Pyuria

Pyuria generally indicates the presence of inflammation in the urinary tract or, less commonly, widespread systemic inflammation. An offending causative agent is met with the body’s cellular immune defence system. Mediated by chemicals, like cytokines, interleukins and other inflammatory substances, and brought about, in most part, by white blood cells, this protective phenomenon produces troublesome signs and symptoms as well as the appearance of leukocytes in urine.

Urinary tract infections: Urinary tract infections (UTIs) are the most common cause of pyuria. They more commonly affect the lower urinary tract comprising the bladder and urethra, producing cystitis and urethritis, respectively. Microbes can also, at times, ascend and affect the upper urinary tract consisting of the kidneys and the ureters, producing more severe infection called pyelonephritis (kidney infection). Although usually caused by bacteria and fungi, sometimes viruses too can be the cause. The most common source of urinary tract infections is E. coli, a bacteria normally present in the human intestines that appears in faeces and can, due to improper hygiene, be transmitted through the urethra to the tract. 

(Read more: E. Coli Infection) 

Sterile pyuria: White blood cells can appear in urine with or without significant bacteriuria (bacterial cells in urine). However, a negative urine culture does not exclude infectious causes. Leukocytes may appear in the urine due to other infectious causes. Bacterial urinary tract infections that are being treated with antibiotics and sexually transmitted infections (STI) can also test negative on culture. Widespread inflammation in the body can cause excessive leukocytes to overflow into the urine. Recent antibiotic therapy and chronic use of some drugs too can cause sterile pyuria. Following are all the causes of sterile pyuria:

• Infectious:
  • Sexually transmitted diseases (STD) like chlamydia, gonorrhoea, etc
  • Genitourinary tuberculosis
  • Fungal urinary tract infection
  • Viral urinary tract infections caused by adenovirus, BK polyomavirus, and cytomegalovirus
  • Impartially treated urinary tract infection
  • Severe infection elsewhere in the body like pneumonia
• Non-infectious:
  • Kidney stones
  • Postmenopausal atrophic vaginitis
  • Balanitis
  • Prostatitis
  • Sepsis
  • Systemic lupus erythematosus (SLE)
  • Kidney disease
  • Interstitial cystitis (Bladder pain syndrome)
  • Kawasaki disease (inflammation of medium-sized vessels throughout the body in children)
• Chronic drug treatment: 
  • Aspirin
  • Diuretics
  • Olsalazine
  • Cyclophosphamide
  • Indinavir
  • Glucocorticoids like dexamethasone
  • Nitrofurantoin
  • Non-steroidal anti-inflammatory drugs (NSAID) such as ibuprofen
  • Proton pump inhibitors (PPI) like omeprazole  

Asymptomatic pyuria: In some conditions, like pregnancy, the leukocyte presence in urine is naturally increased and not a cause for concern.

Risk factors of pyuria are mostly the same as risk factors of contraction of a urinary tract infection. They include the following:

• Advanced age: The elderly are increasingly susceptible to contracting urinary tract infections.
• Being female: Due to the shorter length of the urethra, bacteria ascend the urinary tract more easily in women than in men. 
• Post surgical treatments: Due to prolonged inactivity and bed rest, inadequate hygiene, prolonged catheterisation or even hospital-acquired infections, postoperative patients are at an increased risk for urinary tract infections.
• Kidney stones: Stones can act as niduses for bacterial growth and infection.
• Urinary tract obstructions or blockages: An enlarged prostate, kidney stones and certain forms of cancer can provide bacteria with the environment required to proliferate and cause infection.
• Catheterisation: Unduly prolonged, aseptic use of urinary catheters can introduce bacteria, especially those causing hospital-acquired infections, into the bladder.
• Diabetes mellitus: Increased blood glucose levels make patients increasingly susceptible to various infections. Urinary tract infections are very common in adjunct to poorly controlled diabetes due to the presence of glucose in urine that supports bacterial growth.
• Pregnancy: Increased white blood cell count in urine during pregnancy is normal and not a cause for alarm. This is so because the body adapts to the increased demands of maintaining a healthy pregnancy. However, it is important to differentiate asymptomatic pyuria of pregnancy from urinary tract infections and sexually transmitted diseases as the latter can result in the premature birth of babies or transmission of infection to them. (Read more: Caring for a premature baby)
• Abnormally developed urinary structures from birth: Congenital anomalies such as polycystic kidneys can increase your risk of developing pyuria. 
• Weak immune system: When your immune system is not at its best, it provides room for many opportunistic infections to arise.

The presentation of pyuria is accompanied by other signs and symptoms depending on the underlying cause. 

Signs and symptoms of lower urinary tract infection:

• Burning with urination
• Increased frequency of urination without passing much urine
• Increased urgency of urination
• Blood in urine
• Cloudy urine
• Urine that looks like cola or tea
• Urine that has a strong odour
• Pelvic pain in women
• Rectal pain in men

Signs and symptoms of upper urinary tract infection:

• Pain and tenderness in the upper back and sides 
• Pain that radiates from loin to the groin
• Chills
• Fever
• Nausea and vomiting

Causes other than urinary tract infections can present with the following generalised signs and symptoms:

• Bladder pain
• Nausea or vomiting
• Cloudy urine
• Discharge from genitals
• Abdominal pain
• Fever and chills

It’s also important to keep in mind the many possible underlying diseases that could cause pyuria and their varying presentations.

The doctor will first take a detailed medical history focusing on the distressing symptoms and signs described by the patient. Attention is also paid to other pre-existing medical conditions and medications that the patient is on as they too can result in pyuria. After this, a thorough physical examination will be conducted to rule out all possible differential diagnoses. While in some cases changes in the physical properties of urine – colour, opacity, odour, viscosity – may be appreciable, a definitive diagnosis can be drawn only after laboratory investigations. Additionally, other blood investigations and radiological imaging may be required in conjunction with a to exclude other possible diseases and uncover the underlying cause.

In case of pregnancy, upon the first antenatal checkup, the woman is made to undergo routine urine microscopy irrespective of the presence or absence of symptomatology. This is done in order to differentiate harmless pyuria of pregnancy from potentially dangerous urinary tract infections that can harm both the mother and the baby. 

(Read more: Check up during pregnancy)

There are three major types of tests that you may be asked to get done if you have pyuria:  

• Blood tests:
  • Complete blood count: Altered ratios of white blood cells can indicate the presence of infection in the body.
  • Blood culture: Septicaemia and impending sepsis may be diagnosed through a blood culture. 
  • Blood glucose test: Uncontrolled diabetes mellitus can promote urinary tract infections. 
  • Kidney/Renal function tests: These may be deranged due to kidney disease or as a result of kidney damage due to the underlying cause of persistent pyuria. 
  • Antibody testing: Autoimmune inflammatory conditions like systemic lupus erythematosus (SLE) are diagnosed by specific antibodies. 
  • ESR and CRP: These two inflammatory markers can prove useful to diagnose Kawasaki disease in children.
• Urine tests:
  • Urine routine microscopy: Presence of 10 or more white blood cells per cubic millimetre of urine is defined as pyuria. On microscopy, if 3 or more white blood cells are present per high-power field in unspun urine or Gram staining of unspun urine is positive, pyuria is diagnosed.
  • Urine culture and sensitivity: Urine is routinely tested for bacterial presence and their antibiotic sensitivity using MacConkey’s agar medium. Pyuria can be present with both a positive or a negative (sterile) culture report. Sensitivity testing helps initiate the correct antibiotic therapy.
  • Urine dipstick tests: Readymade kits detect white blood cells in urine by testing leukocyte enzymatic activity.
• Radiological imaging tests:
  • KUB (Kidney, ureters and bladder) X-ray: Obstruction due to stones, tumours or other structural anomalies are detected in the kidneys, ureters and bladder.
  • Ultrasound: Growths, stones, tumours, anomalous structures, prostate enlargement and more can be visualised.
  • DMSA scan: Visualises kidney scarring due to chronic infections after radioactive dye injection. 
  • Chest X-ray: It helps diagnose pneumonia or pulmonary tuberculosis associated with genitourinary tuberculosis. 
• Other tests:
  • Mantoux test: A small amount of toxin derived from tuberculosis bacteria is injected into the skin on the arm and the induration formed is studied to detect tuberculosis.
  • Sputum testing: In suspected tuberculosis patients, sputum will be tested for tuberculosis bacilli by staining microscopy, culture and CB-NAAT sensitivity testing. (Read more: Sputum Culture)

Treatment of pyuria depends on the underlying cause. For example, genitourinary tuberculosis, systemic lupus erythematosus and Kawasaki disease require disease-specific treatment. In some cases, prescription drugs for pre-existing diseases might have to be reduced or stopped by the doctor.

Urinary tract infections are usually treated with a course of appropriate antibiotics after urine culture and sensitivity testing. Drinking plenty of water is advised to flush out the microbes faster. Antifungal medicines may be prescribed if the root cause is a fungal infection.

(Read more: Home remedies for UTIs)

You can prevent pyuria caused by urinary tract infections by taking the following precautions:  

• Wiping front to back: While cleaning up after using the toilet, a front to back motion should be used to prevent introducing faecal bacteria to the urethra.
• Drink plenty of fluids: Liquid intake helps flush the bacteria that may have entered through the urethra out. It is recommended that you have six to eight glasses of water on a daily basis.
• Not holding urine in for long periods of time: Holding urine due to lack of availability of a toilet can promote bacterial growth and infection. It should be avoided.
• Urinating before and after sexual intercourse: Sexual intercourse can introduce bacteria into the urinary tract and therefore women should urinate before and after the act. If possible, the genital area should also be cleaned.
• Avoid scented vaginal products: Douching or using scented tampons and sanitary napkins can alter the pH of the vagina, creating an imbalance. This can lead to bacterial and yeast infections.
• Choosing an appropriate contraception method: Birth control methods like non-lubricated condoms and spermicidal jellies can cause bacterial overgrowth. If you notice any adverse reaction, it is best to talk to a doctor about alternative methods.
• Probiotics: Curd, yoghurt and some fermented foods promote the growth of protective bacteria in the gut and the vagina. 
• Hormone replacement therapy (HRT) for menopause: Urinary tract infections due to menopause-induced atrophic vaginitis can be prevented by regulating oestrogen levels with HRT.
• Catheter replacement: Patients who are on catheters should have theirs switched regularly to prevent microbial infection.  

If left untreated, or inadequately or incorrectly treated, persistent pyuria can damage the kidneys and spread the infection to the bloodstream. The complications from this could be: 

• Septicaemia
• Sepsis
• Septic shock
• Multiple organ dysfunction syndrome
• Acute kidney injury
• Chronic kidney disease
• End-stage renal disease or kidney failure