Can levothyroxine cause weight gain
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Can Levothyroxine Cause Weight Gain?
Introduction to Levothyroxine and Weight Gain
Levothyroxine is a synthetic form of the thyroid hormone thyroxine, commonly prescribed to treat hypothyroidism. While it is generally expected to help manage weight by normalizing thyroid function, some patients report weight gain during treatment. This article explores the relationship between levothyroxine and weight gain, drawing on recent research findings.
Levothyroxine and BMI: Independent of TSH Levels
Several studies have investigated the association between levothyroxine medication and body mass index (BMI). One large cross-sectional study found that levothyroxine use was significantly associated with higher BMI, independent of thyroid-stimulating hormone (TSH) levels 2. This suggests that factors other than thyroid hormone levels might contribute to weight gain in patients taking levothyroxine.
Childhood Weight Gain and Later Levothyroxine Use
Research has shown that overweight or excessive weight gain during childhood can increase the risk of hypothyroidism and the need for levothyroxine later in life. A study involving a large population-based birth cohort found that childhood weight gain was positively associated with later levothyroxine use and the presence of thyroid autoimmunity, particularly in women 1. This indicates a complex relationship between early-life weight gain and thyroid function in adulthood.
Hunger and Food Intake During Levothyroxine Therapy
Levothyroxine therapy can influence hunger sensations and food intake, which may contribute to weight changes. A study on individuals with hypothyroidism found that while levothyroxine increased resting energy expenditure, it also heightened hunger sensations. Despite the increase in energy expenditure, there was no significant loss of fat mass, suggesting that increased hunger might offset the potential weight loss benefits of the therapy 3.
Adverse Effects and Weight Gain
Changes in levothyroxine formulations have been linked to adverse effects, including weight gain. For instance, a new formulation introduced in France led to numerous reports of weight gain among other symptoms. This was attributed to changes in excipients, which might have affected the drug's bioavailability and efficacy 5. Such findings highlight the importance of formulation consistency in managing hypothyroidism effectively.
Conclusion
While levothyroxine is essential for managing hypothyroidism, its association with weight gain is complex and influenced by various factors, including childhood weight, hunger sensations, and formulation changes. Further research is needed to fully understand the mechanisms behind levothyroxine-induced weight gain and to optimize treatment strategies for patients.
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Most relevant research papers on this topic
Thyroid function: Childhood weight gain increases risk of thyroid disorders
Childhood weight gain increases the risk of hypothyroidism or thyroid autoimmunity later in life, particularly in women.
Observational StudyLevothyroxine medication is associated with adiposity independent of TSH.
Levothyroxine medication is independently associated with a higher BMI, regardless of TSH levels.
Observational StudyEffects of levothyroxine substitution therapy on hunger and food intake in individuals with hypothyroidism
Levothyroxine therapy increases resting energy expenditure but does not cause fat mass loss, suggesting hunger may be a factor in the lack of fat mass loss in individuals with hypothyroidism.
Non-RCTHypothyroidism in Context: Where We’ve Been and Where We’re Going
Levothyroxine is the main tool for treating hypothyroidism, but optimal treatment requires further research on accurate prevalence assessments, optimal substitution doses, and optimal duration of treatment.
Highly CitedComment on: Levothyrox® New and Old Formulations: Are They Switchable for Millions of Patients?
The new Levothyrox® formula in France may have increased adverse reactions due to the presence of a levothyroxine-citric acid adduct, which may not be switchable for millions of patients.
Levothyroxine and Non-alcoholic Fatty Liver Disease: A Mini Review.
Levothyroxine may help mobilize hepatic fat and potentially mitigate Non-Alcoholic Fatty Liver Disease (NAFLD) in individuals with underactive thyroid conditions.
Oral levothyroxine therapy postbariatric surgery: Biopharmaceutical aspects and clinical effects.
Bariatric surgery may compromise levothyroxine absorption or decrease dose requirements, requiring close monitoring of thyroid hormone levels.
Systematic ReviewLaboratory characteristics analysis of the efficacy of levothyroxine on subclinical hypothyroidism during pregnancy: a single-center retrospective study
Levothyroxine treatment alone is insufficient for pregnant women with subclinical hypothyroidism, and vitamin B12 and folic acid supplementation may be needed to improve pregnancy outcomes.
Pseudomalabsorption of levothyroxine: a case report.
Pseudomalabsorption of levothyroxine may occur in patients with resistant hypothyroidism, where oral intake of levothyroxine is ineffective due to patient's factitiousness.
Case ReportLevothyroxine Dosing Following Bariatric Surgery
Bariatric surgery may lead to decreased levothyroxine requirements due to weight loss, counteracting malabsorptive effects, and reversing impaired pharmacokinetics and thyroid hormone homeostasis.
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