Vitamin D inhibits bone loss in mice with thyrotoxicosis by activating the OPG/RANKL and Wnt/ß-catenin signaling pathways.

Objective: Vitamin D and thyroid hormones have crucial roles in bone metabolism. This study aims to explore the effects of vitamin D on bone metabolism in mice with thyrotoxicosis and its mechanisms. Methods: 12-week-old mice were randomly divided into 6 groups (6 mice/group), the control (CON) group, vitamin D (VD) group, low-dose LT4 (Low LT4) group, low-dose LT4+VD (Low LT4+VD) group, high-dose LT4 (High LT4) group, high-dose LT4+VD (High LT4+VD) group, LT4 was provided every day and vitamin D3 every other day for 12 weeks. Thyroid function, 25-hydroxy vitamin D, type I collagen carboxy-terminal peptide (CTX), and type I procollagen amino-terminal peptide were determined. In addition, microcomputed tomography, bone histology and histomorphometry, a three-point bending test, and the mRNA expression of osteoprotegerin (OPG), receptor activator of nuclear factor-κB ligand (RANKL) and ß-catenin in bone were conducted. Results: The BMD of lumbar vertebrae and femur decreased and the bone microstructure was destroyed significantly in thyrotoxicosis mice. Addition of vitamin D improved the BMD and bone microstructure only in the low LT4+VD group. Mice with thyrotoxicosis had a significantly higher level of CTX (P<0.05), which was decreased by treatment with vitamin D (P<0.05). The eroded surface per bone surface (Er. S/BS) of the cancellous bone and elongated surface/endocortical perimeter (Er. S/E Pm) of the cortical bone significantly increased in the Low LT4 and High LT4 groups (P<0.05). Treatment with vitamin D significantly decreased the Er. S/BS and Er. S/E Pm. But, treatment with vitamin D did not significantly improve the toughness and rigidity of bones. The ratio of OPG to RANKL and mRNA expression of ß-catenin in the Low LT4+VD group were higher than that in the Low LT4 group (P<0.05). Conclusion: In mice with thyrotoxicosis, treatment with vitamin D can inhibit bone resorption and improve the BMD and trabecular bone architecture by increasing the ratio of OPG to RANKL and upregulating the expression of Wnt/ß-catenin.

[Performance Verification of Plasma Renin and Aldosterone Examination with Chemiluminescence Immunoassay and Its Screening Efficacy for Primary Aldosteronism].

OBJECTIVE: To evaluate the performance of chemiluminescence immunoassay (CLIA) in examining renin and aldosterone and to determine its value for screening for primary aldosteronism (PA). METHODS: According to the relevant documents of Clinical and Laboratory Standards Institute (CLSI), we verified the precision, linear range and carryover rate of examining renin and aldosterone with CLIA. The study included 91 suspected PA patients, using two methods, CLIA and radioimmunoassay (RIA), to examine renin and aldosterone levels in order to compare the correlation between the two methods and their value for PA screening. RESULTS: The precision, linear range and carryover rate of examining renin and aldosterone with CLIA met the requirements. In patients with suspected PA, the correlation coefficients of renin, aldosterone and aldosterone-to-renin ratio (ARR) assessed by CLIA and RIA were 0.901, 0.861 and 0.847 respectively (all P<0.001). When the patients were in the upright position and the ARR was 5.636 (ng/dL)/(ng/L), the CLIA method had 79.1% sensitivity and 93.7% specificity for PA screening; when ARR was 14.084 (ng·dL －1)/(ng·[mL·h] －1), the RIA method had 93.0% sensitivity and 83.3% specificity for PA screening. When the patients were in the supine position, and the ARR was 5.640 (ng/dL)/(ng/L), the CLIA method had 97.7% sensitivity and 81.2% specificity for PA screening; when ARR was 33.494 (ng·dL －1)/(ng·[mL·h] －1), RIA had 95.3% sensitivity and 70.8% specificity for PA screening . CONCLUSION: The performance of the CLIA kit in assessing the concentration of renin and aldosterone meets the clinical requirements. Regarding preliminary PA screening, upright-position ARR had higher specificity, but lower sensitivity compared with supine-position ARR.