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Test Code TSHR TSH REFLEX CASCADE to FT4, FT3

Important Note

The results of this assay can be falsely lowered due to the consumption of Biotin.  Please instruct patients to discontiue the use of vitamins or supplements that contain Biotin 12hrs before blood draw.

Performing Location

Southwestern Vermont Medical Center

Specimen Required/Volume

1.0 mL

Specimen Type

Plasma or serum

Collection Container

Light Green (lithium heparin), Gold top, or Marble Red top vacutainer

Collection Instructions

 Refer to venipuncture protocol

Reference Values

TSH: 0..47– 4.68 uIU/mL
Free T4: 0.8- 2.2 ng/dL
T3 Free  2.3 – 4.2 pg/mL
To review the Thyroid Cascade testing algorithm, refer to the Reflex Testing section of this manual.

Turn-Around Guidelines

Upon arrival

Method

Electrochemiluminescence immunoassay - Roche cobas

LOINC

 3016-3 - TSH

(3024-7 - T4 Free reflex)

(3051-0 - T3 Free reflex)

CPT

84443 - TSH

+ reflex Free T4 - 84439 as appropriate

+ reflex T3 Free - 84481 as appropriate