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Register NowTriiodothyronine (T3), Free, Dialysis and LC/MS-MS
Create a Free Account to View PricesTurnaround Time: 6 - 10 days
CPT Code:
84481
Test Type: 1 mL Serum (preferred) or plasma, frozen
Reference Range:
|
Age |
Range (pg/mL) |
Mean (pg/mL) |
|---|---|---|
|
Premature (0 to 4 wk) |
1.35−6.25 |
3.13 |
|
Newborn |
||
|
0 to 2 wk |
0.99−8.03 |
4.21 |
|
2 wk to 12 m |
1.59−6.15 |
3.87 |
|
Prepubertal 1 to 10 y |
2.21−4.99 |
3.60 |
|
Children >10 y and adults |
1.81−4.06 |
2.77 |
|
Pregnant female |
||
|
first trimester |
1.6−3.3 |
2.5 |
|
second trimester |
To be determined |
|
|
third trimester |
1.0−3.2 |
2.1 |
Overview:
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.1-4 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);1 pregnancy;1-5 administration of oral contraceptives or hormone therapy;6 administration of atypical antipsychotic medications;7 malignancy or other critical illnesses.8
1. Yue B, Rockwood Al, Sandrock T, La'ulu SL, Kushnir MM, Meikle AW. Free thyroid hormones in serum by equilibrium dialysis and online solid-phase extraction-liquid chromatography/tandem mass spectrometry. Clin Chem. 2008 Apr; 54(4):642-651. PubMed 18258669
2. Soldin SJ, Soukhova N, Janicic N, Jonklaas J, Soldin OP. The measurement of free thyroxine by isotope dilution tandem mass spectrometry. Clin Chim Acta. 2005 Aug; 358(1-2):113-118. PubMed 16018881
3. Nelson JC, Weiss RM, Wilcox RB. Underestimates of serum free thyroxine (T4) concentrations by free T4 immunoassays. J Clin Endocrinol Metab. 1994 Jul; 79(1):76-79. PubMed 8027258
4. Nelson JC, Tomei RT. Direct determination of free thyroxine In undiluted serum by equilibrium dialysis/radioimmunoassay. Clin Chem. 1988 Sep; 34(9):1737-1744. PubMed 3138040
5. Kahric-Janicic N, Soldin SJ, Soldin OP, West T, Gu J, Jonklaas J. Tandem mass spectrometry improves the accuracy of free thyroxine measurements during pregnancy. Thyroid. 2007 Apr; 17(4):303-311. PubMed 17465859
6. Mazer N. Interaction of estrogen therapy and thyroid hormone replacement in postmenopausal women. Thyroid. 2004; 14(Suppl 1):S27-34. PubMed 15142374
7. Surks MI, DeFesi CR. Normal serum free thyroid hormone concentrations in patients treated with phenytoin or carbamazepine. A paradox resolved. JAMA. 1996 May 15; 275(19):1495-1498. PubMed 8622224
8. De Groot L. Dangerous dogmas in medicine: The nonthyroidal illness syndrome. J Clin Endocrinol Metab. 1999 Jan; 84(1):151-164. PubMed 9920076
Collection Details:
Collection Instructions:
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.
Freeze (preferred) or refrigerate. Stable at room temperature or refrigerated for five days. Stable frozen for 70 days.