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What are Leukocytes in Urine?

Leukocytes, or white blood cells (WBCs), are immune cells that help fight infection. When they appear in urine—a condition called leukocyturia or pyuria—it usually indicates inflammation or infection somewhere in the urinary tract. In healthy individuals, urine contains very few or no white blood cells. Elevated levels detected during a urinalysis often point to conditions like urinary tract infections (UTIs), kidney infections, or other urinary system disorders that may require medical evaluation.

Normal Ranges

  • Normal: 0–5 WBCs per high-power field (hpf) on microscopic exam
  • Borderline elevated: 6–10 WBCs/hpf
  • Significant elevation: >10 WBCs/hpf
  • Dipstick: Negative to trace amounts considered normal

Counts above 5 WBCs/hpf typically warrant further investigation, especially if accompanied by urinary symptoms.

Common Causes of Leukocytes in Urine

  • Urinary tract infections (UTIs): Bacterial infection of bladder (cystitis) or urethra.
  • Kidney infections (pyelonephritis): More serious infections with potential fever, flank pain.
  • Interstitial cystitis: Chronic bladder inflammation without bacterial cause.
  • Kidney stones: Can irritate urinary tract and trigger inflammation.
  • Sexually transmitted infections (STIs): Chlamydia, gonorrhea, and others.
  • Prostatitis: Inflammation of the prostate gland in men.
  • Pregnancy-related changes: Possible temporary elevation.
  • Kidney disease: Nephritis, glomerulonephritis.
  • Bladder or kidney cancer: Less common but possible cause of persistent leukocyturia.

Associated Symptoms

Leukocytes in urine may be present without symptoms, but often occur with:

  • Burning or pain during urination
  • Frequent urge to urinate
  • Cloudy or foul-smelling urine
  • Lower abdominal or back pain

Seek immediate care if you have fever, chills, nausea, severe flank pain, blood in urine, or persistent symptoms despite initial treatment—these may indicate kidney infection or a more serious condition.

Testing and Diagnosis

  • Dipstick urinalysis: Detects leukocyte esterase, an enzyme from WBCs.
  • Microscopic exam: Directly counts WBCs in urine sediment.
  • Urine culture: Identifies bacteria and guides antibiotic choice.
  • Additional testing: May include imaging or specialized labs if structural or systemic disease is suspected.

Proper sample collection (clean-catch, midstream) is important to avoid contamination that could produce false-positive results.

Treatment

Management depends on the underlying cause:

  • Bacterial UTIs: Treated with antibiotics tailored to culture results.
  • Kidney infections: Often require longer courses or intravenous antibiotics.
  • Non-infectious inflammation: Addressed with targeted therapies (e.g., for stones, interstitial cystitis).
  • Chronic/recurrent issues: May need prophylactic strategies or treatment of underlying risk factors.

Prevention Strategies

  • Stay well-hydrated.
  • Practice proper genital hygiene; wipe front to back.
  • Urinate promptly when you feel the urge; empty bladder fully.
  • Urinate before and after sexual activity.
  • Avoid irritating hygiene products in the genital area.
  • Maintain a healthy immune system with balanced diet, exercise, and adequate sleep.

Bottom line: Leukocytes in urine signal an immune response to infection or inflammation in the urinary tract. Even without symptoms, persistent leukocyturia should be evaluated to identify and treat the underlying cause, preventing complications.