Variation in the biochemical response to l-thyroxine therapy and relationship with peripheral thyroid hormone conversion efficiency

Endocrine Connections
John E M MidgleyRudolf Hoermann

Abstract

Several influences modulate biochemical responses to a weight-adjusted levothyroxine (l-T4) replacement dose. We conducted a secondary analysis of the relationship of l-T4 dose to TSH and free T3 (FT3), using a prospective observational study examining the interacting equilibria between thyroid parameters. We studied 353 patients on steady-state l-T4 replacement for autoimmune thyroiditis or after surgery for malignant or benign thyroid disease. Peripheral deiodinase activity was calculated as a measure of T4-T3 conversion efficiency. In euthyroid subjects, the median l-T4 dose was 1.3 μg/kg per day (interquartile range (IQR) 0.94,1.60). The dose was independently associated with gender, age, aetiology and deiodinase activity (all P<0.001). Comparable FT3 levels required higher l-T4 doses in the carcinoma group (n=143), even after adjusting for different TSH levels. Euthyroid athyreotic thyroid carcinoma patients (n=50) received 1.57 μg/kg per day l-T4 (IQR 1.40, 1.69), compared to 1.19 μg/kg per day (0.85,1.47) in autoimmune thyroiditis (P<0.01, n=76) and 1.08 μg/kg per day (0.82, 1.44) in patients operated on for benign disease (P< 0.01, n=80). Stratifying patients by deiodinase activity categories of <23, 23-29 and >29 nmol/...Continue Reading

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Citations

Dec 5, 2015·Frontiers in Endocrinology·Rudolf HoermannJohannes W Dietrich
Jan 30, 2018·Frontiers in Endocrinology·Rudolf HoermannJohannes W Dietrich
Jul 5, 2016·Frontiers in Endocrinology·Johannes W DietrichRudolf Hoermann
Aug 11, 2017·Therapeutic Advances in Endocrinology and Metabolism·Rudolf HoermannRolf Larisch
Nov 21, 2017·PloS One·Rudolf HoermannJohannes Wolfgang Christian Dietrich
Jun 21, 2018·Frontiers in Endocrinology·Johannes W DietrichRudolf Hoermann
Apr 20, 2019·BMC Endocrine Disorders·John E M MidgleyRudolf Hoermann
Oct 17, 2019·Frontiers in Endocrinology·Rudolf HoermannJohannes W Dietrich
Apr 1, 2016·Thyroid : Official Journal of the American Thyroid Association·Jacqueline Jonklaas, Kenneth D Burman
Nov 23, 2016·Frontiers in Endocrinology·Rudolf HoermannJohannes W Dietrich

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