Specimen Requirements

Container/Tube:

Preferred:  Green-top (lithium heparin) tube

Acceptable:  EDTA lavender(see note), Gold-top serum gel tube or plain, red-top tube

Note:  No studies have been performed on unseparated whole blood stability.  Do not recommend adding testing onto unseparated plasma or serum.

Minimum Specimen Volume: 30 µL plus dead volume

Stability for TSH:  Separated samples stored at 2 – 8°C are stable 14 days, 8 days at 20‑25 °C, and 

24 months at ‑20 °C (± 5 °C). Freeze only once.

Stability for Free T4:  Separated samples stored at 2 – 8°C are stable 7 days,58 days at 20‑25 °C, and 30 days at ‑20 °C (± 5 °C). Freeze only once.