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Diagnostic impact of dysmorphic red blood cells on evaluating microscopic hematuria: the urologist's perspective
Kyo Chul Koo1, Kwang Suk Lee1, Ah Ran Choi2
1Department of Urology, Yonsei University College of Medicine, 211 Eonju-ro, Gangnam-gu, Seoul, 135-720, Republic of Korea.
Insights
Dysmorphic red blood cells (dRBCs) indicate glomerular disease, but urological evaluation is crucial for microscopic hematuria (MH). Omitting urological assessment risks missing significant conditions, including malignancies.
Area of Science:
- Nephrology
- Urology
- Internal Medicine
Background:
- Dysmorphic red blood cells (dRBCs) are key indicators of glomerular disease in microscopic hematuria (MH) evaluation.
- Current guidelines vary on whether to pursue urological evaluation alongside nephrological assessment for MH.
Purpose of the Study:
- To assess the feasibility and safety of omitting urological evaluation in patients presenting with microscopic hematuria.
- To determine the diagnostic value of dRBCs in differentiating glomerular from urological causes of MH.
Main Methods:
- Retrospective analysis of 411 patients with MH (≥3 RBCs/high-power field) between 2012-2014.
- All patients underwent comprehensive urological and nephrological evaluations, including imaging and biopsy when indicated.
Main Results:
- A higher median %dRBC was observed in glomerular disease (40.4%) compared to urological disease (21.1%).
- Among patients with ≥40% dRBCs, 34% had urological conditions, including malignancies and those requiring immediate treatment.
- Proteinuria was a stronger predictor of glomerular disease than %dRBC ≥40%.
Conclusions:
- While %dRBC ≥40% has modest value for glomerular disease, proteinuria is more indicative of a glomerular origin.
- Urological evaluation is essential in patients with MH due to the significant prevalence of treatable urological conditions.
Purpose:
Dysmorphic red blood cells (dRBCs) are indicative of glomerular disease and considered a first step in evaluating microscopic hematuria (MH). The predominance of dRBCs does not preclude urological disease; however, some contemporary guidelines advise nephrological evaluation without further urological evaluation, in contrast to the American Urological Association guideline. We investigated the feasibility and safety of omitting urological evaluation in patients presenting with MH.
Methods:
A retrospective analysis was performed on 411 consecutive patients who presented with MH between January 2012 and December 2014. MH was defined as ≥3 RBCs per high-power field. All patients received full urological and nephrological evaluations including history and physical assessment, renal function, urine cytology, %dRBC, cystoscopy, computed tomography (CT) imaging, and renal biopsy when indicated.
Results:
The median %dRBC was higher in patients with glomerular disease than in those with urological disease (40.4 vs. 21.1 %; p < 0.001). Among patients exhibiting %dRBC ≥ 40, 33/97 (34.0 %) had urological and 28/97 (28.9 %) had glomerular diseases. Urological diseases included 9/33 (27.3 %) clinically meaningful malignancies and 17/33 (51.5 %) conditions requiring immediate treatment. The rate of malignancy was comparable between %dRBC groups (p = 0.087). Among patients with final diagnoses who exhibited %dRBC ≥ 40, 32/61 (52.5 %) treatment-requiring conditions would have been unrecognized had cystoscopy and/or CT not been performed. For predicting glomerular disease, the presence of proteinuria demonstrated higher AUC than %dRBC ≥ 40 (0.77 vs. 0.65; p < 0.001).
Conclusions:
Identification of %dRBC ≥ 40 had modest diagnostic value in identifying glomerular disease, and concomitant presence of proteinuria was more indicative of glomerular origin in patients presenting with MH. Urological evaluation should not be omitted in these patients considering the prevalence of treatment-requiring urological disease.
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