Discrepancies Between Transcutaneous and Serum Bilirubin Measurements

Abstract

OBJECTIVE: To characterize discrepancies between transcutaneous bilirubin (TcB) measurements and total serum bilirubin (TSB) levels among newborns receiving care at multiple nursery sites across the United States.METHODS: Medical records were reviewed to obtain data on all TcB measurements collected during two 2-week periods on neonates admitted to participating newborn nurseries. Data on TSB levels obtained within 2 hours of a TcB measurement were also abstracted. TcB -TSB differences and correlations between the values were determined. Data on demographic information for individual newborns and TcB screening practices for each nursery were also collected. Multivariate regression analysis was used to identify characteristics independently associated with the TcB -TSB difference.RESULTS: Data on 8319 TcB measurements were collected at 27 nursery sites; 925 TSB levels were matched to a TcB value. The mean TcB -TSB difference was 0.84 6 1.78 mg/dL, and the correlation between paired measurements was 0.78. In the multivariate analysis, TcB -TSB differences were 0.67 mg/dL higher in African-American newborns than in neonates of other races (P , .001). The TcB -TSB difference also varied significantly based on brand of TcB meter used and hour of age of the infant. For 2.2% of paired measurements, the TcB measurement underestimated the TSB level by $3 mg/dL. CONCLUSIONS: During routine clinical care, TcB measurement provided a reasonable estimate of TSB levels in healthy newborns. Discrepancies between TcB and TSB levels were increased in African-American newborns and varied based on brand of meter used. WHAT'S KNOWN ON THIS SUBJECT:In most previous studies, transcutaneous bilirubin measurement has been found to provide an accurate estimate of total serum bilirubin levels. However, most of these studies were conducted in settings that optimized accuracy. WHAT THIS STUDY ADDS:This study provides a "real-world" assessment of the accuracy of transcutaneous bilirubin measurements in multiple clinical settings and identification of sources of discrepancy between transcutaneous and total serum bilirubin measurements.

Differences Between Transcutaneous and Serum Bilirubin Measurements in Black African Neonates

“…This observation may possibly be attributable to the dynamic processes, such as changes in hemoglobin concentration, in the early hours of life. 13 The association between exclusive breastfeeding and TSB overestimation appears to be supported by other reports on TcB patterns in relation to feeding mode. 31 -33 Itoh and colleagues, 33 for example, proposed that increased unconjugated bilirubin in breastfed infants may be underpinned by the high enterohepatic circulation of unconjugated bilirubin from deconjugation by β-glucuronidase of the conjugated bilirubin in meconium.…”

“…9, 10, 14, 15, 21 -23 The TSB overestimation is also corroborated by several studies among multiracial populations 10,13,24 and black neonates. 14,15 For example, although Maisels et al 10 found a close correlation between TcB and TSB values among 849 neonates across all ethnic groups, by using JM-103, TSB was overestimated by ≥2 mg/ dL in 37.9% of blacks, compared with 1.8% of whites or 5.4% of other races.…”

“…27 To date, only 1 study is known to have explored the independent predictors of TcB-TSB divergence. 13 In that study, a postnatal age…”

“…Similarly, in a multicenter study of 769 racially and ethnically diverse newborns with at least 1 TcB-TSB pair, Taylor et al found that African-American race was independently associated with a higher chance of TSB overestimation by at least 2 mg/dL (OR, 2.19; 95% CI, 1.09-4.39). 13 In a predominantly black population, 1 study from Malawi reported TSB overestimation in term neonates not receiving phototherapy as indexed by a mean bias of 1.5 (SD, 4.2) mg/dL in the TcB measurements. 15 JM-103 overestimated TSB in this population by a greater magnitude than BiliChek.…”

“…12 Limited evidence exists on the pattern and predictors of individual TcB-TSB divergence, especially in settings with predominantly dark-skinned infants or limited access to timely and reliable TSB measurements. [13][14][15] This study, therefore, set out to determine the prevalence and correlates of significant TcB overestimation in a black African population to facilitate optimal decisions for appropriate clinical intervention.…”