Thyroxine (T4) and Thyroid-stimulating Hormone (TSH)

TEST: 024026
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CPT: 84436; 84443
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Synonyms

  • T4 and TSH
  • TSH and T4

Test Includes

Thyroxine (T4); thyroid-stimulating hormone (TSH)

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.

Expected Turnaround Time

Within 1 day

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

Specimen Requirements

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.

Collection

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

Storage Instructions

Room temperature

Stability Requirements

Temperature

Period

Room temperature

14 days

Refrigerated

14 days

Frozen

14 days

Freeze/thaw cycles

Stable x3

Causes for Rejection

Plasma specimen

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
024026 T4 and TSH 24348-5 004264 TSH uIU/mL 11580-8
024026 T4 and TSH 24348-5 001149 Thyroxine (T4) ug/dL 3026-2

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