Introduction
Preeclampsia is defined by appearance of hypertension & proteinuria after 20 weeks of gestation. It affects approximately 3–10% of all pregnancies.1 It leads to maternal morbidity and mortality, because of several complications such as eclampsia, fetal growth retardation, and premature birth.2 Though pregnancy induced hypertension (PIH) is regarded as a disease of unknown etiology, elevated homocysteine level has always been hypothesized as a key risk factor. Homocysteine is a sulphur containing amino acid, produced from the essential amino acid methionine in body. It undergoes transsulfuration reaction to produce cysteine or can be further remethylated to produce methionine. The transsulfuration reaction requires vitamin B6 as a coenzyme in presence of the enzyme cystathionine-ß-synthase. Hyperhomocysteinemia is considered to be risk factor for cardiovascular diseases. An increase of 5 micromol/L of homocysteine in serum elevates the risk of coronary artery disease by as much as cholesterol increases of 20 mg/dl. Homocysteine interacts with lysyl residues of collagen and bind to fibrillin producing endothelial dysfunction.Conditions leading to high Homocysteine levels, such as low levels of folic acid and vitamin B12 can also increase the risk of vascular damage. It is therefore difficult to determine whether high homocysteine levels only or low concentrations of vitamin B12 and folic acid are atherogenic factors that leads to vascular damage leading to endothelial dysfunction.
Materials and Methods
This study was carried out at Department of Biochemistry, in collaboration with Department of Gynecology & Obstetrics of College of Medicine & JNM Hospital, Kalyani. Patients who matched the inclusion criteria within the stipulated time duration (12 months) were included in the study population. At the end of 12 months, the number of patients was found to be 40.
40 pre-eclamptic patients in the age group of 18–40 years were enrolled in the study after obtaining detail medical history & taking informed consent. Parameters included Serum homocysteine, folic acid, and vitamin B12. 40 healthy normotensive pregnant subjects of identical age without any disease were randomly selected as controls.
Inclusion criteria
Patients with symptoms and signs suggestive of preeclampsia supported by laboratory investigations & with normal renal and liver function tests were included in the study.
Exclusion criteria
Either patient/caregiver who didn’t provide written consent. Detailed drug history was obtained. Patients with history of medications such as, anticonvulsants, tamoxifen were excluded. Patients suffering from Cancer, Anemia, Systemic illness like diabetes & primary hypertension were excluded. History of major substance abuse & history of chronic inflammatory diseases were also excluded.
The Institutional Ethical Committee approved the study. Detailed informed consent was obtained from patients as well as control population.
Materials and Methods
Serum Homocysteine, folic acid & Vitamin B12 concentration were measured by electrochemiluminescence immunoassay method using Cobas e411 analyzer.
Hyperhomocysteinemia was defined as a serum homocysteine concentration greater than 15 mcmol/l.
Statistical analysis
The statistical analysis was done using SPSS 15.0 version. The continuous variables of demographic and biochemical parameters were presented as mean ± S.D. (standard deviation). Pearson correlation analysis was carried out to find the association (if any) of the confounding (independent) variables with biochemical parameters (dependent variables). The significance was considered with p values less than 0.05.
Results
Body mass index (BMI), systolic blood pressure (SBP) and diastolic blood pressure (DBP) were significant increased (p<0.05) in cases as compared with control group (Table 1).
Table 1
Demographic parameters in cases & controls
|
Parameters |
Control group(n=40) |
Cases(n=40) |
P value |
|
Age |
26.5±5.68 |
28.5±4.33 |
0.12 |
|
BMI |
20.5±4.23 |
24.8±3.28 |
0.034* |
|
SBP |
118.2±5.08 |
148.4±6.76 |
0.01* |
|
DBP |
80.3±5.45 |
92.3±4.14 |
0.02* |
Table 2
Serum homocysteine, folic acid & Vit B12 levels in cases & controls
|
Parameters |
Control group (n=40) |
Cases (n=40) |
P value |
|
Homocysteine (mcmol/l) |
9.58±3.67 |
17.1±4.12 |
0.008* |
|
Folic acid (ng/ml) |
11.92±3.02 |
8.93±3.44 |
0.04* |
|
Vitamin B12 (pg/ml) |
408±96.4 |
322.8±74.4 |
0.03* |
As can be seen, significant increase (P value 0.008) were observed in serum homocysteine whereas, folic acid and vitamin B12 levels showed significant decrease (P<0.05).
Table 3
Correlation between homocysteine levels with Folic acid & vitamin B12 levels in cases
|
Parameters |
r value |
p value |
|
Folic acid |
-0.23 |
0.34 |
|
Vitamin B12 |
-0.89 |
0.005* |
A negative and statistically significant correlation was observed between serum homocysteine with vitamin B12. (Table 3).
Discussion
Our study shows that levels of serum homocysteine, folic acid and vitamin B12 are altered in preeclampsia patients than control population. It shows that there was significant hyperhomocysteinemia and deficiency of folic acid and vitamin B12 patients with preeclampsia.
Several factors may increase homocysteine levels in women with preeclampsia. Metabolism in the kidney is the major route by which homocysteine is cleared from plasma and this route of elimination may be affected by preeclamptic changes in the kidney.
In our study, the levels of vitamins B12 and folic acid were significantly lowered in the preeclamptic as compared to control groups.
Hyperhomocysteinemia in such preeclamptic patients were found in our Study might be due to modulation in homocysteine metabolism, which corroborates with the work of Walker et al,3 Vollset et al4 & Hogg et al.5
Carmel R6 found that differences in folic acid concentrations are seen between preeclamptic and normal pregnant women.
Similarly, in a systematic review by Mignini et al,7 folic acid and vitamin B12 concentrations were lower in preeclamptic women when compared with those of normotensive women.
Homocysteine causes activation of Hageman’s factor. This may lead to increased platelet adhesiveness and life-threatening intravascular thrombosis. Homocysteine also interacts with lysyl residues of collagen and bind to fibrillin, ultimately leading to endothelial dysfunction. In preeclampsia there is widespread endothelial dysfunction & vascular damage in body. Conditions leading to high Homocysteine levels, such as low levels of folic acid and vitamin B12 can also increase the risk of vascular damage.8, 9, 10, 11 Hyperhomocysteinemia leads to coronary artery diseases. There is also some evidence to associate hyperhomocysteinemia with myocardial infarction. Folic acid and vitamin B12 are required for the remethylation of homocysteine to methionine; vitamin B6 is required for the transsulfuration of homocysteine to cysteine. Thereby providing adequate quantity of pyridoxine, Vit B12 & folic acid specially in pregnancy keeps homocysteine levels in blood to normal levels as their metabolism are interlinked. Maternal hyperhomocysteinemia thus leads to neural tube defects in foetus. Thereby high dose of folic acid is advised in pregnancy.
A good correlation between serum homocysteine and folic acid, and vitamin B12 levels observed in our study support this view.
Conclusion
From the above discussion we can assume that biochemical screening such as homocysteine, folic acid, vitamin B12 are of paramount importance in preeclampsia.
The inverse relation between homocysteine and folic acid, and vitamin B12 indicates that severity associated with metabolic disturbances in preeclampsia that can be contributed to CVD.
On the other hand, there is an absolute need for large studies designed to answer the question as to whether hyperhomocysteinemia and vitamin B deficiency are associated with increased risk for CVD and whether therapy of these disorders might influence cardiovascular mortality.
Further studies should help define the role of genetic polymorphism in enzymes of homocysteine, folic acid, vitamin B12 metabolism and their role in preeclampsia.
