Send letter to journal:
Re: Rebound bilirubin: what is the keypoint to recommence phototherapy?

Dear Editor,

I read with great interest the recent paper by Kaplan et al. about post-phototherapy bilirubin rebound. The incidence of significant rebound bilirubin was reported as 13.3% (30/226) and a great number of neonates rebounded (26/30) were among those in whom phototherapy had been commenced £72 hours (1). We had conducted a similar study with a total of 375 newborns; the general rate of neonates with significant rebound bilirubin that required phototherapy was 5.1% (19/375), and 16 of 19 patients were from birth hospitalisation group (≤48 h)(2). The keypoint, which is not standart and limits the value of evaluation of studies for meta-analysis or comparison, is the definition of rebound bilirubin level that may be presumed for reinstitution of phototherapy. Kaplan et al. had recommenced phototherapy at bilirubin values >256 mmol/L, and they added that the decision to reinstitute phototherapy had been influenced by the presence of risk factors for hyperbilirubinemia (1). In our study, we used charts which were recommended by American Academy of Pediatrics (3) in similar with their study (3), but recommenced phototherapy if the rebound bilirubin level was above the value which was appropriate for the patient’s age and risks. This is the considerable point because, otherwise the accepted level for reinstitution of phototherapy can not be presumed similar for birth hospitalisation or readmission groups depending on the age of the patients. This might be the major difference that may explain the higher incidence rate reported by Kaplan et al. than the other large series (2,4). If a standart design is used for reinstitution of phototherapy, I believe that routine measurement of bilirubin level after termination of phototherapy in infants, regardless of low birth weight, prematurity, and positive direct Coombs’ test result, may not be required as it was in our study.

References

1. Kaplan M, Kaplan E, Hammerman C, et al. Post-phototherapy neonatal bilirubin rebound: a potential cause of significant hyperbilirubinaemia. Arch Dis Child 2006;91:31-4.

2. Erdeve O, Tiras U, Dallar Y. Rebound bilirubin measurement is not required for hyperbilirubinemia regardless of the background attributes of the newborns. J Trop Pediatr 2004;50(5):309.

3. American Academy of Pediatrics, Provisional Committee for Quality Improvement and Subcommittee on Hyperbilirubinemia. Practice parameter: Management of hyperbilirubinemia in the healthy term newborns. Pediatrics 1994;94:558-65.

Send letter to journal:
Re: Author's Response: Post-phototherapy bilirubin rebound

Dear Editor,

We thank Dr. Erdeve (e letter posted March 14, 2006) for his comments and for his interest in our paper (1). There appears to be some misunderstanding in Dr Erdeve's interpretation of our data. Dr. Erdeve states that " Kaplan et al. had recommenced phototherapy at bilirubin values >256 µmol/L ". This is incorrect, as we stated explicitly that while we defined rebound as a post-phototherapy total bilirubin > 256 µmol/L, "phototherapy was not reinstituted in all cases of rebound". Our definition of rebound was not synonymous with reinstitution of phototherapy; indeed, in only 73% of the neonates meeting our criteria for rebound was phototherapy restarted. Neither did we attempt to define levels of total bilirubin at which phototherapy should be reinstituted.

Unfortunately, no internationally accepted definition of post- phototherapy bilirubin rebound exists. Although our decision to use a cut- off point of total bilirubin >256µmol/L was somewhat arbitrary, we did expound upon the reasons for using this particular bilirubin concentration in our original paper and our definition was accepted by the experts who participated in the peer-review process. While a bilirubin concentration of 256 µmol/L may not necessarily endanger a post-phototherapy neonate, rise to this concentration of bilirubin does serve to point out the potential for further increase. Indeed, in some of our cases the highest noted rebound value was close to or exceeded 340 µmol/L, a bilirubin concentration that may certainly be of concern in neonates with haemolytic conditions or prematurity

There are some important differences between our study and that of Dr Erdeve (2). Dr Erdeve based his conclusions on a period of follow up of 12 hours. We continued to follow our babies until the bilirubin levels either stabilized or decreased, or the neonates were retreated with phototherapy. If 5.1% of Dr Erdeve's newborns required repeat phototherapy after a 12 hour observation period, it is possible that even more would have required repeat phototherapy had they been followed for longer periods of time. In our opinion, and contrary to Dr Erdeve's statement, the 5.1% retreatment rate is sufficiently high to justify post- phototherapy bilirubin follow up.

We stand by our recommendation that neonates in the high risk groups we identified (direct Coombs’ positive, borderline prematurity and those in whom phototherapy had been instituted <72 hours), be vigilantly followed for the development of potentially dangerous post-phototherapy rebound hyperbilirubinemia.

Michael Kaplan, MB ChB,
Cathy Hammerman, MD.

Department of Neonatology
Shaare Zedek Medical Center
Jerusalem
Israel.

References:

1. Kaplan M, Kaplan E, Hammerman C, Algur N, Bromiker R, Schimmel MS, Eidelman AI. Post-phototherapy neonatal bilirubin rebound: a potential cause of significant hyperbilirubinaemia. Arch Dis Child 2006;91: 31-34