Specimen

Plasma

Collection Medium:

Alternate
Collection Media:

Call laboratory for additional acceptable specimen collection 
containers.

Minimum:

2 mls 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:

0.8 - 2.0 ng/ml

Comments:

New analytical immunoassay with different reference range instituted 
4/24/00 at 1000.

Test
Limitations:

The assay is unaffected by icterus (bilirubin is less than 35 mg/dl), 
hemolysis (Hb is less than 2.0 g/dl), lipemia (Intralipid is less than 
1800 mg/dl) and biotin is less than 20 ng/ml (criterion: recovery 
within plus or minus 10% of initial value).

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

No interference was observed from rheumatoid factor (up to 1500 U/ml) 
and samples from dialysis patients.

Twenty-six commonly used pharmaceuticals were tested in vitro. No 
interference with the assay was found.

Therapy with amiodarone can lead to depressed T3 values.

Phenytoin, phenylbutazone and salicylates cause release of T3 from the 
binding proteins, thus leading to a reduction in the total T3 hormone 
level at normal fT3 levels.*

Auto-antibodies to thyroid hormones can interfere with the test.

Pathological concentrations of binding proteins (TBG, albumin) can lead 
to total T3 values outside the normal range being found despite a 
euthyroid metabolic state (e.g. in NTI-patients, pregnancy, use of oral 
contraceptives). In patients with very serious general diseases, 
differ-ences to Enzymun-Test T3 results may occasionally occur. In such 
cases an fT3 or fT4 determination is indicated.

The risk of interference from potential immunological interactions 
between test components and rare sera has been minimized by the 
inclusion of additives.

In rare cases, interference due to extremely high titers of antibodies 
to ruthenium can occur.

T3 reagent contains additives which minimize these effects.

Extremely high titers of antibodies to streptavidin can occur in 
isolated cases and cause interference.

For diagnostic purposes, the T3 findings should always be assessed in 
conjunction with the patient's medical history, clinical examination 
and other findings.

*Wild D. The Immunoassay Handbook. Stockton Press, 1994:338.

Methodology:

Electrochemiluminescence Immunoassay

CPT Code:

84480