ANTENATAL GLUTATHIONE AND SUPEROXIDE DISMUTASE ESTIMATION FOR PREDICTION OF PRE-ECLAMPSIA

Abstract

Introduction: Pre-eclampsia is still a significant cause of foeto-maternal morbidity and mortality in our environment. Exaggerated oxidative stress is a characteristic of this disease and studies have shown altered levels of antioxidants in patients with pre-eclampsia. Current research is being directed towards identification of effective screening tools and predictors. The role of antioxidants in predicting the onset of pre-eclampsia among Nigerian women is therefore being evaluated in this dissertation. Objectives: The primary objective was to determine the value of plasma glutathione and superoxide dismutase estimation for prediction of clinical onset of pre-eclampsia in women with pregnancies less than 20 weeks. The specific objectives were as follows:

1. To determine the mean plasma glutathione and superoxide dismutase levels among women presenting for booking at less than 20 weeks gestation in Ibadan.
2. To evaluate the change between plasma glutathione and superoxide dismutase levels in the first/early second trimester and at onset of pre-eclampsia or delivery.
3. To determine the plasma glutathione and superoxide dismutase levels at which preeclampsia occurs.
Methods:
This was a prospective cohort study conducted in the antenatal clinic and labour ward of the University College Hospital, Ibadan. One hundred and sixty six women with pregnancies <20 weeks of gestation were recruited at booking for antenatal care. A structured proforma was utilised to extract socio-demographic, obstetric, medical and drug history. Their plasma antioxidant levels- glutathione (GLU) and superoxide dismutase (SOD) were determined and this cohort was followed longitudinally. A repeat assessment of these enzymatic antioxidants was
done on presentation in labour, before caesarean delivery or at the point of clinical evidence of pre-eclampsia, whichever came first. Data entry and analysis was done using the Statistical Package for Social Sciences software (SPSS), version 16. The level of significance for significant associations was p<0.05.

Results The mean age of the cohort and mean gestational age at recruitment were 30.51±4.10 (SD) years and 17.3±8.9 (SD) weeks respectively. Mean plasma GLU was 0.424±0.303µM (SD) while mean plasma SOD at recruitment was 0.172±0.082U/ml (SD). Only 4 patients out of 166 (2.4%) developed pre-eclampsia while 16 (9.6%) of the cohort had gestational or post partum hypertension (HDP). The mean plasma GLU at delivery in all participants was 0.007±0.028 µM (SD) while the mean reduction in antioxidant levels was 0.418±0.307 µM (SD). Mean plasma SOD at delivery in all participants was 0.047±0.014U/ml (SD) while the mean decrease in antioxidant levels was 0.124±0.084U/ml (SD). There was no significant difference in reduction of plasma GLU and SOD between participants with pre-eclampsia, HDP and normal women.

Plasma GLU values of ≤ 0.442 µM had a sensitivity of 25%, specificity of 29%, positive predictive value of 1% and negative predictive value of 94% for pre-eclampsia. A cut off value of 0.442 µM and below had 81% sensitivity, 30% specificity, positive predictive value of 11.3% and a negative predictive value of 94% for HDP. An SOD value of ≤0.110U/ml at recruitment had a sensitivity value of 50%, specificity value of 75%, PPV of 4.8% and NPV of 98.3% for the prediction of pre-eclampsia. When applied to HDP, a value of ≤0.110U/ml had a sensitivity value of 12.5%, specificity value of 74.0%, PPV of 5% and NPV of 88.5%. These values were however not significant for prediction of either entity.

Conclusion Plasma glutathione and plasma superoxide dismutase values before 20 weeks gestation may not be useful in predicting clinical onset of pre-eclampsia among low risk women in Ibadan. Further community based research is needed to confirm these findings.

ANTENATAL GLUTATHIONE AND SUPEROXIDE DISMUTASE ESTIMATION FOR PREDICTION OF PRE-ECLAMPSIA