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Test Code FRT4D T4 (Thyroxine), Free, Dialysis, Serum

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Serum


Advisory Information


The routine free thyroxine test (FRT4 / T4 [Thyroxine], Free, Serum) is faster and provides useful information in most patients.



Necessary Information


Include name and telephone number of contact physician.



Specimen Required


Collection Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Submission Container/Tube: Plastic vial

Specimen Volume: 2.6 mL

Collection Instructions:

1. Draw blood immediately before next scheduled dose.

2. Centrifuge and aliquot serum into plastic vial within 2 hours of draw.


Specimen Minimum Volume

1.2 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 28 days
  Frozen  21 days
  Ambient  7 days

Reference Values

0.8-2.0 ng/dL

Reference values apply to all ages.

Day(s) and Time(s) Performed

Monday, Wednesday, Thursday; 3 p.m.

CPT Code Information

84439 

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject

Method Name

Equilibrium Dialysis/Tandem Mass Spectrometry (MS/MS)

Secondary ID

8859