Thyroid function test. Decreased in hypothyroidism and in the third stage of (painful) subacute thyroiditis; increased with hyperthyroidism, with subacute thyroiditis in its first stage and with thyrotoxicosis due to Hashimoto disease.3 Used to diagnose T4 toxicosis.
Synonyms: T4, Total; Tetraiodothyronine
SST, Serum. Volume 1 (0.5) mL serum. Stability: Refrigerated – 4 Days, Frozen – 2 Months