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 urinalysis confirmation, complete metabolic panel, urine culture, urine cytology, and risk stratification to determine the need for imaging studies and specialist referral. 1

Definition and Confirmation

• Microscopic hematuria is defined as ≥3 red blood cells per high-power field (RBC/HPF) on microscopic evaluation from two of three properly collected urinalysis specimens 2, 1
• First step: Exclude benign causes including:
  • Menstruation
  • Vigorous exercise
  • Sexual activity
  • Viral illness
  • Trauma
  • Infection 2

Initial Laboratory Evaluation

• Complete urinalysis to confirm hematuria and assess for:
  • Pyuria
  • Bacteriuria
  • Crystals
  • Red cell casts 1
• Complete metabolic panel including:
  • BUN and creatinine (to assess kidney function)
  • Electrolytes
  • Serum albumin and total protein 1
• Urine culture to rule out infection 1
• Urine cytology to evaluate for malignant cells 1

Risk Stratification

Risk factors that warrant more aggressive evaluation include:

• Age >40 years (particularly >60 years)
• Smoking history
• Occupational exposure to chemicals or dyes (benzenes or aromatic amines)
• History of gross hematuria
• Previous urologic disorder or disease
• History of irritative voiding symptoms
• History of recurrent urinary tract infection
• Male gender
• Hypertension
• Diabetes 2, 1

Renal vs. Urologic Evaluation Pathway

Evaluation for Primary Renal Disease

If any of the following are present, pursue renal evaluation or nephrology referral:

• Significant proteinuria (>1,000 mg/24 hours or >500 mg/24 hours if persistent)
• Dysmorphic red blood cells
• Red cell casts
• Elevated serum creatinine level 2, 1

Urologic Evaluation

If conditions suggestive of primary renal disease are not present, or if risk factors for urologic disease exist, pursue urologic evaluation:

1. Imaging studies:

   • CT Urography is preferred (92% sensitivity, 93% specificity) 1
   • Alternatives for patients with renal insufficiency or contrast allergy:
     • MR urography
     • Renal ultrasound 1

2. Cystoscopy:

   • Recommended for all patients >40 years
   • Also recommended for younger patients with risk factors for bladder cancer 2, 1

Specialist Referral

• Urology referral indicated for:

  • Patients with gross hematuria
  • Age >60 years
  • Uncertain pelvic calcification 1

• Nephrology referral indicated for:

  • eGFR <60 ml/min/1.73m²
  • Persistent significant proteinuria
  • Elevated BUN or creatinine 1

Follow-up for Negative Initial Evaluation

For patients with negative initial evaluation:

• Repeat urinalysis, urine cytology, and blood pressure at 6,12,24, and 36 months 2
• Immediate urologic reevaluation if:
  • Gross hematuria develops
  • Abnormal urinary cytology appears
  • Irritative voiding symptoms develop in absence of infection 2
• If hematuria persists despite negative evaluation, consider further nephrology evaluation 2

Common Pitfalls to Avoid

• Do not attribute hematuria to anticoagulant therapy without proper evaluation 1
• Do not assume hematuria is due to UTI without supporting evidence of infection 1
• Do not ignore clinical changes such as new symptoms, gross hematuria, or increased degree of microscopic hematuria 1
• Do not defer evaluation in high-risk patients, as up to 25.8% of at-risk populations may have malignant tumors 3

Following this systematic approach ensures thorough evaluation of microscopic hematuria while appropriately triaging patients based on risk factors for significant urologic or renal disease.