Glucose tolerance and lipid profile in longterm exogenous subclinical hyperthyroidism and the effects of restoration of euthyroidism, a randomised controlled trial

K. A. Heemstra, J. W.A. Smit, C. F.A. Eustatia-Rutten, A. C. Heijboer, M. Frölich, J. A. Romijn, E. P.M. Corssmit*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Objective: The impact of prolonged subclinical hyperthyroidism on glucose and lipid metabolism is unclear. Therefore, we evaluated glucose and lipid metabolism in patients with differentiated thyroid carcinoma (DTC) on TSH suppressive thyroxine therapy as a model for subclinical hyperthyroidism and investigated whether restoration to euthyroidism affects metabolism. Design: We performed a prospective, single-blinded, placebo-controlled, randomised trial of 6 months duration with 2 parallel groups. Patients: Twenty-five subjects with a history of differentiated thyroid carcinoma with > 10 years TSH-suppressive therapy with l-thyroxine completed the study. l-thyroxine dose was replaced by study medication containing l-thyroxine or l-thyroxine plus placebo. Medication was titrated to establish continuation of TSH suppression (low-TSH group, 13 patients) and euthyroidism (euthyroidism group, 12 patients). Measurements: We evaluated glucose metabolism by glucose tolerance test and HOMA (IR) and lipid metabolism by lipid profile. In addition, we measured plasma concentrations of glucoregulatory hormones. Results: At baseline, glucose tolerance, HOMA (IR), lipid profile and plasma concentrations of glucoregulatory hormones were within the normal range. No significant differences between the low TSH and euthyroidism group were observed. After 6 months, neither glucose nor lipid metabolism in the low TSH group were different from baseline values. Conclusion: In summary, glucose and lipid metabolism in patients with DTC and long-term subclinical hyperthyroidism in general are not affected. Restoration of euthyroidism in general does not affect glucose and lipid metabolism.

Original languageEnglish
Pages (from-to)737-744
Number of pages8
JournalClinical Endocrinology
Volume65
Issue number6
DOIs
Publication statusPublished - Dec 2006

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