A comparative study on renal function parameters and age in females with and without pre-eclampsia in a tertiary health care setup

Background and objective: Pathogenesis of preeclampsia is known to be associated with renal dysfunction. But the best suited renal function parameter to quantify pathogenesis of this clinical condition is unclear. This study is aimed to assess the renal parameters in preeclampsia. Materials and Methods: 185 consecutive mothers in 20th week of gestational period were enrolled into the study. Based on the presence or absence of preeclampsia they were divided into two subgroups: Group A (82 mothers with preeclampsia) and Group B (103 normotensive mothers). Results: In all the mothers serum urea, serum creatinine and serum uric acid was measured. Serum uric acid of group A was very significantly higher compared to group B ( p < 0.0001). Serum urea and serum creatinine of group A was just significantly higher compared to group B (p<0.05). Conclusions: Among the renal function parameters measured uric acid was better suited in assessing renal dysfunction in mothers with preeclampsia.


Introduction
The hypertensive disorders during pregnancy affect up to 8.0% of all pregnancies 1 and remain a major cause of maternal and neonatal mortality and morbidity worldwide. 2 Pre-eclampsia, a multi-system disorder, associated with raised blood-pressure and proteinuria with or without accompanying symptoms, abnormal maternal laboratory test results, intrauterine growth retardation, or reduced amniotic fluid volume. In women with pre-eclampsia, a history of symptoms is obtained antenatally, with the key alarming clinical symptoms being headache, vomiting, visual disturbances and epigastric pain. However the unpredictable onset and progression of these symptoms warrants the need for an early and appropriate detection. 3 The objective of this was to study the renal manifestations by measuring serum urea, serum creatinine, serum uric acid levels and albuminuria in subjects with and without preeclampsia.

Materials and Methods
This study was done in teaching hospitals attached to Kasturba Medical College after obtaining permission from ethical committee of the institution overseeing human studies and consent from the study participants.
185 consecutive mothers in 20th week of gestational period were enrolled into the study, in whom fresh medical report on serum protein, serum urea, serum creatinine and random blood sugar was available. They were divided into two groups namely, group A (n = 82) diagnosed with preeclampsia and group B (n = 103) comprising of normotensive mothers.
In this study the diagnosis of preeclampsia was based on the definition of American College of Obstetrics and Gynecologists. 4 In all the subjects, height and weight was measured and body mass index was calculated using the formula weight in kilogram divided by height in meters squared. Systolic and diastolic blood pressure was measured in sitting position.
Data was analyzed employing unpaired student t test. When data was not uniformly distributed non-parametric methods namely Mann-Whitney test was used. p value less than 0.05 was taken as statistically significant.

Result
Data is presented as mean ± SD. Comparison of data on baseline characteristics of mothers with preeclampsia and normotensive mothers are presented in Table 1. Data on renal function parameters in these two groups are presented in Table 2.
The mean systolic and diastolic blood pressure of mothers with preeclampsia was significantly higher compared to normotensive mothers (p < 0.0001, Table 1). Mean age of the mothers with preeclampsia was significantly higher compared to normotensive mothers (p = 0.0004). Mean random sugar and body mass index of mothers with preeclampsia did not differ significantly compared to normotensive mothers ( Table 1).
All the measured renal function parameters were significantly higher in mothers with preeclampsia ( Table 2). Mean protein and uric acid was significantly higher in preeclampsia group compared to normotensive mothers (p < 0.0001, table 2). In mothers with preeclampsia serum urea ranged from 4-55 mg/dl. In normotensive mothers serum urea ranged from 4-45 mg/dl. In mothers with preeclampsia creatinine level ranged from 0.3 mg/dl to 1mg/dl. In normotensive mothers serum creatinine level ranged from 0.3-1.4. Mean urea and creatinine was significantly higher in mothers with preeclampsia compared to normotensive mothers (p< 0.05, Table 2).

Discussion
In this study we compared the baseline characteristics and renal parameters between mothers with preeclampsia and normotensive mothers.
Among the baseline characteristics studied, mean age of preeclampsia group was significantly higher compared to normotensive mothers (Table 1). This finding suggests that women are at greater risk of preeclampsia with advancing age.
Pregnancy induced hypertension is associated with greater risk of intrauterine growth retardation and intrauterine death of foetus. Preeclampsia is a pregnancy-specific disease manifested by hypertension, coagulopathy, and impaired tissue perfusion. Its etiology remains unclear, and it is possible that the rise in blood pressure is a manifestation of more than one pathophysiological condition. [5][6][7][8] One of these conditions is related to abnormal renal function. 9 , 10 Accordingly in the IJBAR (2013) 04 (10) www.ssjournals.com present study, mean serum urea, serum creatinine and serum uric acid was significantly higher in women with preeclampsia compared to normotensive pregnant women (Table 2).
In the present study, serum uric acid level was much higher in mothers with preeclampsia unlike the other renal function parameters namely serum urea and serum creatinine compared to normotensive mothers (Table2). This finding suggests that measurement of uric acid may be suitable marker in identifying pregnant women at greater risk for preeclampsia. Findings of previous research work on association between uricemia and pregnancy induced hypertension is conflicting. Wake et al 11 have observed that in subjects with pre-eclampsia plasma uric acid level will help to predict those that will develop eclampsia. Hawkins et al 12 have reported that hyperuricemia in hypertensive pregnancy remains an important finding because it identifies women at increased risk of adverse foetal outcome even women with gestational hypertension without any other features of pre-eclampsia. In the study of Mustaphi et al 13 high positive correlation was observed between levels of serum uric acid and severity of pregnancy induced hypertension in relation to hypertension and proteinuria. However, Hickman et al 14 have noted serum uric acid as an unreliable indicator of developing hypertension in the individual women. Salako et al 15 have reported that single estimation of serum uric acid level early in pregnancy are of little value in the prediction of pre-eclampsia. However our study finding suggests serum uric acid level is associated with preeclampsia.

Conclusion
Abnormal renal function is related to pathophysiology of preeclampsia. Aging increases the possibility of preeclampsia during pregnancy.