Thyroxine free, dialysis/mass spectrometry-994

Test info

  
Thyroxine free, dialysis/mass spectrometry
  
994
  
LAB994
  
MSO
  
Free thyroxine T4
T4 free, dialysis/mass spectrometry
Free T4 by equilibrium
  

Free Thyroxine is used to evaluate thyroid gland function and to diagnose thyroid disease, as well as to monitor effectiveness of thyroid hormone treatment.

Specimen

  
Serum
  

Gold serum separator (SST) tube

  
1.0 mL
  
0.5 mL
Submission of the minimum volume does not allow for repeat testing
  

Immediatley following collection, mix sample by gently inverting 5 times

  
  1. Allow sample to clot for a minimum of 30 minutes
  2. Spin within 45 minutes of sample collection
  3. Transfer serum to a Screw-cap polypropylene frozen transport vial/tube - 4mL (LabCorp), labelled as serum
  4. Freeze 
  

Screw-cap polypropylene frozen transport vial/tube - 4mL (LabCorp)

  
EDTA plasma
  

Red serum vial/tube, 5 mL

Lavender (EDTA), 4mL

  

Lavender:

Immediately following collection, mix sample thoroughly by gentle inverting 8 - 10 times, to prevent clotting

  

Red:

  1. Allow sample to clot 
  2. Spin within 45 minutes of sample collection
  3. Transfer serum to a Screw-cap polypropylene frozen transport vial/tube - 4mL (LabCorp), labelled as serum
  4. Freeze 

Lavender:

  1. Spin within 45 minutes of sample collection
  2. Transfer plasma to a Screw-cap polypropylene frozen transport vial/tube - 4mL (LabCorp), labelled as EDTA plasma
  3. Freeze 
  

Frozen (preferred) - 453 days

Refrigerated - 5 days

Ambient - 2 days

Freeze/thaw cycles - stable x3

Performance

  
Esoterix Endocrinology (500329) via LabCorp (501902): R-NX
  
Mo - Fr
  
6+11 days
  

Direct dialysis mass spectrometry

High pressure liquid chromatography/mass spectrometry (HPLC/MS)

Clinical and Interpretive info

  
Age Range (ng/dL)
Premature (0-4 wks) 0.86−4.46
Newborn 0–2 wks 0.84−4.97
2 weeks – 12 months 0.81 – 2.12
1 – 11 years 0.65 – 1.9
Pubertal children and adults 0.8 – 1.7
Pregnant female  
First trimester          (0 – 13.3 wk) 0.65 – 1.4
Second trimester (13.4 – 26.6 wk) 0.5 – 1.3
Third trimester   (>26.6 wk) 0.5 – 1.1

Billing

  
84439
  
Yes
  

Medical necessity

  
Result 6892-4

Tracking

  
05/22/2019
  
12/20/2023
  
12/20/2023