Diagnostic Utility of Dysmorphic Erythrocyte Identification Using the Atellica 1500 Automated Urinalysis System in the Evaluation of Glomerular Hematuria

Context.—: Dysmorphic red blood cells (dRBCs) in urine are useful noninvasive markers for distinguishing glomerular hematuria. Objective.—: To assess the diagnostic utility of dRBC identification, using image data from the Atellica 1500 Automated Urinalysis System (Siemens Healthineers). Design.—: We retrospectively evaluated 162 patients from Severance Hospital (n = 46; August 2019-February 2024) and Yongin Severance Hospital (n = 116; between March 2020 and February 2024) who underwent renal, urinary, and/or urogenital biopsies during periods when the same Atellica 1500 Automated Urinalysis System was in use. dRBCs were evaluated by trained medical technologists following recent literature criteria. Inclusion requires hematuria (≥2+ on dipstick) and dRBC testing within 3 months before biopsy. From biopsy, imaging, and clinical findings, patients were classified as having glomerular hematuria (n = 90) or nonglomerular diseases (n = 72). Results.—: The area under the receiver operating characteristic curve (AUROC) for %dRBC in diagnosing glomerular disease was 0.766. At cutoffs of 17% and 28% dRBCs, sensitivity was 32.2% and 21.1% with specificity of 95.8% and 97.2%, respectively. %G1-dRBC yielded an AUROC of 0.636, with sensitivities of 31.1% and 26.7% at 1% and 2% cutoffs, respectively, for corresponding specificities. In immunoglobulin A nephropathy (n = 67), %G1-dRBC was higher in cases with segmental glomerulosclerosis (n = 53). Multivariate analysis identified that younger age, higher %dRBC, lower dipstick blood/leukocyte esterase, and higher dipstick protein grades were independent predictors of glomerular diseases. Conclusions.—: dRBC identification using digital urine sediment analyzer provides high specificity and positive predictive value for glomerular hematuria, with advantages in efficiency, reproducibility, and image archiving.