Does skin pigmentation affect transcutaneous bilirubin (Total Bilirubin) measurements?

From the Guidelines

Skin pigmentation does affect transcutaneous bilirubin (Total Bilirubin) measurements, with devices being less accurate in infants with darker skin tones. This is because melanin in darker skin absorbs and scatters light differently than lighter skin, interfering with the spectrophotometric technology used by TcB devices 1. The accuracy of transcutaneous instruments in different racial groups requires additional study, as noted in the management of hyperbilirubinemia in the newborn infant 35 or more weeks of gestation study published in Pediatrics in 2004 1. Key points to consider include:

• TcB devices generally provide measurements within 2 to 3 mg/dL (34 –51mmol/L) of the TSB and can replace a measurement of serum bilirubin in many circumstances, particularly for TSB levels less than 15 mg/dL (257 mmol/L) 1
• The ability of transcutaneous instruments to provide accurate measurements in different racial groups requires additional study, implying that skin pigmentation may impact the accuracy of TcB measurements 1
• Healthcare providers should be aware of this limitation and consider using serum bilirubin testing for more accurate results in infants with darker skin pigmentation
• Clinical protocols often recommend confirming elevated TcB readings with serum bilirubin measurements, especially in infants with darker skin tones or when readings approach treatment thresholds, to ensure appropriate jaundice management across diverse patient populations while minimizing unnecessary blood draws when possible.

From the Research

Skin Pigmentation and Transcutaneous Bilirubin Measurements

• Skin pigmentation has been found to affect transcutaneous bilirubin (TcB) measurements in several studies 2, 3, 4, 5.
• A study published in 2024 found that TcB measurements were influenced by skin pigmentation, with larger underestimations of TcB at higher bilirubin levels and greater skin pigmentation 2.
• Another study published in 2021 found that the correlation between TcB and serum bilirubin was very good, but with slight differences between darker and lighter skin colors, and that TcB tended to overestimate serum bilirubin in darker-skinned neonates 3.
• A 2024 study found that the reliability of TcB measurements during and after phototherapy depended on skin color, with differences among skin tones after the treatment 4.
• An earlier study published in 2004 found that TcB measurements correlated well with serum total bilirubin levels in indigenous African infants with varying degrees of skin pigmentation 5.
• The influence of skin anatomy on TcB determinations has also been evaluated, with findings suggesting that skin anatomy can considerably influence TcB determinations in non-standard situations, such as on preterm newborns or alternative body locations 6.

Key Findings

• Skin pigmentation affects TcB measurements, with underestimations of TcB at higher bilirubin levels and greater skin pigmentation 2.
• TcB measurements tend to overestimate serum bilirubin in darker-skinned neonates 3.
• The reliability of TcB measurements during and after phototherapy depends on skin color 4.
• TcB measurements are a useful and reliable index for estimating serum total bilirubin levels in pigmented neonates 5.
• Skin anatomy can influence TcB determinations, particularly in non-standard situations 6.