Pyuria is a urinary condition that involves an elevated number of white blood cells in the urine.

Doctors define a high number as at least 10 white blood cells per cubic millimeter (mm3) of centrifuged urine. Pyuria can cause the urine to look cloudy or as if it contains pus.

The presence of pyuria often occurs in a urinary tract infection (UTI). In rare cases, it can be a sign of a complicated UTI or sepsis.

Sterile pyuria is a form of pyuria that occurs without a detected presence of bacteria. In these cases, it may be related to non-detected bacteria, a virus or other germ type, or some other underlying medical condition.

In this article, learn about the causes and symptoms of pyuria, as well as treatment options.

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Pyuria is usually caused by a UTI.

Pyuria can occur as a result of many different conditions. It is most commonly caused by a UTI, which is an infection in any area of the urinary system, including the kidneys, ureters, urethra, or bladder.

Sterile pyuria is most often caused by sexually transmitted infections (STIs), such as gonorrhea or viral infections.

Other causes of sterile pyuria include:

  • interstitial cystitis
  • bacteremia with sepsis
  • tuberculosis
  • urinary tract stones
  • kidney disease
  • prostatitis
  • pneumonia
  • autoimmune diseases, such as SLE or Kawasaki’s disease
  • parasites
  • tumors in the urinary tract
  • polycystic kidney disease

Pyuria can also be a reaction to taking certain types of medications, including:

Pyuria can cause cloudy urine and urine with pus that may not be accompanied by any other symptoms. The change in color or texture is due to the increased number of white blood cells.

If a UTI is present, symptoms may also include:

  • frequent urges to urinate
  • a burning sensation when urinating
  • blood in urine
  • foul-smelling urine
  • pelvic pain
  • fever

Other symptoms that may occur if another underlying condition causes pyuria:

  • fever
  • abdominal pain
  • abnormal discharge
  • shortness of breath
  • nausea or vomiting

A doctor will do a urinalysis to diagnose pyuria. This involves taking a urine sample, which is then analyzed based on its appearance, concentration, and content.

Cloudy urine with an abnormal white blood cell count may indicate pyuria.

The urinalysis might also highlight other abnormalities. For example, the presence of nitrite or leukocyte esterase can indicate a UTI, while elevated protein levels might indicate kidney disease.

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Pyuria may be treated with antibiotics.

Treatment for pyuria depends on the underlying cause. Usually, a UTI causes pyuria and treatment will involve a short course of antibiotic therapy, such as oral trimethoprim-sulfamethoxazole or nitrofurantoin.

Antibiotics can also treat bacterial STIs and tuberculosis. If there is no improvement after taking a full course of antibiotics, a more serious underlying condition may be present.

In some cases, stopping the medications that are triggering the increase in urine white blood cells may treat pyuria. However, it is essential to consult a doctor before stopping or changing any medications.

Pyuria and UTIs often occur during pregnancy. This is due to anatomical and hormonal changes during pregnancy that allows bacteria to enter the urinary tract and grow.

Anyone experiencing pyuria during pregnancy should speak to a doctor to determine the underlying cause. An infection or even asymptomatic bacterial presence in the urine during pregnancy can be harmful and may cause complications with the baby.

Most cases of pyuria do not pose any serious health risk, but anyone experiencing pyuria should speak to a doctor to help determine the underlying cause.

UTIs are a common cause of pyuria that doctors can treat with a short course of antibiotics. If antibiotics fail to treat the symptoms, a person should seek further medical attention.

If a person is experiencing pyuria during pregnancy, they should talk to their doctor about the best way to minimize the risk of complications.