Bilirubin and Bilirubin Fractions


Core Lab Study

Conjugated/direct bilirubin, unconjugated/indirect bilirubin, delta bilirubin, TBil.

A multipurpose laboratory test that is an indicator for various diseases of the liver or conditions associated with RBC hemolysis.

A small group of studies in this manual have been identified as Core Lab Studies. The designation is meant to assist the reader in sorting the basic “always need to know” laboratory studies from the hundreds of other valuable studies found in the manual—a way to begin putting it all together.

Normal, abnormal, or various combinations of core lab study results can indicate that all is well, reveal a problem that requires further investigation with additional testing, signal a positive response to treatment, or suggest that the health status is as expected for the associated situation and time frame.

Bilirubin is included in the liver function test panels (LFTs) and in the comprehensive metabolic panel (CMP). LFTs are used to identify liver disease, assess severity of injury, or monitor disease process and response to treatment. CMPs are used as a general health screen to identify or monitor conditions such as bone disease, diabetes, hypertension, kidney disease, liver disease, or malnutrition.Patient Preparation
There are no food, fluid, activity, or medication restrictions unless by medical direction.

Normal Findings
(Method: Spectrophotometry) Total bilirubin levels in infants should decrease to adult levels by day 15 as the development of the hepatic circulatory system matures. Values in breastfed infants may take longer to reach normal adult levels. Values in premature infants may initially be higher than in full-term infants and also take longer to decrease to normal levels.

AgeConventional UnitsSI Units (Conventional Units × 17.1)
Total Bilirubin
  Newborn–1 dLess than 6 mg/dLLess than 103 micromol/L
  1–2 dLess than 10 mg/dLLess than 171 micromol/L
  3–5 dLess than 12 mg/dLLess than 205 micromol/L
  7–14 dLess than 15 mg/dLLess than 256 micromol/L
  15 d–17 yrLess than 1 mg/dLLess than 17 micromol/L
  18 yr–older adultLess than 1.2 mg/dLLess than 21 micromol/L
Conjugated (direct) bilirubin
  1 yr–older adultLess than 0.3 mg/dLLess than 5 micromol/L
Unconjugated (indirect) bilirubinLess than 1.1 mg/dLLess than 19 micromol/L
Delta bilirubinLess than 0.2 mg/dLLess than 3 micromol/L
The use of different equipment and reagents between laboratories can produce variability in results.

Critical Findings and Potential InterventionsAdults and Children (TBil)

  • Greater than 15 mg/dL (SI: Greater than 257 micromol/L)

Newborns (TBil)

  • Greater than 13 mg/dL (SI: Greater than 222 micromol/L)

Timely notification to the requesting health-care provider (HCP) of any critical findings and related symptoms is a role expectation of the professional nurse. A listing of these findings varies among facilities.

Consideration may be given to verification of critical findings before action is taken. Policies vary among facilities and may include requesting recollection and retesting by the laboratory.

Sustained hyperbilirubinemia can result in brain damage. Kernicterus refers to the deposition of bilirubin in the basal ganglia and brainstem nuclei. There is no exact level of bilirubin that puts infants at risk for developing kernicterus. Symptoms of kernicterus in infants include lethargy, poor feeding, upward deviation of the eyes, and seizures. Intervention for infants may include early frequent feedings to stimulate gastrointestinal (GI) motility, phototherapy, and exchange transfusion.

There's more to see -- the rest of this topic is available only to subscribers.