Abnormal Urinalysis Findings
Sterile Pyuria
Common Causes
- Infectious: Tb, STI, Mycoplasma, Ureaplasma, recently treated UTI, Schistosomiasis, Adenovirus, prostatitis, intraurethral HPV, HIV, fungus, Trichomonas
- Weight loss: Tb, pelvic malignancy
- Prior surgery/XRT: pelvic XRT, recent cystoscopy, stents/PCNs/catheters
- Hematuria: stones, ADPKD, renal papillary necrosis, tubulointerstitial nephritis (TIN)
- Pertinent PMHx: SLE, DM, Kawasaki, pregnancy, malignant HTN
- Pertinent medications: NSAIDs, steroids, olsalazine, nitrofurantoin, penicillins, vancomycin, PPI
Workup
- Initial workup (PCP): Tb-PCR, STI screen, renal US, cytology
- Eosinophilia: seen in tubular interstitial nephritis (TIN), Schistosomiasis
- Urologic workup: cystoscopy + CTU if concerned
Different causes of urine color, from Campbell's
Proteinuria algorithm, from Campbell's
Other UA findings
Things that look like hematuria (but aren't hematuria)
- Myoglobinuria: seen during rhabdo, can cause positive blood on a dipstick but will be negative for RBCs on the microscopic UA
- Pyridium: turns urine bright orange, will cause positive nitrites without leukocyte esterase
- Menstruation: confirm clean catch (check squamous cells)
Non-hematuria findings
- Excess urine on dipstick or holding vertical can alter results
- Phosphaturia: phosphate crystals in alkaline urine, can cause non-infected turbid urine appearance, urine will immediately clear with acidification of sample
- UTI + pH > 7.5: suggests presence of urea-splitting organism
- RBC casts: indicate glomerular source, usually associated with proteinuria
- Proteinuria: always from renal source, may have false negative if albumin is not the primary protein (Tamm-Horsfall, Bence-Jones protein)
- Glucosuria: seen when glucose levels exceed renal reabsorption threshold
- Ketonuria: seen with DKA, pregnancy, starvation, weight loss
- Microscopic examination:: assess for cells, casts, crystals, bacteria, yeast, and parasites
References
- AUA Core Curriculum
- Boorjian, et al. "Evaluation and management of hematuria." Campbell-Walsh Urology. 12th ed. Philadelphia, PA: Elsevier (2020): 247-259.
- Castle, E., C. Wolter, and M. Woods. "Evaluation of the Urologic Patient: Testing and Imaging." Campbell-Walsh Urology 12 (2020).
- Glen, Peter, Akash Prashar, and Amr Hawary. "Sterile pyuria: a practical management guide." The British Journal of General Practice 66.644 (2016): e225.
- Goonewardene, Sanchia, and Raj Persad. "Sterile pyuria: a forgotten entity." Therapeutic advances in urology 7.5 (2015): 295-298.
- Wieder JA: Pocket Guide to Urology. Sixth Edition. J.Wieder Medical: Oakland, CA, 2021.
- Wise, Gilbert J., and Peter N. Schlegel. "Sterile pyuria." New England Journal of Medicine 372.11 (2015): 1048-1054.