Thyroid Function Alteration in Obesity and the Effect of Bariatric Surgery

Area of Science:

• Endocrinology
• Metabolic Disorders
• Obesity Medicine

Background:

• Hypothyroidism is common in obesity, but its causal relationship with increased adiposity remains unclear.
• Obesity is associated with central resistance to thyroid hormone, which may be reversible with weight loss.

Purpose of the Study:

• To review controversial aspects of the relationship between obesity and thyroid function.
• To examine the effects of bariatric surgery on thyroid function in obese patients.
• To discuss thyroid hormone treatment (THT) strategies for obese patients with hypothyroidism.

Main Methods:

• Review of existing literature on obesity, thyroid function, and bariatric surgery.
• Analysis of thyroid-stimulating hormone (TSH) levels in morbidly obese individuals.
• Evaluation of levothyroxine dosage adjustments post-weight loss.

Main Results:

• Morbid obesity is linked to moderately increased TSH levels and mild central thyroid hormone resistance.
• Bariatric surgery positively impacts thyroid function in obese patients.
• Levothyroxine dosage per ideal weight remained stable post-weight loss, while dosage per actual weight increased.

Conclusions:

• Diagnosing mild hypothyroidism in morbid obesity presents challenges.
• Bariatric surgery can improve thyroid function in obese individuals.
• Optimizing THT in obese patients may require basing levothyroxine dosage on ideal body weight.