FT3 Dialysis/Mass Spec

Test ID: 


CPT code:



Free T3

Free Triiodothyronine (T3)


Triiodothyronine (T3), Free, Dialysis and LC/MS-MS

Test Information:

Direct measurement of FT3 by equilibrium dialysis, high-pressure liquid chromatography, and tandem mass spectrometry (ED-HPLC/MS-MS) provides enhanced accuracy over commonly used analog (automated) methods and is not affected by clinical conditions that impact protein binding capacity. Examples of clinical conditions in which the FT3 by dialysis and MS/MS method may be preferred include congenital absence of thyroxine-binding protein (TBG); pregnancy; administration of oral contraceptives or hormone therapy; administration of atypical antipsychotic medications; malignancy or other critical illnesses.

Specimen Type:

Serum (preferred) or plasma, frozen

Requested Volume: 

1 mL

Minimum Volume: 

0.3 mL

Container Type: 

Red-top tube, gel-barrier tube, lavender-top (EDTA) tube, or green-top (sodium heparin) tube


Serum/plasma must be separated from cells within 45 minutes of venipuncture. Send serum/plasma in a plastic transfer tube.

Storage Instructions:

Freeze (preferred) or refrigerate.

Stability Requirements:

Stable at room temperature or refrigerated for five days. Stable frozen for 70 days.

Rejection Criteria

Whole blood

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MCI Diagnostic

Providing top patient care with fast results. 

7018 South Utica Avenue

Tulsa, Oklahoma 74136

Hours of Operation

Mon – Sat: 7AM-11PM

Sun: 7AM-3PM

Government Contract

Mon – Sat: 7AM-11PM

Sun: 7AM-3PM


Mon – Sat: 7AM-11PM

Sun: 7AM-3PM

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