Transcutaneous bilirubin (TcB) measurement is a way to find out how much bilirubin is in the blood. Bilirubin is released into the blood when red blood cells break down. The liver uses bilirubin to make bile.
Normally there is only a small amount of bilirubin in the blood. High levels may be caused by liver or blood problems. When the bilirubin level rises, it causes the skin and whites of the eyes to become yellow. This change to yellow is called jaundice.
Bilirubin often builds up to higher levels in newborn babies. Usually this does not cause a problem. However, sometimes it causes serious problems.
The test sends a quick flash of light through the skin. (Transcutaneous means through the skin.) The measurement is usually taken by gently pressing the meter against the breast bone (sternum). TcB measures the bilirubin without having to do a blood test.
The test is repeated three times and the average of the three measurements shows on the meter.
TcB may be used to check bilirubin if the baby:
Using the TcB meter can help check for changes in the bilirubin level. This allows doctors to follow the baby’s bilirubin level closely. TcB measurements have been shown to be good tests for bilirubin. When bilirubin levels are low, using TcB may prevent a child from having blood drawn. But TcB tests do not take the place of blood tests. Certain types of blood problems associated with jaundice, such as blood group problems, make it especially important to do blood tests for bilirubin.
If the bilirubin is increasing, a blood test may need to be done and bilirubin lights may have to be used to help reduce the bilirubin.