Switching from Natural Desiccated Thyroid to a Liquid Formulation of Levothyroxine for Hypothyroidism

Natural desiccated thyroid (NDT) is a treatment option for many patients with hypothyroidism, but some still exhibit symptoms despite achievement of normal levels of thyroid stimulating hormone (TSH). In this retrospective case series, 13 patients with hypothyroid symptoms were switched from NDT to a liquid formulation of levothyroxine (LT4; Tirosint®-SOL). Laboratory values ≥4 weeks following the switch showed a decrease in TSH levels, maintenance of free triiodothyronine (fT3) levels, and significant increases in free thyroxine (fT4) levels. Patients reported good tolerability, and case summaries are presented for four patients. In summary, this small retrospective case series showed that patients who still had hypothyroid symptoms despite use of NDT can respond well to oral LT4 liquid formulation, including patients who are intolerant of gluten and/or lactose or on hormone replacement therapy or iron supplementation.