From the Guidelines
The next step in evaluating this 38-year-old man with microscopic hematuria and >80% dysmorphic RBCs should be a nephrology referral and further workup for glomerular disease. The presence of dysmorphic RBCs at this high percentage strongly suggests a glomerular source of bleeding rather than a urologic cause, as indicated by the American Urological Association's best practice policy recommendations 1.
Key Considerations
- The evaluation should include a comprehensive panel of serologic tests, such as serum creatinine, blood urea nitrogen, complete blood count, urinalysis with protein quantification, complement levels, antinuclear antibody, anti-neutrophil cytoplasmic antibodies, anti-glomerular basement membrane antibodies, hepatitis serologies, and HIV testing.
- A renal ultrasound should be performed to assess kidney size and structure, as recommended by the American College of Radiology 1.
- The patient will likely need a kidney biopsy to determine the specific glomerular pathology causing the hematuria, given the high percentage of dysmorphic RBCs.
- While awaiting nephrology consultation, blood pressure should be monitored and controlled if elevated, as hypertension commonly accompanies glomerular disease.
Rationale
The approach is warranted because dysmorphic RBCs indicate damage to the glomerular filtration barrier, and early diagnosis and treatment of glomerulonephritis can prevent progression to chronic kidney disease. The American Urological Association's guidelines support this approach, emphasizing the importance of evaluating for glomerular disease in patients with microscopic hematuria and dysmorphic RBCs 1.
Additional Recommendations
- Consideration should be given to repeating urinalysis, voided urine cytology, and blood pressure determination at regular intervals, as recommended by the American Urological Association 1.
- Immediate urologic reevaluation, with consideration of cystoscopy, cytology, or repeat imaging, should be performed if any concerning symptoms or abnormal test results occur.
From the Research
Evaluation of Microscopic Hematuria
The presence of microscopic hematuria, defined as three or more red blood cells per high-power field in a properly collected urine specimen, requires further evaluation to determine the underlying cause. In the case of a 38-year-old man with microscopic hematuria and greater than 80% dysmorphic Red Blood Cells (RBCs), the next step in evaluation is crucial for identifying potential urological or nephrological conditions.
Considerations for Evaluation
- The American Urological Association guideline suggests that the presence of dysmorphic red blood cells, among other factors, should prompt concurrent nephrologic and urologic referral 2.
- However, the presence of dysmorphic RBCs does not preclude urological disease, and some studies suggest that urological evaluation should not be omitted in patients with microscopic hematuria, even with a high percentage of dysmorphic RBCs 3.
- The evaluation of microscopic hematuria may involve various diagnostic tests, including urinalysis, urine cytology, imaging studies such as computed tomography (CT) urography, and cystoscopy.
Diagnostic Tests
- CT urography is considered a comprehensive imaging modality for evaluating the upper and lower urinary tract, allowing for the detection of hydronephrosis, urinary calculi, and renal and ureteral lesions 4.
- Cystoscopy is essential for evaluating the lower urinary tract, including the bladder and urethra, and can help identify conditions such as urethral stricture disease, benign prostatic hyperplasia, and bladder masses 2.
- Urine cytology may be considered in patients with risk factors for malignancy, but it is no longer recommended as part of the routine evaluation of asymptomatic microscopic hematuria 2.
Next Steps
Given the presence of greater than 80% dysmorphic RBCs in the patient's urinalysis, the next step in evaluation could involve:
- Repeat microscopic urinalysis to confirm the presence of hematuria and assess for any changes in the urine sediment.
- Consideration of CT urography to evaluate the upper and lower urinary tract for potential causes of hematuria.
- Potential referral to a nephrologist and/or urologist for further evaluation and management, depending on the results of the diagnostic tests.
Potential Diagnoses
- Urological conditions such as urinary tract infection, benign prostatic hyperplasia, or urinary calculi.
- Nephrological conditions such as glomerular disease or renal parenchymal abnormalities.
- Malignancies of the urinary tract, although less likely in a 38-year-old man without other risk factors.