No abstract

No abstract

No abstract

Hypothyroidism is resulting from a deficiency of thyroid hormones, which is common condition with potentially devastating health consequences that affect all populations worldwide. 1 Thyroid hormones are essential for growth, neuronal development, reproduction and the regulation of energy metabolism. The prevalence of hypothyroidism varies considerably across the general population, ranging between 0.2% and 5.3% in Europe, 2 0.3% and 3.7% in the USA, 3 11% in India 4 and 17.8% in China (overt hypothyroidism: 1.1%; subclinical hypothyroidism: 16.7%). 5 Longitudinal studies from large UK cohorts report an incidence rate of spontaneous hypothyroidism of 3.5-5.0 per 1000 and 0.6-1.0 per 1000 in women and men, respectively. 6The clinical presentation of hypothyroidism is nonspecific and variable. Therefore, the diagnosis of hypothyroidism is based primarily on biochemical abnormalities. The pituitary hormone thyrotropin (TSH) has a complex inverse relationship with the thyroid hormones thyroxine (T4) and triiodothyronine (T3). 7 Accordingly, overt hypothyroidism is defined as serum TSH concentrations above the reference range with low free T4 (FT4) levels, while subclinical hypothyroidism is diagnosed when TSH levels are high and circulating Abstract Purpose: To compare the effects of l-thyroxine (L-T4) administration before breakfast and administration at bedtime on hypothyroidism. Methods: The PubMed, EMBASE, Cochrane Library, Web of Science, China National Knowledge Infrastructure (CNKI) and Wanfang databases were searched to identify relevant articles. All prospective or randomized controlled studies (RCTs) comparing L-T4 administration before breakfast to the administration at bedtime in patients with hypothyroidism were included in the analysis. Results: Initially, 2884 articles were retrieved from the databases, and 10 articles were included in the quantitative analysis. The effect of L-T4 administration before breakfast compared with administration at bedtime had no statistically significant association with hormone thyrotropin (TSH) (Standardized mean differences [SMD] = 0.09, 95% confidence intervals (CI): −0.12, 0.30; P = .39), or free triiodothyronine (FT3) (SMD=−0.19, 95% CI: −0.53, 0.15; P = .28) in patients with hypothyroidism. However, the result of FT4 level was favourable for L-T4 bedtime administration group (SMD=−0.27, 95% CI: −0.52, −0.02; P = .03). Conclusion:Our meta-analysis revealed that L-T4 administration at bedtime is as effective as administration before breakfast for patients with hypothyroidism. Taking L-T4 at bedtime may be an attractive option for patients with hypothyroidism. K E Y W O R D Sadministration timing, hypothyroidism, l-thyroxine, meta-analysis How to cite this article: Pang X, Pu T, Xu L, Sun R. Effect of l-thyroxine administration before breakfast vs at bedtime on hypothyroidism: A meta-analysis. Clin Endocrinol (Oxf).

No abstract

No abstract

To ensure the safety and reliability of the distribution network and adapt to the uncertain development of renewable energy sources and loads, a two-stage distributionally robust optimization model is proposed for the active distribution network (ADN) optimization problem considering the uncertainties of the source and load in this paper. By establishing an ambiguity set to capture the uncertainties of the photovoltaic (PV) power, wind power and load, the piecewise-linear function and auxiliary parameters are introduced to help characterize the probability distribution of uncertain variables. The optimization goal of the model is to minimize the total expected cost under the worst-case distribution in the ambiguity set. The first-stage expected cost is obtained based on the predicted value of the uncertainty variable. The second-stage expected cost is based on the actual value of the uncertainty variable to solve the first-stage decision. The generalized linear decision rule approximates the two-stage optimization model, and the affine function is introduced to provide a closer approximation to the second-stage optimization model. Finally, the improved IEEE 33-node and IEEE 118-node systems are simulated and analyzed with deterministic methods, stochastic programming, and robust optimization methods to verify the feasibility and superiority of the proposed model and algorithm.

In the AC/DC hybrid microgrids equipped with power electronic transformer (PET), different AC grids and DC grids are connected through multiport PET to operate the entire network in a secure and economic manner. This paper proposes a decentralized optimal power flow model, considering the multiport coordinated control strategy of PET, for running autonomous AC/DC hybrid microgrids. To optimize the power flow in the network, the steady state model of PET is established, including voltage source converter power injection model and Kriging model. By introducing a secondary droop control layer can realize the autonomous operation of AC/DC hybrid microgrids and increase the utilization efficiency of distributed generations. Then using the analytical target cascading approach, each AC/DC sub-microgrid is regarded as different autonomous subjects. The distributed PET is as power coupling node and information interaction node to decompose the optimal problem of AC/DC hybrid microgrids equipped with PET which is solved in parallel. The obtained subproblems for these grid levels are solved with a nested solution process. The simulation results verify the correctness and effectiveness of the proposed model in this paper. INDEX TERMS AC/DC hybrid microgrids, power electronic transformer, steady state model, autonomous operation, decentralized optimal power flow.