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Test ID BLOD0212 T4 (Thyroxine), Free, Dialysis, Serum

Test Down Notes

Effective August 23, 2024:  This test is temporarily unavailable due to increased volume of testing requests.  The downtime is expected to be >30 days.  Order FFT4T as an alternative. See test notification here.

Useful For

Determining thyroid status of sick, hospitalized patients

 

Determining thyroid status of patients in whom abnormal binding proteins have been identified

 

Possibly useful in pediatric patients

Specimen Type

Serum


Ordering Guidance


The routine free T4 is faster and provides useful information for most patients; order FRT4 / T4 (Thyroxine), Free, Serum.



Necessary Information


Include name and telephone number of contact physician



Specimen Required


Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Collection Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Submission Container/Tube: Plastic vial

Specimen Volume: 2.6 mL

Collection Instructions:

1. Collect specimen immediately before next scheduled dose.

2. Within 2 hours of collection, centrifuge, and aliquot serum into a plastic vial.


Specimen Minimum Volume

1.2 mL

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject

Specimen Stability Information

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

Day(s) Performed

Monday, Wednesday, Thursday

Report Available

3 to 8 days

Method Name

Equilibrium Dialysis/Tandem Mass Spectrometry (MS/MS)

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

84439

Reporting Name

T4 (Thyroxine), Free by Dialysis, S

Reference Values

0.8-2.0 ng/dL

Reference values apply to all ages.

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

Secondary ID

8859
Sanford Laboratories - Fargo Additional Information:

SANFORD INTERFACE BUILD INFORMATION

Result Code Result Code Description
17334 T4 (Thyroxine), Free by Dialysis, S