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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