Pig thyroid gland, often referred to as "desiccated thyroid extract," has a long history of use in the treatment of hypothyroidism and other thyroid-related disorders. The product is derived from the thyroid glands of pigs and contains the hormones thyroxine (T4) and triiodothyronine (T3), which are naturally produced by the human thyroid gland as well. The scientific justification for its use lies in its ability to replace or supplement the endogenous thyroid hormones in individuals with thyroid insufficiency.

Desiccated thyroid extract was the standard therapy for hypothyroidism before the development of synthetic levothyroxine (T4) and liothyronine (T3). Clinical trials and decades of medical use have confirmed that desiccated pig thyroid effectively normalizes thyroid hormone levels and alleviates symptoms of hypothyroidism. The U.S. Pharmacopeia recognizes desiccated thyroid as a standardized pharmaceutical preparation, and it remains an FDA-approved medication for certain thyroid disorders.

Although synthetic options are now more commonly prescribed due to precise dosing and fewer fluctuations in hormone levels, some patients report better symptom control with desiccated thyroid products. Modern scientific consensus acknowledges that pig thyroid gland extract directly supports the thyroid gland system by providing the necessary hormones, and its use is well-documented in both historical and contemporary medical literature.