Evaluation of the Clinical and Biological Consequences of Levothyrox® Formula Modification

Study Overview
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Brief Summary
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The purpose of this study is to determine whether the recent excipient modification of Levothyrox® in France for a bioequivalent formula has clinical and biological consequence for the patients. The investigators also plan to describe the patient journey in terms of levothyroxine based drugs since this formula modification of Levothyrox®.

Detailed Description
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Levothyrox® is a levothyroxine based drug marketed in France in order to substitute a lack of thyroid hormones. Because of a lack of stability during time and because of wide inter-batch variability in terms of active molecule, the National Agency of Safety of Medicaments (ANSM) ask to the market authorization holder to develop a new formula without lactose. This new formula, which has been proven to be bioequivalent has been marketed since march 2017 in France. Some patients were predicted to have their thyroid function imbalance because of this modification. The purpose of the study is to analyse, on the patients treated by Levothyroxine® in how many patients this modification has clinical and biological consequences.

Official Title
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Evaluation of the Clinical and Biological Consequences of Levothyrox® Formula Modification

Conditions
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Thyroid Disorder

Intervention / Treatment
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* Other: self completed questionnaire


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Thyroid disorder treated by Levothyroxine Age over 18 year old TSH plasma level within the 12 months before formulation modification TSH plasma level within the 6 months after formulation modification Exclusion Criteria: - Thyroid dysfunction (hypo or hyperthyroidism) despite Levothyroxine treatment, ie TSH plasma level out of normal range within the 6 months before formula modification

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Intervention/Treatment |
| --- |
|Other: self completed questionnaire|self completed questionnaire|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of abnormal Thyroid Stimulating Hormone (TSH) level after change of levothyrox formulation | Evaluated with a self completed questionnaire | 1 day | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of patients treated with new formulation of levothyrox | Evaluated with a self completed questionnaire | 1 day | 
| Difference betweenTSH plasma levels before and after formulation change | Evaluated with a self completed questionnaire | 1 day | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Levothyrox®, thyroid hormones, bioequivalent