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Thyroid-stimulating Hormone (TSH) and Free T4

CPT 84439; 84443
Synonyms
  • TSH and Free T4

Test Details

Methodology

Electrochemiluminescence immunoassay (ECLIA)

Result Turnaround Time

Within 1 day

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

Test Includes

Thyroid-stimulating hormone (TSH); free thyroxine, direct

Specimen

Serum (preferred) or plasma

Volume

1 mL

Minimum Volume

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

Container

Red-top tube, gel-barrier tube, or green-top (lithium heparin) tube. Do not use oxalate, EDTA, or citrate plasma.

Storage Instructions

Room temperature

Causes for Rejection

Citrate plasma specimen; improper labeling

Collection Instructions

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

Stability Requirements

Temperature

Period

Room temperature

7 days

Refrigerated

14 days

Frozen

14 days

Freeze/thaw cycles

Stable x3

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
224576 TSH+Free T4 004264 TSH uIU/mL 11580-8
224576 TSH+Free T4 019745 T4,Free(Direct) ng/dL 3024-7
Order Code224576
Order Code NameTSH+Free T4
Order Loinc
Result Code004264
Result Code NameTSH
UofMuIU/mL
Result LOINC11580-8
Order Code224576
Order Code NameTSH+Free T4
Order Loinc
Result Code019745
Result Code NameT4,Free(Direct)
UofMng/dL
Result LOINC3024-7