Overview
The episode covers the evaluation and workup of hematuria (blood in urine), focusing on distinguishing between nephrologic (kidney) and urologic causes. Practical clinical frameworks, diagnostic workups, and key historical and lab findings are discussed, with Dr. Derek Fine as a guest expert.
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Introduction of Dr. Derek Fine
- Dr. Fine is a nephrologist at Hopkins with interests in HIV kidney disease and lupus.
- Enjoys chess as a hobby and emphasizes the importance of family and work-life balance.
Foundational Concepts in Hematuria
- Hematuria is defined as three or more red blood cells per high-power field on urinalysis.
- Gross hematuria is visible blood in urine, while microscopic hematuria is detected only in labs.
- Initial clinical responsibility is to distinguish urologic from nephrologic causes.
Key History and Risk Factors
- Important history includes age, smoking, chemical exposures, medication use (anticoagulants, NSAIDs), recent infections, trauma, and exercise.
- High-risk features for malignancy: age >35, gross hematuria, smoking, chemical exposures.
Urologic vs. Nephrologic Evaluation
- Urologic causes are more likely with gross hematuria, clots, or high-risk features.
- Imaging for workup: CT urography is preferred for high-risk, ultrasound for low-risk patients.
- Cystoscopy is needed if initial imaging is negative.
Laboratory Workup and Interpretation
- Trace protein on dipstick is unreliable; direct urine albumin or protein-to-creatinine ratio is recommended.
- Automated urinalysis may not detect red cell casts; consider manual review if findings are unclear.
- Persistent or severe albuminuria suggests glomerular (kidney) origin and warrants nephrology referral.
Distinguishing Glomerular Causes
- Important tests: creatinine, GFR, albuminuria, serology (complements, ANA, ANCA, anti-GBM).
- Categorization includes anti-GBM disease, ANCA-associated vasculitis, and immune complex glomerulonephritis.
- Complement levels help narrow diagnosis (e.g., low C3/C4 in lupus, post-infectious GN).
Follow-Up and Special Considerations
- Negative workup in low-risk, asymptomatic hematuria can be followed with annual or semi-annual urinalysis.
- Renal biopsy indicated if unexplained albuminuria, rising creatinine, or specific clinical suspicion.
- Consider unique etiologies in transplant recipients or patients with geographic exposure risks (e.g., schistosomiasis).
Decisions
- Refer hematuria with gross presentation or high-risk features to Urology for imaging/cystoscopy.
- Refer to Nephrology if significant albuminuria or evidence of glomerular disease is present.
Action Items
- TBD – Primary Care: Repeat urinalysis in 6–12 months for low-risk patients with negative workup.
- TBD – Primary Care: Obtain kidney function and proteinuria labs for all patients with hematuria.
- TBD – Urology: Perform cystoscopy and imaging for patients with gross hematuria or high-risk history.
Recommendations / Advice
- Take a thorough patient history and review medication/exposure history.
- Always work up hematuria in patients on anticoagulation; do not attribute solely to medications.
- Gross hematuria requires urgent evaluation; time is kidney in possible glomerular disease.
- Communicate findings clearly to patients; update the problem list when etiology remains uncertain.
Questions / Follow-Ups
- Assess etiology if urinalysis and microscopy results are discordant; a fresh sample may be needed.
- Be alert to geographic exposure risks and special causes (e.g., schistosomiasis, TB, malaria).
- Monitor for recurrence of hematuria and reinitiate workup if symptoms reappear.