osteoprotegerin and Hashimoto-Disease

Osteoprotegerin (OPG) is a recently identified inhibitor of bone resorption. Recent studies indicated that OPG also acts as an important regulatory molecule in the vasculature. The purpose of this study was to investigate the change of OPG and its associations with endothelial function before and after exercise training in Hashimoto's thyroiditis (HT) with euthyroidism.The study subjects included 62 newly diagnosed sedentary Chinese Han HT women with euthyroidism and 28 sedentary Chinese Han female healthy subjects. All individuals participated in an exercise training of 6 months. Plasma OPG concentrations were measured in duplicate by a sandwich enzyme-linked immunosorbent assay, and high resolution ultrasound was used to measure brachial artery diameter at rest, after reactive hyperemia, and after sublingual glyceryltrinitrate.. The OPG concentration in HT patients with euthyroidism before exercise was 3.0±0.81 ng/L, which was significantly higher than that in control subjects (2.44±0.24 ng/L, p<0.001). After 6 months of exercise, OPG levels decreased markedly (2.40±0.61 ng/L, p<0.001). Flow-mediated dilation (FMD) in HT patients with euthyroidism before exercise was 4.06±0.78%, which was significantly lower than that in control subjects (5.54±0.61%, p<0.001), and it improved markedly after 6 months of exercise (5.0±0.79, p<0.001). The absolute changes in OPG showed significant correlation with the changes in FMD (r= - 0.432, p=0.001), TBARS (r= - 0.370, p=0.004) and CRP (r= - 0.503, p<0.001).. The current study demonstrates that plasma OPG levels increased significantly at baseline, decreased dramatically after 6 months regular aerobic exercise training, and are correlated with endothelium-dependent arterial dilation in HT patients with euthyroidism.

Topics: Adult; Asian People; Brachial Artery; C-Reactive Protein; China; Endothelium, Vascular; Enzyme-Linked Immunosorbent Assay; Exercise; Female; Hashimoto Disease; Humans; Middle Aged; Osteoprotegerin; Oxygen Consumption; Sedentary Behavior; Severity of Illness Index; Thyroid Gland; Thyroid Hormones; Ultrasonography; Vasodilation; Vasodilator Agents

Hypothyroidism is associated with changes in bone metabolism. The impact of hypothyroidism and the associated autoimmunity on the mediators of bone turnover in Hashimoto's thyroiditis (HT) is not known. In this study, we assessed the levels of OPG, RANKL, and IL-6 along with markers of bone formation as osteocalcin (OC) and markers of bone resorption as type 1 collagen C telopeptide (CTX) and tartrate-resistant acid phosphatase isoform 5b (TRAcP 5b) in 30 hypothyroid and 30 euthyroid premenopausal HT patients and 20 healthy premenopausal controls. We found that TRAcP 5b (p = 0.006), CTX (p = 0.01), OC (p = 0.017), and IL-6 (p < 0.001) levels were lower in the hypothyroid group compared to euthyroid HT patients and controls. OPG levels were higher (p < 0.001) and RANKL levels were lower (p = 0.021) in hypothyroid and euthyroid HT patients compared to controls. TSH was negatively correlated with IL-6 (rho = -0.434, p < 0.001), OC (rho = -0.313, p = 0.006), TRAcP 5b (rho = -0.335, p = 0.003), and positively correlated with OPG (rho = 0.248, p = 0.029). RANKL/OPG ratio was independently associated with the presence of HT. In conclusion, bone turnover is slowed down by hypothyroidism in premenopausal patients with HT. Thyroid autoimmunity might have a unique impact on OPG/RANKL levels apart from the resultant hypothyroidism.

Topics: Adult; Autoimmunity; Body Mass Index; Bone and Bones; Bone Remodeling; Collagen Type I; Cross-Sectional Studies; Female; Hashimoto Disease; Humans; Hypothyroidism; Interleukin-6; Middle Aged; Osteoprotegerin; Peptides; Premenopause; RANK Ligand; Risk Factors; Tartrate-Resistant Acid Phosphatase; Thyroid Gland; Ultrasonography