Lactate Dehydrogenase Enzyme Level in Women with Severe Preeclampsia: A Cross-sectional Study

Aim: To determine the frequency of raised lactate dehydrogenase enzyme in women with severe preeclampsia. Study Design: Cross-sectional study. Place and Duration: Obstetrics and Gynecology department at Liaquat University Hospital Hyderabad from June 2018 to December 2018. Methodology: There were 141 primiparous women with severe preeclampsia, included in this study. After taking history regarding hypertension and obstetrical examination, patients were subjected to a relevant investigation that is, 5ml of blood sent to an institutional laboratory for the measurement of lactate dehydrogenase enzyme, if it is >400 U/L then it was labeled as raised. Results: The frequency of raised lactate dehydrogenase enzyme (400 U/L) was 13.48% (19/141) women with severe preeclampsia. Original Research Article Hameed et al.; JPRI, 34(21B): 28-33, 2022; Article no.JPRI.82403 29 Conclusion: About 14% of women having Pre-eclampsia had raised lactate dehydrogenase enzyme. Severe preeclampsia is associated with severe multisystemic involvement. Raised LDH levels are indicative of cellular damage and severe hypertension in pregnancy.


INTRODUCTION
Globally preeclampsia is responsible for fetal and maternal mortality and morbidity [1].
It causes vascular dysfunction and vasospasm. It usually occurs after 20 weeks of pregnancy but it can occur 4-6 weeks postpartum. It is defined as proteinuria, hypertension with or without edema [2]. Preeclampsia affects about 5-10% of all pregnancies [3] and the exact incidence of preeclampsia is unknown, but in the United States, it ranges from 2% to 6% in healthy women [4,5].
Hypertension during pregnancy is responsible for significant maternal and fetal morbidity and mortality [6]. Although eclampsia is a lethal condition preeclampsia caused more death comparatively. Pregnancy-induced hypertension (Eclampsia, Preeclampsia) manifests in the third trimester of pregnancy [7].
About 15% of pregnancies manifest as mild preeclampsia, 8% as moderate, and 2% as severe preeclampsia [8]. Altered endothelial cell function is the pathognomic factor in preeclampsia. The lactate dehydrogenase enzyme (LDH) rises in case of tissue damage. Normally LDH is present in many tissues like cardia, renal, hepatic, and pulmonary tissues. Endothelial cell dysfunction causes platelet aggregation and vasoconstriction, all of these leads to hypertension and atherosclerosis [9]. Levels of LDH in preeclampsia are directly related to fetal outcomes [10].
Preeclampsia causes a lot of changes in the cardiovascular system [11]. As a biomarker, LDH levels reflect the severity of preeclampsia [12].
According to a study hypertension and raised diastolic blood pressure are very common in preeclampsia women [13].
The objective of this study is to pick up the severity of disease at an earlier stage so that major complications including HELLP syndrome could be prevented by means of earlier and timely intervention and further management can be planned and implemented in order to reduce maternal illness, fetal illness, and death.

METHODOLOGY
This Cross-sectional study was conducted at Obstetrics and Gynecology Department, Liaquat University Hospital Hyderabad from June to December 2018 by non-probability consecutive sampling technique. Total 141 primiparous women aged 20-35 years with severe preeclampsia were included in the study. Women having a history of chronic hypertension, diabetes mellitus, urinary tract infection, fetal congenital anomaly, or epilepsy were excluded.
Preeclampsia is defined as the development of new hypertension after 20 th -week gestation that is accompanied by new-onset proteinuria. Severe preeclampsia is defined as systolic blood pressure >160 mmHg and > 300 milligrams of protein collected in a 24-hour urine sample after the 20th week of gestation.
Primiparous women with severe preeclampsia visiting OPD of Liaquat university hospital with raised blood pressure were enrolled in the study. After taking history regarding hypertension and obstetrical examination, the patient was subjected to relevant investigation i.e. 5 ml of blood sent to the institutional laboratory for the measurement of lactate dehydrogenase enzyme, if it is >400 U/L was labeled as significant. Age, economic status, educational status, and LDH level were noted and entered into the proforma. After the collection of data, the analyses were conducted by using Statistical Package for Social Science (SPSS) software version 22. Mean and standard deviation were calculated for the quantitative variable is age and levels of Lactate Dehydrogenase (LDH). Frequency and percentages were computed for qualitative variables like raised LDH, educational status, and economic status. Effect modifier age, educational status, economic status, and gestational age were controlled by stratification. A Chi-square test was applied. P-value <0.05 was taken as significant.

RESULTS
There were 141 primiparous women aged 20-35 years with severe preeclampsia were included in this study. Most of the patients were 20 to 30 years of age. The average age of the patients was 25.91±3.33 years similarly the average Lactate dehydrogenase Level (LDL) was 386.96 ± 163.95 U/L as presented in Table 1.
The frequency of raised lactate dehydrogenase enzyme was 13.48% (19/141) women with severe preeclampsia. With respect to age groups, raised lactate dehydrogenase (LDH) was 43.8% (7/16) in 31 to 35 years of age patients, 17.9% (10/141) in 26 to 30 years of age patients, and 2.9% (2/69) in 20 to 25 years of age cases. The rate of LDH was significantly high in 31 to 35 years of patients (p=0.0005) as shown in Table  2. The rate of LDH was insignificant between gestational ages (Table 3) while LDH was high in lower socioeconomic status (16.3%) but statistically insignificant among the socioeconomic class as presented in Table 4. Table 5 showed that the rate of LDH was also insignificant among the education level of the patients. Chi-Square= 20.12 Chi-Square= 1.82 Similarly in a study, most of the women belonged to the age group of 20-25 years and the mean LDH was significantly higher in women with preeclampsia as compared to normal pregnant women [14].
Furthermore, in an Indian study, 30.8% of women had high LDH levels among them half had severe preeclampsia while the remaining 50% had mild preeclampsia. The rise in the LDH levels was observed with increasing severity of preeclampsia [15]. In another similar Pakistani study, the mean LDH was 337.89±173.15 in mild preeclampsia while it was 556.41±193.02 in severe preeclampsia. It signifies that LDH level increases with the severity of preeclampsia [16].
An international study concludes a positive correlation between increasing severity of preeclampsia and median LDH concentrations (p = 0.037) [17]. According to the results of a study mean LDH was normal (257.24 U/L) in normotensive pregnant women, it increased to 417.84 U/L in preeclampsia while it increased significantly (565.51 U/L) in eclampsia women [18].
Maternal and perinatal morbidity and mortality are linked to hypertension in pregnancy. A number of studies reflected on the magnitude of this problem globally. Elevated levels of LDH in severe preeclampsia are associated with fetal problems like low birth weight, low Apgar score, and neonatal mortality. Although we did not monitor the fetal and neonatal outcome in our study but is proven in other studies [19,20].

LIMITATIONS OF THE STUDY
It was a cross-sectional single-center study with a small sample size, so further cohort studies at various hospitals should be conducted to validate the results.

CONCLUSION
In our study about 14% of women having Preeclampsia had raised lactate dehydrogenase enzyme. Severe preeclampsia is associated with severe multisystemic involvement. Raised LDH levels are indicative of cellular damage and severe hypertension in pregnancy.

DISCLAIMER
The products used for this research are commonly and predominantly used products in our area of research and country. There is absolutely no conflict of interest between the authors and producers of the products because we do not intend to use these products as an avenue for any litigation but for the advancement of knowledge. Also, the research was not funded by the producing company rather it was funded by the personal efforts of the authors.

ETHICAL APPROVAL AND CONSENT
The study was performed after the permission of the ethical committee of the hospital, and verbal informed consent for the study from the study participants.