ABSTRACT Objective This study aimed to present the impact of age and gender on thyroid hormone levels in a large Chinese population with sufficient iodine intake. Subjects and methods A total of 83643 individuals were included and were stratified by age and gender. The median, 2.5th and 97.5th of thyrotropin (TSH), free triiodothyronine (FT3), free thyroxine (FT4) and FT3/FT4 ratio were calculated for both genders for every decade from 18 to over 80 years. TSH, FT3, FT4, FT3/FT4 distribution in each age group was evaluated for females and males using smoothing splines in the generalized additive models (GAM). TSH concentrations were compared in the different age groups in gender. Results In the over 80s age group, the TSH level (median: 2.57 mIU/L, 2.5th-97.5th: 0.86-7.56 mIU/L) was significantly higher than other age groups, irrespective to gender (P<0.001). Females had a higher TSH value than males in all age groups (P<0.001). Results of the smoothing curves showed that TSH increased with age, FT3 concentration was higher in males than in females and the tendency of the FT3/FT4 ratio was basically similar to that of FT3. TSH concentration in the 50s age group (median 2.48 mIU/L for females versus 2.00 mIU/L for males) was significantly higher than that in the 30s age group (median 2.18 mIU/L for females versus median 1.85 mIU/L for males). Conclusions In accord with increasing TSH values during aging, females and older adults have lower FT3 values and lower FT3/FT4 ratios, while the FT4 values remain stable.

Purpose: The G-protein β3-subunit gene C825T polymorphism (GNB3-C825T) has been reported to be associated with essential hypertension (EH), but results from previous studies are conflicting. The present study aimed at investigating the association between this polymorphism and risk of EH using a meta-analysis on the published studies. Materials and Methods: PubMed, Embase, CBM (China Biological Medicine Database), Wanfang and VIP databases were searched to identify eligible studies published in English and Chinese before March 2013. Data were extracted using standardized methods. The association was assessed by the odds ratio (OR) with 95% confidence intervals (CI). Begg's test was used to measure publication bias. Results: A total of 40 case-control studies containing 16,518 EH patients and 20,284 controls were involved in this meta-analysis. Overall, a significant association was found between GNB3 C825T polymorphism and risk of EH when all studies were pooled with a random-effects model for T versus C (OR=1.09, 95% CI: 1.04-1.19). In the subgroup analysis, the same association was found in overall Caucasian (T versus C, OR=1.16, 95% CI 1.08-1.24) and Chinese populations (TT versus CC, OR=1.23, 95% CI 1.06-1.57). No associations were detected between GNB3-C825T and the risk of EH overall in Asian and Japanese people. Conclusions: Meta-analysis results suggest that the GNB3-C825T polymorphism is associated with risk of EH in the overall population, the Caucasians and the Chinese. The effect of the variants on the expression levels and the possible functional role of the variants in EH should be addressed in further studies.