Impaired autonomic function and somatosensory disturbance in patients with treated autoimmune thyroiditis.

Despite treatment with levothyroxine, hypothyroidism and autoimmune thyroiditis (AIT) may be associated with reduced quality of life (QoL), an enigmatic condition referred to as "syndrome T". Peripheral neuropathy, described in untreated thyroid disease, could be a contributing mechanism. We analysed autonomic and somatosensory function in 29 patients with AIT and treated hypothyroidism and 27 healthy volunteers. They underwent heart rate variability (HRV) analysis and quantitative sensory testing (n = 28), comprising 13 parameters of small and large nerve fibre function and pain thresholds. Autonomic cardiovascular function was assessed in rest, deep respiration and orthostasis. Additionally, biomarkers for autoimmunity and thyroid function were measured. Anxiety, depression and QoL were assessed using validated questionnaires. 36% of the patients showed at least one sign of somatosensory small or large fibre dysfunction. 57% presented with mild hyperalgesia to at least one stimulus. Several markers of autonomic function and some detection thresholds were related to the antibody titres. Anxiety, depression scores and QoL correlated to antibody titres and HRV measures. Autonomic and somatosensory dysfunction indicate that in treated hypothyroidism and AIT a subgroup of patients suffers from neuropathic symptoms leading to impaired QoL. Additionally, mild hyperalgesia as a possible sensitisation phenomenon should be considered a target for symptomatic treatment.

Takotsubo syndrome outcomes predicted by thyroid hormone signature: insights from cluster analysis of a multicentre registry.

BACKGROUND: Recently, abnormal thyroid function was shown to be common in patients with Takotsubo syndrome (TTS), being classified into "endocrine-type" and "stress-type" responses. The aim of this study was to investigate the association between thyroid homeostasis and TTS in a larger international registry. METHODS: In total 288 patients with TTS were enrolled through the GEIST multicentre registry from Germany, Italy and Spain. Thyrotropin (TSH), free T4 (FT4) and free T3 (FT3) concentrations were analysed at admission. Data were collected both retrospectively and prospectively from 2017 onwards. Primary endpoints included in-hospital and all-cause fatality, determined by cluster analysis using an unsupervised machine learning algorithm (k-medoids). FINDINGS: Three clusters were identified, classifying TTS with low (TSLT), high (TSHT) and normal (TSNT) thyroid output, based on TSH and FT4 levels in relation to the median thyroid's secretory capacity (SPINA-GT). Although TSH and FT4 concentrations were similar among survivors and non-survivors, these clusters were significantly associated with patient outcomes. In the longitudinal Kaplan-Meier analysis including in- and out-of-hospital survival, the prognosis related to concentrations of TSH, FT4, and FT3 as well as SPINA-GT, deiodinase activity (SPINA-GD) and clusters. Patients in the TSHT cluster and with cardiogenic shock had a lower initial left ventricular ejection fraction (LVEF). INTERPRETATION: This study suggests that thyroid hormones may impact the evolution and prognosis of TTS. The findings indicate that thyroid-derived biomarkers may help identify high-risk patients and pave the way for novel personalized and preventive therapeutic options. FUNDING: This research was not funded by any public, commercial, or not-for-profit agencies.

Whole-exome sequencing in familial type 2 diabetes identifies an atypical missense variant in the RyR2 gene.

Genome-wide association studies have identified several hundred loci associated with type 2 diabetes mellitus (T2DM). Additionally, pathogenic variants in several genes are known to cause monogenic diabetes that overlaps clinically with T2DM. Whole-exome sequencing of related individuals with T2DM is a powerful approach to identify novel high-penetrance disease variants in coding regions of the genome. We performed whole-exome sequencing on four related individuals with T2DM - including one individual diagnosed at the age of 33 years. The individuals were negative for mutations in monogenic diabetes genes, had a strong family history of T2DM, and presented with several characteristics of metabolic syndrome. A missense variant (p.N2291D) in the type 2 ryanodine receptor (RyR2) gene was one of eight rare coding variants shared by all individuals. The variant was absent in large population databases and affects a highly conserved amino acid located in a mutational hotspot for pathogenic variants in Catecholaminergic polymorphic ventricular tachycardia (CPVT). Electrocardiogram data did not reveal any cardiac abnormalities except a lower-than-normal resting heart rate (< 60 bpm) in two individuals - a phenotype observed in CPVT individuals with RyR2 mutations. RyR2-mediated Ca2+ release contributes to glucose-mediated insulin secretion and pathogenic RyR2 mutations cause glucose intolerance in humans and mice. Analysis of glucose tolerance testing data revealed that missense mutations in a CPVT mutation hotspot region - overlapping the p.N2291D variant - are associated with complete penetrance for glucose intolerance. In conclusion, we have identified an atypical missense variant in the RyR2 gene that co-segregates with diabetes in the absence of overt CPVT.

Effect of Radioiodine Treatment on Quality of Life in Patients with Subclinical Hyperthyroidism: A Prospective Controlled Study.

Radioiodine treatment (RIT) has a high success rate in both the treatment of hyperthyroidism and improving the quality of life (QoL) of symptomatic patients. In asymptomatic patients with subclinical hyperthyroidism thyroid related QoL outcomes are less well known. METHODS: Study aim was to evaluate thyroid-related QoL in patients with subclinical hyperthyroidism mostly due to toxic nodular goitre undergoing RIT, compared to a control group of euthyroid subjects. Study design was monocentric, prospective, controlled. Fifty control subjects were enrolled and 51 RIT patients. Most subjects were examined at least twice at an interval of 6 months, with visits immediately before and 6 months after treatment in the RIT group. QoL was estimated with the ThyPRO questionnaire, using its composite scale as primary outcome. Treatment effect was the mean adjusted difference (MAD) between groups over time, using repeated? measures mixed? effects models. RESULTS: TSH concentrations were lower in the RIT group prior to treatment and recovered thereafter slightly above the level of the control group. Correspondingly, QoL improved significantly after 6 months from a worse level in the RIT group, compared to controls (MAD -10.3 [95% CI -14.9, -5.7], p<0.001). QoL improvements were strong for general items, but less pronounced for the hyperthyroid domain. Compared to controls, thyroid volume, thyroid functional capacity (SPINA-GT) and deiodinase activity (SPINA-GD) were significantly reduced in the RIT group. CONCLUSION: Patients with subclinical hyperthyroidism improve both biochemically and in their QoL after RIT, compared to controls. QoL assessment should have a wider role in clinical practice to complement biochemical tests and help with treatment decisions.

A novel simple disposition index (SPINA-DI) from fasting insulin and glucose concentration as a robust measure of carbohydrate homeostasis.

AIMS: The widely used dynamic disposition index, derived from oral glucose tolerance testing, is an integrative measure of the homeostatic performance of the insulin-glucose feedback control. Its collection is, however, time consuming and expensive. We, therefore, pursued the question if such a measure can be calculated at baseline/fasting conditions using plasma concentrations of insulin and glucose. METHODS: A new fasting-based disposition index (structure parameter inference approach-disposition index [SPINA-DI]) was calculated as the product of the reconstructed insulin receptor gain (SPINA-GR) times the secretory capacity of pancreatic beta cells (SPINA-GBeta). The novel index was evaluated in computer simulations and in three independent, multiethnic cohorts. The objectives were distribution in various populations, diagnostic performance, reliability and correlation to established physiological biomarkers of carbohydrate metabolism. RESULTS: Mathematical and in-silico analysis demonstrated SPINA-DI to mirror the hyperbolic relationship between insulin sensitivity and beta-cell function and to represent an optimum of the homeostatic control. It significantly correlates to the oral glucose tolerance test based disposition index and other important physiological parameters. Furthermore, it revealed higher discriminatory power for the diagnosis of (pre)diabetes and superior retest reliability than other static and dynamic function tests of glucose homeostasis. CONCLUSIONS: SPINA-DI is a novel simple reliable and inexpensive marker of insulin-glucose homeostasis suitable for screening purposes and a wider clinical application.

[Frequency of Chronic Pain after Work-Related Trauma: A Preliminary Status Survey during Workers' Compensation Rehabilitation in a Tertiary Clinic]. / Häufigkeit chronischer Schmerzen nach Arbeitsunfall ­ Eine erste Statuserhebung im BG-lichen Heilverfahren einer Tertiärklinik.

BACKGROUND: Chronic pain after trauma and surgery is a long-term complication. Its relevance for patients within the workers' compensation rehabilitation process has not been adequately investigated. OBJECTIVES: Initial evaluation of frequency of chronic pain after occupational accidents. METHODS: In 2017, surgical inpatients (18-65 y) treated in a tertiary hospital were asked about chronic pain arising from an occupational trauma recognized by statutory occupation insurance (interval 2.8±6.9 years), regardless of care received, first at the time of hospitalization and then by telephone interview 6 months later. The focus was on patients with a work-related trauma (A) within the past month or (B) >6 months. PRIMARY OUTCOME: frequency of work trauma-related chronic pain (>6 months) at the initial interview (point prevalence), secondary outcomes: frequency of chronicity at 6 months (A) and persistence of chronic pain (B). Tertiary outcomes: ability to work, occupational injury classification, burden based on pain intensity, localization, and medication, functional deficits due to the existence of chronic pain, and comorbidity. RESULTS: Out of 415 patients included in the survey, 85% (160/188) reported accident-related chronic pain (predominantly moderate to highly severe in intensity, localized at joints and bones). 90% (131/145) also reported this pain six months later. 67% (64/96) reported chronic pain for the first time. Patients with chronic pain at follow-up (281/369) were less likely to return to work (p=0.003), required analgesics in 60%, were more often comorbid (p<0.002) and had greater functional deficits (p<0.002). CONCLUSION: Despite the preliminary nature of the data, chronic pain seems to be common after occupational trauma and negatively affects the recovery of work ability in the long term. Based on the present observational data, a further differentiated re-evaluation of prospective data considering therapeutic measures is strongly recommended.

Primary Thyroid Dysfunction Is Prevalent in Hidradenitis Suppurativa and Marked by a Signature of Hypothyroid Graves' Disease: A Case-Control Study.

Hidradenitis suppurativa (HS) is a chronic skin disease that can have an association with endocrine disorders. There is conflicting information in the literature regarding the role of the thyroid gland in HS. This study aimed to close this knowledge gap and investigate how thyroid disease is involved in patients with HS. We carried out a case-control study with a total of 160 patients, of whom 108 were patients with HS and 52 were controls matched for age and sex. Parametric and non-parametric methods were used to analyze the results. We calculated structural parameters of thyroid homeostasis to detect subclinical thyroid disease, non-thyroid disease syndrome and other forms. The severity of HS was not associated with thyroid hormone levels and antibodies (p > 0.05). HS patients with or without hypothyroidism had decreased FT4 levels and a decreased thyroid secretory capacity (SPINA-GT). Titers of TSH receptor autoantibodies (TRAb) were significantly higher in smoking HS patients compared to non-smokers (median: 1.18 vs. 1.08; p = 0.042). The rate of subclinical hypothyroidism was significantly higher in HS patients; thus, subclinical hypothyroidism is an important comorbidity of HS (p < 0.05). Further studies are needed to investigate whether the chronic inflammation of HS is a cause of increased rates of (subclinical) hypothyroidism.

Stress-Mediated Abnormalities in Regional Myocardial Wall Motion in Young Women with a History of Psychological Trauma.

BACKGROUND: Psychosocial stress has been associated with the development and progression of atherosclerotic cardiovascular disease (CVD). Previously, we reported subtle differences in global longitudinal strain in somatically healthy women with a psychiatric diagnosis of borderline personality disorder (BPD). This study aimed to investigate the impact of BPD on segmental myocardial wall motion using speckle tracking echocardiography (STE) analysis. METHODS: A total of 100 women aged between 18 and 38 years were included in this study. Fifty patients meeting the diagnostic criteria for BPD were recruited from the Department of Psychiatry (LWL-University Hospital Bochum) and compared with fifty age-matched healthy control subjects without previous cardiac disease. Laboratory tests and STE were performed with segmental wall motion analysis. RESULTS: The BPD group had a higher prevalence of risk factors for CVD, with smoking and obesity being predominant, when compared with the control group. Other cardiovascular parameters such as blood pressure, glucose, and cholesterol levels were also elevated, even though not to pathological values. Moreover, in the STE analysis, the BPD group consistently exhibited decreased deformation in nine myocardial wall regions compared with the control group, along with a shift toward higher values in the distribution of peak pathological segments. Additionally, significantly higher values of free thyroxine concentration and thyroid's secretory capacity were observed in the BPD group, despite falling within the (high-) normal range. CONCLUSIONS: BPD is associated with chronic stress, classical risk factors, and myocardial wall motion abnormalities. Further exploration is warranted to investigate the relationship between high-normal thyroid metabolism, these risk factors, and myocardial function in BPD patients. Long-term follow-up studies would be valuable in confirming the potential for predicting adverse events.

Characteristics predicting the efficacy of SGLT-2 inhibitors versus GLP-1 receptor agonists on major adverse cardiovascular events in type 2 diabetes mellitus: a meta-analysis study.

BACKGROUND: Recent large clinical trials have demonstrated cardiovascular benefits of similar overall magnitude for sodium-glucose cotransporter-2 inhibitor (SGLT-2i) and glucagon-like peptide-1 receptor agonist (GLP-1RA) therapy in subjects with type 2 diabetes. We sought to identify subgroups based on baseline characteristics with a differential response to either SGLT-2i or GLP-1RA. METHODS: PubMed, Cochrane CENTRAL, and EMBASE were searched from 2008 to 2022 for SGLT-2i or GLP-1RA randomized trials that reported 3-point major adverse cardiovascular events (3P-MACE). Baseline clinical and biochemical characteristics included age, sex, body mass index (BMI), HbA1c, estimated glomerular filtration rate (eGFR), albuminuria, preexisting cardiovascular disease (CVD), and heart failure (HF). Absolute and relative risk reductions (ARR and RRR) regarding incidence rates for 3P-MACE with a 95% confidence interval were calculated. The association of average baseline characteristics in each study with the ARR and RRR for 3P-MACE was investigated by meta-regression analyses (random-effects model, assuming inter-study heterogeneity). Meta-analysis was also conducted to investigate whether the efficacy of SGLT-2i or GLP-1RA on 3P-MACE reduction could differ according to the patient's characteristics (e.g., HbA1c above/below cutoff). RESULTS: After a critical assessment of 1,172 articles, 13 cardiovascular outcome trials with a total of 111,565 participants were selected. In meta-regression analysis, the more patients with reduced eGFR in the studies, the greater ARR by SGLT-2i or GLP-1RA therapy. Similarly, in the meta-analysis, SGLT-2i therapy tended to be more effective in reducing 3P-MACE in people with eGFR < 60 ml/min/1.73 m2 than in those with normal renal function (ARR - 0.90 [-1.44 to - 0.37] vs. - 0.17 [-0.34 to - 0.01] events/100 person-years). Furthermore, people with albuminuria tended to respond better to SGLT-2i therapy than those with normoalbuminuria. However, this was not the case for the GLP-1RA treatment. Other factors including age, sex, BMI, HbA1c, and preexisting CVD or HF did not affect the efficacy of either SGLT-2i or GLP-1RA treatment on the ARR or RRR of 3P-MACE. CONCLUSIONS: Because decreased eGFR [significant] and albuminuria [trend] were found to predict a better efficacy for SGLT-2i in 3P-MACE reduction, this class of drug should be preferred in such patients. However, GLP-1RA may be considered for patients with normal eGFR because it showed better efficacy than SGLT-2i in this subgroup [trend].

Modelling of the thyroid hormone synthesis as a part of nonlinear reaction mechanism with feedback.

The synthesis of thyroid hormones in the hypothalamic-pituitary-thyroid (HPT) axis was studied. For this purpose, a reaction model for HPT axis with stoichiometric relations between the main reaction species was postulated. Using the law of mass action, this model has been transformed into a set of nonlinear ordinary differential equations. This new model has been examined by stoichiometric network analysis (SNA) with the aim to see if it possesses the ability to reproduce oscillatory ultradian dynamics founded on the internal feedback mechanism. In particular, a feedback regulation of TSH production based on the interplay between TRH, TSH, somatostatin and thyroid hormones was proposed. Besides, the ten times larger amount of produced T4 with respect to T3 in the thyroid gland was successfully simulated. The properties of SNA in combination with experimental results, were used to determine the unknown parameters (19 rate constants of particular reaction steps) necessary for numerical investigations. The steady-state concentrations of 15 reactive species were tuned to be consistent with the experimental data. The predictive potential of the proposed model was illustrated on numerical simulations of somatostatin influence on TSH dynamics investigated experimentally by Weeke et al. in 1975. In addition, all programs for SNA analysis were adapted for this kind of a large model. The procedure of calculating rate constants from steady-state reaction rates and very limited available experimental data was developed. For this purpose, a unique numerical method was developed to fine-tune model parameters while preserving the fixed rate ratios and using the magnitude of the experimentally known oscillation period as the only target value. The postulated model was numerically validated by perturbation simulations with somatostatin infusion and the results were compared with experiments available in literature. Finally, as far as we know, this reaction model with 15 variables is the most dimensional one that have been analysed mathematically to obtain instability region and oscillatory dynamic states. Among the existing models of thyroid homeostasis this theory represents a new class that may improve our understanding of basic physiological processes and helps to develop new therapeutic approaches. Additionally, it may pave the way to improved diagnostic methods for pituitary and thyroid disorders.

Screening for Diabetes Mellitus in Patients with Hidradenitis Suppurativa-A Monocentric Study in Germany.

Hidradenitis suppurativa (HS) is a chronic skin disease that is often associated with metabolic disorders. Diabetes mellitus (DM) is a frequent comorbidity in HS. There is currently no established screening for DM in HS patients. The aim of our study was to identify high-risk groups of HS patients that develop DM and to assess the frequency of different types of DM present in HS patients. To do so, we conducted a monocentric study in 99 patients with HS. All patients underwent detailed clinical and laboratory assessments, including the determination of glycated hemoglobin. Among the 20.2% of patients that presented with DM, type 2 was by far the most prevalent (19 out of 20 patients). Moreover, male gender, age, BMI, Hurley stage, modified Hidradenitis Suppurativa Score (mHSS), DLQI and hypertension all correlated with the glycated hemoglobin levels in the HS patients. In the multivariable analysis, Hurley stage III, older age, and higher BMI were significantly associated with DM. Specifically, patients at Hurley stage III were at a 5.3-fold increased risk of having DM type II compared to patients at earlier Hurley stages. Since many of the HS patients had not been diagnosed, our study reveals shortcomings in the screening for DM and suggest that this should be routinely performed in HS patients at high risk to avoid secondary complications.

Mortality rates of severe COVID-19-related respiratory failure with and without extracorporeal membrane oxygenation in the Middle Ruhr Region of Germany.

The use of extracorporeal membrane oxygenation (ECMO) is discussed to improve patients' outcome in severe COVID-19 with respiratory failure, but data on ECMO remains controversial. The aim of the study was to determine the characteristics of patients under invasive mechanical ventilation (IMV) with or without veno-venous ECMO support and to evaluate outcome parameters. Ventilated patients with COVID-19 with and without additional ECMO support were analyzed in a retrospective multicenter study regarding clinical characteristics, respiratory and laboratory parameters in day-to-day follow-up. Recruitment of patients was conducted during the first three COVID-19 waves at four German university hospitals of the Ruhr University Bochum, located in the Middle Ruhr Region. From March 1, 2020 to August 31, 2021, the charts of 149 patients who were ventilated for COVID-19 infection, were included (63.8% male, median age 67 years). Fifty patients (33.6%) received additional ECMO support. On average, ECMO therapy was initiated 15.6 ± 9.4 days after symptom onset, 10.6 ± 7.1 days after hospital admission, and 4.8 ± 6.4 days after the start of IMV. Male sex and higher SOFA and RESP scores were observed significantly more often in the high-volume ECMO center. Pre-medication with antidepressants was more often detected in survivors (22.0% vs. 6.5%; p = 0.006). ECMO patients were 14 years younger and presented a lower rate of concomitant cardiovascular diseases (18.0% vs. 47.5%; p = 0.0004). Additionally, cytokine-adsorption (46.0% vs. 13.1%; p < 0.0001) and renal replacement therapy (76.0% vs. 43.4%; p = 0.0001) were carried out more frequently; in ECMO patients thrombocytes were transfused 12-fold more often related to more than fourfold higher bleeding complications. Undulating C-reactive protein (CRP) and massive increase in bilirubin levels (at terminal stage) could be observed in deceased ECMO patients. In-hospital mortality was high (Overall: 72.5%, ECMO: 80.0%, ns). Regardless of ECMO therapy half of the study population deceased within 30 days after hospital admission. Despite being younger and with less comorbidities ECMO therapy did not improve survival in severely ill COVID-19 patients. Undulating CRP levels, a massive increase of bilirubin level and a high use of cytokine-adsorption were associated with worse outcomes. In conclusion, ECMO support might be helpful in selected severe cases of COVID-19.

The role of supporting and disruptive mechanisms of FT3 homeostasis in regulating the hypothalamic-pituitary-thyroid axis.

Background: Thyroid hormones are controlled by the hypothalamic-pituitary-thyroid (HPT) axis through a complex network of regulatory loops, involving the hormones TRH, TSH, FT4, and FT3. The relationship between TSH and FT4 is widely used for diagnosing thyroid diseases. However, mechanisms of FT3 homeostasis are not well understood. Objective: We used mathematical modelling to further examine mechanisms that exist in the HPT axis regulation for protecting circulating FT3 levels. Methods: A mathematical model consisting of a system of four coupled first-order parameterized non-linear ordinary differential equations (ODEs) was developed, accounting for the interdependencies between the hormones in the HPT axis regulation. While TRH and TSH feed forward to the pituitary and thyroid, respectively, FT4 and FT3 feed backward to both the pituitary and hypothalamus. Stable equilibrium solutions of the ODE system express homeostasis for a particular variable, such as FT3, if this variable stays in a narrow range while certain other parameter(s) and system variable(s) may vary substantially. Results: The model predicts that (1) TSH-feedforward protects FT3 levels if the FT4 production rate declines and (2) combined negative feedback by FT4 and FT3 on both TSH and TRH production rates keeps FT3 levels insensitive to moderate changes in FT4 production rates and FT4 levels. The optimum FT4 and FT3 feedback and TRH and TSH-feedforward ranges that preserve FT3 homeostasis were found by numerical continuation analysis. Model predictions were in close agreement with clinical studies and individual patient examples of hypothyroidism and hyperthyroidism. Conclusions: These findings further extend the concept of HPT axis regulation beyond TSH and FT4 to integrate the more active sister hormone FT3 and mechanisms of FT3 homeostasis. Disruption of homeostatic mechanisms leads to disease. This provides a perspective for novel testable concepts in clinical studies to therapeutically target the disruptive mechanisms.

Perspectives of (/memorandum for) systems thinking on COVID-19 pandemic and pathology.

Is data-driven analysis sufficient for understanding the COVID-19 pandemic and for justifying public health regulations? In this paper, we argue that such analysis is insufficient. Rather what is needed is the identification and implementation of over-arching hypothesis-related and/or theory-based rationales to conduct effective SARS-CoV2/COVID-19 (Corona) research. To that end, we analyse and compare several published recommendations for conceptual and methodological frameworks in medical research (e.g., public health, preventive medicine and health promotion) to current research approaches in medical Corona research. Although there were several efforts published in the literature to develop integrative conceptual frameworks before the COVID-19 pandemic, such as social ecology for public health issues and systems thinking in health care, only a few attempts to utilize these concepts can be found in medical Corona research. For this reason, we propose nested and integrative systemic modelling approaches to understand Corona pandemic and Corona pathology. We conclude that institutional efforts for knowledge integration and systemic thinking, but also for integrated science, are urgently needed to avoid or mitigate future pandemics and to resolve infection pathology.

The Role of Hormones in Hidradenitis Suppurativa: A Systematic Review.

Hidradenitis suppurativa (HS) is a chronic inflammatory disease manifesting in inverse body regions. In a systematic review, the role of hormones in HS will be presented to better understand the pathomechanisms of HS. The review is based on the PRISMA criteria. Systematic research was carried out using keywords. Subsequently, the data were analyzed based on the clinical response and other relevant information. The main focus of our systematic review was on HS manifestation, exacerbation, sex hormones, antiandrogen therapy, thyroid function, polycystic ovary syndrome, insulin resistance, and adipokines. In HS, there appears to be a dysregulated adipokine release that is shifted towards pro-inflammatory adipokines. Insulin resistance is significantly more common in HS than in healthy patients regardless of BMI, age, and gender. Insulin resistance in HS patients leads to further cardiovascular disease. The mechanism of insulin resistance and role of adipokines should be investigated in future studies to better provide the pathomechanisms of HS. The role of androgens seems to be important in a certain subgroup of female patients. Anti-androgenic therapy can be useful and helpful in some patients. However, further studies are needed to better understand the hormonal relationship in HS.

Mathematical modeling and simulation of thyroid homeostasis: Implications for the Allan-Herndon-Dudley syndrome.

Introduction: A mathematical model of the pituitary-thyroid feedback loop is extended to deepen the understanding of the Allan-Herndon-Dudley syndrome (AHDS). The AHDS is characterized by unusual thyroid hormone concentrations and a mutation in the SLC16A2 gene encoding for the monocarboxylate transporter 8 (MCT8). This mutation leads to a loss of thyroid hormone transport activity. One hypothesis to explain the unusual hormone concentrations of AHDS patients is that due to the loss of thyroid hormone transport activity, thyroxine (T 4) is partially retained in thyroid cells. Methods: This hypothesis is investigated by extending a mathematical model of the pituitary-thyroid feedback loop to include a model of the net effects of membrane transporters such that the thyroid hormone transport activity can be considered. A nonlinear modeling approach based on the Michaelis-Menten kinetics and its linear approximation are employed to consider the membrane transporters. The unknown parameters are estimated through a constrained parameter optimization. Results: In dynamic simulations, damaged membrane transporters result in a retention of T 4 in thyroid cells and ultimately in the unusual hormone concentrations of AHDS patients. The Michaelis-Menten modeling approach and its linear approximation lead to similar results. Discussion: The results support the hypothesis that a partial retention of T 4 in thyroid cells represents one mechanism responsible for the unusual hormone concentrations of AHDS patients. Moreover, our results suggest that the retention of T 4 in thyroid cells could be the main reason for the unusual hormone concentrations of AHDS patients.

SPINA Carb: a simple mathematical model supporting fast in-vivo estimation of insulin sensitivity and beta cell function.

Modelling insulin-glucose homeostasis may provide novel functional insights. In particular, simple models are clinically useful if they yield diagnostic methods. Examples include the homeostasis model assessment (HOMA) and the quantitative insulin sensitivity check index (QUICKI). However, limitations of these approaches have been criticised. Moreover, recent advances in physiological and biochemical research prompt further refinement in this area. We have developed a nonlinear model based on fundamental physiological motifs, including saturation kinetics, non-competitive inhibition, and pharmacokinetics. This model explains the evolution of insulin and glucose concentrations from perturbation to steady-state. Additionally, it lays the foundation of a structure parameter inference approach (SPINA), providing novel biomarkers of carbohydrate homeostasis, namely the secretory capacity of beta-cells (SPINA-GBeta) and insulin receptor gain (SPINA-GR). These markers correlate with central parameters of glucose metabolism, including average glucose infusion rate in hyperinsulinemic glucose clamp studies, response to oral glucose tolerance testing and HbA1c. Moreover, they mirror multiple measures of body composition. Compared to normal controls, SPINA-GR is significantly reduced in subjects with diabetes and prediabetes. The new model explains important physiological phenomena of insulin-glucose homeostasis. Clinical validation suggests that it may provide an efficient biomarker panel for screening purposes and clinical research.

Minor perturbations of thyroid homeostasis and major cardiovascular endpoints-Physiological mechanisms and clinical evidence.

It is well established that thyroid dysfunction is linked to an increased risk of cardiovascular morbidity and mortality. The pleiotropic action of thyroid hormones strongly impacts the cardiovascular system and affects both the generation of the normal heart rhythm and arrhythmia. A meta-analysis of published evidence suggests a positive association of FT4 concentration with major adverse cardiovascular end points (MACE), but this association only partially extends to TSH. The risk for cardiovascular death is increased in both subclinical hypothyroidism and subclinical thyrotoxicosis. Several published studies found associations of TSH and FT4 concentrations, respectively, with major cardiovascular endpoints. Both reduced and elevated TSH concentrations predict the cardiovascular risk, and this association extends to TSH gradients within the reference range. Likewise, increased FT4 concentrations, but high-normal FT4 within its reference range as well, herald a poor outcome. These observations translate to a monotonic and sensitive effect of FT4 and a U-shaped relationship between TSH and cardiovascular risk. Up to now, the pathophysiological mechanism of this complex pattern of association is poorly understood. Integrating the available evidence suggests a dual etiology of elevated FT4 concentration, comprising both ensuing primary hypothyroidism and a raised set point of thyroid function, e. g. in the context of psychiatric disease, chronic stress and type 2 allostatic load. Addressing the association between thyroid homeostasis and cardiovascular diseases from a systems perspective could pave the way to new directions of research and a more personalized approach to the treatment of patients with cardiovascular risk.