(264) How to Best Utilize a Urine Protein Creatinine Ratio to Rule Out Preeclampsia

24-hour urine protein (24UP) collection remains the gold standard for detecting proteinuria in the setting of preeclampsia. This method is time-consuming and error-prone, while urine protein creatinine ratio (UPCR) offers a faster, more convenient alternative. The objective of this study is to reevaluate the utility of UPCR in detecting significant proteinuria.

Study Design:

Inclusion criteria for this retrospective cross-sectional study included singleton pregnancies with a 24UP collection between 2019-2022 for baseline or diagnostic evaluation. Patients with chronic kidney disease or nephropathy were excluded. Data including 24UP, comorbidities, delivery information and demographics was collected. UPCR was stratified into low (< 0.15), intermediate (0.15-0.29) and elevated (≥ 0.30) categories. Significant proteinuria was defined as 24UP of ≥ 300 mg/day. Concordance of the UPCR calculated from the same sample of 24-hour urine collection was determined and assessed using the area under the curve (AUC) of the receiver operating characteristic (ROC) curve. Sensitivity, specificity, and positive and negative predictive values (PPV, NPV) of each of the three categories were calculated.

Results:

A total of 150 patients were included. The ROC revealed an AUC of 0.938. Using a UPCR cutoff of < 0.15 yielded sensitivity of 75% with a NPV of 96% for excluding significant proteinuria. Surprisingly, UPCR ≥ 0.30 had a sensitivity of only 50% though PPV was 97% for detecting significant proteinuria. For UPCR values between 0.15–0.29, 28 of 52 patients had significant proteinuria on 24UP yielding a NPV of 27.5% for ruling out significant proteinuria.

Conclusion:

Our study questions the clinical utility of the standard UPCR cutoff of ≥ 0.30. While this threshold has a high PPV, it misses approximately half of patients with significant proteinuria. Conversely, a UPCR cutoff of < 0.15 reliably ruled out proteinuria suggesting that patients with intermediate values (0.15-0.29) may benefit most from a 24UP collection. Further research should assess how demographics and comorbidities influence the accuracy of these tests.