see also:

• urinalysis
• urinary tract infections (UTIs) / cystitis

• sterile pyuria is the finding of > 10 white cells per microlitre of uncentrifuged urine of leukocytes in clean urine samples without bacterial growth on culture

• partially treated urinary tract infections (UTIs) / cystitis
• urolithiasis / renal stones / renal calculi
• tuberculosis (TB)
• sexually acquired urethritis
• senile urethritis
• perinephric abscess
• urethral syndrome
• fungal infections
• fastidious organisms causing UTI such as Gardnerella vaginalis in prepubertal girls?
• uric acid and hypercalcaemic nephropathy
• lithium carbonate and heavy metal toxicity
• sarcoidosis and other granulomatous diseases
• interstitial cystitis
• polycystic kidney disease
• bladder cancer
• renal transplant rejection
• any periurethral process
  • eg. appendicitis - esp. if appendix near the ureter
• Kawasaki disease
• medications:
  • paracetamol (acetaminophen) apparently