Thyroid hormones and the metabolic syndrome

Area of Science:

• Endocrinology
• Metabolic Health
• Cardiovascular Risk

Background:

• Metabolic syndrome, characterized by abdominal obesity, hyperglycemia, low HDL cholesterol, high triglycerides, and hypertension, is a key predictor of cardiometabolic risk.
• Thyroid dysfunction is known to influence multiple components of the metabolic syndrome.

Purpose of the Study:

• To review and synthesize current data on how thyroid hormones affect the various components of the metabolic syndrome.

Main Methods:

• A comprehensive literature search was conducted on PubMed.
• Keywords included thyroid dysfunction (hyperthyroidism, thyrotoxicosis, hypothyroidism) and metabolic syndrome components (blood pressure, hypertension, hyperlipidemia, cholesterol, HDL cholesterol, glucose, diabetes mellitus, body weight, visceral fat).
• Studies published from 2000 to the present were included, along with highly cited older papers.

Main Results:

• There is substantial evidence demonstrating a significant impact of thyroid function on all aspects of the metabolic syndrome.
• Thyroid dysfunction profoundly alters energy homeostasis through various mechanisms.

Conclusions:

• The interplay between thyroid function and metabolic syndrome is complex in both animal models and humans.
• Euthyroid (normal thyroid function) states are associated with the highest insulin sensitivity and the least adverse effects on the metabolic system.