Urinary Podocyte Enumeration: A Noninvasive Assay for Early Prediction of Preeclampsia [ID 3697]

INTRODUCTION: Podocyte loss reflects glomerular injury, an early and specific pathogenic event in preeclampsia. Urinary podocyte assays remain clinically unavailable due to their rarity and detection challenges. We evaluate a novel assay that isolates urinary podocytes for early preeclampsia prediction. METHODS: We conducted a two-phase study: Phase 1: case–control study of 42 third-trimester patients (21 preeclampsia, 21 controls); Phase 2: prospective study of 36 patients with 40 samples (7–38 weeks of gestation). Urine samples were refrigerated and processed within 72 hours. Podocytes were isolated and quantified using a proprietary rare-cell capture platform incorporating high-speed immunomagnetic microfluidic separation and immunofluorescence. RESULTS: Podocyte counts were significantly higher in preeclampsia versus controls (9.5±6.6 versus 1.8±1.5 podocytes/10 mL urine; P <.001). In Phase 2, the assay achieved an area under the curve of 0.98, identifying all five patients who later developed preeclampsia (lead time prior to diagnosis: 14–27 weeks), including one at 11 2/7 weeks. At a predefined cutoff of 3 podocytes/10 mL urine, sensitivity was 100% (6/6; 95% CI, 61.0–100%), and specificity 94.1% (32/34; 95% CI, 80.9–98.4%). Of five positives collected at 14 weeks or earlier, three had follow-up samples: the true positive increased further; two initial false positives declined below the cutoff. The assay showed 100% sensitivity in patients with (n=13, 3/3) and without (n=27, 3/3) risk factors (pregestational diabetes, hypertension, history of preeclampsia), with specificity of 90.0% (9/10) and 95.8% (23/24). CONCLUSIONS/IMPLICATIONS: The urine-based podocyte assay is a promising noninvasive tool for early preeclampsia detection with high predictive accuracy. Larger prospective studies are underway to validate performance across a clinically heterogeneous pregnant population.