From the Guidelines
The workup for microscopic hematuria should begin with a thorough history and physical examination, followed by laboratory tests and imaging studies, with a definition of microscopic hematuria as 3 or more red blood cells per high-power field on urinalysis, as recommended by the American Urological Association 1. The initial evaluation should include a complete urinalysis to assess for proteinuria, dysmorphic RBCs, or casts; a urine culture to rule out infection; and measurement of serum creatinine to evaluate kidney function. Some key points to consider in the workup of microscopic hematuria include:
- The patient's risk factors for urologic malignancy, such as age >35, smoking history, chemical exposures, prior pelvic radiation, chronic urinary tract infections, or family history of urologic cancers, which may necessitate cystoscopy and upper tract imaging 1.
- The use of upper tract imaging, typically consisting of a CT urogram, to provide detailed images of the kidneys, ureters, and bladder, with alternative options such as renal ultrasound with retrograde pyelography for patients with contraindications to CT 1.
- The consideration of nephrology consultation for possible kidney biopsy if the initial evaluation suggests glomerular disease, characterized by the presence of proteinuria, dysmorphic RBCs, or RBC casts 1.
- The importance of repeat urinalysis in 6-12 months for patients with persistent microscopic hematuria but negative initial workup, to ensure that any underlying conditions are not missed 1. It is essential to note that microscopic hematuria can be a sign of serious conditions, including urologic malignancies, kidney stones, or glomerular diseases, although benign causes like vigorous exercise or certain medications may also be responsible 1.
From the Research
Work-up for Microscopic Hematuria
The work-up for microscopic hematuria involves a thorough history and physical examination to determine potential causes and assess risk factors for malignancy 2.
- Laboratory tests to rule out intrinsic renal disease
- Imaging of the urinary tract
- Referral to nephrology and urology subspecialists if no benign cause is found 2
Imaging Tests
Imaging tests for hematuria include:
- Low-dose CT for detection of urinary tract calculi 3
- MDCT urography, which is preferred over excretory urography in most cases 3
- Ultrasound, although it is often insufficient for imaging of hematuria and may not be able to differentiate renal transitional cell carcinoma from other causes of filling defects 3
Referral to Specialists
Patients with microscopic hematuria should be referred to a urology subspecialist for:
- Abnormal genitourinary anatomy
- Trauma
- Stones
- Tumors
- Nonglomerular gross hematuria
- Persistent microscopic hematuria 4 Patients with proteinuria or hematuria should be referred to a nephrology subspecialist if:
- Proteinuria is drug-resistant
- There is persistent hematuria with concomitant proteinuria
- A renal biopsy is being considered 4
Diagnostic Evaluation
The diagnostic evaluation for hematuria should take into account:
- Age of the patient
- Medical history
- Family history
- Concurrent symptoms
- Initial physical examination findings
- Basic office laboratory test results 4