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Mint Green Top (Lithium Heparin Gel)
Specimen Requirements
Preferred:
Container/Tube: Mint Green Top (Lithium Heparin Gel)
Minimum Volume: 1.0 mL
Collection Instructions: Centrifuge within 2 hours
Also Acceptable:
Container/Tube: Gold Top (SST-Gel)
Specimen Stability
Ambient: 8 hours
Refrigerate: 48 hours
Frozen: aliquot for longer storage
Reference Range
2.5-3.9 pg/mL
Methodology
Chemiluminescent Immunoassay
CPT
84481
Interferences
Please add biotin interference section with:
Biotin concentrations > 10 ng/mL can lead to significant (> 10%) positive bias in Free T3 results.
If unexpected results are obtained, and biotin interference is suspected, the Beckman Coulter TSH
assay may provide a better assessment of thyroid function as it is not susceptible to biotin interference.