Liothyronin

Liothyronin is a brand name used for liothyronine sodium, the synthetic form of the thyroid hormone triiodothyronine (T3). It is used as thyroid replacement therapy in cases of hypothyroidism and, in certain clinical settings, to rapidly restore thyroid function.

Liothyronine provides the biologically active hormone T3 and acts more quickly than levothyroxine (T4). Because of its faster onset and shorter duration, dosing must be individualized and closely monitored with clinical response and thyroid function tests. In routine primary hypothyroidism, levothyroxine is the preferred first‑line treatment, while liothyronine may be considered as an adjunct in selected patients or when there is inadequate response to T4 alone under specialist supervision.

In addition to chronic replacement, liothyronine may be used in hospital settings for acute conditions such as myxedema coma or severe hypothyroidism, where rapid improvement is desired and intravenous administration is available.

Common adverse effects mirror excess thyroid hormone and may include palpitations, rapid heart rate, anxiety, tremor, insomnia, weight loss, and sweating. Long‑term use can contribute to bone loss and, in susceptible individuals, increased risk of atrial fibrillation. It can interact with anticoagulants, antidiabetic agents, and other medications, requiring dose adjustments of concomitant therapies.

Liothyronin is a prescription medication available in oral and, for some indications, intravenous forms. Its use requires careful medical supervision, dose titration, and periodic monitoring of thyroid function and clinical status.