Urine Protein/Creatinine Ratios during Labor: A Prospective Observational Study - PubMed (original) (raw)

Urine Protein/Creatinine Ratios during Labor: A Prospective Observational Study

Vaya W Tanamai et al. PLoS One. 2016.

Abstract

Purpose: To evaluate the utility of urine protein/creatinine ratio (uPCR) measurements among healthy parturients at term we performed a prospective cohort study at a community teaching hospital.

Methods: Serial urine samples were collected. Ninety-three women contributed 284 urine samples. uPCRs were determined. Multiple imputation and paired sampled analysis was performed when appropriate.

Results: Two-thirds (63/93) of women had at least one measured uPCR ≥ 0.3. One-third (31/93) had a uPCR ≥ 0.3 at admission, including 39.1% (9/23) of women not in labor. Median (IQR) uPCRs increased during labor and after delivery: latent phase/no labor, 0.15 (0.06-0.32); active phase, 0.29 (0.10-0.58); early postpartum, 0.45 (0.18-1.36) (all p < 0.04). Median uPCRs were significantly < 0.3 in the latent phase and significantly > 0.3 in the immediate postpartum period (p < 0.01). Women who labored before cesarean delivery had the highest early postpartum uPCRs: median (IQR) 1.16 (0.39-1.80). A negative urine dipstick protein result did not exclude uPCR ≥ 0.3. uPCRs were similar when compared by method of urine collection.

Conclusion: uPCR ≥ 0.3 is common among healthy women with uncomplicated pregnancies at term. uPCR increases during labor and is not a reliable measure of pathologic proteinuria at term or during the peripartum period.

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Conflict of interest statement

Competing Interests: The authors have declated that no competing interests exist.

Figures

Fig 1

Fig 1. Urine protein/creatinine ratio (uPCR) by urine creatinine and protein concentrations.

uPCR measurements plotted by urine random creatinine (top) and protein (bottom) concentrations and colored by phase of labor and delivery admission. Horizontal line on each graph represents uPCR = 0.3.

Fig 2

Fig 2. Urine protein/creatinine ratio (uPCR) measurements in all 284 urine samples from 93 women plotted against the timing of the sample collection relative to delivery time.

The phase of labor at the time of sample collection is shown for each individual sample by one of four different colors. The horizontal line represents the threshold uPCR value of 0.3.

Fig 3

Fig 3. Box plots of urine protein/creatinine ratio (uPCR) measurements by phase of labor at the time of collection and subsequent delivery outcome.

uPCR measurements from samples collected before and after delivery among women who had a scheduled cesarean delivery without labor (top left), all laboring women (top right), laboring women who delivered vaginally (bottom left), and laboring women who subsequently delivered by cesarean (bottom right) are shown. The horizontal line on each graph represents the threshold uPCR value of 0.3. When the distribution of observed uPCR values is significantly different than the threshold value of 0.3, the p-value (Mann-Whitney u test) is shown.

Fig 4

Fig 4. Box plots of urine protein/creatinine ratio (uPCR) measurements by urine protein dipstick result.

The horizontal line on each graph represents the threshold uPCR value of 0.3. When the distribution of observed uPCR values is significantly different than the threshold value of 0.3, the p-value (Mann-Whitney u test) is shown. Three uPCR outlier values (4.9, 6.1, and 8.9 in the Negative, 1+, and 2+ groups, respectively) are not shown.

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Funded by the Danbury Hospital Development Fund. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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