TSH with reflex Free T4, TSH with reflex FT4, Thyrotropin with reflex Free T4
Up to 24 hours
Electrochemiluminescence (ECLIA)
Accredited NRL Laboratory
Daily
The clinical utility of TSH with reflex Free Thyroxine (Free T4) lies in its cost-effective and efficient diagnostic pathway for evaluating thyroid function. It screens with the most sensitive marker available (TSH) and automatically measures Free T4 only when the TSH is abnormal.
Serum or Plasma
1 mL
Serum Separator Tube (SST, Gold Top) Plain Tube (Red Top) Lithium-heparin Plasma (Green Top) EDTA Plasma (Lavender Top)
No special preparation is required for this test. You may eat, drink, and take your medications as normal, unless instructed otherwise by your healthcare provider.
This test does not require any special collection or pre-analytical handling. Follow routine specimen collection protocols.
| Temperature | Period |
|---|---|
| Room Temperature | 5 days |
| Refrigerated | 7 days at 2 to 8°C |
| Frozen | 30 days at -20°C (as an aliquot, thaw only once) |