Thyroid Panel

The active form of thyroid hormone responsible for regulating metabolism, energy, and body temperature. Free T3 is converted from T4 in tissues and is three to four times more potent than T4.

The unbound, active form of the main thyroid hormone T4. Free T4 directly reflects thyroid gland output and is used alongside TSH to diagnose and monitor thyroid disorders.

Free triiodothyronine; high levels indicate hyperthyroidism, low levels hypothyroidism.

Free thyroxine; high levels indicate hyperthyroidism, low levels hypothyroidism.

A group of proteins in blood including antibodies (immunoglobulins), transport proteins, and enzymes. Elevated globulin can indicate chronic infection, inflammation, or blood cancers. Calculated by subtracting albumin from total protein.

An inactive form of T3 produced when the body converts T4. Elevated reverse T3 can occur during illness, stress, or caloric restriction and may indicate impaired thyroid hormone activation despite normal TSH levels.

Antibodies against thyroid peroxidase, an enzyme essential for thyroid hormone production. Positive TPO antibodies indicate autoimmune thyroid disease, most commonly Hashimoto's thyroiditis, even before symptoms or TSH changes appear.

The primary screening test for thyroid function. TSH is produced by the pituitary gland to regulate thyroid hormone production. High TSH indicates an underactive thyroid (hypothyroidism), while low TSH suggests an overactive thyroid (hyperthyroidism).