Cat (feline) diagnosis free T4 Hyperthyroid Hyperthyroidism Thyroid thyroid gland thyroxine (T4) Confirming the Diagnosis of Hyperthyroidism in Cats: Serum Free T4 Concentrations Thyroxine (T4) is the main thyroid hormone secreted by the thyroid gland. As discussed in my recent post about T4 measurement , c… Saturday, July 23, 2011 Add Comment Edit