Detecting low concentrations of thyroxine hormone (T4) is of utmost importance to prevent diseases and medical issues caused by hypothyroidism. In this work, we propose the use of a simple technique for T4 sensing, the well-known surface-enhanced Raman spectroscopy (SERS). Spherical Au and Ag nanoparticles (NPs) and functionalized with ascorbic acid and tannic acid, respectively. They synthesized by a seed-mediated growth method, were used as SERS substrates to quantify T4 at different concentrations. The NPs were characterized by UV-VIS spectroscopy and scanning electron microscopy. Both, Au and Ag NPs, have an average diameter of 50 nm, the first ones have a surface plasmon resonance at 537 nm, while the latter have it at 421 nm. It was noticed the SERS substrates are composed of isolated and agglomerated NPs. From theoreti-cal-numerical calculations, we identified the hot spots |E| of the agglomerate NPs is at least 7 times more intense than that of the isolated NPs. We show the substrates can detect up to 0.01 mM and, for the range of concentration studied, the Ag substrate is more sensitive than Au. Thus, the proposed substrates and the SERS technique constitute a potential prospect for sensing hormones and organic molecules at low concentrations.

There is a have been positive correlations between the existence of type 2 diabetes mellitus (T2DM) and the development of thyroid disorders. Prediabetes is a progressive state of moderate insulin resistance that often precedes the onset of type 2 diabetes mellitus (TT2DM) however the association between prediabetes and thyroid function is unknown. This study assessed changes in markers of thyroid function in diet-induced prediabetes. 12 male Sprague Dawley rats were randomly allocated into two groups. Rats in the non-prediabetic (NPD) group were fed a standard rat diet while rats in the prediabetic (PD) were fed a high-fat high carbohydrate diet for 20 weeks to induce prediabetes. Thereafter, fasting blood glucose levels were measured. Plasma samples were assessed for triiodothyronine (T3), thyroxine (T4), thyroxine peroxidase (TPO) antibody, insulin and glycated haemoglobin (HbA1c) concentrations. The elevated blood glucose, HbA1c and plasma insulin levels coincided with increased T3 and reduced T4 levels in the PD group when compared to the NPD group. There was also an increase in the concentration of TPO antibodies in the PD group. Additionally, there was a significant correlation between the thyroid hormone concentrations and HbA1c levels. In conclusion, these results indicated that there is a positive association between thyroid dysfunction and diet-induced prediabetes.

Introduction/Aim: Central sensitivity to thyroid hormones refers to the sensitivity of the hypothalamic-pituitary-thyroid (HPT) axis to changes in circulating free thyroxine (fT4). The relationship between fT4 levels and iodine intake is complex. The aim of the present study was to assess central sensitivity to thyroid hormones in pregnancy against iodine intake. Materials & Methods: One thousand one hundred two blood and urine samples were collected from pregnant women (with a mean age+SD of 30.4+4.6 years) during singleton pregnancies; women with known/diagnosed thyroid disease were excluded. Specifically, TSH & fT4 and 24-hour urinary iodine excretion (UI) were measured in each trimester and at two months postpartum. The Thyroid Feedback Quantile-based Index (TFQI) was calculated to assess central sensitivity to thyroid hormones. For the statistical analysis of TFQI by time period, analysis of variance (ANOVA) was used, while Pearson's correlation was used to assess TFQI versus UI. Results: The mean TFQI index ranged from -0.06 (first trimester) to -0.07 (two months postpartum), while the corresponding UI was 141 and 172 μg/L, respectively. The TFQI-UI correlation was negative (Pearson r: -0.325, p: 0.04 and r: -0.399, p: 0.023), for UI values over 250 μg/L, in the first and the third trimester of pregnancy, respectively. Discussion: TFQI is a new index reflecting central sensitivity to thyroid hormones. Lower TFQI indicates higher sensitivity to thyroid hormones. In our sample TFQI was inversely related to iodine intake, in the first trimester of pregnancy (the critical period of organogenesis) and the third trimester (the critical period of fetal growth). Thus, the observed changes in TFQI may reflect different ways of central action of thyroid hormones, according to the phase of pregnancy. The negative association between maternal TFQI (indicative of central sensitivity to thyroid hormone) and urine iodine levels during the third trimester of pregnancy may reflect the combined influence of maternal and fetal thyroid function. Our results are intriguing and have the potential to enhance our comprehension of the changes in the HPT axis’ function via variations in central sensitivity to thyroid hormones and its interplay with nutritional iodine status during pregnancy.