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Objective: A common variant in mitochondrial DNA (mtDNA) at bp 16189 (T-->C transition) has been associated with small birth size, adulthood hyperglycemia, and insulin resistance in Caucasians. In this study, we investigated whether mtDNA 16189 variant is associated with metabolic syndrome in Chinese subjects., Methods: Six hundred fifteen Chinese adults, aged 40 yr or older, were recruited in this study. The 16189 variant of mtDNA was detected using PCR and restriction enzyme digestion. Metabolic syndrome was diagnosed on modified National Cholesterol Education Program Adult Treatment Panel III guidelines, using body mass index (BMI) instead of waist circumference. An association study was performed with chi2 test and logistic regression analysis., Results: The prevalence of the 16189 variant was higher in patients with metabolic syndrome than in those without: 44% (125 of 284) vs. 33.2% (110 of 331) (P = 0.006). The association between this 16189 variant of mtDNA and metabolic syndrome (P = 0.021) remained significant even after correcting for age and BMI. As to the individual traits, the prevalence of fasting plasma glucose of at least 110 mg/dl (> or =6.1 mmol/liter) [(51.5% (121 of 235) vs. 42.1% (160 of 380); P = 0.023], type 2 diabetes mellitus [48.1% (113 of 235) vs. 39.2% (149 of 380); P = 0.031], and hypertriglyceridemia [44.3% (104 of 235) vs. 35.8% (136 of 380); P = 0.037] were significantly higher in subjects harboring the 16189 variant of mtDNA than those with the wild type. However, the prevalence of hypertension [53.2% (125 of 235) vs. 47.6% (181 of 380); P = 0.180], BMI greater than 25 kg/m2 [48.5% (114 of 235) vs. 43.9% (167 of 380); P = 0.270], and low high-density lipoprotein cholesterol [61.3% (144 of 235) vs. 54.7% (208 of 380); P = 0.111] did not reach a significant difference between the two groups. Furthermore, there was a trend of increasing frequency of occurrence of the 16189 variant in individuals having an increasing number of components of metabolic syndrome (Ptrend < 0.005)., Conclusion: Our data strongly suggest that mtDNA 16189 variant underlies susceptibility to metabolic syndrome in the Chinese population.

Background and Purpose: Most patients with well-differentiated thyroid carcinoma have an excellent prognosis and are likely to live long enough to be subjected to osteoporosis. The purpose of this study was to investigate the consequences of treatment with a supraphysiological dose of levothyroxine (l-T4) on bone mineral density (BMD) in Taiwanese women with differentiated thyroid cancer., Methods: A total of 69 (44 premenopausal, 25 postmenopausal) Taiwanese women with differentiated thyroid cancer were included in this retrospective study. These patients were free of disease recurrence after initial near-total thyroidectomy and I-131 radioablation, and had undergone regular l-T4 suppressive therapy for more than 3 years (mean, 7.3 +/- 3.0 years; range, 3 to 15 years). The degree of thyroid-stimulating hormone (TSH) suppression was determined based on the mean TSH score for each patient which was determined by analysis of all available follow-up TSH data, where 1 = undetectable TSH (< 0.2 mIU/mL); 2 = subnormal TSH (0.2 to 0.39 mIU/mL); 3 = normal TSH (0.4 to 4.0 mIU/mL); and 4 = elevated TSH (> 4.0 mIU/mL). The patients were divided into a full TSH suppression group with a mean TSH score in the range 1.0 to 1.99, and a partial TSH suppression group with a mean TSH score in the range 2.0 to 2.99. BMD was measured by dual-energy X-ray absorptiometry at the lumbar spine, femoral neck, Ward's triangle and total hip. Comparisons between subgroups of patients and controls were performed by unpaired t test. Correlation between BMD and other clinical variables was assessed by Pearson's correlation analysis., Results: Postmenopausal patients (aged 57.7 +/- 6.9 years) had significantly higher serum calcium levels and decreased BMD at all sites of the spine and hip as compared with premenopausal patients (aged 38.6 +/- 6.7 years) with similar BMI and duration of TSH suppression. Comparison of BMD between postmenopausal patients and BMI- and age-matched controls revealed that the patient group had decreased BMD at all sites of measurement, although this difference was not significant. This phenomenon was not observed in the premenopausal patients. Furthermore, when BMD was compared between patients categorized as having full and partial suppression of TSH, only patients with full suppression in the postmenopausal group showed a tendency to lower BMD. There was a strong correlation of BMD with age, BMI and serum calcium level. However, no correlation was found between BMD and degree of TSH suppression or duration of l-T4 suppression therapy., Conclusion: Women with differentiated thyroid cancer who had long-term (mean, 7.3 +/- 3.0 years) l-T4 therapy and suppressed TSH levels had no evidence of lower BMD. However, patients with full suppression in the postmenopausal group showed a tendency towards lower BMD. Therefore, careful monitoring of BMD in postmenopausal women during suppression therapy is mandatory.