Association between Serum Uric Acid Levels and Perinatal Outcome in Women with Preeclampsia

Endostatin and Cystatin C as Potential Biomarkers for Early Prediction of Preeclampsia

Preeclampsia (PE) is characterized by new onset hypertension and proteinuria. Undoubtedly, some individuals do not fit precisely into this description, and it could be challenging to spot newly developed PE in females who already have hypertension or renal illness. Monitoring the disease's progression enables the optimization of delivery time while minimizing premature births. The current study explores the diagnostic benefits of serum endostatin and cystatin C in addition to serum and urinary magnesium (Mg) and fractional excretion magnesium (FEMg) for early prediction of PE. The population sample included 82 pregnant women divided into 3 groups: normal pregnancy group served as a control (n = 26), nonpreeclampsia (NPE, n = 34) group included pregnant women with one or more risk factors but did not progress to PE, and pregnant women who developed preeclampsia (PE, n = 22) group. Blood samples were withdrawn at two sampling times: at 12th to 16th and 24th to 26th weeks of gestation. Compared to normal pregnancy, results (X̅ ± SD) indicated a significant increase in serum endostatin in NPE at the first sample (10.78 ± 3.63 ng/mL) and the second sample (28.03 ± 3.79 ng/mL), while cystatin C was at the first sample (0.68 ± 0.06 mg/dL) and the second sample (0.71 ± 0.07 mg/dL). In the PE group, the serum endostatin was 18.86 ± 4.37 ng/mL at the first sampling time and 53.56 ± 9.76 ng/mL for the second sample. Serum cystatin C was also elevated in PE with X̅ ± SD equivalent to 0.73 ± 0.08 and 0.89 ± 0.08 mg/dL at the first and second samples, respectively. On the other hand, serum and urinary Mg in addition to FEMg levels did not significantly differ across the groups under study. Receiver operating characteristic (ROC) curve analysis proved that both endostatin and cystatin C could be good indicators for PE. The findings imply that measuring endostatin and cystatin C at early pregnancy and before progression to PE may be effective in detecting the likelihood of PE. Endostatin could be more precise and sensitive in assessing the probability of PE than cystatin C; however, coupling of the two parameters may be promising.

Association of first trimester serum uric acid with preeclampsia: an observational cohort study with propensity score matching

To elucidate whether uric acid changes in early pregnancy are associated with the development of preeclampsia and their association with preeclampsia-related adverse pregnancy outcomes. We conducted a retrospective cohort study of 4725 singleton pregnant women between January 2017 and July 2019 using propensity score matching. The primary outcome of the cohort was preeclampsia, and the secondary outcomes were preterm delivery, preterm preeclampsia and low birth weight infants. Multivariable predicted marginal proportions from logistic regression models were used to compute adjusted risk ratios. The quantitative-effect relationship between serum uric acid and preeclampsia development was observed by a dose‒response graph, and the effect of serum uric acid on the week of gestation at delivery was assessed using the Kaplan‒Meier method and the log-rank test. The risk of preeclampsia development increased with higher serum uric acid levels. After adjusting for confounders, the risk ratio for the development of preeclampsia with uric acid levels ≥240 µmol/l was 1.25 (95% CI: 0.96-1.65) compared with the group with uric acid levels <240 µmol/l. In the subgroup analysis of KM (Kaplan-Meier) curves, the gestational week at delivery was earlier when uric acid levels ≥240 µmol/l occurred at 8-12 weeks of gestation. Elevated serum uric acid levels before 20 weeks of gestation are associated with the development of preeclampsia, especially in the first 8-12 weeks of gestation, and the effect is attenuated with increasing gestational weeks, which suggests that elevated uric acid levels in early pregnancy may be a causative factor in preeclampsia. Elevated serum uric acid levels before 20 weeks of gestation are associated with the development of preeclampsia, especially in the early 8-12 weeks of gestation, and the effect attenuates with increasing gestational weeks, which suggest that elevated uric acid in early pregnancy may be a causative factor in preeclampsia.

Relationship between maternal serum uric acid level and preeclampsia with or without severe features

Hyperuricaemia is common in preeclampsia. Its relationship and the utility in predicting of preeclampsia must be evaluated. The objective was to determine the association between maternal serum uric acid level and preeclampsia with or without severe features, including maternal and neonatal outcomes. A retrospective study was conducted at Rajavithi Hospital between June 2015 and May 2019. Inferential analysis comparison using binary logistic regression analysis and correlation using Chi-Square test/Fisher's exact test were used for analysis. Among the 400 participants, 331 (82.7%) women were preeclampsia with severe features. The mean uric acid level was significantly higher in women with preeclampsia with severe features compared to those without (6.44 ± 1.44 vs 5.87 ± 1.53 mg/dL, p-value = .016). Uric acid greater than 7 mg/dL was associated with renal involvement and preeclampsia with severe features. Uric acid 5-7 and greater than 7 mg/dL correlated with preterm birth (OR 2.67, 95% CI 1.59-4.49 and OR 4.89, 95% CI 2.75-8.68, respectively). Uric acid greater than 7 mg/dL also increased the risk of RDS and NICU admission. In conclusion, a high uric acid level is associated with preeclampsia with severe features and adverse pregnancy outcomes and may be the predictor of the severity of preeclampsia.Impact statementWhat is already known on this subject? Hyperuricaemia is a common finding in preeclamptic pregnancy due to reduction of uric acid clearance secondary to reduced glomerular filtration rate, increased reabsorption, and decreased secretion. The correlation of increase maternal uric acid level and preeclampsia including adverse pregnancy outcomes has been evaluated and supported the use of uric acid as a predictor for preeclampsia development. However, its clinical utility is still debateable.What the results of this study add? The present study demonstrated the association between higher maternal serum uric acid level and severity of preeclampsia. Particularly, serum uric acid greater than 7 mg/dL was associated with preeclampsia with severe features. Additionally, serum uric acid level 5-7 mg/dL and greater than 7 mg/dL had a positive correlation with adverse maternal and neonatal outcomes.What the implications are of these findings for clinical practice and/or further research? Maternal serum uric acid may be used as the predictor of severity of preeclampsia. However, the sensitivity and specificity and the precise clinical utility of uric acid related to preeclampsia need to be further evaluated in larger sample size.

The diagnostic potential of oxidative stress biomarkers for preeclampsia: systematic review and meta-analysis

Background

Preeclampsia is a multifactorial cardiovascular disorder of pregnancy. If left untreated, it can lead to severe maternal and fetal outcomes. Hence, timely diagnosis and management of preeclampsia are extremely important. Biomarkers of oxidative stress are associated with the pathogenesis of preeclampsia and therefore could be indicative of evolving preeclampsia and utilized for timely diagnosis. In this study, we conducted a systematic review and meta-analysis to determine the most reliable oxidative stress biomarkers in preeclampsia, based on their diagnostic sensitivities and specificities as well as their positive and negative predictive values.

Methods

A systematic search using PubMed, ScienceDirect, ResearchGate, and PLOS databases (1900 to March 2021) identified nine relevant studies including a total of 343 women with preeclampsia and 354 normotensive controls.

Results

Ischemia-modified albumin (IMA), uric acid (UA), and malondialdehyde (MDA) were associated with 3.38 (95% CI 2.23, 4.53), 3.05 (95% CI 2.39, 3.71), and 2.37 (95% CI 1.03, 3.70) odds ratios for preeclampsia diagnosis, respectively. The IMA showed the most promising diagnostic potential with the positive predictive ratio (PPV) of 0.852 (95% CI 0.728, 0.929) and negative predictive ratio (NPV) of 0.811 (95% CI 0.683, 0.890) for preeclampsia. Minor between-study heterogeneity was reported for these biomarkers (Higgins’ I² = 0–15.879%).

Conclusions

This systematic review and meta-analysis identified IMA, UA, and MDA as the most promising oxidative stress biomarkers associated with established preeclampsia. IMA as a biomarker of tissue damage exhibited the best diagnostic test accuracy. Thus, these oxidative stress biomarkers should be further explored in larger cohorts for preeclampsia diagnosis.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13293-022-00436-0.

Biomarkers of oxidative stress are related to the pathogenesis of preeclampsia and might be indicative of evolving preeclampsia and utilized for timely diagnosis and management of preeclampsia.

Systematic review and meta-analysis were conducted to evaluate the diagnostic accuracy of oxidative stress markers based on their diagnostic sensitivities and specificities.

Clinically relevant positive predictive values (PPVs) and negative predictive values (NPVs) were determined for each biomarker.

IMA, UA, and MDA were associated with 3.38, 3.05, and 2.37 odds ratios for preeclampsia onset.

IMA exhibited the most promising diagnostic potential with an average PPV of 0.852 and NPV of 0.811, respectively. Minor heterogeneity was reported for these biomarkers (Higgins’ I² = 0–15.879%).

These oxidative stress markers should be further explored in larger cohorts for preeclampsia diagnosis.

Assessing the Role of Uric Acid as a Predictor of Preeclampsia

We assessed the diagnostic utility of uric acid for the prediction of preeclampsia. An observational prospective approach was carried out during 2014. Preeclamptic women were classified into 4 groups accordingly to the onset of preeclampsia and the presence of intrauterine growth restriction (IUGR). Serum uric acid levels, urea, and creatinine were measured. Receiver operating curves (ROC) of the uric acid levels ratio (UAr) between a dosage before and after the 20th week of gestation were performed. One thousand two hundred and ninety-third pregnant women were enrolled in this study. Eight hundred ten had non-complicated pregnancies, 40 preeclampsia, 33 gestational hypertension, and 20 IUGR without preeclampsia. Uric acid significantly raised after 20 weeks of gestation in women who develop preeclampsia before 34 weeks (Group A) or in those who develop preeclampsia after 37 weeks associated with IUGR (Group C). In women who develop preeclampsia after 34 weeks without IUGR (Groups B and D), uric acid increased after the 30th week of gestation. In all groups, UAr was greater than 1.5. In gestational hypertension, UAr was superior to 1.5 toward the end of gestation, while in IUGR without preeclampsia, the behavior of serum uric acid was similar to non-complicated pregnancies. In all cases, urea and creatinine showed normal values, confirming that patients had no renal compromise. ROC area was 0.918 [95% confidence interval (CI): 0.858–0.979) for the preeclampsia group and 0.955 (95% CI: 0.908–1.000) for Group A. UAr at a cut-off point ≥1.5 had a very low positive predictive value, but a high negative predictive value of 99.5% for preeclampsia and it reached 100% for Group A. Thus, a UAr less than 1.5 may be a helpful parameter with a strong exclusion value and high sensitivity for those women who are not expected to develop preeclampsia. Additionally, this low-cost test would allow for better use of resources in developing countries.

Characterizing and Evaluating Diurnal Salivary Uric Acid Across Pregnancy Among Healthy Women

Uric acid levels during pregnancy have been examined as a potential indicator of risk for gestational diabetes mellites, hypertension, and related adverse birth outcomes. However, evidence supporting the utility of serum uric acid levels in predicting poor maternal and fetal health has been mixed. The lack of consistent findings may be due to limitations inherent in serum-based biomeasure evaluations, such as minimal repeated assessments and variability in the timing of these assessments. To address these gaps, we examined repeated measurements of diurnal salivary uric acid (sUA) levels in a sample of 44 healthy women across early-mid and late pregnancy. We assessed potential covariates and confounds of sUA levels and diurnal trajectories, as well as associations between maternal weight gain and blood pressure during pregnancy and sUA concentrations. Using multilevel linear models, we found sUA increased across pregnancy and displayed a robust diurnal pattern with the highest concentrations at waking, a steep decline in the early morning, and decreasing levels across the day. Maternal pre-pregnancy BMI, age, prior-night sleep duration, and fetal sex were associated with sUA levels and/or diurnal slopes. Maternal blood pressure and gestational weight gain also showed significant associations with sUA levels across pregnancy. Our results expand upon those found with serum UA measurements. Further, they demonstrate the feasibility of using at-home, minimally-invasive saliva sampling procedures to track UA levels across pregnancy with potential applications for the long-term monitoring of maternal cardiometabolic risk.

Maternal-Perinatal Variables in Patients with Severe Preeclampsia Who Develop Acute Kidney Injury

Introduction: At present, we are witnessing an increase in preeclampsia, especially the most severe forms, which are associated with an increased risk of maternal-perinatal morbidity and mortality. As a severity criterion, acute kidney injury (AKI) has been associated with a worse prognosis, and for this reason, the maternal and perinatal variables associated with AKI in patients with severe preeclampsia (SP) were analysed in this study. Methods: An observational, retrospective, single-centre study of patients with SP treated at a tertiary hospital between January 2007 and December 2018 was conducted. The case criteria based on the criteria established by the ACOG Practice Guidelines for Gestational Hypertension and Preeclampsia. AKI is considered when serum creatinine exceeds 1.1 mg/dL in a pregnant woman with previously normal renal function. In patients with existing chronic kidney disease (CKD), it is referred to as AKI if the baseline serum creatinine increases by 1.5 fold. Pregestational, gestational and postpartum variables were analysed up to 12 weeks postpartum using univariate and multivariate logistic regression analysis. Results: During the study period, 76,828 births were attended, and 303 pregnant women were diagnosed with SP. The annual incidence of SP increased gradually throughout the study period, reaching 1.79/100 births/year in 2018. Acute kidney injury (AKI) occurred in 24.8% of the patients. The multivariate analysis revealed an increased association with a history of previous CKD, the use of assisted reproductive techniques and caesarean section. Uric acid and thrombotic microangiopathy (TMA) had a high correlation with AKI. Indications for caesarean section are associated with AKI in SP. Regarding perinatal outcomes in cases of AKI, there was a higher percentage of neonates who required foetal lung maturation with steroids and an increased need for NICU admission. No case of maternal death was recorded; however, an increase in neonatal mortality was found among patients who did not develop AKI. After 12 weeks postpartum, 72 patients were referred to the nephrology consultation for persistent hypertension, proteinuria or renal failure. Conclusions: In preeclampsia, AKI is a common complication, especially among patients with a history of CKD, those who became pregnant using assisted reproduction techniques and those who delivered via caesarean section. The perinatal impact of AKI is mainly centred on a higher rate of NICU admission and a lower mortality rate. Among biochemical and haematological markers, the uric acid level prior to renal failure has a direct and significant correlation with the risk of AKI, as does the development of TMA in patients with preeclampsia. Therefore, the monitoring of renal function in cases of preeclampsia should be strict, and referral for a nephrology consultation may be necessary in some cases.