Trial reportEndocrine2018
Effect of timing of levothyroxine administration on the treatment of hypothyroidism: a three-period crossover randomized study.
Trial report in Endocrine, 2018. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 14 papers, 2 of them syntheses that pooled it.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
14 citing papers in PubMed, 2 syntheses or guidelines pooled it, 30 citations in OpenAlex.
- ETA guidelines for the use of levothyroxine sodium preparations in monotherapy to optimize the treatment of hypothyroidism.European thyroid journal · 2025Guideline
- Pooled it
- A Novel Levothyroxine Solution Results in Similar Bioavailability Whether Taken 30 or Just 15 Minutes Before a High-Fat High-Calorie Meal.Thyroid : official journal of the American Thyroid Association · 2022Trial
- Analysis of clinical pharmacist interventions in the neurology unit of a Brazilian tertiary teaching hospital.PloS one · 2019Trial
- Italian guidelines for the management of adult individuals with primary hypothyroidism outside pregnancy.Journal of endocrinological investigation · 2025Article
- Effect of different initiation timing of levothyroxine on pregnancy outcomes and development of offspring in women with gestational subclinical hypothyroidism.Pakistan journal of medical sciences · 2024Article
- Association of pharmacogenomic, clinical and behavioural factors with oral levothyroxine (LT-4) dose of hypothyroid patients in Sri Lanka: a matched case control study.BMC medical genomics · 2024Article
- Factors influencing the levothyroxine dose in the hormone replacement therapy of primary hypothyroidism in adults.Reviews in endocrine & metabolic disorders · 2022Review
- Optimal Thyroid Hormone Replacement.Endocrine reviews · 2022Article
- Evaluation of Bedtime vs. Morning Levothyroxine Intake to Control Hypothyroidism in Older Patients: A Pragmatic Crossover Randomized Clinical Trial.Frontiers in medicine · 2022Article
- Levothyroxine Interactions with Food and Dietary Supplements-A Systematic Review.Pharmaceuticals (Basel, Switzerland) · 2021Review
- Non-inferiority trials using a surrogate marker as the primary endpoint: An increasing phenotype in cardiovascular trials.Clinical trials (London, England) · 2020Article
- Liquid Levothyroxine Formulation Taken during Lunch in Italy: A Case Report and Review of the Literature.Case reports in endocrinology · 2020Article
- Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
13 authors at 6 institutions in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
aimHypothyroidism is a common clinical problem that is successfully treated with hormone substitutes in the form of levothyroxine (LT4). LT4 is a drug with a narrow therapeutic index and is usually administered by strict rules, standardly at least half an hour before breakfast. The aim of this study was to investigate a possible effect of different timings of administration on thyroid function status and lipid profile.
methodsThe study included patients with the diagnosis of primary hypothyroidism, which were using a stable dose of levothyroxine. They were randomized into three different groups regarding the timing of LT4 administration in a crossover fashion. Each timing regimen lasted for at least 8 weeks; timing regimen A-half an hour before breakfast; timing regimen B-an hour before the main meal of the day; timing regimen C-at bedtime (minimally 2 h after dinner). The hormones (TSH, fT3, fT4) and lipid profile (triglycerides, HDL-, LDL-, and total cholesterol) were measured before the study, at the beginning of every timing regimen and at the end of the study.
resultsAltogether, 84 patients finished the study. Different timings of LT4 administration were non-inferior in comparison to the standard one and between each other. Median differences in TSH level between baseline and timing regimens were: baseline vs. A = -0.017 95% C.I. (-0.400-0.192); baseline vs. B = -0.325 95% C.I. (-0.562-0.023); baseline vs. C = -0.260 95% C.I. (-0.475-0.000). There were no statistically significant differences in either TSH, fT4, or fT3 when compared between all three timing regimens of LT4 administration and the baseline. There were no statistically significant differences in any of the lipid profile parameters (triglycerides, HDL-, LDL-, and total cholesterol) when compared between all three timing regimens of LT4 administration and the baseline.
conclusionThe three investigated timing regimens of LT4 administration were equally efficient and offer additional options regarding the treatment individualization.
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