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Thyroxine (T4), Thyroxine-binding Globulin (TBG), and T4−TBG Index

CPT 84436; 84442
Synonyms
  • TBG, Thyroxine (T4), and T4−TBG Index

Test Details

Result Turnaround Time

2 - 3 days

Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.

Related Documents

Special Instructions

This test may exhibit interference when sample is collected from a person who is consuming a supplement with a high dose of biotin (also termed as vitamin B7 or B8, vitamin H, or coenzyme R). It is recommended to ask all patients who may be indicated for this test about biotin supplementation. Patients should be cautioned to stop biotin consumption at least 72 hours prior to the collection of a sample.

Specimen Requirements

Specimen

Serum

Volume

2 mL

Minimum Volume

0.5 mL (Note: This volume does not allow for repeat testing.)

Container

Red-top tube or gel-barrier tube

Collection Instructions

If a red-top tube is used, transfer separated serum to a plastic transport tube.

Stability Requirements

Temperature

Period

Room temperature

7 days

Refrigerated

14 days

Frozen

14 days

Freeze/thaw cycles

Stable x3

Storage Instructions

Refrigerate

Causes for Rejection

Plasma specimen

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
004457 T4, TBG and T4-TBG Index 001735 Thyroxine Binding Globulin ug/mL 3021-3
004457 T4, TBG and T4-TBG Index 001149 Thyroxine (T4) ug/dL 3026-2
004457 T4, TBG and T4-TBG Index 011735 T4-TBG Index index 3027-0
Order Code004457
Order Code NameT4, TBG and T4-TBG Index
Order Loinc
Result Code001735
Result Code NameThyroxine Binding Globulin
UofMug/mL
Result LOINC3021-3
Order Code004457
Order Code NameT4, TBG and T4-TBG Index
Order Loinc
Result Code001149
Result Code NameThyroxine (T4)
UofMug/dL
Result LOINC3026-2
Order Code004457
Order Code NameT4, TBG and T4-TBG Index
Order Loinc
Result Code011735
Result Code NameT4-TBG Index
UofMindex
Result LOINC3027-0