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Test Code THSCM Thyroid Function Cascade, Serum

Additional Codes


Powerchart: Thyroid Function Cascade

Epic: LAB3499 Thyroid Function Cascade

Reporting Name

Thyroid Function Cascade, S

Useful For

Screening for a diagnosis of thyroid disease

Profile Information

Test ID Reporting Name Available Separately Always Performed
STSHC TSH, Sensitive, S Yes, (order STSH) Yes

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
FRT4C T4 (Thyroxine), Free, S Yes, (order FRT4) No
TPOC Thyroperoxidase Ab, S Yes, (order TPO) No
T3C T3 (Triiodothyronine), Total, S Yes, (order T3) No

Testing Algorithm

If thyroid-stimulating hormone (TSH) is <0.3 mIU/L, then free T4 (FT4) is performed at an additional charge.

If FT4 is normal and the TSH is <0.1 mIU/L, then T3 is performed at an additional charge.

If TSH is >4.2 mIU/L, then FT4 and thyroperoxidase antibodies are performed at an additional charge.


See Thyroid Function Ordering Algorithm in Special Instructions.

Performing Laboratory

Mayo Medical Laboratories in Rochester

Specimen Type


Specimen Required

Patient Preparation: In patients receiving therapy with high biotin doses (ie, >5 mg/day), no specimen should be taken until at least 8 hours after the last biotin administration.


Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 1.5 mL

Collection Instructions:

1. Serum gel tubes should be centrifuged within 2 hours of collection.

2. Red-top tubes should be centrifuged and aliquoted within 2 hours of collection.

Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Refrigerated (preferred) 7 days
  Frozen  30 days
  Ambient  72 hours

Reference Values

0-5 days: 0.7-15.2 mIU/L

6 days-2 months: 0.7-11.0 mIU/L

3-11 months: 0.7-8.4 mIU/L

1-5 years: 0.7-6.0 mIU/L

6-10 years: 0.6-4.8 mIU/L

11-19 years: 0.5-4.3 mIU/L

>20 years: 0.3-4.2 mIU/L

Day(s) and Time(s) Performed

Monday through Sunday; Continuously

Test Classification

This test has been cleared or approved by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

84443-Thyroid-stimulating hormone-sensitive (s-TSH)

84439-T4 (thyroxine), free (if appropriate)

84480-T3 (triiodothyronine), total (if appropriate)

86376-Thyroperoxidase (TPO) antibodies (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
THSCM Thyroid Function Cascade, S 11579-0


Result ID Test Result Name Result LOINC Value
STSHC TSH, Sensitive, S 11579-0

Reject Due To


Mild OK; Gross reject


Mild OK; Gross OK


Mild OK; Gross OK




Method Name

Electrochemiluminescent Immunoassay