A Cross-Sectional Study of the Association between Thyroid Hormones and Thyroid-Stimulating Hormone with Parameters of the Metabolic Syndrome in Korean Men and Women

Sex Dimorphic Responses of the Hypothalamus-Pituitary-Thyroid Axis to Energy Demands and Stress

“…Sex dimorphism in serum TSH concentration in humans varies with age and health state. Serum FT4 and FT3 concentrations in men are greater than in women ( 50 – 53 ). Estrogen increases the concentration of TBG in the circulation, whereas glucocorticoids diminish it, making TBG concentration another point of regulation; for example, in excess concentrations of estrogens as with usage of contraceptive drugs ( 54 ).…”

“…Before menopause, there are no differences between sexes in serum TSH concentration of healthy adult humans ( 50 , 55 ), whereas after menopause it is higher in women than in men ( 56 ). Furthermore, women with metabolic syndrome have higher TSH concentration than men with this condition ( 51 – 53 ).…”

“…In an extensive US survey, no differences were found between male and female serum TSH concentration, except with women over 50 years old whose values were higher than those of males ( 80 ); central hypothyroidism occurs rarely (<0.1%) ( 79 ). A close association of hypothyroidism with symptoms of metabolic syndrome has been now recognized ( 52 , 81 , 82 ), women with metabolic syndrome having higher serum TSH concentration than men with this condition ( 51 – 53 ). Hyperthyroidism (overt and subclinical) produces low BMI, waist circumference and blood triglyceride concentration, but high blood pressure and serum high-density lipoprotein cholesterol concentration compared with euthyroid men.…”

“…Hyperthyroidism (overt and subclinical) produces low BMI, waist circumference and blood triglyceride concentration, but high blood pressure and serum high-density lipoprotein cholesterol concentration compared with euthyroid men. Women do not present symptoms of hyperthyroidism ( 53 , 81 , 82 ). Men with subclinical hypothyroidism have higher serum triglyceride concentration and abdominal fat weight than women, while subclinical hypothyroid women are more propense to become obese ( 81 , 82 ), an effect increased after menopause ( 51 – 53 ).…”

“…Women do not present symptoms of hyperthyroidism ( 53 , 81 , 82 ). Men with subclinical hypothyroidism have higher serum triglyceride concentration and abdominal fat weight than women, while subclinical hypothyroid women are more propense to become obese ( 81 , 82 ), an effect increased after menopause ( 51 – 53 ). An extensive study performed in China demonstrates that obese women have a higher risk to suffer overt and subclinical hypothyroidism (22.7% and 22.1% respectively) than non-obese women, while in men there is no association between obesity and hypothyroidism ( 83 ).…”