Transcutaneous Bilirubin Measurements Research Articles

Influence of skin colour on diagnostic accuracy of the jaundice meter JM 103 in newborns

AimTo assess the diagnostic accuracy of the JM 103 as a screening tool for neonatal jaundice and explore differential effects based on skin colour.MethodsWe prospectively compared the transcutaneous bilirubin (TcB)...

Simultaneous measurement of total transcutaneous bilirubin on forehead and chest as a predictive model for total serum bilirubin in premature and term newborns

Background: detection of hyperbilirubinemia in neonates has become a challenge for healthcare systems. The objective of this study was to determine the usefulness of simultaneous measurements of total transcutaneous bilirubin on forehead (TTBf) and total transcutaneous bilirubin on chest (TTBs) as a predictive model for total serum bilirubin (TSB) in premature and term neonates.

Medición simultánea de bilirrubina total transcutánea en frente y esternón como modelo predictivo de bilirrubina total sérica en recién nacidos prematuros y de término

Background. Detection of hyperbilirubinemia in newborn has become a challenge for health care systems. The aim of the study was to prove the usefulness of concurrent total transcutaneous bilirubin measurement over forehead (TTBf) and total transcutaneous bilirubin over sternum (TTBs) as predictive model for total serum bilirubin (TSB) in premature and term newborns. Material and Method. Transversal and analytical study in 30-42 gestation week newborns from January 21st to April 30th 2013 in a gynecology, obstetrics and neonatology specialties public hospital. Pearson´s correlation for TSB/TTBf and TSB/TTBs was carried out. Linear regression analysis for one and several predictive variables were performed. Results. For 89 concurrent measurements, the correlation TSB/TTBf was 0.8411 and for TSB/TTBs, 0.7942 (p value < 2.2E-16 in both cases). With simple regression analysis for TSB and TTBf, the equation was: TSB = 2.1187 + 0.7035 × TTBf (p < 2.2E-16, R2 = 70.75%, R2 adjusted = 70.41%); for TSB and TTBs the equation was: TSB = 2.0405 + 0.6349 × TTBs (p < 2.2E-16, R2 = 63.07%, R2 adjusted = 62.65%). With multiple regression analysis for TSB vs. TTBf, TTBs, the equation was: BTS = 1.620 + 0.503 × TTBf + 0.224 × TTBs (p < 2.2 E-16, R2 = 72.87%, R2 adjusted = 72.24%). Conclusions. It was demonstrated that TTBf, TTBs model allowed to obtain better TSB prediction than TTB single measurement models for in-patient premature and term newborns. Key words: Transcutaneous bilirubin, bilirubinometer, neonatal hyperbilirubinemia, kernicterus.

Reproducability of non-invasive bilirubin measurements.

To determine the level of agreement between transcutaneous bilirubin (TcB) measurements when sequentially measured by one and two users. A method comparison study design was used to compare two sequential TcB measurements (JM103, Drager Medical Inc., Telford, PA) obtained by the same user and then by two different users. Users were blinded to each others' results. Differences (bias) and limits of agreement (±2 precision or SD) between sequential measurements with the TcB by a single user and two users were calculated and graphed using the Bland-Altman method. Acceptable levels for bias and precision were set a priori at bias ≤±1.5 mg/dL and/or precision ≤±3.0 mg/dL. A total of 34 newborn infants were studied, with total serum bilirubin (TSB) levels ranging from 2.7 to 8.1 mg/dL, averaging (±SD) 5.5 ± 1.8 mg/dL. Differences (bias) and the level of agreement (precision; SD) for two sequential noninvasive TcB measurements obtained by a single user and two different users (-0.2 ± 0.7 and -0.4 ± 0.7, respectively) were within the acceptable ranges. We found good agreement between TcB measurements obtained sequentially by a single user and by two different users of the device, as well as between laboratory TSB values in low-risk newborn infants with normal bilirubin levels. These findings support the use of a noninvasive bilirubin meter to screen for hyperbilirubinemia, which could reduce the amount of blood obtained invasively from newborns.

Transcutaneous bilirubinometry is not influenced by term or skin color in neonates

BackgroundThe utility of transcutaneous bilirubin measurements (TcB) in screening for hyperbilirubinemia in preterm infants (<34weeks) and in non-white infants remains a matter of debate. AimTo evaluate accuracy of TcB in preterm and term infants of different ethnic backgrounds, using a second generation bilirubinometer. Study designThe Draeger JM-103® device was used to measure TcB. Eighty five measurements of TcB and total serum bilirubin (TSB) were retrospectively compared. Neonates were stratified into groups according to gestational age: <34weeks (group 1, n=44) and >34weeks (group 2, n=41), and according to ethnic origin: Caucasians (group A, n=49) and non-Caucasians (group B, n=36).Statistical analysis, using Pearson's correlation coefficient (r) and Bland–Altman analysis were performed to evaluate correlation and agreement between TSB and TcB values. Multiple linear regression was used to control for confounders for TSB values. ResultsCorrelation between TSB and TcB was high. Pearson's correlation coefficients were over 0.9 in all groups (0.910, 0.908, 0.916 and 0.934, p<0.0001 in groups 1, 2, A, and B respectively). Bland–Altman plots showed acceptable and close limits of agreements (56.8/−57.7, 54.2/−67.2, 57.7/−55.8, and 51.3/−69.9μmol/L in groups 1, 2, A and B respectively) with a trend for TcB to overestimate TSB in groups 2 and B. Birth term and skin color were not identified as confounding factors for predicting TSB in multiple linear regression. ConclusionsTcB measurements using the Draeger JM-103® device correlate significantly with TSB, regardless of term and skin color. Transcutaneous bilirubinometry seems to be a safe and cost-effective screening method for severe hyperbilirubinemia in newborns of different terms and ethnic origins.

Validation of transcutaneous bilirubin nomogram for identifying neonatal hyperbilirubinemia in healthy Chinese term and late-preterm infants: a multicenter study

Objectiveto prospectively validate a previously constructed transcutaneous bilirubin (TcB) nomogram for identifying severe hyperbilirubinemia in healthy Chinese term and late-preterm infants. Methodsthis was a multicenter study that included 9,174 healthy term and late-preterm infants in eight hospitals of China. TcB measurements were performed using a JM-103 biliru-binometer. TcB values were plotted on a previously developed TcB nomogram, to identify the predictive ability for subsequent significant hyperbilirubinemia. Resultsin the present study,972 neonates (10.6%)developedsignificant hyperbilirubinemia. The 40th percentile of the nomogram could identify all neonates who were at risk of significant hyperbilirubinemia, but with a low positive predictive value (PPV) (18.9%). Of the 453 neonatesabove the 95th percentile, 275 subsequently developed significant hyperbilirubinemia, with a high PPV (60.7%), but with low sensitivity (28.3%). The 75th percentile was highly specific (81.9%) and moderately sensitive (79.8%). The area under the curve (AUC) for the TcB nomogram was 0.875. Conclusionsthis study validated the previously developed TcB nomogram, which could be used to predict subsequent significant hyperbilirubinemia in healthy Chinese term and late-preterm infants. However, combining TcB nomogram and clinical risk factors could improve the predictive accuracy for severe hyperbilirubinemia, which was not assessed in the study. Further studies are necessary to confirm this combination.

Recém-nascido no Serviço de Urgência: casuística do ano 2011 de um Centro Hospitalar

Introduction: The birth of a child is a challenge for parents. Thus, during the neonatal period many questions arise to parents, leading to frequent visits to the Emergency Department (ED), often unjustified from a clinical point of view. Objectives: Characterization of newborn visits to the paediatric ED for a 12 months’ period, and evaluation of the need for emergency paediatric care.. Material and methods: Retrospective study of all neonates’ visits to the ED in our hospital from January to December 2011, analysing clinical and demographic data. Results: During the study period, a total of 394 neonates were admitted in the ED (20% visited more than once), representing 1,3% of all paediatric visits; 20% were referred by health professionals. The main causes of ED utilisation were alimentary tract complaints (31%), dermatological issues (18%), jaundice(17%) and respiratory symptoms (15%). Diagnostic tests were required in 44%, mostly transcutaneous bilirubin measurement and urine analysis. Only 18% of the patients received treatment. The most frequent diagnoses were benign neonatal pathology and healthy care child issues in 57% of cases (n=283). The majority of neonates (75,6%) was discharged. 56,8% of mothers were primiparous and the median maternal age was 30 years. Half of the mothers with known literacy skills, studied during more than nine years. Conclusions: Most neonatal utilisation of emergency paediatric services is due to non-urgent conditions that could be managed in primary care. We underline the importance of proper support and education of mothers during pregnancy and neonatal period. Nevertheless due to the lack of specificity of the neonatal symptoms, paediatricians must be alert to rule out severe disease.

Plotting Transcutaneous Bilirubin Measurements on Specific Transcutaneous Nomogram Results in Better Prediction of Significant Hyperbilirubinemia in Healthy Term and Near-Term Newborns: A Pilot Study

Background: The American Academy of Pediatrics has recommended a systematic assessment before discharge for the risk of severe hyperbilirubinemia. Plotting total serum bilirubin (TSB) or transcutaneous bilirubin (TcB) on a TSB hour-specific nomogram is proposed as a tool for laboratory evaluation. Objectives: The aim of this study was to compare the predictive characteristics, particularly the incidence of false negative rate (FNR), of the practice of plotting TcB values on the TSB hour-specific risk nomogram versus on transcutaneous nomogram. Methods: Paired TSB and TcB measurements were conducted on 141 newborns. Risk of developing significant hyperbilirubinemia was defined as infants with bilirubin level ≥75% on TSB or ≥95% on TcB nomogram. TSB values, plotted on the TSB nomogram of Bhutani et al. [Pediatrics 1999;103:6-14], were used as reference. TcB values were plotted on the TSB nomogram and on the transcutaneous nomograms of Maisels and Kring [Pediatrics 2006;117:1169-1173] and Fouzas et al. [Pediatrics 2010;125:e52-e57]. Results: Plotting TcB measurements on a TSB nomogram resulted in a trend towards a higher FNR when compared to Maisels' and Fouzas' nomograms (18.0/1,000 compared to 10.2/1,000 and 8.6/1,000 respectively). Although not statistically significant, plotting TcB on transcutaneous nomogram resulted in better predictive values with the Fouzas' nomogram, having the best sensitivity (90.0%) and specificity (87.79%) as well as the highest positive (35.97%) and negative (99.14%) predictive value. Conclusion: Plotting TcB on a TSB nomogram may result in increased rate of FNR and decreased predictive characteristics. The practice of plotting TcB on a TSB nomogram needs further evaluation.

Validation of transcutaneous bilirubin nomogram for identifying neonatal hyperbilirubinemia in healthy Chinese term and late‐preterm infants: a multicenter study

Objectiveto prospectively validate a previously constructed transcutaneous bilirubin (TcB) nomogram for identifying severe hyperbilirubinemia in healthy Chinese term and late‐preterm infants. Methodsthis was a multicenter study that included 9,174 healthy term and late‐preterm infants in eight hospitals of China. TcB measurements were performed using a JM‐103 bilirubinometer. TcB values were plotted on a previously developed TcB nomogram, to identify the predictive ability for subsequent significant hyperbilirubinemia. Resultsin the present study, 972 neonates (10.6%) developed significant hyperbilirubinemia. The 40th percentile of the nomogram could identify all neonates who were at risk of significant hyperbilirubinemia, but with a low positive predictive value (PPV) (18.9%). Of the 453 neonates above the 95th percentile, 275 subsequently developed significant hyperbilirubinemia, with a high PPV (60.7%), but with low sensitivity (28.3%). The 75th percentile was highly specific (81.9%) and moderately sensitive (79.8%). The area under the curve (AUC) for the TcB nomogram was 0.875. Conclusionsthis study validated the previously developed TcB nomogram, which could be used to predict subsequent significant hyperbilirubinemia in healthy Chinese term and late‐preterm infants. However, combining TcB nomogram and clinical risk factors could improve the predictive accuracy for severe hyperbilirubinemia, which was not assessed in the study. Further studies are necessary to confirm this combination.

Interscapular site for transcutaneous bilirubin measurement in preterm infants: a better and safer screening site

To prevent bilirubin induced brain injury in the newborn, repeated blood withdrawals are necessary to ascertain bilirubin levels and institute care. Noninvasive, painless and bloodless screening using transcutaneous bilirubinometry is the standard of care for term and near term neonates but there is still debate about its use with preterm neonates. The aims of this study were to determine how transcutaneous bilirubin (TcB) level measured from the interscapular site related to total serum bilirubin (TSB) level and to compare performance of TcB from the forehead, sternum and interscapular sites in identifying preterm neonates in need of phototherapy. This was a cross sectional study conducted at Groote Schuur level III neonatal unit. Over a 5-month period 122 consecutive preterm neonates <35 weeks gestational age were enrolled. TcBs were measured over the forehead, sternum and interscapular area. Pearson's correlation coefficients and differences between TSB and TcBs were computed. P-value <0.05 was considered significant. The median gestational age of the study participants was 31 weeks (range: 24 to 34 weeks), the median TSB level was 81.5 μmol l(-1) (range: 25 to 229 μmol l(-1)) and 45% had a TSB at the phototherapy threshold. The correlation coefficients for TcBs ranged from 0.859 to 0.929 (P<0.001). The difference between TSB and TcBs ranged from -86 to +51 μmol l(-1). With respect to initiating phototherapy, the interscapular site had the highest sensitivity of 94% and lowest false negative rate of 6%. Using transcutaneous bilirubinometry, the interscapular site is superior and safer for screening preterm neonates.

Can transcutaneous bilirubinometry safely guide phototherapy treatment of neonatal jaundice in Malawi?

Objectives:To assess the correlation between total serum bilirubin (TSB) and transcutaneous bilirubin (TcB) values in Malawian newborn infants, and to investigate whether TcB can be used safely to guide phototherapy treatment in the absence of TSB results.Methods:128 newborn jaundiced infants were studied in the neonatal nursery at Queen Elizabeth Central Hospital, Blantyre. Paired TSB and TcB measurements (from forehead and sternum) were compared using the linear regression and Bland–Altman methods. Clinical decisions based on TcB results were compared with those based on ‘gold standard’ TSB results.Results:For infants not under phototherapy, the lowest TcB reading (from forehead or sternum) gave the strongest correlation with TSB: r = 0·83 for term infants and r = 0·71 for premature infants. For infants undergoing phototherapy, the highest TcB reading gave the strongest correlation with TSB: r = 0·66 for term infants and r = 0·71 for premature infants. TcB values overestimated the degree of jaundice. For infants not under phototherapy, the mean (SD) bias and imprecision of TcB was 25 (72) μmol/L for term infants and 37 (73) μmol/L for premature infants. For infants under phototherapy, the mean bias and imprecision was 30 (79) μmol/L for term infants and 44 (77) μmol/L for premature infants. For infants not under phototherapy, using the lowest TcB reading to guide treatment decisions (n = 167) had good sensitivity (91%) and specificity (90%). For infants undergoing phototherapy, using the highest TcB reading to guide treatment decisions (n = 129) had good sensitivity (94%), but lower specificity (36%).Conclusions:TcB can be used to safely guide phototherapy treatment in a resource-poor setting.

Validation of a transcutaneous bilirubin meter in Mongolian neonates: comparison with total serum bilirubin

BackgroundNeonatal hyperbilirubinemia, especially kernicterus, can be prevented by screening for neonatal jaundice. The transcutaneous bilirubin (TcB) meter is a non-invasive medical device for screening neonates. The study aimed to investigate the validity of a TcB meter in a resource-limited setting such as Mongolia.MethodsTerm and late preterm neonates from the National Center for Maternal and Child Health of Ulaanbaatar in Mongolia who met the inclusion criteria (gestational age ≥35 weeks, birth weight ≥2000 g, postnatal age ≤ 1 month) were enrolled in the study. We used a TcB meter, JM-103 to screen for neonatal jaundice. TcB measurements at the infant’s forehead and midsternum were performed within 3 h of obtaining samples for total serum bilirubin (TSB) measurement. We analyzed the correlation between TcB measurements and TSB measurements to validate the meter.ResultsA total of 47 term and six late preterm neonates were included in the study. TcB measured by the meter at both the forehead and the midsternum showed a strong correlation with TSB measured in the laboratory. The correlation equations were TSB = 1.409+0.8655 × TcB (R2=0.78871) at the forehead, and TSB = 0.7555+0.8974 × TcB (R2=0.78488) at the midsternum. Bland-Altman plots and the Bradley-Blackwood test showed no significant differences between the two methods at all measured ranges of bilirubin. The mean areas under the curves of TcB at the forehead and midsternum at three TSB levels (>10 mg/dL, >13 mg/dL, >15 mg/dL) of TcB were greater than 0.9, and all had high sensitivity and specificity.ConclusionsThis study established the validity of the JM-103 meter as a screening tool for neonatal jaundice in term and late preterm infants in Mongolia. Future studies are needed, including the establishment of a TcB hour-specific nomogram, for more effective clinical practice to prevent severe hyperbilirubinemia.

Hour-specific nomogram for transcutaneous bilirubin in Japanese neonates

The measurement of transcutaneous bilirubin (TcB) is very important to screen for hyperbilirubinemia in newborns. Until now, however, there has been no hour-specific, percentile-based TcB nomogram during the early neonatal period in Japanese neonates. The aim of this study was to develop a TcB nomogram within 72 h of birth in Japanese neonates. A total of 3152 TcB measurements for 181 healthy Japanese neonates (gestational age ≥36 weeks, birthweight ≥2300 g) were obtained within 72 h of birth. All measurements were performed with a Konica Minolta jaundice meter, the JM-103. A nomogram curve was plotted to show the trend of TcB level over time. The nomogram curves rose almost linearly for all percentiles until 72 h after birth. An hour-specific, percentile-based TcB nomogram during the first 72 h after birth in Japanese neonates was successfully developed. Because Japanese neonates have higher and later peak bilirubin, an original hour-specific 97.5th percentile-based TcB nomogram may be needed to identify early-onset jaundice and manage neonatal hyperbilirubinemia.

Accuracy of transcutaneous bilirubin measurement in preterm low-birth-weight neonates

The objective of this study was to evaluate the correlation and agreement between transcutaneous and serum bilirubin among preterm low-birth-weight neonates. Neonates born at <35 weeks of gestation with birth weight <2,000 g were enrolled prospectively. Transcutaneous bilirubin (TcB) was measured at forehead, sternum, and abdomen at 24 ± 6 and 72 ± 12 h after birth and when icterus involved arms or legs (Kramer zone 4-5). Serum total bilirubin (STB) was measured by microbilimeter (STB-M) at all these time-points and by high-performance liquid chromatography (STB-H) at one randomly chosen time-point. A total of 1,619 observations were made in 256 neonates (median gestation, 34 weeks (IQR, 32-35), birth weight 1,522 ± 288 g). Overall there was excellent correlation and agreement between TcB and STB-M with TcB on forehead being most accurate (r = 0.84, mean difference, 0.3 ± 1.9 mg/dL) followed by TcB on abdomen (r = 0.73, mean difference, 1.5 ± 2.6 mg/dL) and sternum (r = 0.72, mean difference, 1.5 ± 2.6 mg/dL). TcB performed well at all three points of measurement with best correlations being observed at icterus level 4/5. Correlation between TcB and STB-H measured by high-performance liquid chromatography was less strong but significant (r = 0.59 to 0.69 at different time points of measurement). TcB has good correlation and agreement with STB in preterm low-birth-weight neonates born at ≥28 weeks of gestation.

Sixth hour transcutaneous bilirubin predicting significant hyperbilirubinemia in ABO incompatible neonates

Neonates with ABO hemolytic disease are at greater risk for developing significant hyperbilirubinemia. We aimed to determine whether sixth hour transcutaneous bilirubin (TcB) could predict such a risk. TcB measurements were obtained at the 6th hour of life in blood group A or B neonates born to blood group O, rhesus factor compatible mothers. Subsequent hyperbilirubinemia was monitored and considered significant if a neonate required phototherapy/exchange transfusion. The predictive role of sixth hour TcB was estimated. Of 144 ABO incompatible neonates, 41(OA, 24; O-B, 17) had significant hyperbilirubinemia. Mean sixth hour TcB was significantly higher among neonates who developed significant hyperbilirubinemia than those who did not (5.83±1.35 mg/dL vs. 3.65±0.96 mg/dL, P<0.001). Sixth hour TcB value >4 mg/dL had the highest sensitivity of 93.5% and >6 mg/dL had the highest specificity of 99%. Area under receiver operating characteristic curve was 0.898. Sixth hour TcB predicts subsequent significant hyperbilirubinemia in ABO incompatible neonates.

Accuracy and precision of transcutaneous bilirubinometry in postdischarge Asian neonates

A prospective cross-sectional study was conducted in a tertiary care center to determine the accuracy of transcutaneous bilirubin measurements (TcB) measured by the Konica Minolta JM-103™ meter compared to total serum bilirubin (TSB) in Asian infants aged 5-14 days. There were 405 late-preterm and term infants involved, and 455 paired samples were obtained by venepuncture and analyzed for bilirubin levels. TcB measurements were performed using the average of three measurements (TcB3) and a single measurement (TcB1) method. The overall correlation between TSB and the TcB was 0.80 (p ≤ 0.001) for TcB3 and 0.76 (p ≤ 0.001) for TcB1, respectively. The mean (SD) difference between TcB3 and TSB was -17.6 (29.5) μmol/L (median, -17.0; interquartile range (IQR), -39.1 to 1.7) and between TcB1 and TSB was -20.7 (32.3) μmol/L (median, -20.4; IQR, -42.5 to 1.7). The mean difference (SD) between the TcB3 and TSB in the low-risk (TSB < 170 μmol/L), intermediate-risk (TSB 170-254 μmol/L), and high-risk (TSB ≥ 255 μmol/L) groups was -2.8 (27.2), -13.4 (27.0), and -33.4 (29.1) μmol/L, respectively. To detect a TSB level of ≥255 μmol/L, using the TcB cutoff level of 204 μmol/L provides a sensitivity of 96 % with a specificity of 58 %. The TcB meter using a specific cutoff level can be reliably used as a screening tool for jaundice detection in older, postdischarge neonates, including the Asian population. Lower cutoff values can be set to capture all infants who merit closer surveillance, potential investigation, and treatment with higher accompanying screening costs.

The Value of Transcutaneous Bilirubin Measurement from a Protected Forehead Skin during Phototherapy in Newborns with Neonatal Hyperbilirubinemia

The Value of Transcutaneous Bilirubin Measurement from a Protected Forehead Skin during Phototherapy in Newborns with Neonatal Hyperbilirubinemia

1742 A Comparison of Neonatal Bilirubin Determined by Blood gas Analyzer and auto Analyzer

As high levels of serum bilirubin well known to be toxic to the brain especially preterm neonates, many methods adapted for bilirubin measurement. We evaluated total bedside blood gas analyzer...

Neonatal Bilirubin Triage With Transcutaneous Meters: When is a Blood Draw Necessary?

To find the optimal transcutaneous bilirubin (TcB) screening level in term neonates that minimizes the discomfort of phlebotomy, while protecting the child from harm and controlling costs. All available TcB and total serum bilirubin (TSB) measurements taken between 27 and 51 hours of life from a cohort of term newborns were analyzed in a retrospective chart review. TcB cutoffs between 6 and 12 mg/dL were evaluated for their negative predictive values (NPVs) for high risk (HR) and for the combination of high-intermediate risk and HR on the Bhutani TSB risk nomogram. One thousand seventy-one full-term newborns were entered into the study. Of 601 newborns with TcB < 7 mg/dL, none were HR by TSB. Of newborns with a TcB of < 8 mg/dL, 1 in 759 was HR. The NPVs for screening levels of 7 and 8 mg/dL were of 100% and 99.9%, respectively, for HR and 99% and 97.60%, respectively, for high-intermediate/HR. A cutoff at 12 mg/dL had NPVs of 99.3% for HR, with 7 neonates, and 92.7% for high-intermediate/HR, with 76 infants of 1041. In our center, term infants with a TcB of < 8 mg/dL may be safely discharged without a follow-up TSB, with the understanding that -1/1000 infants may be at HR for developing severe hyperbilirubinemia. Practices with universal follow-up may safely choose cutoffs up to 12 mg/dL. An institution's degree of comfort and confidence in follow-up of the newborn cohort will guide the choice of an appropriate TcB cutoff requiring a TSB.

Trends of Transcutaneous Bilirubin in Neonates Who Develop Significant Hyperbilirubinemia

To provide data on the natural course of transcutaneous bilirubin (TcB) levels in neonates before the development of significant hyperbilirubinemia, and to assess the effect of different demographic and perinatal factors on the rate of TcB increase. We analyzed 2454 TcB measurements from 419 neonates before the development of significant hyperbilirubinemia. Mean TcB values and TcB percentiles for designated times were calculated, and the effect of different risk factors on the rate of TcB increase was assessed. TcB percentile curves were plotted for comparison on a population-based TcB nomogram. Blood incompatibilities and glucose-6-phosphate dehy-drogenase deficiency were associated with higher rates of TcB in-crease during the first 36 to 48 postnatal hours, whereas smaller gestational age, increased weight loss, and exclusive breastfeeding had a similar but later effect. Compared with general population norms, a different pattern of TcB increase was noted in neonates who developed significant hyperbilirubinemia, but with a sub-stantial overlap of TcB values during the first 24 to 48 postnatal hours. We provide data on the natural course of TcB levels before the development of significant hyperbilirubinemia in a white population of term and near-term neonates. Smaller gestational age, blood incompatibilities, glucose-6-phosphate dehydrogenase deficiency, increased weight loss, and exclusive breastfeeding significantly affected the rate of TcB increase in a time-dependent manner. These findings may assist in assessing the risk for significant hyperbilirubinemia and planning appropriate follow-up strategies for neonates with borderline bilirubin levels.