TSH (Thyroid Stimulating Hormone)
Collect SST/0.5 mL serum. After 30 minutes of clotting, promptly centrifuge and send refrigerated.
Refrigerated: 1 week; Frozen: 1 month
The ability to quantitate circulating levels of TSH is important in evaluating thyroid function. It is especially useful in the differential diagnosis of primary (thyroid) from secondary (pituitary) and tertiary (hypothalamus) hypothyroidism. In primary hypothyroidism, TSH levels are significantly elevated, while in secondary and tertiary hypothyroidism, TSH levels are low.