|Year : 2014 | Volume
| Issue : 2 | Page : 66-68
Assessment of oxidative stress in babies under phototherapy for neonatal jaundice
Anitha Nancy Thiagarajan1, Parkash Chand1, Ballambattu Vishnu Bhat2, Magadi Gopalakrishna Sridhar3
1 Department of Anatomy, Jawaharlal Institute of Post Graduate Medical Education and Research, Puducherry, India
2 Department of Pediatrics, Jawaharlal Institute of Post Graduate Medical Education and Research, Puducherry, India
3 Department of Biochemistry, Jawaharlal Institute of Post Graduate Medical Education and Research, Puducherry, India
|Date of Web Publication||29-Dec-2014|
Anitha Nancy Thiagarajan
Department of Anatomy, Jawarharlal Institute of Post Graduate Medical Education and Research, Puducherry - 605 006
Source of Support: None, Conflict of Interest: None
Background: Neonatal jaundice is a common condition that can be treated with phototherapy. Phototherapy may cause oxidative stress in addition to the usual side effects. Aim: In this study, the oxidative stress in babies with neonatal jaundice was assessed before and after phototherapy by estimating plasma malondialdehyde (MDA) level. Methods: Eighty babies with neonatal jaundice were chosen for the study. Among them, 40 babies whose total serum bilirubin level was >15 mg/dl formed the case group and the other 40 babies with total serum bilirubin level <15 mg/dl who did not require phototherapy formed the control group. Total serum bilirubin was measured using Automated Clinical Chemical Analyser with standard reagent kit. Plasma MDA was estimated by Satoh's method using spectrophotometry. Results: The plasma MDA level, which is one of the oxidant markers, was significantly elevated in post-phototherapy cases compared to pre-phototherapy and controls. Conclusion: Phototherapy results in significant oxidative stress among babies with neonatal hyperbilirubinemia. So, usage of phototherapy should be restricted to those with significant hyperbilirubinemia.
Keywords: Malondialdehyde level, neonatal jaundice, oxidative stress, phototherapy
|How to cite this article:|
Thiagarajan AN, Chand P, Bhat BV, Sridhar MG. Assessment of oxidative stress in babies under phototherapy for neonatal jaundice. Int J Adv Med Health Res 2014;1:66-8
|How to cite this URL:|
Thiagarajan AN, Chand P, Bhat BV, Sridhar MG. Assessment of oxidative stress in babies under phototherapy for neonatal jaundice. Int J Adv Med Health Res [serial online] 2014 [cited 2018 Nov 17];1:66-8. Available from: http://www.ijamhrjournal.org/text.asp?2014/1/2/66/148004
| Introduction|| |
Approximately 60% of all term newborns and a higher number of premature infants develop clinical jaundice. Neonatal jaundice is visible in a newborn when the serum bilirubin level is >5 mg/dl. In hyperbilirubinemic babies, phototherapy is advocated to convert bilirubin to its product (lamirubin) which can bypass the liver and get excreted in the bile or urine without further metabolism.  The lipid peroxidation product, i.e., malondialdehyde (MDA), is one of the oxidative stress markers found to increase significantly in babies with neonatal jaundice.  The reported side effects of phototherapy include rashes, loose stools, temperature instability, and dehydration.  But it is not clear whether oxidative stress is increased among babies who receive phototherapy. Hence, this study was undertaken to assess the level of oxidative stress by plasma MDA estimation using peripheral blood sample in babies with neonatal jaundice who received phototherapy.
| Methods|| |
This prospective cohort study was conducted in the Department of Anatomy of JIPMER in collaboration with the departments of Pediatrics and Biochemistry from September 2010 to May 2012. The study was approved by the institute scientific subcommittee and the Institute Ethics Committee. The sample size was estimated based on an earlier published report on the estimates of mean difference of total oxidant/antioxidant status in jaundiced newborn before and after phototherapy  at 90% power and 5% levels of significance. The minimum sample size required for the study was estimated as 40 in each group. Forty term newborn babies aged 2-7 days with birth weight ranging from 2.2 to 3.0 kg and a total serum bilirubin level of >15 mg/dl who required phototherapy were chosen as cases and 40 term age-, weight-, and gender-matched babies with a total serum bilirubin level of <15 mg/dl and not requiring phototherapy were chosen as controls. Preterm babies and infants with congenital malformation, birth asphyxia, sepsis, those with signs and symptoms suggestive of severe illness, and babies who had received phototherapy before recruitment to the study were excluded.
Informed written consent was obtained from the parents of the babies. Two milliliters of peripheral blood was collected from cases in pre-phototherapic phase as well as 48 h after receiving phototherapy and from controls in heparinized tubes under sterile and aseptic conditions. The samples were divided into two parts; one part was centrifuged and the plasma was separated for the estimation of MDA level and the other part was utilized for serum bilirubin estimation. Conventional phototherapy was given to all the 40 cases at 420-470 nm wavelength with blue fluorescence lamp by taking standard precautionary measures. Estimation of MDA level was done by Satoh's method using spectrophotometry.  Bilirubin was estimated by Automated Clinical Chemical Analyser (Olympus AU 400; Olympus, Tokyo, Japan) using Beacon Reagent kit.
Based on the distribution of data, appropriate parametric independent Student t-test was used to compare the continuous data between the groups. All statistical analyses were carried out using Instat Graphpad version 3 Software at 5% level of significance and P value <0.05 was considered as significant.
| Results|| |
Of the babies enrolled, there were 25 males and 15 females among cases and 26 males and 14 females among controls. The age and sex distribution in the two groups were comparable. The mean total serum bilirubin for controls was 10.13 ± 2.47 mg/dl and for cases in pre-phototherapy group was 17.85 ± 1.82 mg/dl and in post-phototherapy study group was 15.19 ± 1.56 mg/dl. It shows that total serum bilirubin decreased significantly with phototherapy treatment with P <0.000.
Plasma MDA, which is one of the oxidant markers, was significantly increased after phototherapy compared to before phototherapy. The mean plasma MDA was 12.61 ± 2.32 μmol/l (pre-phototherapy) and 13.79 ± 2.85 μmol/l (post-phototherapy) in cases and 6.05 ± 2.17 μmol/l in controls [Table 1]. Although oxidative stress was higher among cases with elevated serum bilirubin compared to controls, MDA level continued to increase with lowering of bilirubin after phototherapy with P < 0.005.
|Table 1: Mean serum bilirubin and plasma malondialdehyde levels in cases and controls|
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| Discussion|| |
Newborn babies have more circulating red cells and a short red cell lifespan. The breakdown and excretion of bilirubin is also slower due to immature hepatic system, which results in indirect hyperbilirubinemia. The increased amount of unconjugated bilirubin is capable of penetrating the blood-brain barrier when its concentration in plasma exceeds that which can be tightly bound by albumin (20-30 mg/dl). This can result in hyperbilirubinemic toxic encephalopathy or kernicterus, which can cause mental retardation.  Total serum bilirubin levels higher than 10 mg/dl are reported to be hazardous to chromosomes.  Phototherapy is the most widely used form of therapy for newborn infants with hyperbilirubinemia (>15 mg/dl) in order to decrease the body burden of neurotoxic bilirubin. The effective use of phototherapy has eliminated the need for exchange transfusion in most patients. 
But in cultured cells, blue light phototherapy showed a potential for forming more photo-oxidation products and for causing more severe cellular damage in the presence of bilirubin.  Bilirubin elimination depends on the rates of formation as well as the rates of clearance of the photoproducts. Photoisomerization occurs rapidly during phototherapy, and isomers appear in the blood long before the level of plasma bilirubin begins to decline.  Antioxidant activity is lower in neonates than in adults due to immature defense system and increases with age.  There is increase in free radical generation and impaired antioxidant defense in peroxidation which has been reported in neonatal jaundice.  Rise in MDA could be due to increased generation of reactive oxygen species (ROS) as a result of phototherapy. Since bilirubin acts as a photosensitizer and becomes energized by phototherapy, the energy thus gained is subsequently transferred to molecular oxygen, thereby generating singlet oxygen and other ROS.  Serum bilirubin is an antioxidant at <6 mg/dl and it will also act like an oxidative stress inducer at a higher level.  This is evident from our study since higher serum bilirubin level among cases showed increased MDA level.
Aycicek et al. stated that after phototherapy, serum total oxidant status (TOS), lipid hydroperoxide, and oxidative stress index (OSI) levels were significantly higher, but MDA level was reduced due to interference with some aldehyde structures.  Later Aycicek et al. also observed that conventional phototherapy increases serum lipid hydroperoxides in full-term infants. 
Red cell bilirubin acts as a photosensitizer in the presence of phototherapy and brings about oxidative damage. Dahiya et al. observed that levels of MDA were elevated significantly in the presence of phototherapy, indicating increased oxidative stress in the study subjects.  Our study also revealed significant increase in plasma MDA level after exposure to phototherapy. Demirel et al. stated that the increase in total oxidant status seen after conventional phototherapy was not observed after light emitting diodes (LED) phototherapy. 
Surapaneni et al. observed that there was a statistically significant increase in the MDA levels in neonatal jaundice patients compared to controls. The results demonstrated that jaundice can produce an increased oxidative stress which can be counteracted by increase in antioxidant enzymes like superoxide dismutase and glutathione peroxidase.  Even though the erythrocyte MDA is specific in neonatal jaundice, there is no clear evidence suggesting a significant difference between erythrocyte and plasma MDA levels in literature. The plasma MDA level is increased and consistent with earlier observation.
| Conclusion|| |
In our study, the oxidant marker MDA had increased significantly in post-phototherapy compared to pre-phototherapy cases in spite of the reduced serum bilirubin level. The increase in MDA level in post-phototherapy babies indicates that phototherapy induces oxidative stress. Even though phototherapy is the mainstay of treatment for neonatal jaundice, it induces oxidative stress, and hence, usage of phototherapy should be restricted to those with significant hyperbilirubinemia.
We have studied only MDA level in the present study. Inclusion of other oxidant and antioxidant levels could have given clearer picture. As the study was done in a tertiary care center, the results need not reflect the actual scenario in the population.
| Acknowledgment|| |
We thank Mr. Harichandrakumar K. T., Department of Medical Biometrics and Informatics (Biostatistics) for assistance in statistical analysis.
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