Metabolic syndrome and its components are associated with thyroid volume in adolescents

To explore the association between metabolic syndrome (MetS) and its component and thyroid volume in Chinese adolescents, and to compare the detection rate of MetS under the three different diagnostic criteria.

A total of 1097 school students (610 males and 487 females, ages 12-15 years) were enrolled. All the participants underwent physical examination, biochemical test, and thyroid gland ultrasonography. The thyroid volume of normal, overweight and obese group was compared. We also analyzed the association between the number of MetS components and thyroid volume. Linear and multiple linear regression were applied to explore the association between metabolic parameters and thyroid volume.

The thyroid volume of the males in overweight (t = 3.784, P < 0.001) and obese group (t = 5.068, P < 0.001) was significantly larger than that in normal group; the thyroid volume of the females in overweight group (t = 4.627,P < 0.001) was significantly larger than that of normal group. As the number of MetS components increased, the thyroid volume also increased significantly (F = 10.64, P < 0.01). Height, weight, body mass index (BMI), waist circumference, hip circumference, systolic blood pressure, fasting insulin, homeostasis model assessment of insulin resistance (HOMA-IR), uric acid and triglyceride were all positively associated with thyroid volume in the adolescents (P all < 0.001). Meanwhile, there was a negative association between high-density lipoprotein cholesterol (HDL-C) and thyroid volume (P < 0.001). According to multiple linear regression, waist circumference (β = 0.029, 95 %CI: 0.015 ~ 0.042; P < 0.01) and waist height ratio (β = 3.317, 95 %CI: 1.661 ~ 4.973; P < 0.01) were predict factors of thyroid volume. No statistical difference was found in the detection rates of metabolic syndrome under the three diagnostic criteria.

Overweight, obesity and metabolic syndrome was associated with adolescent thyroid volume. Central obesity may be an independent risk factor for thyroid enlargement in adolescents.