscope the urine sediment with a high-power magnification.

Which does an abnormal result mean?

The presence of more than 5 leukocytes per HPF (High Power Field) is considered important for diagnosis. The number of WBCs cells identified using the high-power objective is reported.

Elevated numbers of white blood cells in the urine is called pyuria, which indicates infection (mainly bacterial) or inflammation of the urinary tract. Pyuria is defined as the presence of 10 or more WBCs per cubic millimeter in a urine sample.

Some conditions that may be related to pyuria or a high number of WBCs in a urine test are:

  • Pyelonephritis
  • Cystitis
  • Prostatitis
  • Urethritis
  • Glomerulonephritis
  • Lupus
  • Interstitial nephritis
  • Kidney stones
  • Renal tuberculosis
  • Tumors of the urinary tract

It is common to see bacteria in urine when pyuria is present.

Medically reviewed by our Medical staff on 02-12-2021

Bibliography

  • Laboratory tests and diagnostic procedures with nursing diagnoses (8th ed), Jane Vincent Corbett, Angela Denise Banks, ISBN: 978-0-13-237332-6, Pag. 75.
  • Essentials of Medical Laboratory Practice. Constance L. Lieseke, Elizabeth A. Zeibig. 2012. ISBN: 978-0-8036-1899-2 Pag: 442.
  • Concise Book of Medical Laboratory Technology: Methods and Interpretations. 2nd Edition. 2015. Ramnik Sood. ISBN: 978-93-5152-333-8. Pag. 98.
  • Urinalysis and Body Fluids. Susan King Strasinger. Marjorie Schaub Di Lorenzo. 5th edition. 2008. ISBN 978-0-8036-1697-4 Pag. 94.

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