Hypothyroidism - or low-thyroid - is a common endocrine disorder affecting mostly women. Its incidence increases with age. The typical symptoms of hypothyroidism include fatigue, cold intolerance, weight gain, and constipation, among others. First-line treatment is usually with T4 (Levothyroxine); however, many patients’ symptoms are not relieved with T4 alone. For relief of symptoms a growing body of medical literature supports the use of a T4 (Levothyroxine) with its active form - T3 (Liothyronine) - at patient specific combinations. This approach is meant to maintain appropriate levels of active thyroid hormone - T3 (Liothyronine) - in blood and tissue, something that T4 alone may not accomplish sufficiently.