Uric acid in pregnancy and preeclampsia: an alternative hypothesis

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.

Cancer antigen 125 and C-reactive protein inflammatory mediators and uric acid in association with preeclampsia in North Kordofan State, Western Sudan

Pathophysiology of pre-eclampsia depends on a defective trophoblastic invasion of uteroplacental blood vessels that leads to placental ischemia and induction of an inflammatory process within the placenta. This process may trigger the expression of Cancer antigen 125 (CA 125), C-reactive protein (CRP) and uric acid (UA). This research aimed to evaluate the association of serum CA 125, CRP and uric acid with Preeclampsia. The study recruited 200 singleton Sudanese pregnant women, who were divided into three groups: controls (n = 100), mild preeclampsia (n = 46) and severe preeclampsia (n = 54). The study subjects were matched for maternal age, gestational age and body mass index. Blood samples were taken for measurement of the different variables using immune- assay and enzymatic automated chemical analysis. The levels of CA 125 in mild and severe preeclampsia were (21.94±0.749 IU/ml) and (40.78±1.336 IU/ml) respectively, which was significantly different (P<0.001) from the control mean (16.48±0.584 IU/ml). There was also a significant difference between the mean levels of CRP in mild and severe preeclampsia (15.17±0.788 mg/L), (31.50±1.709 mg/L) compared with controls (4.79±0.178 mg/L), (P<0.01). There was also a significant difference in the mean levels of UA in mild and severe cases (6.44±0.293 and7.37±0.272) in comparison with the controls (4.00±0.061); (P<0.001). There were significant differences between severe and mild groups (P<0.05). Cancer antigen 125, CRP and UA levels‎ correlated positively with mean arterial blood pressure (MAP) where (r >0.7; P < 0.001). ROC curve validates the utility of these biomarkers for monitoring preeclampsia (AUC >0.8; P < 0.001). In conclusion CA 125, CRP and UA were significantly higher in preeclampsia compared with the controls. The rise of the analytes was directly associated with the severity of the disease.

Foetal and maternal outcomes in hyperuricaemia pre-eclampsia patients in Hospital Universiti Sains Malaysia

Preeclampsia patients have frequently been found to experience hyperuricaemia and this may result in poor outcomes compared to those with normal uric acid levels. This study aimed to determine the relationship of hyperuricaemia in pre-eclampsia patients with foetal and maternal outcomes. This prospective cohort study involved 79 patients in a tertiary centre from year 2016 to 2018. Blood samples were taken antenatally and at the 6th week, post-delivery for renal function including serum uric acid level. Our findings indicate that there was a higher incidence of poor maternal and foetal outcomes in the hyperuricaemia group than the normal uric acid group. Serum uric acid has been shown to be a significant predictor for low birth weight and premature delivery in preeclampsia patients. It was also found that there was a significant negative correlation between uric acid level and antenatal creatinine clearance (r_s = -0.338, p = .002). The assessment of the serum uric acid level seems to be important to ensure better outcomes in patients with preeclampsia.Impact statementWhat is already known on this subject? Preeclampsia is a serious pregnancy-related complication and remains as one of the most important cause of maternal and foetal morbidity and mortality, affecting 2-8% in all pregnancy. Many studies have established the association between hyperuricaemia and preeclampsia. Besides, numerous studies have found that hyperuricaemia contributed to adverse maternal and foetal outcomes.What the results of this study add? There was a significant increase in adverse foetal and maternal outcomes in the hyperuricaemia group compared to the normal uric acid group. This study revealed that serum uric acid remains a significant predictor for low birth weight and premature delivery in preeclampsia patients.What the implications are of these findings for clinical practice and/or further research? Hyperuricaemia does not merely become an indicator for the severity of disease in preeclampsia patients but also indicates adverse foetal outcomes. Large population-based studies are required to establish the absolute maternal and foetal outcomes in patients with hyperuricaemia. Besides, further studies are recommended on long-term implication of hyperuricaemia which is not limited to only during antenatal period.

Utero-placental haemodynamics in the pathogenesis of pre-eclampsia

Pre-eclampsia is associated with insufficient adaptations of spiral arteries which theoretically alter haemodynamics within the intervillous space. Such changes could damage the syncytiotrophoblast and release factors which instigate maternal endothelial dysfunction. We tested this hypothesis using an in vitro dual perfusion model of the human placenta, representing putative changes in flow arising from these spiral artery maladaptations. Whilst fetal-side flow rates remained constant (6 ml/min) perfusion rates on the maternal side were increased from 14 ml/min to 45 ml/min. As well as increasing placental derived intervillous hydrostatic pressures, and changes in flow dynamics observed by colour Doppler, these elevated flow rates resulted in morphologic damage, vacuolation and shedding of the syncytiotrophoblast, focal features previously defined in pre-eclampsia. The collected maternal perfusates recovered under high flow conditions also contained significantly elevated levels of biochemical markers of syncytial damage, including lactate dehydrogenase, alkaline phosphatase and human chorionic gonadotrophin. There were also significant elevations in chemokines GROalpha and RANTES, compared with the low flow perfusions. The soluble components of the maternal high flow rate perfusions decreased the number and proliferation of HUVECs after 24h exposure. These results could not be attributed to GROalpha or RANTES alone or in combination. This study provides evidence that alterations in intervillous flow have the potential to influence both the integrity of the syncytiotrophoblast and the liberation of potentially pathogenic soluble factors. This therefore offers a putative link between utero-placental maladaptations in pregnancy and the vascular endothelial complications of pre-eclampsia.

Trophoblast infiltration

Sexual reproduction in the ocean necessitates only the combination of gametes, followed by absorption of nutrients and oxygen from the surrounding watery medium. As life moved from the sea to the land, reproductive strategies required compensation for the loss of this aquatic environment. For the mammals, and scattered other animals, the solution to this problem was the development of the placenta, the means by which the fetus extracts nutrients from its environment. As the animals that utilized the placenta evolved from small rodent-like creatures with short gestations to larger animals with prolonged gestations, the demands of the developing fetus grew. Whereas the placenta of the fetal pig, with a gestational period of a little less than four months, can extract sufficient nutrients from the mother by simple diffusion across the uterus to the placenta, the human fetus needs a far more complex uteroplacental relationship.

Hyperuricaemia and preeclampsia: is there a pathogenic link?

OBJECTIVE

A hypothesis, based on animal studies and human observational studies, was developed proposing a direct pathogenic link between hyperuricemia and preeclampsia. Epidemiological characteristics of preeclampsia such as its uniqueness to humans and an increased incidence of preeclampsia in multiple pregnancies, increased body mass index, renal and hypertensive disease all have uric acid as their common denominator. Animal studies have linked hyperuricaemia to hypertensive, cardiovascular and renal disease. The aim of the study was to determine whether lowering the serum uric acid levels in preeclampsia would affect biochemical parameters and hypertensive control.

DESIGN

A randomized, double-blind, placebo controlled study.

SETTING

A tertiary referral center.

POPULATION

Forty women with preeclampsia between 26 and 32 weeks gestation.

INTERVENTION

Probenecid 250 mg twice daily for seven days.

MAIN OUTCOME MEASURES

Renal function and haematological parameters, hypertensive control.

RESULTS

In the Probenecid group, there was a significant drop in the serum uric acid levels. Lower uric acid levels in the Probenecid group had no significant effect on blood pressure. Patients in the Probenecid group had a significantly lower serum creatinine value at the end of the study when compared to patients in the placebo group. Other renal function parameters (creatinine clearance, urea, 24 h urinary protein excretion) did not show any significant difference between the two groups. Platelet count differed between the two groups with the platelet count being significantly higher in the Probenecid group at the end of the study.

CONCLUSION

The significant improvement in the platelet count in the Probenecid group warrants further study.

Antioxidants in the treatment of severe pre-eclampsia: an explanatory randomised controlled trial

OBJECTIVE

To determine whether antioxidant therapy alters the disease process in severe early onset pre-eclampsia, in support of the hypothesis that increased lipid peroxides and reactive oxygen species production-play an important role in the pathogenesis of the disease.

DESIGN

Randomised, double-blind, placebo controlled trial.

SETTING

Two tertiary care, referral hospitals in Johannesburg, South Africa.

PARTICIPANTS

Women with severe pre-eclampsia diagnosed between 24 and 32 weeks of gestation.

INTERVENTION

Combined antioxidant treatment with vitamin E (800 IU/day), vitamin C (1000 mg/day), and allopurinol (200 mg/day).

MAIN OUTCOME MEASURES

PRIMARY OUTCOMES

1. prolongation of pregnancy and 2, biochemical assessment of lipid peroxides and antioxidants.

SECONDARY OUTCOMES

data on maternal complications, side effects of treatment, infant outcomes and regular assessment of haematologic and renal parameters.

RESULTS

The proportion of women delivered within 14 days in the antioxidant group was 52% (14/27) compared with 76% (22/29) in the placebo group (relative risk 0.68, 95% confidence interval 0.45-1.04). One woman in each group had eclampsia. Eleven women (42%) in the antioxidant and 16 (59%) in the placebo group required two antihypertensives for blood pressure control. Trial medications were well tolerated with few side effects. Lipid peroxide levels were not significantly altered in the antioxidant and placebo groups. Serum uric acid levels decreased and vitamin E levels increased significantly.

CONCLUSION

The results of this explanatory randomised trial do not encourage the routine use of antioxidants against pre-eclampsia. However, further research with modified strategies such as earlier initiation of therapy or different combinations seem worthwhile.

The role of serotonin in preeclamptic hypertension. A review and case report

Generalized arteriolar vasospasm and subsequent damage to vascular endothelium are fundamental to the development of preeclampsia. A possible mechanism underlying this involves increased deportation of trophoblast cells into maternal venous circulation with 5-hydroxytryptamine (serotonin, 5-HT) release as a consequence of platelet aggregation onto these fragments. Ketanserin, a 5-HT(2) receptor blocker, has been used successfully to treat preeclampsia. An examination of the therapeutic role of ketanserin indicates that there should now be a much more detailed assessment of serotonin antagonists in the treatment and prophylaxis of preeclampsia and eclampsia.