TBG (Thyroxine Binding Globulin)
Quest Diagnostics
Sample type: Serum
Requires fasting: No
Phlebotomy required
Details
TBG (Thyroxine Binding Globulin) - Thyroxine-binding globulin (TBG), a glycoprotein produced in the liver, binds both thyroxine (T4) and triiodothyronine (T3) with high affinity. Because TBG accounts for 76% of plasma protein thyroxine-binding activity, an increase or decrease in its circulating level alters total concentrations of T4 and T3 in blood, leading to potential confusion with true thyroid gland dysfunction. A number of diseases and medications, as well as inherited alterations in TBG gene expression, can change the serum TBG concentration. Measurement of TBG is useful in distinguishing quantitative TBG derangements from thyroid dysfunction. This analyte is elevated with estrogen therapy (especially oral contraceptive agents), during pregnancy and or hepatitis. Serum TBG may be decreased in cirrhosis, in the nephritic syndrome and by androgens.
- TBG (Thyroxine Binding Globulin)
Estimated days for results: Results should be available in 2 - 5 business days after the sample is collected
2–5 business days
Sex Reference Range
Male 12.7–25.1 mcg/mL
Female 13.5–30.9 mcg/mL
Pediatric
Age Reference Range
4–6 Years 14.8–32.9 mcg/mL
7–8 Years 16.3–30.7 mcg/mL
9–10 Years 15.8–27.4 mcg/mL
11 Years 15.5–27.4 mcg/mL
12 Years 14.8–26.2 mcg/mL
13 Years 13.8–25.2 mcg/mL
14 Years 12.2–25.2 mcg/mL
15 Years 10.8–23.8 mcg/mL
16 Years 10.0–23.8 mcg/mL
17 Years 8.5–23.1 mcg/mL
Blood Draw Options with Fullscript
Fullscript offers several convenient phlebotomy options to complete your lab testing:
Quest Diagnostics Patient Service Centers (PSC)
- Location: Visit a nearby Quest Diagnostics Patient Service Center.
- Cost: $10 sample collection fee (paid during lab order checkout).
- Scheduling: Schedule your appointment here. Appointments are recommended to reduce wait times. Walk-ins are accepted, but may experience delays. Aim to arrive 10 minutes before your appointment.
- Collection Instructions:
- Bring a valid ID.
- Bring your digital or printed requisition form, available in the Labs tab of your Fullscript account.
- Check-in: Scan the QR code from your confirmation email or follow kiosk instructions.
- More Info: Quest Diagnostics blood draw guide
Getlabs Mobile Phlebotomy
- Location: Sample collection at your home or office.
- Cost: $85 sample collection fee (paid during lab order checkout).
- Availability: Available in most locations – enter your ZIP code during checkout to confirm.
- Scheduling: Schedule your appointment here through your Fullscript account.
- Collection Instructions:
- Have your digital or printed requisition form and valid ID ready.
- Your phlebotomist will contact you by phone to coordinate arrival.
- More Info: Getlabs blood draw guide
- Preferred Specimen(s): 1 mL serum
- Alternative: NA
- Minimum Volume: 0.5 mL
- Collection Instructions: NA
- Transport Container: Transport tube
- Transport Temperature: Room Temperature
- Specimen Stability:
- Room temperature: 7 days
- Refrigerated: 7 days
- Frozen: 28 days
- Reject Criteria:
- Gross hemolysis
State restrictions:
Patient can't order this test if they are located in Hawaii, Puerto Rico, New Jersey, New York, or Rhode Island
