Thyroxine-Binding Globulin Deficiency Screening, Dried Blood Spot — Interpretation
A dried blood spot screening test used to help identify possible thyroxine-binding globulin deficiency, a condition that can affect thyroid hormone transport.
["An abnormal screening result may indicate reduced thyroxine-binding globulin and should be confirmed with additional testing."]
Key facts at a glance
- LOINC
- 46764-7
- Short code
- TBG Deficiency DBS-Imp
- Synonyms
- TBG Deficiency DBS-Imp
- Category
- thyroid
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- 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
What is this test?
This test uses a dried blood spot to screen for possible thyroxine-binding globulin deficiency. Thyroxine-binding globulin, or TBG, is a blood protein that carries thyroid hormones throughout the body.
Why might I need this test?
This screening is often part of newborn or early-childhood blood testing because inherited TBG deficiency may cause abnormal thyroid test results even when a person's thyroid gland is functioning normally. It may also be used when unexplained thyroid findings suggest a problem with thyroid hormone transport.
How is the test performed?
A few drops of blood are collected, usually by a heel prick in newborns, and placed on a filter-paper card to form a dried blood spot. The laboratory analyzes the specimen and reports whether the screening result is normal, abnormal, or needs further evaluation.
How do I prepare for the test?
This test usually requires no special preparation. Follow the instructions provided by the laboratory or healthcare professional, and tell them if you have had a recent blood transfusion because it may affect the results.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
An abnormal result may suggest low or absent TBG, which can alter the amount of thyroid hormone measured in blood. This may reflect an inherited condition or another cause of altered TBG and does not by itself confirm a thyroid disorder. Follow-up testing is often needed to clarify the result and assess thyroid function.
Short name
TBG deficiency screening (dried blood spot)
Frequently asked questions
Does an abnormal result mean I have a thyroid disease?
What happens after an abnormal screening result?
Can this test diagnose the cause of low TBG?
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