The use of liquid levothyroxine in the treatment of patients with hypothyroidism and comorbiditiesa review of the literature

Objective: The primary drug used to treat hypothyroidism is synthetic levothyroxine.Patients with other diseases besides hypothyroidism often have malabsorption of levothyroxine administered in tablet form.In many cases, resistance to levothyroxine decreases or disappears when the drug is used in liquid form.The purpose of this paper is to systematize current knowledge about the effectiveness of using levothyroxine in liquid form when patients have comorbidities in addition to hypothyroidism.Materials and methods: The literature publicly available in the following databases was reviewed: PubMed and Google Scholar.Articles from january 2015-May 2025 were considered.The following keywords were used: "levothyroxine", "hypothyroidism", "levothyroxine absorption", "levothyroxine pharmacokinetics".Results: Patients are given levothyroxine in various forms.The most popular of these is the tablet, but in many cases, its use does not lead to euthyroidism.The main cause is malabsorption in the gastrointestinal tract associated with Helicobacter pylori infection, celiac disease, autoimmune gastritis, and other conditions.The liquid form has a therapeutic effect due to more favorable pharmacokinetics.Conclusion: The absorption efficiency in the gastrointestinal tract of liquid levothyroxine is higher than that of levothyroxine administered in tablet form.This is especially important in patients with comorbidities, where this absorption is often impaired by pathophysiological mechanisms or medications used.For such patients, the use of liquid levothyroxine appears to be the only option, which should be taken into account when recommending treatment for hypothyroidism.