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Editor—I read the interesting article by Yigitet al about the lipid peroxidation in the first 10 days of life.1 A few points need explanation. Table 1 showed the range for collecting control group samples as 2–10 days, which contradicts the statement of the authors that samples were drawn on the day of admission.
Secondly, the mode of delivery was not mentioned. Rogerset al have reported higher levels of malondialdehyde (MDA) in cord blood after labour as compared with caesarean section,2 so the higher levels in the study group might have been because they were delivered vaginally.
Thirdly, the range for MDA in study and control groups was 2.5–22.5 μmol/l and 3.8–10.5 μmol/l, respectively. What is the normal range?
Finally, if there is a positive correlation between MDA and bilirubin, why did none of the neonates in the control group have any evidence of clinical jaundice?
With all these queries, I think the validity of the study becomes unreliable and the conclusions questionable.
Dr Yigit responds: I wish to make the following points in response to Dr Manzar: 1 With reference to the perceived contradiction concerning age at sample collection, samples were drawn on the day of admission to our hospital as most babies were born outside and later transferred in. 2 We are aware of the effect of the mode of delivery. In another paper we studied malondialdehyde (MDA) variations in preterm babies.1-1 MDA levels were measured at one hour, 24 hours, 48 hours, and seven days. Mode of delivery only gave rise to statistically different variation at one and 24 hours; beyond that period there was no significant effect of delivery route on MDA levels. In our study published in this journal we again found no significant difference in MDA levels according to mode of delivery.1-2 3 We are not sure what Dr Manzar means by “the normal range”. Our control group gives the norm for this population under this condition. Only a large scale study would determine more precisely the normal range of MDA in infants up to 10 days old. 4 His final query reflects the fact that Dr Manzar has missed a key point about MDA and bilirubin. All human beings, not just neonates, have a detectable level of MDA. Our study is the first to show that MDA levels are higher in babies with hyperbilirubinaemia than in normal infants. Furthermore, we investigated the difference between babies with and without haemolytic jaundice. Only those with haemolytic jaundice showed a positive correlation between MDA and bilirubin levels. This difference is clearly illustrated in the figures in our paper, as well as explained in the third paragraph of the results section.
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