BRIEF REPORT
Transcutaneous bilirubinometry
should be carried out in
newborn infants at least seven
hours after phototherapy
finishes
Bilirubin rebound, which is a reincrease in serum bilirubin levels after the cessation of phototherapy, may develop due to variations in the rates of bilirubin production and clearance. The most commonly used method for testing bilirubin rebound is measuring total serum bilirubin (TSB) levels, because transcutaneous bilirubin (TcB) gives false-negative results in newborn infants receiving phototherapy or when phototherapy has justfinished. However, TcB is a more preferable method, because TSB is invasive and time-consuming. Limited data exist about when TcB measurement should be carried out after phototherapy has ceased.
This study aimed to determine the earliest point when these two tests could be carried out both simultaneously and accurately after pho-totherapy had ceased.
The study cohort comprised 200 term and late preterm newborns, born at at least 35 weeks of gestation, who were diagnosed with significant hyperbilirubinaemia and started phototherapy. Each group contained 40 infants of various gestational ages. There was also a control group that comprised 40 newborn infants, without significant jaundice, who were born at at least 35 weeks and had undergone testing, using venous blood samples, for metabolic screening or jaundice.
In all cases, the total serum and direct bilirubin levels were measured with the colori-metric method and TcB measurements were taken before phototherapy in the case of thefive study groups and at study entry for the control group. After 24 hours of phototherapy, the blood samples for rebound TSB measurements were drawn, after three, four,five, six or seven hours in study groups one tofive, respectively, and TcB measured simultaneously with a transcutaneous bilirubinometer (Bilichek; Respironics Inc, Mon-roeville, PA, USA). The TcB measurements were taken on the sternum/thoracic region. The maximum time between the blood withdrawal
for TSB measurement and TcB measurement was a maximum of 10 minutes in all cases.
The data were analysed with SPSS for Windows, version 23.0 (IBM Corp, Armonk, NY, USA). The Shapiro–Wilk test was used to determine the normal distribution in the TSB and TcB values. The Pearson correlation test
and linear regression analysis were used to analyse the correlation between the simultane-ous TcB and TSB measurements. Intercept and slope values of regression equation were used to compare the regression models.
The mean rebound TSB value in all of the study groups was 8.72 2.16 mg/dL. The
Figure 1 Comparison of the correlation analysis between rebound transcutaneous and total serum bilirubin measurements after phototherapy among the study and control groups.
1100 ª2018 Foundation Acta Pædiatrica. Published by John Wiley & Sons Ltd 2018 107, pp. 1100–1101
correlation coefficient (r) between the TSB and TcB measurements in the control group was 0.98, and in study groups one tofive, it was 0.60, 0.77, 0.81, 0.94 and 0.93, respectively. When we compared the regression analysis (R2) among the groups using the slope and intercept values of the regression equation, group five, taken at seven hours after phototherapy ceased, was the closest correlation to the control group (r= 0.98), with slope and intercept values of 0.902 and 0.113, respectively (Fig. 1).
Juster-Reicher et al. (1) evaluated 171 jaun-diced newborns with simultaneous TcB and TSB measurements in different postphotother-apy time periods: 1–8, 9–16, 17–24, 25–48, 49–72, 73–95 and 96 hours and reported correlation coefficients of 0.56, 0.73, 0.65, 0.71, 0.72, 0.68 and 0.80, respectively. Similarly, Grabenhenrich et al. (2) compared three time periods– 8–16, 17–24 and more than 24 hours – in 86 newborn infants to assess the correla-tion between TcB and TSB measurements and reported the lowest correlation 1–8 hours after phototherapy. Lucanova et al. (3) reported a correlation coefficient of 0.45 between TcB and TSB measurements two hours after photother-apy in newborn infants who received 9– 126 hours of phototherapy.
Ourfinding that the closest correlation to the control group with regard to TcB and TSB was in study groupfive indicates that the best time to carry out TcB measurements was seven hours or more after stopping phototherapy.
Radfar et al. (4) reported that rebound TSB values measured 30 minutes to three hours after stopping phototherapy were 9.5 2.8 mg/dL in 36 preterm- and 134 term-born jaundiced newborn infants. Grabenhenrich et al. (2) reported that rebound TSB values
measured 1–8 hours after stopping photother-apy were 12.8 2.5 mg/dL in 70 newborn infants receiving phototherapy. And Murli et al. (5) reported that rebound TSB values measured 12 hours after stopping phototherapy were 11.3 2.7 mg/dL in 100 newborn infants with significant hyperbilirubinaemia.
The 200 newborn infants in our five study groups had a mean rebound TSB value, measured 3–7 hours after stopping photother-apy, of 8.72 2.16 mg/dL. The differences between our measurements and other studies were probably due to the different hours when TSB measurements were taken.
There are limited data about the best time to carry out postphototherapy TcB measurement so that it provides the closest correlation to TSB measurements. This study found that when TcB measurements were taken to test for bilirubin rebound, a period of at least seven hours after stopping phototherapy provided the best correlation with TSB measurements. Our recommendation is that TcB can be used both noninvasively and safely after this period as an alternative to the more invasive method of TSB.
FINANCIAL SUPPORT
This study did not receive any specific funding. CONFLICT OF INTERESTS
The authors have no conflict of interests to declare.
References
1. Juster-Reicher A, Flidel-Rimon O, Rozin I, Shinwell ES. Correlation of transcutaneous bilirubinometry (TcB) and total serum bilirubin
(TsB) levels after phototherapy. J Matern Fetal Neonatal Med 2014; 30: 1–3.
2. Grabenhenrich J, Grabenhenrich L, B€uhrer C, Berns M. Transcutaneous bilirubin after phototherapy in term and preterm infants. Pediatrics 2014; 134: e1324.
3. Lucanova LC, Matasova K, Zibolen M, Krcho P. Accuracy of transcutaneous bilirubin measurement in newborns after phototherapy. J Perinatol 2016; 36: 858–61.
4. Radfar M, Hashemieh M, Shirvani F, Madani R. Transcutaneous bilirubinometry in preterm and term newborn infants before and during phototherapy.Arch Iran Med 2016; 19: 323–8. 5. Murli L, Thukral A, Sankar MJ, Vishnubhatla S,
Deorari AK, Paulet VK, et al. Reliability of transcutaneous bilirubinometry from shielded skin in neonates receiving phototherapy: a prospective cohort study. J Perinatol 2017; 37: 182–7.
DOI:10.1111/apa.14272
Agah Akin1, Serdar Umit Sarici1, Murat Ozcan2, Melis Akpinar1, Demet Altun (draltundemet@ gmail.com)1, Yuksel Yasartekin1, Muhittin A. Serdar3, Dilek Sarici4
1.Division of Neonatology, Department of Pedi-atrics, Faculty of Medicine, Ufuk University, Ankara, Turkey
2.Department of Pediatrics, State Hospital, Haymana, Ankara, Turkey
3.Department of Biochemistry, Faculty of Medicine, Acibadem University, Ankara, Turkey
4.Division of Neonatology, Department of Pedi-atrics, Kecioren Education and Research Hospital, Ankara, Turkey
Correspondence
Dr. D Altun, Department of Pediatrics, Ufuk Univer-sity Faculty of Medicine, Balgat-06520, Ankara, Turkey.
Tel: +90 507 491 4749| Fax: +90 312 287 2390| Email: draltundemet@gmail.com
ª2018 Foundation Acta Pædiatrica. Published by John Wiley & Sons Ltd 2018 107, pp. 1100–1101 1101
