Causes of sterile pyuria

Pyuria
WBC’s in urine microscopy

Sterile pyuria refers to the presence of more than 5 white blood cells per high power field ( WBC’s / HPF ) in the absence of bacteria in a routine urine specimen.

Causes of sterile pyuria

Sterile pyuria can arise due to various causes. The following conditions must be considered as differential diagnosis for a case of sterile pyuria.

  • Infectious etiology
    • Urinary tract infection after treatment
    • Bacteria like like Chlamydia trachomatis, Ureaplasma urealyticum and Mycobacterium tuberculosis
    • Viral or fungal UTI
    • Prostatitis
    • Appendicitis
  • Systemic conditions
    • Acute febrile illness
    • Congenital cyanotic heart disease
    • Malignant hypertension
    • Pregnancy
    • Kawasaki disease
    • Sarcoidosis
  • Structural defects and impairment of renal physiology
    • Hydronephrosis
    • Nephrocalcinosis / Urolithiasis
    • Vesicoureteral reflux
    • Retained foreign body in urinary tract
    • Polycystic kidney disease (PKD)
  • Intrinsic pathology of kidney
    • Papillary necrosis secondary to chronic analgesic nephropathy / obstructive uropathy / sickle cell nephropathy / diabetic nephropathy
    • Tubulointerstitial diseases like interstitial nephritis, lupus nephritis and renal transplant rejection

Ref: Sterile pyuria: A differential diagnosis, Robert S. Dieter, Comprehensive Therapy, Fall 2000, Volume 26, Issue 3, pp 150-152

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