Effects of thyroid hormones on serum levels of adipokines as studied in patients with differentiated thyroid carcinoma during thyroxine withdrawal.

OBJECTIVE

Previous studies addressing the influence of thyroid hormones on serum levels of adipokines yielded conflicting results. We aimed to study the impact of short-term overt hypothyroidism on serum leptin, resistin, and adiponectin levels in an in vivo human model.

DESIGN

Twenty-two women with differentiated thyroid carcinoma were studied the last day of their thyroxine-suppressive treatment, 4-7 days after withdrawal, and the day before whole-body scanning. Evaluations included serum thyroid hormone, leptin, resistin, and adiponectin concentrations, fasting glucose and insulin, lipid profiles, body temperature, body mass index, and total body fat mass.

MAIN OUTCOMES

Thyroid function changed from subclinical or mild hyperthyroidism to normal free thyroxine and triiodothyronine levels, ending in overt hypothyroidism. Thyroxine withdrawal resulted in an increase in serum resistin (p = 0.007) and leptin (p = 0.006) concentrations, whereas adiponectin levels remain unchanged. A significant decrease in body temperature during thyroxine withdrawal was paralleled by a decrease in fasting glucose (p = 0.006) and insulin resistance (p = 0.033), which occurred despite an increase in estimated total body fat mass.

CONCLUSION

Thyroid hormones are important regulators of energy balance and intermediate metabolism, influencing the serum concentrations of leptin and resistin.