Thyroid hormonal profile in elderly patients treated with two different levothyroxine formulations: A single institute survey

Abstract

PurposeRecent evidences suggest that, despite the large use of levothyroxine (L-T4), up to 40% of patients are over-treated developing sub-clinical hyperthyroidism. We compared TSH, fT4 and fT3 serum levels of elderly patients in treatment with liquid and tablet L-T4 formulations over a period of time of five years. SubjectsPatients were recruited by searching the database of those treated and followed at the Thyroid Unit of the University of Brescia. ResultsTwo hundred and ninety-nine patients (251 females, 48 males) were treated with L-T4 in tablet form (groupT) and 118 subjects (107 female, 11 male) with liquid LT4 (groupL). The two groups were super-imposable by age, median L-T4 dosage, TSH, fT4 and fT3 values. A slightly but not significantly higher BMI value was observed among patients of group L over those of group T (26.9±2.9 vs. 26.4±2.1 kg/cm2, respectively). During five years of LT-4 treatment, sub-clinical or over-hypothyroidism was found in 13 (4.3%) and 3 (2.5%) patients of group T and group L (P=0.335), whereas, subclinical or clinical hyperthyroidism was significantly more frequent among patients of group T than those of group L [69 (23%) vs. 5 (4.2%) patients, (P=0.0001)]. Logistic regression analysis showed that only the Tablets were associated with the risk of developing subclinical or hyperthyroidism [OR 2·354 (1·136–4·827), P=0.021]. ConclusionsWe show a greater stability in the thyroid profile of hypothyroid elderly patients in treatment with liquid thyroxine as opposed to those being treated by tablet formulation over five years of follow-up.