Transcutaneous bilirubinometers inaccurate in black African neonates

Last Updated: 2016-08-30

By Will Boggs MD

NEW YORK (Reuters Health) - Transcutaneous bilirubinometers significantly overestimate serum bilirubin and may result in overtreatment in black African neonates, researchers from Nigeria report.

"The magnitude of total plasma/serum bilirubin (TSB) overestimation was most intriguing: transcutaneous bilirubin (TcB) is likely to overestimate serum bilirubin by at least 3 mg/dL in one out of every three black neonates; and the over-estimation may reach 8 mg/dL in some neonates," Dr. Bolajoko O. Olusanya from Center for Healthy Start Initiative, Ikoyi, Lagos, Nigeria told Reuters Health by email.

TcB tends to underestimate TSB in neonates with light or medium skin color and to overestimate TSB in neonates with dark skin color, but there is limited evidence on the divergence between TcB and TSB in settings with predominantly dark-skinned infants or limited access to timely and reliable TSB measurements.

Dr. Olusanya's team investigated the prevalence and correlates of significant TcB overestimation in a black African population to facilitate optimal decisions for appropriate clinical intervention.

Among 1553 healthy infants with 2107 paired TcB-TSB measurements, TcB ranged from 2.1 to 19.9 mg/dL and TSB ranged from 0.3 to 19.5 mg/dL, according to the August 30th Pediatrics online report.

TcB overestimated TSB by at least 2 mg/dL in 64.5%, by at least 3 mg/dL in 42.7%, and by at least 4 mg/dL in 25.7% of all measurements.

Of the 1774 (84.2%) overestimated TSB values  1 mg/dL, only 3.1% of cases required phototherapy.

Underestimation of TSB was uncommon - only 1.1% of all measurements underestimated TSB by 2 mg/dL or more.

"TcB is not a substitute for TSB in this racial group," Dr. Olusanya said. "As much as possible, TSB measurements should serve as basis for initiating treatment for jaundiced neonates. Where timely TSB measurement cannot be assured, physician judgment on the overall clinical conditions of the neonates is critical in initiating treatment based solely on TcB results."

"Until further improvements on available TcB devices are realized, population-based TcB nomograms in this racial group should be considered for identifying infants at high risk of significant hyperbilirubinemia," she said. "Efforts to develop more reliable low-cost point-of-care devices should be accelerated, particularly for low and middle-income countries that presently bear a disproportionate burden of avoidable bilirubin-induced neonatal morbidities."

Dr. Michael Kaplan from The Hebrew University of Jerusalem, who has published extensively on hyperbilirubinemia and glucose-6-phosphate dehydrogenase (G6PD) deficiency, told Reuters Health, "Serum bilirubin measurements are frequently hard to come by in Nigeria. So are transcutaneous devices, in fact, and in the present study were specially provided."

"Transcutaneous bilirubin readings frequently overestimate the serum bilirubin measurement in this population, and TcB readings in the phototherapy zone should be confirmed with a serum test in order to avoid unnecessary hospitalization and treatment," he agreed.

SOURCE: http://bit.ly/2bTv8Ol

Pediatrics 2016.