Levothyroxine Liquid Solution Versus Tablet for Replacement Treatment in Hypothyroid Patients

Abstract

Although replacement treatment with L-thyroxine (LT4) seems easy to manage, about one-third of hypothyroid patients show thyroid-stimulating hormone (TSH) values outside the normal range. To explore whether LT4 liquid formulation (monodose vials or drops) affects TSH stability values and to assess its ability to maintain TSH within the normal range compared to tablets. A total of 100 hypothyroid patients on replacement treatment with LT4 liquid solution were enrolled (Liquid Group) at a follow-up visit (revisit). The inclusion criteria were 1) treatment for surgical hypothyroidism for at least 2 years or autoimmune hypothyroidism for at least 5 years, 2) normal TSH at the previous visit 12 months before enrollment (baseline visit), and 3) maintenance of the same LT4 dosage during the time interval between the baseline and the follow-up visit. Using the same selection process, we also enrolled 100 hypothyroid patients on replacement treatment with LT4 tablets (Tablet Group). At the follow-up visit, 19 patients of the Tablet Group and 8 patients of the Liquid Group had abnormal TSH values (P = .023). Weekly and daily LT4 dosage per kilogram were higher in Tablet Group (P = .016 and .006, respectively). The magnitude of TSH change from baseline to follow-up visit was greater in the Tablet Group (P<.001). The use of LT4 liquid formulation compared to tablet resulted in a significantly higher number of hypothyroid patients who maintained the euthyroid state in a 12-month follow-up period and a reduced variability in TSH values.