What is the initial workup for a patient presenting with microscopic hematuria?

Initial Workup for Microscopic Hematuria

The initial workup for microscopic hematuria should include complete urinalysis with microscopic examination, urine culture, urine cytology, complete metabolic panel, and renal ultrasound, followed by risk-stratified evaluation for further testing and specialist referral. 1

Confirmation and Initial Laboratory Evaluation

• First step: Confirm microscopic hematuria with urinalysis showing ≥3 RBCs per high-power field on a properly collected specimen

• Complete urinalysis should assess:

  • RBC morphology (dysmorphic RBCs suggest glomerular source)
  • Presence of casts (RBC casts suggest glomerular disease)
  • Crystals (may indicate stone disease)
  • Pyuria (suggests infection)
  • Proteinuria (suggests possible glomerular pathology) 1

• Additional initial laboratory tests:

  • Urine culture to rule out infection
  • Urine cytology to evaluate for malignant cells
  • Complete metabolic panel including BUN and creatinine to assess renal function
  • Serum creatinine and BUN to evaluate kidney function 1

Risk Stratification

Risk factors for urologic malignancy that warrant more aggressive evaluation:

• Age >40 years (higher risk if >60 years)
• Male gender
• Smoking history
• Occupational exposure to chemicals or dyes
• Previous urologic disorders
• History of gross hematuria (even if resolved) - associated with 7.2x higher odds of urologic cancer 1

Imaging Evaluation

• Initial imaging: Renal ultrasound - appropriate first-line imaging test for most patients 1, 2
• For higher-risk patients: Consider CT urography (92% sensitivity, 93% specificity for urologic pathology) 1
• For patients with renal insufficiency or contrast allergy: MR urography or ultrasound 1

Specialist Referral Considerations

• Urology referral is indicated for:

  • Any history of gross hematuria (>10% risk of malignancy)
  • Persistent microscopic hematuria after treatment of benign causes
  • High-risk patients (age >40, smoking history, occupational exposures) 1, 3

• Nephrology referral should be considered when there are signs of glomerular disease:

  • eGFR <60 ml/min/1.73m²
  • Significant proteinuria
  • Dysmorphic RBCs or red cell casts 1

Common Pitfalls to Avoid

1. Overlooking benign causes: Most microscopic hematuria (approximately 80%) is idiopathic or has benign causes like UTI, BPH, or urinary calculi 4, 3

2. Inadequate follow-up: Patients with persistent hematuria require continued surveillance with repeat urinalysis within 12 months 1

3. Missing glomerular causes: The presence of hematuria with proteinuria and systemic symptoms suggests possible glomerular pathology requiring thorough evaluation 1

4. Assuming low risk in younger patients: While malignancy is less common in patients ≤40 years, they still require evaluation, particularly for stones (noncontrast CT or ultrasound) 5

Follow-up Recommendations

• If initial evaluation is negative but microscopic hematuria persists at 3-month follow-up, consider additional imaging with CT urography 6
• New symptoms, gross hematuria, or increased degree of microscopic hematuria should prompt immediate re-evaluation 1

The diagnostic approach to microscopic hematuria should be risk-adapted, with more intensive evaluation for patients with risk factors for malignancy. While most cases have benign causes, a systematic approach is essential to identify potentially serious underlying conditions.