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Test Code LAB5725 TSH with Reflex, Plasma

Performing Laboratory

Barnes-Jewish Hospital Laboratory

Methodology

Electrochemiluminescence Immunoassay (ECLIA)

Testing Algorithm:

If TSH result is <0.30 mcIUnits/mL or >4.2 mcIUnits/mL, LAB127 T4 (Thyroxine), Free will be performed, at an additional charge.

If TSH is <0.30 mcIUnits/mL and FT4 is ≤ 1.7 ng/dL, LAB137 T3 (Triiodothyronine), Free will be performed, at an additional charge.

 

Literature References:

Package Insert: Thyrotropin TSH. Roche Corporation 04/2022

Package Insert: Free Thyroxine FT4 II. Roche Corporation 08/2021.

Package Insert: Free Thyroxine FT3 III. Roche Corporation 03/2021.

Specimen Requirements

Specimen Type: Plasma

Container/Tube: Mint-green top (lithium heparin)

Specimen Volume: Full tube

 

Day(s) Test Set Up

Monday through Sunday

Turnaround Time:
STAT: 1 hour after receipt in laboratory 
Routine: 4 hours after receipt in laboratory

Test Classification and CPT Coding

84443-TSH

84439-Free T4 (if appropriate)

84481-Free T3 (if appropriate)

Reference Values

TSH

Age Reference Interval
< 4 days 1.00 - 25.00 mcIUnit/mL
4 days - 30 days 0.50 - 10.00 mcIUnit/mL
> 30 days 0.30 - 4.20 mcIUnit/mL

Free T4

  Reference Interval
  0.90 - 1.70 ng/dL

FT3

  Reference Interval
  2.0-4.4 pg/mL

Specimen Transport Temperature

Ambient

Additional Information

For BJH Laboratory Use Only

Alternate Tube(s):

1 plain, red-top tube

Dark gree top (LiHep)

Analyte Stability:

See Analyte Stability Chart in Special Instructions.

Laboratory Processing Instructions:

Test performed in BJH Core Lab. Processed by automated line for delivery to the Cobas 8000. Completed specimens are stored refrigerated for 5 days.

Test performed in Ambulatory Cancer Building Lab.  Centrifuge sample and deliver to the Cobas.  Completed specimens are stored refrigerated for 5 days. 

LOINC Code Information

Name LOINC Code
TSH, Plasma 11579-0
T4, Free 3024-7
T3, Free, Plasma 3051-0