Timing of Levothyroxine Administration Affects Serum Thyrotropin Concentration
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TLDR
If a specific serum TSH goal is desired, thereby avoiding iatrogenic subclinical thyroid disease, then fasting ingestion of levothyroxine ensures that TSH concentrations remain within the narrowest target range.Abstract:
Context: Patients treated with levothyroxine typically ingest it in a fasting state to prevent food impairing its absorption. The serum thyrotropin concentration is the therapeutic index of levothyroxine action.
Objective: The study objective was to determine the effect of the timing of levothyroxine administration in relationship to food on serum thyrotropin levels.
Design: Participants were randomized to one of six sequences, each consisting of three 8-wk regimens in a three-period crossover design. These regimens were in a fasting state, at bedtime, and with breakfast. The concentrations of TSH, free T4, and total T3 during each of the three timing regimens were documented. The primary outcome was the difference between serum TSH concentrations under fasting conditions compared with concentrations during the other 8-wk regimens.
Setting: The study was conducted in an academic medical center.
Participants: Study participants were receiving levothyroxine for treatment of hypothyroidism or thyroid cancer.
Results: Sixty-five patients completed the study. The mean thyrotropin concentration was 1.06 ± 1.23 mIU/liter when levothyroxine was administered in the fasting state. When levothyroxine was taken with breakfast, the serum thyrotropin concentration was significantly higher (2.93 ± 3.29 mIU/liter). When levothyroxine was taken at bedtime, the serum TSH concentration was also significantly higher (2.19 ± 2.66 mIU/liter).
Conclusion: Nonfasting regimens of levothyroxine administration are associated with higher and more variable serum TSH concentrations. If a specific serum TSH goal is desired, thereby avoiding iatrogenic subclinical thyroid disease, then fasting ingestion of levothyroxine ensures that TSH concentrations remain within the narrowest target range.read more
Citations
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Journal ArticleDOI
Clinical Practice Guidelines for Hypothyroidism in Adults: Cosponsored by the American Association of Clinical Endocrinologists and the American Thyroid Association
Jeffrey R. Garber,Jeffrey R. Garber,Rhoda H. Cobin,Hossein Gharib,James V. Hennessey,Irwin Klein,Jeffrey I. Mechanick,Rachel Pessah-Pollack,Peter Singer,Kenneth A. Woeber +9 more
TL;DR: Fifty-two evidence-based recommendations and subrecommendations were developed to aid in the care of patients with hypothyroidism and to share what the authors believe is current, rational, and optimal medical practice for the diagnosis and care of hyp Timothyroidism.
Journal ArticleDOI
Guidelines for the Treatment of Hypothyroidism: Prepared by the American Thyroid Association Task Force on Thyroid Hormone Replacement
Jacqueline Jonklaas,Antonio C. Bianco,Andrew J. Bauer,Kenneth D. Burman,Anne R. Cappola,Francesco S. Celi,David S. Cooper,Brian W. Kim,Robin P. Peeters,M. Sara Rosenthal,Anna M. Sawka +10 more
TL;DR: It is concluded that levothyroxine should remain the standard of care for treating hypothyroidism and no consistently strong evidence for the superiority of alternative preparations is found.
Journal ArticleDOI
Clinical practice guidelines for hypothyroidism in adults: cosponsored by the American Association of Clinical Endocrinologists and the American Thyroid Association.
Garber,Rhoda H. Cobin,Hossein Gharib,James V. Hennessey,Irwin Klein,Jeffrey I. Mechanick,Rachel Pessah-Pollack,Peter Singer,Kenneth A. Woeber +8 more
TL;DR: Fifty-two evidence-based recommendations and subrecommendations were developed to aid in the care of patients with hypothyroidism and to share what the authors believe is current, rational, and optimal medical practice for the diagnosis and care of hyp Timothyroidism.
Journal ArticleDOI
2013 ETA Guideline: Management of Subclinical Hypothyroidism
Simon H. S. Pearce,Georg Brabant,Leonidas H. Duntas,Fabio Monzani,Robin P. Peeters,Salman Razvi,Jean-Louis Wemeau +6 more
TL;DR: Subclinical hypothyroidism (SCH) should be considered in two categories according to the elevation in serum thyroid-stimulating hormone (TSH) level: mildly increased TSH levels (4.0-10.0 mU/l) and more severelyincreased TSH value (>10 m U/l).
Journal ArticleDOI
Thyroid Hormone Therapy for Older Adults with Subclinical Hypothyroidism.
David J. Stott,Nicolas Rodondi,Patricia M. Kearney,Ian Ford,Rudi G. J. Westendorp,Simon P. Mooijaart,Naveed Sattar,Carole E. Aubert,Drahomir Aujesky,Douglas C. Bauer,Christine Baumgartner,Manuel R. Blum,John Browne,Stephen Byrne,Tinh-Hai Collet,Olaf M. Dekkers,Wendy P. J. den Elzen,Robert S. Du Puy,Graham Ellis,Martin Feller,Carmen Floriani,Kirsty Hendry,Caroline Hurley,J. Wouter Jukema,Sharon Kean,Maria Kelly,Danielle Krebs,Peter Langhorne,Gemma McCarthy,Vera J. C. McCarthy,Alex McConnachie,Mairi McDade,Martina Messow,Anne Marie O'Flynn,David O'Riordan,Rosalinde K. E. Poortvliet,Terence J. Quinn,Audrey Russell,Carol Sinnott,Jan W. A. Smit,H. Anette Van Dorland,Kieran A. Walsh,Elaine Walsh,Torquil Watt,Robbie Wilson,Jacobijn Gussekloo +45 more
TL;DR: Levothyroxine provided no apparent benefits in older persons with subclinical hypothyroidism and there was no significant excess of serious adverse events prespecified as being of special interest.
References
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Journal ArticleDOI
Replacement dose, metabolism, and bioavailability of levothyroxine in the treatment of hypothyroidism. Role of triiodothyronine in pituitary feedback in humans.
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TL;DR: The findings suggest the possibility that in humans, serum triiodothyronine may play a more important part than serum thyroxine in regulating the serum thyrotropin concentration.
Journal ArticleDOI
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Marco Centanni,Lucilla Gargano,Gianluca Canettieri,N Viceconti,Antonella Franchi,Gianfranco Delle Fave,Bruno Annibale +6 more
TL;DR: Patients with impaired acid secretion require an increased dose of thyroxine, suggesting that normal gastric acid secretion is necessary for effective absorption of oral thyrotropin.