Specimen Requirements

Specimen Type: Plasma/serum

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Serum: Yellow top

The VITROS TSH assay tolerates up to 2–5 ng/mL of Biotin/VItamin B7. Patients taking high-dose supplements may exceed this threshold, resulting in falsely low TSH values.  It's recommended that Biotin supplementation be discontinued 48 hours prior to blood draw

Plasma: Green top

Specimen Volume: 1 mL