Unresponsiveness to exogenous TSH in obesity

Area of Science:

• Endocrinology
• Metabolic Disorders

Background:

• Massive obesity is often associated with subtle endocrine abnormalities.
• Thyroid function is crucial in regulating metabolism and body weight.

Purpose of the Study:

• To investigate thyroidal and related indices in a large cohort of obese individuals.
• To explore the prevalence of thyroid dysfunction and TSH responsiveness in severe obesity.

Main Methods:

• Assessed thyroidal iodine-131 uptake, ankle reflex time, serum cholesterol, and TSH levels in 275 obese patients.
• Evaluated responses to exogenous TSH administration.

Main Results:

• Approximately 20% of obese patients showed absent thyroidal I131 uptake responses to TSH.
• Minority exhibited low basal uptake, prolonged ankle reflex, or high cholesterol.
• Elevated serum TSH titers were occasionally observed.
• Abnormalities correlated with increased body weight excess and age.

Conclusions:

• Sporadic thyroid abnormalities are common in massive obesity, often without overt hypothyroidism.
• Unresponsiveness to TSH is frequent and represents an unexplained endocrine anomaly.
• This TSH unresponsiveness may contribute to obesity by reducing energy expenditure.