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How accurate is transcutaneous bilirubin testing in newborns with darker skin tones?

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Fairly accurate. Photometric transcutaneous bilirubin (TcB) testing may overestimate total serum bilirubin (TSB) in neonates with darker skin tones by a mean of 0.68 to > 2 mg/dL (strength of recommendation [SOR]: C, diagnostic cohort studies with differing reference standards).

Overall, TcB meters retain acceptable accuracy in infants of all skin tones across a range of bilirubin levels, despite being more likely to underestimate lighter skin tones and overestimate darker ones (SOR: C, diagnostic cohort studies with differing reference standards). It is unclear if the higher readings prompt an increase in blood draws or otherwise alter care.




Some evidence suggests overestimation in all skin tones

In a prospective diagnostic cohort study of 1553 infants in Nigeria, the accuracy of TcB measurement with 2 transcutaneous bilirubinometers (Konica Minolta/Air Shields JM- 103 and Respironics BiliChek) was analyzed. 1 The study population was derived from neonates delivered in a single maternity hospital in Lagos who were ≥ 35 weeks gestational age or ≥ 2.2 kg.

Using a color scale generated for this population, researchers stratified neonates into 1 of 3 skin tone groups: light brown, medium brown, or dark brown. TcB and TSB paired samples were collected in the first 120 hours of life in all patients. JM-103 recordings comprised 71.9% of TcB readings.

Overall, TcB testing overestimated the TSB by ≥ 2 mg/dL in 64.5% of infants, ≥ 3 mg/dL in 42.7%, and > 4 mg/dL in 25.7%. TcB testing underestimated the TSB by ≥ 2 mg/dL in 1.1% of infants, ≥ 3 mg/dL in 0.5%, and > 4 mg/dL in 0.3%.1

Local variation in skin tone was not associated with changes in overestimation, although the researchers noted that a key limitation of the study was a lack of lighttoned infants for comparison.1

A prospective diagnostic cohort study of 1359 infants in Spain compared TcB measurements to TSB levels using the Dräger Jaundice Meter JM-105.2 Patients included all neonates (gestational age, 36.6 to 41.1 weeks) born at a single hospital in Barcelona.

Using a validated skin tone scale, researchers stratified neonates at 24 hours of life to 1 of 4 skin tones: light (n = 337), medium light (n = 750), medium dark (n = 249), and dark (n = 23). They then obtained TSB samples at 48 to 72 hours of life, along with other routine screening labs and midsternal TcB measurements.

TcB testing tended to overestimate TSB (when < 15 mg/dL) for all skin tones, although to a larger degree for neonates with dark skin tones (mean overestimation, 0.7 mg/dL for light; 1.08 mg/dL for medium light; 1.89 mg/dL for medium dark; and 1.86 mg/dL for dark; P < .001 for light vs medium dark or dark).2

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