Specimen:

Plasma

Collection Medium:

Alternate
Collection Media:

Call laboratory for additional acceptable specimen collection 
containers.

Minimum:

2 mL whole blood in light green top or TWO 0.6 mL microtubes

Testing
Schedule:

24 hrs/day, 7 days a week, including holidays.

Analytic Time:

2 hours (upon receipt in laboratory)

Reference Range:

Less than 1 month: 0.14–0.55 ng/dL or 1.4-5.5 pg/mL or 2.2- 9.5 pmol/L
Less than 1 year:  0.2- 0.69 ng/dL or  2- 6.9 pg/mL or 3.1-10.6 pmol/L
1 - 5 years:       0.24-0.67 ng/dL or 2.4-6.7 pg/mL or 3.7-10.3 pmol/L
5 years to adults: 0.23-0.55 ng/dL or 2.3-5.5 pg/mL or 3.5- 8.5 pmol/L
Euthyroid:         2.57-4.43 pg/mL

Test
Limitations:

The assay is unaffected by icterus (bilirubin is less than 33 mg/dL), 
hemolysis (Hb is less than 4.3 g/dL), lipemia (Intralipid is less than 
2000 mg/dL) and biotin is less than 100 ng/ml (criterion: recovery 
within plus or minus 10% of initial value).

In patients receiving therapy with high biotin doses (i.e. is greater 
than 5 mg/day) no sample should be taken until at least 8 hours after 
the last biotin administration.

18 commonly used pharmaceuticals were tested in vitro. No interference 
with the assay was found with 24 of them.

Therapeutic concentrations of acetylsalicylic acid and furosemide lead 
to elevated FT3 values.

Autoantibodies to thyroid hormones can interfere with the assay.

The risk of interference from potential immunological interactions 
between test components and rare sera has been minimized by the 
inclusion of suitable additives. In rare cases, interference due to 
extremely high titers of antibodies to streptavidin and ruthenium can 
occur. FT3 contains additives which minimize these effects.  For 
diagnostic purposes, the FT3 findings should always be assessed in 
conjunction with the patient's medical history, clinical examination 
and other findings.

Methodology:

Electrochemiluminescence Immunoassay

Sample
Processing:

Centrifuge at 3000 RPM for 10 minutes.
Aliquot plasma into labeled container and cap.

Sample
Storage:

Refrigerate.

Transport
Instructions:

Place requisition into outside pocket of bag.
Place specimen into zip-lock type bag, seal bag.
Transport in cooler with refrigerated coolant packs.

CPT Code:

84481