Background: The fact that serum thyrotropin (TSH) levels increase with age may influence the diagnosis of thyroid diseases in older adults. This study aimed to establish an age-specific serum TSH reference range, examine the prevalence of thyroid diseases in older adults ≥65 years, and analyze the risk factors. Methods: A cross-sectional study of adult populations in 10 cities in China was conducted from 2010 to 2011. A total of 15,008 subjects were randomly selected and completed the present study. Urinary iodine concentration, serum TSH, thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TgAb) titers were measured. Thyroid ultrasonography and questionnaires were completed by all the subjects. When the TSH level was abnormal, free thyroxine and/or free triiodothyronine levels were measured. Results: When the reference range of the general population was used, the prevalence rates of overt hypothyroidism (Ohypo) and subclinical hypothyroidism (Shypo) in older adults ≥65 years were significantly higher than those in younger adults <65 years (2.09% vs. 0.80% and 19.87% vs. 16.23%, respectively; p < 0.001). Positive TPOAb and positive TgAb were associated with the prevalence of Shypo in older adults. An age-specific serum TSH reference range was formulated according to guidelines set forth by the National Academy of Clinical Biochemistry. Both the median and upper limit values of serum TSH in older adults were higher than those in younger adults (2.58 [0.75-8.86] mIU/L vs. 2.38 [0.76-6.57] mIU/L; p < 0.001). Using the age-specific serum TSH reference range, the prevalence of Shypo in older adults was 3.3%, which was significantly lower than the prevalence based on the reference range of the general population (3.3% vs. 19.87%). The prevalence rates of Ohypo, overt hyperthyroidism (Ohyper), and subclinical hyperthyroidism (Shyper) did not change much (Ohypo: 1.6% vs. 2.09%; Ohyper: 0.7% vs. 0.52%; and Shyper: 3.8% vs. 0.73%). Positive TPOAb, but not positive TgAb, was also associated with the prevalence of Shypo as diagnosed with the age-specific serum TSH reference range. Conclusion: The serum TSH level increases with age, which may represent a normal compensatory phenomenon in older adults ≥65 years. To prevent misdiagnosis and mistreatment, the use of an age-specific serum TSH reference range is recommended in older adults for the diagnosis of thyroid diseases.
The time-varying (TV) chaos unitary matrix based differential multiple-input multiple-output (D-MIMO) system is capable of achieving beneficial performance gains without channel state information (CSI). To elaborate a little further, the chaos sequence is embedded into the data-carrying matrices by a unique time-varying matrix. By employing differential coding during two adjacent signal blocks, a non-coherent detector can be developed without CSI knowledge. However, its theoretical performance analysis becomes challenging due to its complex construction. To address this issue, the theoretical average bit error probability (ABEP) lower and upper bounds of the TV-D-MIMO system are analyzed using the moment generating function (MGF) over generalized fading channel. The experimental results are shown that the derived ABEP upper and lower bounds are tight with the simulation results, which is helpful for future performance evaluation.
In this paper, a golden angle modulation (GAM) aided differential orthogonal frequency division multiplexing with index modulation (DOFDM-IM-GAM) system for low-earth orbit (LEO) satellite communications is proposed, which amalgamates the concept of differential coding to exploit the advantage of GAM and OFDM-IM without channel state information (CSI) at the receiver. Specifically, in the DOFDM-IM-GAM system, L subcarriers are divided into Q subblocks, and differential coding based on power normalization is applied to adjacent subblocks. Furthermore, the average bit error probability (ABEP) and mutual information (MI) of the proposed DOFDM-IM-GAM system are derived over the Rayleigh fading channel and LEO satellite channel. Simulation results demonstrate that the proposed DOFDM-IM-GAM system offers significant performance improvements compared to conventional DOFDM-IM systems.
In this paper, we propose golden angle modulation aided orthogonal frequency division multiplexing with index modulation (OFDM-IM-GAM) for an arbitrary number of subcarriers, which includes integer OFDM-IM-GAM (I-OFDM-IM-GAM) and fractional OFDM-IM-GAM (F-OFDM-IM-GAM).Furthermore, a general mapping optimization algorithm is developed for our proposed systems, where it is implemented by minimizing the hamming distance (HD) of transmission vectors with larger values of pairwise error probability (PEP) to minimize average bit error probability (ABEP).The simulation results illustrate the superiority of the I-OFDM-IM-GAM and F-OFDM-IM-GAM systems with the proposed mapping optimization algorithm over the conventional counterparts in the cases of uncoded and coded systems.
Autoimmune thyroiditis (AITD) is a T-cell-mediated, organ- specific autoimmune disease caused by interactions between genetic and environmental factors. Patients with AITD show thyroid lymphocyte infiltration and an increase in the titer of thyroid autoimmune antibodies, thereby altering the integrity of thyroid follicle epithelial cells and dysregulating their metabolism and immune function, leading to a decrease in multi-tissue metabolic activity. Research has shown that patients with AITD have a significantly higher risk of adverse pregnancy outcomes, such as infertility and miscarriage. Levothyroxine(LT 4 ) treatment can improve the pregnancy outcomes of normal pregnant women with thyroid peroxidase antibodies(TPOAb) positivity, but it is not effective for invitro fertilization embryo transfer (IVF-ET) in women with normal thyroid function and positive TPOAb. Other factors may also influence pregnancy outcomes of patients with AITD. Recent studies have revealed that the gut microbiota participates in the occurrence and development of AITD by influencing the gut-thyroid axis. The bacterial abundance and diversity of patients with Hashimoto thyroiditis (HT) were significantly reduced, and the relative abundances of Bacteroides , fecal Bacillus , Prevotella , and Lactobacillus also decreased. The confirmation of whether adjusting the composition of the gut microbiota can improve pregnancy outcomes in patients with AITD is still pending. This article reviews the characteristics of the gut microbiota in patients with AITD and the current research on its impact in pregnancy.
Gray mapping is a well-known way to improve the performance of regular constellation modulation, but it is challenging to be applied directly for irregular alternative. To address this issue, in this paper, a unified bit-to-symbol mapping method is designed for generalized constellation modulation (i.e., regular and irregular shaping). The objective of the proposed approach is to minimize the average bit error probability by reducing the hamming distance (HD) of symbols with larger values of pairwise error probability. Simulation results show that the conventional constellation modulation(i.e., phase shift keying and quadrature amplitude modulation (QAM) with the proposed mapping rule yield the same performance as that of classical gray mapping. Moreover, the recently developed golden angle modulation (GAM) with the proposed mapping method is capable of providing around 1 dB gain over the conventional mapping counterpart and offers comparable performance to QAM with Gray mapping.
Gestational diabetes mellitus is one of the most common endocrine diseases that occur during pregnancy. Disorders of blood glucose metabolism during pregnancy can increase the risk of adverse pregnancy outcomes, such as pregnancy-related hypertension, preeclampsia, eclampsia, miscarriage, macrosomia, and neonatal hypoglycemia. Continuous glucose monitoring (CGM) can safely and effectively monitor blood glucose changes in patients with gestational hyperglycemia, thereby reducing adverse pregnancy outcomes. Hence, this article aimed to provide a comprehensive review of the progress and indications for using CGM in pregnant patients with diabetes. CGM can reduce blood glucose fluctuations and the occurrence of serious hypoglycemia and hyperglycemia events and can provide time in range (TIR). TIR is an important indicator of blood glucose level. Patients with a higher TIR during pregnancy have better gestational outcomes.
Medullary thyroid carcinoma (MTC) is an infrequent form malignant tumor with a poor prognosis. Because of the influence of competitive risk, there may suffer from bias in the analysis of prognostic factors of MTC.By extracting the data of patients diagnosed with MTC registered in the Surveillance, Epidemiology, and End Results (SEER) database from 1998 to 2016, we established the Cox proportional-hazards and competing-risks model to retrospectively analyze the impact of related factors on lymph nodes statistically.A total of 2,435 patients were included in the analysis, of which 198 died of MTC. The results of the multifactor competing-risk model showed that the number of total lymph nodes (19-89), positive lymph nodes (1-10,11-75) and positive lymph node ratio (25%-53%,>54%), age (46-60,>61), chemotherapy, mode of radiotherapy (others), tumor size(2-4cm,>4cm), number of lesions greater than 1 were poor prognostic factors for MTC. For the number of total lymph nodes, unlike the multivariate Cox proportional-hazards model results, we found that it became an independent risk factor after excluding competitive risk factors. Competitive risk factors have little effect on the number of positive lymph nodes. For the proportion of positive lymph nodes, we found that after excluding competitive risk factors, the Cox proportional-hazards model overestimates its impact on prognosis. The competitive risk model is often more accurate in analyzing the effects of prognostic factors.After excluding the competitive risk, the number of lymph nodes, the number of positive and the positive proportion are the poor prognostic factors of medullary thyroid cancer, which can help clinicians more accurately evaluate the prognosis of patients with medullary thyroid cancer and provide a reference for treatment decision-making.
Iodine is involved in the synthesis of thyroid hormones and plays a crucial role in human life. Both iodine deficiency and excess are common issues in certain populations. Iodine also has extrathyroidal effects on organs that can uptake it independently of thyroid hormones. Recently, multiple clinical studies have shown a connection between iodine intake and metabolic disorders, such as metabolic syndrome, obesity, diabetes, hypertension, and dyslipidemia. However, the results of these studies have been inconsistent, and the mechanisms behind these associations are still not well understood. Therefore, in this review, we aim to examine the recent research progress regarding the relationship between iodine and metabolic disorders, along with the relevant mechanisms.
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