A Comparative Study of Serum and Salivary Uric Acid Measurement in Pre-eclampsia and Normal Pregnancy in a Tertiary Care Hospital in Punjab: A Pilot Study.

Background Pre-eclampsia is a multisystem progressive disorder associated with significant maternal and neonatal morbidity and mortality. It is essential to identify the potential indicators of associated complications in pre-eclampsia to improve pregnancy outcomes. Serum uric acid (UA) levels are increased in pregnancies complicated by pre-eclampsia. This study was performed to validate salivary UA as an alternative non-invasive biomarker to serum UA in pre-eclampsia. Methodology A total of 150 pregnant women were enrolled in the study. They were divided equally into three groups with 50 participants in each group. Group 1 included healthy normotensive pregnant women as control, group 2 included participants with non-severe pre-eclampsia and group 3 included participants with severe pre-eclampsia. Both salivary and serum UA were estimated in all the study participants and comparative analyses were done. Results Serum UA was elevated in 33(66%) and 48(96%) of participants in groups 2 and 3 respectively while saliva uric acid in 30(60%) and 43(86%) as compared with healthy controls who had serum UA raised in 14(28%) and salivary UA in 12(24%) with a significant p-value of 0.0001. The mean values of serum and salivary UA in group 1 were 4.5 ±1.16 mg/dl and 4.11±1.74 mg/dl respectively whereas in group 2 these were 6.12±1.86mg/dl and 5.96±1.90mg/dl and in group 3 these were 8.24±2.31mg/dl and 8.17±3.31mg/dl respectively. There was a significant correlation between serum and salivary UA values in groups 1 and 2, groups 1 and 3, and groups 2 and 3 with a p-value of 0. 001. The serum and salivary UA levels showed an increasing trend from healthy controls (group 1) to non-severe pre-eclampsia (group 2) with the highest values in severe pre-eclampsia (group 3). Oligohydramnios was present in 10(20%) cases in group 1 whereas 24(48%) cases in group 3. The appearance, pulse, grimace, activity, respiration (APGAR) score at 1 and 5 minutes was abnormal in 5(1.23%) and 7(1.33%) cases in group 1, 6(1.26%) and 7(1.29%) cases in group 2 and 5(1.73%) and 6(1.53%) cases in group 3. The area under curve (AUC) in group 2 was 0.778 for serum UA and 0.779 for salivary UA. In group 3, the AUC for serum UA values was 0.938 and for salivary UA 0.882. A statistically significant correlation between serum and salivary UA values in group 2 (non-severe pre-eclampsia) was found with a p-value of 0.001 and Pearson's correlation coefficient r of 0.738. Conclusions Serum and salivary UA levels correlate with the severity of pre-eclampsia with maximum levels in severe pre-eclampsia (group 3) followed by group 2 (non-severe pre-eclampsia) with the lowest levels in group 1 (healthy controls). The authors are of the opinion that a non-invasive salivary UA test can replace the serum UA test and can be a useful supplementation for conventional pre-eclampsia prediction.