Clinical features of isolated gestational proteinuria progressing to pre-eclampsia: retrospective observational study

Obstetrical outcomes of women with new-onset isolated proteinuria diagnosed after 24 weeks' gestation

PURPOSE

To assess a possible association between marked proteinuria and the risk of preeclampsia with severe features, as defined by the American College of Obstetricians and Gynecologists.

METHODS

This retrospective study included data recorded at a tertiary university-affiliated hospital between 2017 and 2022. Women at or beyond 24 weeks of gestation with proteinuria (protein levels > 300 mg in a 24 h urine collection) and normal blood pressure during the initial 48 h of admission were included. Obstetrical and neonatal outcomes were compared between women with mild proteinuria (300-1000 mg/24 h) and marked proteinuria (≥ 1000 mg/24 h).

RESULTS

Among the women with marked proteinuria (n = 48) compared to those with mild proteinuria (n = 108), the incidences were higher of preeclampsia (50.0% vs. 22.2%, p = 0.001) and of preeclampsia with severe features (18.8% vs. 2.8%, p < 0.001). In multivariate analysis that adjusted for maternal age, primiparity, multiple pregnancy, uric acid level > 6 mg/dL and aspirin treatment, marked proteinuria was a risk factor for preeclampsia with severe features (adjusted odds ratio [aOR] = 10.2, confidence interval [CI] 95% 1.9-54.0, p = 0.007) and for small-for-gestational-age infants (aOR = 2.4, 95% CI 1.02-5.6, p = 0.001). Among women with marked compared to mild proteinuria, rates were also higher of labor induction (58.3% vs. 25.9%, p < 0.001), indicated preterm delivery (41.7% vs. 25.0%, p = 0.04) and admission to the neonatal intensive care unit (44.1% vs. 25.8%, p = 0.017).

CONCLUSIONS

Women with marked compared to mild isolated proteinuria showed higher risk of developing preeclampsia with severe features and of delivering small-for-gestational-age neonates.

Preeclampsia: The Need for a Biological Definition and Diagnosis

The centuries-old approach to the prevention of eclampsia and its associated maternal morbidity and mortality is based on the recognition of the presence of premonitory signs and symptoms such as hypertension and proteinuria. The spectrum of preceding signs and symptoms came to be known as preeclampsia, which is debatably considered to be an early stage on a clinical continuum possibly leading to eclampsia. The premonitory signs and symptoms were then construed as diagnostic criteria for the poorly understood syndrome of preeclampsia, and this led to a perpetual debate that remains subject to wide disagreement and periodic updates. In this commentary, we will draw attention to the fact that the criteria for preeclampsia should be viewed from the prism of a screening test rather than as diagnostic of a condition in itself. Focusing research on developing better diagnostic and screening methods for what is clinically important, namely maternal and perinatal morbidity and mortality from hypertensive disorders of pregnancy, a long overdue upgrade from what was possible centuries ago, will ultimately lead to better management approaches to what really matters.

Progression from isolated gestational proteinuria to preeclampsia with severe features

INTRODUCTION

The association between the degree of isolated gestational proteinuria and preeclampsia with severe features and other placental-mediated complications is controversial. The aim of this study was to evaluate whether a higher isolated proteinuria level is associated with an increased frequency of preeclampsia with severe features.

MATERIAL AND METHODS

This retrospective cohort study included pregnant women who were past 24 weeks of gestation and were diagnosed as having new-onset proteinuria ≥300 mg in a 24-h urine collection. Exclusion criteria included diagnosis of preeclampsia within 72 h from admission, chronic renal disease or chronic hypertension. The study population was divided into tertiles by proteinuria level and the association with preeclampsia with severe features was assessed in both bivariable and multivariable analysis. The main outcome measures was the development of preeclampsia with severe features.

RESULTS

Overall, 165 women were diagnosed with isolated gestational proteinuria, and 38 (23.0%) of them developed preeclampsia with severe features. Women in the increasing proteinuria tertile were more likely to develop preeclampsia with severe features (5.5%, 21.8%, 41.8%, respectively; p = 0.004). A multivariable logistic regression model controlling for background characteristics as well as gestational age at diagnosis, blood pressure, and kidney and liver function tests showed an increased risk of 14% to develop preeclampsia with severe features for every 500-mg rise in proteinuria level (adjusted odds ratio = 1.14, 95% confidence interval 1.03-1.27).

CONCLUSIONS

A higher isolated gestational proteinuria level was associated with an increased risk to develop preeclampsia with severe features among pregnant women past 24 weeks of gestation.

Earlier onset of proteinuria or hypertension is a predictor of progression from gestational hypertension or gestational proteinuria to preeclampsia

Although gestational hypertension (GH) is a well-known disorder, gestational proteinuria (GP) has been far less emphasized. According to international criteria, hypertensive disorders of pregnancy include GH but not GP. Previous studies have not revealed the predictors of progression from GP to preeclampsia or those of progression from GH to preeclampsia. We aimed to determine both sets of predictors. A retrospective cohort study was conducted with singleton pregnant women who delivered at 22 gestational weeks or later. Preeclampsia was divided into three types: new onset of hypertension/proteinuria at 20 gestational weeks or later and additional new onset of other symptoms at < 7 days or at ≥ 7 days later. Of 94 women with preeclampsia, 20 exhibited proteinuria before preeclampsia, 14 experienced hypertension before preeclampsia, and 60 exhibited simultaneous new onset of both hypertension and proteinuria before preeclampsia; the outcomes of all types were similar. Of 34 women with presumptive GP, 58.8% developed preeclampsia; this proportion was significantly higher than that of 89 women with presumptive GH who developed preeclampsia (15.7%). According to multivariate logistic regression models, earlier onset of hypertension/proteinuria (before or at 34.7/33.9 gestational weeks) was a predicator for progression from presumptive GH/GP to preeclampsia (odds ratios: 1.21/1.21, P value: 0.0044/0.0477, respectively).

The Association Between GFR Evaluated by Serum Cystatin C and Proteinuria During Pregnancy

Introduction

Physiological changes in pregnancy result in increased cardiac output and renal blood flow, with a consequential increase in proteinuria. Data from studies of the relationship between proteinuria caused by isolated proteinuria and glomerular filtration rate (GFR) are still limited. The objective of this study was to investigate the effects of isolated proteinuria on the cystatin C–based GFR in the third trimester of pregnancy.

Methods

Data were collected from pregnant women in their third trimester whose serum creatinine levels were normal. The GFR of each participant was measured using serum cystatin C levels, and proteinuria was measured using urine protein–creatinine ratios. The participants were divided into 3 groups according to their level of proteinuria: normal (<150 mg/d), physiological (150–300 mg/d), and gestational (>300 mg/d). Changes in GFR were recorded for each group.

Results

The study included 89 participants, of whom 66.3% had levels of proteinuria that did not differ from that of the normal population (<150 mg/d). The incidence of physiological and gestational proteinuria was 21.4% and 12.4%, respectively. The results demonstrate that proteinuria >101.50 mg/d was significantly associated with declined estimated glomerular filtration rate (eGFR) (r = –0.34, P = 0.01). The analysis found that proteinuria >491.27 mg/d led to a risk of GFR <90 ml/min with an odds ratio of 12.69, P = 0.02 when adjusted for systolic blood pressure (SBP), diastolic blood pressure (DBP), and body mass index.

Conclusion

This study suggests that the term “physiological proteinuria” is a misnomer. When used in the traditional manner, creatinine level has inadequate sensitivity to estimate GFR in pregnant women. We found that there is a significant decline in GFR when urine protein > 101.5 mg/d, which could be an early biomarker for renal pathology rather than pregnancy physiology, suggesting that further workup and precaution is required.

Placental growth factor (alone or in combination with soluble fms-like tyrosine kinase 1) as an aid to the assessment of women with suspected pre-eclampsia: systematic review and economic analysis

BACKGROUND

Pre-eclampsia (PE) prediction based on blood pressure, presence of protein in the urine, symptoms and laboratory test abnormalities can result in false-positive diagnoses. This may lead to unnecessary antenatal admissions and preterm delivery. Blood tests that measure placental growth factor (PlGF) or the ratio of soluble fms-like tyrosine kinase 1 (sFlt-1) to PlGF could aid prediction of PE if either were added to routine clinical assessment or used as a replacement for proteinuria testing.

OBJECTIVES

To evaluate the diagnostic accuracy and cost-effectiveness of PlGF-based tests for patients referred to secondary care with suspected PE in weeks 20-37 of pregnancy.

DESIGN

Systematic reviews and an economic analysis.

DATA SOURCES

Bibliographic databases including MEDLINE, EMBASE, Web of Science and The Cochrane Library and Database of Abstracts of Reviews of Effects were searched up to July 2015 for English-language references. Conferences, websites, systematic reviews and confidential company submissions were also accessed.

REVIEW METHODS

Systematic reviews of test accuracy and economic studies were conducted to inform an economic analysis. Test accuracy studies were required to include women with suspected PE and report quantitatively the accuracy of PlGF-based tests; their risk of bias was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) criteria. The economic studies review had broad eligibility criteria to capture any types of economic analysis; critical appraisal employed standard checklists consistent with National Institute for Health and Care Excellence criteria. Study selection, critical appraisal and data extraction in both reviews were performed by two reviewers.

ECONOMIC ANALYSIS

An independent economic analysis was conducted based on a decision tree model, using the best evidence available. The model evaluates costs (2014, GBP) from a NHS and Personal Social Services perspective. Given the short analysis time horizon, no discounting was undertaken.

RESULTS

Four studies were included in the systematic review of test accuracy: two on Alere's Triage^® PlGF test (Alere, Inc., San Diego, CA, USA) for predicting PE requiring delivery within a specified time and two on Roche Diagnostics' Elecsys^® sFlt-1 to PlGF ratio test (Roche Diagnostics GmbH, Mannheim, Germany) for predicting PE within a specified time. Three studies were included in the systematic review of economic studies, and two confidential company economic analyses were assessed separately. Study heterogeneity precluded meta-analyses of test accuracy or cost-analysis outcomes, so narrative syntheses were conducted to inform the independent economic model. The model predicts that, when supplementing routine clinical assessment for rule-out and rule-in of PE, the two tests would be cost-saving in weeks 20-35 of gestation, and marginally cost-saving in weeks 35-37, but with minuscule impact on quality of life. Length of neonatal intensive care unit stay was the most influential parameter in sensitivity analyses. All other sensitivity analyses had negligible effects on results.

LIMITATIONS

No head-to-head comparisons of the tests were identified. No studies investigated accuracy of PlGF-based tests when used as a replacement for proteinuria testing. Test accuracy studies were found to be at high risk of clinical review bias.

CONCLUSIONS

The Triage and Elecsys tests would save money if added to routine clinical assessment for PE. The magnitude of savings is uncertain, but the tests remain cost-saving under worst-case assumptions. Further research is required to clarify how the test results would be interpreted and applied in clinical practice.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42015017670.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Urine albumin is a superior predictor of preeclampsia compared to urine plasminogen in type I diabetes patients

Pregnant women with type I diabetes mellitus (T1DM) are at increased risk of developing preeclampsia (PE). Plasminogen is aberrantly filtrated from plasma into tubular fluid in PE patients and activated to plasmin. Plasmin activates the epithelial sodium channel in the collecting ducts potentially causing impaired sodium excretion, suppression of the renin-angiotensin-aldosterone system, and hypertension in PE. The objective of the study was to test whether urinary total plasmin(ogen)/creatinine ratio and plasma concentration of aldosterone were better predictors of PE in pregnant women with T1DM compared with urine albumin and haemoglobin A_1C. The design was a longitudinal observational study of 88 pregnant T1DM patients at 2 Danish centers. Spot urine- and blood samples were collected at gestational weeks 12, 20, 28, 32, and 36. U-plasmin(ogen)/creatinine ratio increased during pregnancy. In gestational week 36, the ratio was significantly increased in the T1DM patients developing PE (P < .05). P-aldosterone was significantly increased in gestational week 20 in the group developing PE (P < .05). U-albumin/creatinine ratio was significantly increased and predicted PE at all tested gestational ages. U-albumin/creatinine ratio had a stronger association with the development of PE compared to u-total plasmin(ogen)/creatinine ratio and p-aldosterone. The positive association between u-total plasmin(ogen) and development of PE late in pregnancy is compatible with involvement in PE pathophysiology. The significance of albumin in urine emphasizes the importance of preventing renal complications when planning pregnancy in patients with type I diabetes.

Second-trimester urine nephrin:creatinine ratio versus soluble fms-like tyrosine kinase-1:placental growth factor ratio for prediction of preeclampsia among asymptomatic women

This prospective observational study compare urine nephrin:creatinine ratio (NCR, ng/mg) with serum soluble fms-like tyrosine kinase-1:placental growth factor ratio (FPR, pg/pg) for preeclampsia (PE) prediction among unselected asymptomatic pregnant women in 2^nd trimester. NCR and FPR were determined in 254 paired urine/blood samples collected simultaneously from 254 women at median gestational week (GW) 24 (range, 22–27) without hypertension or significant proteinuria in pregnancy (SPIP). Fifteen (5.9%) developed SPIP and hypertension at GW 34.0 (26.0–38.6) and 35.3 (27.6–38.6), respectively, and were diagnosed with PE at GW 35.7 (27.6–38.6). The 90^th percentile level determined in 239 women normotensive throughout pregnancy gave NCR (139) sensitivity and positive predictive values (PPV) of 60% (9/15) and 27% (9/33), while those for serum FPR (4.85) were 40% (6/15) and 20% (6/30), respectively. Relative risks (95%CI) of later PE were 10.0 (3.82–26.4; 27% [9/33] vs. 2.7% [6/221]) and 4.98 (1.91–13.0; 20% [6/30] vs. 4.0% [9/224]) for NCR-positive and FPR-positive women, respectively. Cut-offs suggested by ROC gave NCR (86.6) sensitivity and PPV of 87% (13/15) and 17% (13/79), and FPR (8.8) values of 40% (6/15) and 40% (6/15), respectively. Thus, 2^nd trimester NCR was superior to FPR for PE prediction.

Feasibility of nephrinuria as a screening tool for the risk of pre-eclampsia: prospective observational study

OBJECTIVES

To investigate the possibility of nephrinuria as a screening tool for the risk of pre-eclampsia (PE).

DESIGN

Prospective observational study.

SETTING

A single university hospital. Changes in urinary nephrin:creatinine ratio (NCR, ng/mg) and protein:creatinine ratio (PCR, mg/mg) in pregnancy were determined. Significant proteinuria in pregnancy (SPIP) was defined as PCR>0.27. PE was diagnosed in women with both SPIP and hypertension.

PARTICIPANTS

89 pregnant women in whom neither hypertension nor SPIP was present at enrolment, providing 31, 125 and 93 random urine samples during first, second and third trimesters, respectively.

RESULTS

PE developed in 14 of the 89 women. NCR increased with increasing PCR in 14 women with PE (correlation coefficient, 0.862; p<0.0001). In contrast, NCR did not change significantly despite significant increases in PCR in 75 women with normotensive pregnancies defined as neither SPIP nor hypertension, indicating that there was little increase in nephrinuria over the physiological range of proteinuria in pregnancy. Relative risk of later development of PE among asymptomatic second and third trimester women with NCR (ng/mg) >122 (95th centile value for 75 women with normotensive pregnancies) was 5.93 (95% CI 2.59 to 13.6; 60% (6/10) vs 10% (8/79)) and 13.5 (95% CI 3.31 to 55.0; 75% (6/8) vs 5.5% (2/36)), respectively, compared with women with NCR≤122 at that time.

CONCLUSIONS

Nephrinuria was unlikely to increase in normal pregnancy. A certain NCR cut-off may efficiently differentiate women at higher risk of PE.

Alteration of podocyte phenotype in the urine of women with preeclampsia

Podocyte injury has been suggested to induce phenotypic alteration of glomerular podocytes and accelerate the detachment of podocytes from the glomeruli resulting in podocyturia. However, it is not clear whether podocyte phenotypic alteration occurs in the urine of women with preeclampsia (PE). Seventy-seven and 116 pelleted urine samples from 38 and 18 women at various stages of normal and PE pregnancies, respectively underwent quantitative analysis of podocyte-specific or associated protein mRNA expression, including podocin, nephrin, and synaptopodin using RT-PCR. Significant proteinuria in pregnancy (SPIP) is defined as protein:creatinine ratio (P/Cr, mg/mg) ≥0.27 in the urine supernatant. All three urine-pellet mRNAs expression levels were significantly positively correlated with P/Cr levels, suggesting that podocyturia increased with proteinuria. The podocin:nephrin mRNA ratio (PNR) and synaptopodin:nephrin mRNA ratio (SNR) increased significantly with increasing P/Cr, while the podocin:synaptopodin mRNA ratio (PSR) did not change significantly according to P/Cr, resulting in significantly higher PNR and SNR, but not PSR levels, in urine from PE women with than without SPIP. The PNR, SNR, and PSR in urine from PE women before onset of SPIP were comparable to those from controls. Thus, nephrin mRNA expression was reduced in the podocytes recovered from PE women.

Isolated proteinuria is a risk factor for pre-eclampsia: a retrospective analysis of the maternal and neonatal outcomes in women presenting with isolated gestational proteinuria

OBJECTIVE

To examine maternal and neonatal outcomes of isolated proteinuria and define maternal characteristics for progression to pre-eclampsia.

STUDY DESIGN

Retrospective cohort study. Data from all hospitalized pregnant women between 2009 and 2014 with new onset isolated proteinuria of over 300 mg/24 h at admission were obtained. Follow-up was performed from the time of admission to the hospital to the time of discharge postpartum. Obstetrical, maternal and neonatal outcomes were obtained.

RESULT

Ninety-five pregnant women diagnosed with new onset isolated proteinuria were followed to term. Thirteen women developed pre-eclampsia during pregnancy and eight developed pre-eclampsia postpartum. Maternal characteristics for progression to pre-eclampsia were greater maximal values of proteinuria. Earlier pre-eclampsia onset was associated with early-onset proteinuria and multiple gestation. Although greater values of proteinuria were associated with increased risk for intrauterine growth restriction and lower Apgar scores, maternal outcome was favorable, regardless of pre-eclampsia progression. Isolated proteinuria progressing to pre-eclampsia was associated with late pre-eclampsia onset and favorable maternal and neonatal outcomes.

CONCLUSION

A significant proportion of women with new onset isolated proteinuria will develop pre-eclampsia. In these women, close follow-up is recommended until after delivery.

The outcome of pregnancy with new onset proteinuria without hypertension: retrospective observational study

OBJECTIVE

The aim of this study was to evaluate preeclampsia progression of isolated proteinuria and associations with pregnancy outcome.

METHOD

We performed a retrospective analysis in patients who were hospitalized for evaluation of new onset proteinuria without hypertension after 20 weeks of gestation between January 2012 and January 2014. One hundred fifty-seven patients who met the inclusion criteria were enrolled the study.

RESULTS

After detection of new onset proteinuria, 53 of 157 (33.7%) patients developed preeclampsia and the incidence of gestational proteinuria was found to be 0.33%. Twenty-four hours urine proteinuria testing results were significantly higher in preeclampsia (PE) group compared with the gestational proteinuria (GP) group (p < 0.01). Patients who developed preeclampsia delivered significantly earlier than the GP group (p < 0.01). The weights of the infants born to mothers in the PE group were significantly lower than the other group (p < 0.01).

CONCLUSION

The incidence of gestational proteinuria was lower than the previous studies. Preeclampsia developed in 33% of patients with new onset proteinuria in pregnancy. In patients who developed PE had significantly higher proteinuria, lower delivery time and birth weight in their infants. Therefore, patients with new onset proteinuria should be followed-up for preeclampsia development and associated morbidities.

Pregnancy outcome in proteinuria-onset and hypertension-onset preeclampsia

OBJECTIVE

To evaluate pregnancy outcome in preeclampsia (PE), according to the timing of onset of proteinuria and hypertension.

METHODS

Preeclamptic women were retrospectively divided into proteinuria-onset and hypertension-onset PE according to the first symptom. Maternal and perinatal outcome were assessed in both the groups.

RESULTS

One hundred and ninety five single pregnancies complicated by PE were included. According to the first symptom, they were divided into two groups: proteinuria-onset PE (n = 49, 25.1%) and hypertension-onset PE (n = 146, 74.9%). Pregnancy and neonatal outcome was significantly worse in proteinuria-onset PE.

CONCLUSION

Proteinuria-onset PE is associated with an increased risk of adverse pregnancy outcome than hypertension-onset PE.