Postductal Serum Bilirubin (Infant)
This test measures the amount of bilirubin in your baby’s blood after the umbilical cord has been cut (postductal). Bilirubin is a yellow pigment produced when red blood cells break down, and high levels can indicate conditions like jaundice.
["Bilirubin helps identify if your baby’s liver is processing blood breakdown products correctly."]
Key facts at a glance
- LOINC
- 73792-4
- Short code
- Infant active postductal Patient
- Synonyms
- Infant active postductal Patient
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 44
- Ref high
- 147
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 84075
- SNOMED
- 27550007
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why Is This Test Done?
Doctors may order this test if your baby shows signs of jaundice, such as yellowing of the skin or eyes, or if they have a history of conditions that increase bilirubin levels (e.g., prematurity, genetic disorders). It helps monitor whether treatment is needed to prevent complications.
What to Expect Before the Test
No special preparation is needed. The test is typically done by drawing blood from a vein in your baby’s arm. The process is quick and usually painless, though some babies may fuss briefly. Your healthcare provider will explain the procedure and keep your baby calm.
What Happens During the Test?
A healthcare professional will clean the skin with an antiseptic, insert a small needle into a vein, and collect a small amount of blood. The blood is then sent to a lab for analysis. The test itself takes only a few minutes, and your baby may need to rest afterward.
What the Results Mean
Bilirubin levels are measured in milligrams per deciliter (mg/dL). High levels can be dangerous if left untreated, as they may cause brain damage. Your doctor will interpret the results in relation to your baby’s age, symptoms, and overall health to determine if further action is needed.
Reference range
Adult: 44-147 U/LN/A
No special preparation required. Avoid fatty meals before the test if possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Bilirubin Level (Post-Ductal)
Frequently asked questions
Will my baby need to fast before this test?
How long will I have to wait for the results?
Is there anything I can do to prepare my baby for the blood draw?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy