Thyroid disorders and gastrointestinal and liver dysfunction: A state of the art review

Casual associations of thyroid function with inflammatory bowel disease and the mediating role of cytokines

Background

Previous observational epidemiological studies have suggested a potential association between thyroid function and inflammatory bowel disease (IBD). However, the findings remain inconclusive, and whether this association is causal remains uncertain. The objective of this study is to investigate the causal association between thyroid function and IBD.

Methods

Genome-wide association studies (GWAS) involving seven indicators of thyroid function, IBD, and 41 cytokines were analyzed. Bidirectional two-sample Mendelian randomization (MR) and multivariable MR were conducted to examine the causal relationship between thyroid function and IBD and to explore the potential mechanisms underlying the associations.

Results

Genetically determined hypothyroidism significantly reduced the risk of CD (odds ratio [OR] = 0.761, 95% CI: 0.655-0.882, p < 0.001). Genetically determined reference-range TSH was found to have a suggestive causal effect on IBD (OR = 0.931, 95% CI: 0.888-0.976, p = 0.003), (Crohn disease) CD (OR = 0.915, 95% CI: 0.857-0.977, p = 0.008), and ulcerative colitis (UC) (OR =0.910, 95% CI: 0.830-0.997, p = 0.043). In reverse MR analysis, both IBD and CD appeared to have a suggestive causal effect on the fT3/fT4 ratio (OR = 1.002, p = 0.013 and OR = 1.001, p = 0.015, respectively). Among 41 cytokines, hypothyroidism had a significant impact on interferon-inducible protein-10 (IP-10) (OR = 1.465, 95% CI: 1.094-1.962, p = 0.010). The results of multivariable MR showed that IP-10 may mediate the causal effects of hypothyroidism with CD.

Conclusion

Our results suggest that an elevated TSH level reduces the risk of CD, with IP-10 potentially mediating this association. This highlights the pituitary-thyroid axis could serve as a potential therapeutic strategy for CD.

Thyroid disorders and gastrointestinal dysmotility: an old association

Gastrointestinal motility symptoms may be closely related to thyroid diseases. Sometimes, such symptoms are the only thyroid disease-related clue although the degree of the symptoms may vary. The exact mechanism of action of thyroid hormones on gastrointestinal motility is not completely understood, however, a clue lies in the fact that muscle cell receptors can be directly acted upon by thyroxines. Both hypo- and hyperthyroidism can cause impairment of gastrointestinal motility, modifying structure and function of pharynx and esophagus, and regulating esophageal peristalsis through neuro-humoral interaction. In hyperthyroid patients, alterations of postprandial and basic electric rhythms have been observed at gastro-duodenal level, often resulting in slower gastric emptying. Gastric emptying may also be delayed in hypothyroidism, but an unrelated gastric mucosa-affecting chronic modification may also cause such pattern. Hyperthyroidism commonly show malabsorption and diarrhoea, while hypothyroidism frequently show constipation. In summary, it can be stated that symptoms of gastrointestinal motility dysfunction can be related to thyroid diseases, affecting any of the gastrointestinal segment. Clinically, the typical thyroid disease manifestations may be missing, borderline, or concealed because of intercurrent sicknesses. Motility-linked gastrointestinal problems may easily conceal a misdetected, underlying dysthyroidism that should be carefully analyzed. Here, we aim to elaborate on the associations between thyroid disorders and GI dysmotility and the common clinical manifestations associated with GI dysmotility.

Comprehensive Association Analyses of Extraintestinal Manifestations in Inflammatory Bowel Disease

BACKGROUND & AIMS

Patients with inflammatory bowel disease (IBD) frequently develop extraintestinal manifestations (EIMs) that contribute substantially to morbidity. We assembled the largest multicohort data set to date to investigate the clinical, serologic, and genetic factors associated with EIM complications in IBD.

METHODS

Data were available in 12,083 unrelated European ancestry IBD cases with presence or absence of EIMs (eg, ankylosing spondylitis [ankylosing spondylitis and sacroiliitis], primary sclerosing cholangitis [PSC], peripheral arthritis, and skin and ocular manifestations) across 4 cohorts (Cedars-Sinai Medical Center, National Institute for Diabetes and Digestive and Kidney Diseases IBD Genetics Consortium, Sinai Helmsley Alliance for Research Excellence Consortium, and Risk Stratification and Identification of Immunogenetic and Microbial Markers of Rapid Disease Progression in Children with Crohn's Disease cohort). Clinical and serologic parameters were analyzed by means of univariable and multivariable regression analyses using a mixed-effects model. Within-case logistic regression was performed to assess genetic associations.

RESULTS

Most EIMs occurred more commonly in female subjects (overall EIM: P = 9.0E-05, odds ratio [OR], 1.2; 95% CI, 1.1-1.4), with CD (especially colonic disease location; P = 9.8E-09, OR, 1.7; 95% CI, 1.4-2.0), and in subjects who required surgery (both CD and UC; P = 3.6E-19, OR, 1.7; 95% CI, 1.5-1.9). Smoking increased risk of EIMs except for PSC, where there was a "protective" effect. Multiple serologic associations were observed, including with PSC (anti-nuclear cytoplasmic antibody; IgG and IgA, anti-Saccharomyces cerevisiae antibodies; and anti-flagellin) and any EIM (anti-nuclear cytoplasmic antibody; IgG and IgA, anti-Saccharomyces cerevisiae antibodies; and anti-Pseudomonas fluorescens-associated sequence). We identified genome-wide significant associations within major histocompatibility complex (ankylosing spondylitis and sacroiliitis, P = 1.4E-15; OR, 2.5; 95% CI, 2.0-3.1; PSC, P = 2.7E-10; OR, 2.8; 95% CI, 2.0-3.8; ocular, P = 2E-08, OR, 3.6; 95% CI, 2.3-5.6; and overall EIM, P = 8.4E-09; OR, 2.2; 95% CI, 1.7-2.9) and CPEB4 (skin, P = 2.7E-08; OR, 1.5; 95% CI, 1.3-1.8). Genetic associations implicated tumor necrosis factor, JAK-STAT, and IL6 as potential targets for EIMs. Contrary to previous reports, only 2% of our subjects had multiple EIMs and most co-occurrences were negatively correlated.

CONCLUSIONS

We have identified demographic, clinical, and genetic associations with EIMs that revealed underlying mechanisms and implicated novel and existing drug targets-important steps toward a more personalized approach to IBD management.

Co-Morbid Hypothyroidism and Liver Dysfunction: A Review

The liver and thyroid hormones interact at multiple levels to maintain homoeostasis. The liver requires large adequate amounts of thyroid hormones to execute its metabolic functions optimally, and deficiency of thyroid hormones may lead to liver dysfunction. Hypothyroidism has been associated with abnormal lipid metabolism, non-alcoholic fatty liver disease (NAFLD), hypothyroidism-induced myopathy, hypothyroidism-associated gallstones and occasionally, interferon-induced thyroid dysfunction. NAFLD remain an important association with hypothyroidism and further studies are needed that specifically compare the natural course of NAFLD secondary to hypothyroidism and primary NAFLD. Hepatic dysfunction associated with hypothyroidism is usually reverted by normalizing thyroid status. Large scale studies geared towards finding new and effective therapies, especially for NAFLD are needed. The clinician must be aware that there exists overlapping symptomatology between liver dysfunction and severe hypothyroidism which may make delay the diagnosis and treatment of hypothyroidism; this requires a high index of suspicion.

Advances in Thyroid Function Tests: Precision Diagnostics and Clinical Implications

This narrative review explores the evolving field of thyroid function testing, explicitly highlighting the significance of precision diagnostics and their substantial impact on clinical practice. Commencing with a comprehensive examination of the historical progression of thyroid diagnostics, the discourse proceeds to explore recent developments, highlighting the paramount importance of accuracy in testing methods. The primary issue under consideration is the crucial requirement for accuracy in the field of therapeutic practice. The review critically examines the problems related to the interpretation, standardization, and ethical considerations in examining advanced laboratory techniques, novel biomarkers, and state-of-the-art technologies like immunoassays, molecular testing, and automation. The focus on the paradigm shift towards precision diagnostics brings attention to the complex connection between test results and their direct influence on patient care. This investigation expands upon the incorporation of imaging and molecular diagnostics, highlighting the rising significance of precision in customizing treatment strategies. In summary, the study provides a prospective viewpoint, recognizing the persistent obstacles and highlighting the want for dependable, uniform methodologies in thyroid diagnostics. This narrative's primary objective is to guide physicians, researchers, and stakeholders in effectively navigating the intricate nature of contemporary thyroid function tests, with a particular emphasis on resolving the fundamental issue of precision.

Retrospective Evaluation of Gastrointestinal Signs in Hypothyroid Dogs

Few observations about gastrointestinal (GI) signs in hypothyroid dogs (hypo-T dogs) are available. We aimed to evaluate the prevalence and characteristics of concurrent GI signs in hypo-T dogs, describe clinicopathological, hepato-intestinal ultrasound findings in hypo-T dogs, investigate changes in GI signs after thyroid replacement therapy (THRT). Medical records of suspected hypo-T dogs from two hospitals were retrospectively reviewed. The inclusion criteria were: (1) having symptoms and clinicopathological abnormalities related to hypothyroidism (i.e., mild anemia, hyperlipemia); (2) not being affected by systemic acute disease; (3) not having received any treatment affecting thyroid axis. Hypothyroidism had to be confirmed using low fT4 or TT4 with high TSH and/or inadequate TSH-stimulation test response; otherwise, dogs were assigned to a euthyroid group. Clinical history, GI signs, hematobiochemical parameters, and abdominal ultrasound findings were recorded. Hypo-T dogs were assigned to the GI group (at least 2 GI signs) and not-GI group (1 or no GI signs). Follow-up information 3-5 weeks after THRT was recorded. In total, 110 medical records were screened: 31 dogs were hypo-T, and 79 were euthyroid. Hypo-T dogs showed a higher prevalence of GI signs (44%), especially constipation and diarrhea (p = 0.03 and p = 0.001), than euthyroid dogs (24%) (p = 0.04). Among hypo-T dogs, no difference in hematological parameters between GI and non-GI groups was found. Hypo-T dogs had a higher prevalence of gallbladder alterations than euthyroid dogs (20/25; 80% and 32/61; 52% p = 0.04). The hypo-T GI group showed a significant improvement in the GI signs after THRT (p < 0.0001). Specific investigation for concurrent GI diseases in hypo-T dogs was lacking; however, improvement in GI signs following THRT supports this association between GI signs and hypothyroidism.

Prevalence of Lactose Intolerance in Patients with Hashimoto Thyroiditis and Impact on LT4 Replacement Dose

Purpose: to determine lactose intolerance (LI) prevalence in women with Hashimoto’s thyroiditis (HT) and assess the impact of LI on LT4 replacement dose. Methods. consecutive patients with HT underwent Lactose Breath Test and clinical/laboratory data collection. Unrelated gastrointestinal disorders were carefully ruled out. Lactose-free diet and shift to lactose-free LT4 were proposed to patients with LI. Results: we enrolled 58 females (age range, 23−72 years) with diagnosis of HT. In total, 15 patients were euthyroid without treatment, and 43 (74%) euthyroid under LT4 (30 of them with a LT4 formulation containing lactose). Gastrointestinal symptoms were present in 84.5% of patients, with a greater prevalence in change in bowel habits in lactose-intolerant patients (p < 0.0001). The cumulative LT4 dose required did not differ in patients with or without LI. No significant difference in both TSH values and LT4 dose were observed in patients shifted to lactose-free LT4 and diet at 3 and 6 months compared to baseline. Conclusion: the prevalence of LI in patients with HT was 58.6%, not different from global prevalence of LI. In the absence of other gastrointestinal disorders, LI seems not to be a major cause of LT4 malabsorption and does not affect the LT4 required dose in HT patients.

Gastrointestinal Symptoms in Type 1 Diabetes: Relationship With Autoimmune and Microvascular Complications

PURPOSE

To assess reported rates of gastrointestinal (GI) symptoms and their association with autoimmune diseases and microvascular complications in adults and children with type 1 diabetes.

METHODS

The Gastrointestinal Symptom Scale was used to assess GI symptom type and severity in 2370 patients with type 1 diabetes aged 8 to 45 years evaluated as part of a clinical trial screening for celiac disease (CD). The presence and severity of GI symptoms and relationships with demographic, clinical, and other diabetes-related factors were evaluated.

RESULTS

Overall, 1368 adults (57.7%) aged 19 to 45 years and 1002 (42.3%) pediatric patients aged 8 to 18 years were studied. At least 1 GI symptom was reported in 34.1% of adults as compared with 21.7% of children (P < 0.0001). Common symptoms in children included upper and lower abdominal pain while adults more frequently reported lower GI symptoms. Participants with GI symptoms had higher hemoglobin A1c (HbA1c) levels (68 ± 14mmol/mol; 8.35 ± 1.37%) than those without symptoms (66 ± 15mmol/mol; 8.22 ± 1.40%; P = 0.041). Patients with microvascular complications (nephropathy, retinopathy, and/or neuropathy) were 1.8 times more likely to report GI symptoms (95% CI: 1.26-2.60; P < 0.01) after adjusting for age and sex. No association was observed between GI symptoms and the presence of autoimmune conditions, including thyroid and biopsy-confirmed CD (odds ratio = 1.1; 95% CI: 0.86-1.42; P = 0.45).

MAIN CONCLUSIONS

These results highlight that GI symptoms are an important clinical morbidity and are associated with increasing age, duration of type 1 diabetes, HbA1c, and microvascular complications but not with autoimmune comorbidities including CD.

The Role of Thyroid Hormone in Neuronal Protection

Thyroid hormone is essential for brain development and brain function in the adult. During development, thyroid hormone acts in a spatial and temporal-specific manner to regulate the expression of genes essential for normal neural cell differentiation, migration, and myelination. In the adult brain, thyroid hormone is important for maintaining normal brain function. Thyroid hormone excess, hyperthyroidism, and thyroid hormone deficiency, hypothyroidism, are associated with disordered brain function, including depression, memory loss, impaired cognitive function, irritability, and anxiety. Adequate thyroid hormone levels are required for normal brain function. Thyroid hormone acts through a cascade of signaling components: activation and inactivation by deiodinase enzymes, thyroid hormone membrane transporters, and nuclear thyroid hormone receptors. Additionally, the hypothalamic-pituitary-thyroid axis, with negative feedback of thyroid hormone on thyrotropin-releasing hormone (TRH) and thyroid-stimulating hormone (TSH) secretion, regulates serum thyroid hormone levels in a narrow range. Animal and human studies have shown both systemic and local reduction in thyroid hormone availability in neurologic disease and after brain trauma. Treatment with thyroid hormone and selective thyroid hormone analogs has resulted in a reduction in injury and improved recovery. This article will describe the thyroid hormone signal transduction pathway in the brain and the role of thyroid hormone in the aging brain, neurologic diseases, and the protective role when administered after traumatic brain injury. © 2021 American Physiological Society. Compr Physiol 11:1-21, 2021.

Oral and intestinal microbial features in pregnant women with hypothyroidism and their correlations with pregnancy outcomes

The purpose of this study was to explore the characteristics of oral and intestinal microbiota of pregnant women with hypothyroidism during pregnancy, and to find the correlations between the changes of flora and pregnancy outcome of pregnant women with hypothyroidism during pregnancy. In this study, oral and intestinal microbial composition was surveyed by using the 16S rRNA sequencing approach in 61 pregnant women (30 with hypothyroidism and 31 normal controls). Sequentially, we validated the differential microbial features by using the quantitative real-time PCR (qPCR) approach in 10 randomly selected pregnant women (5 with hypothyroidism and 5 normal controls). Furthermore, general clinical data and serological indices were added to the analysis to examine the links between oral and intestinal microbiota and pregnancy outcomes. The 16S rRNA results showed that the relative abundances of Gammaproteobacteria were higher in pregnant women in the hypothyroidism group than in those in the control group, whereas the levels of Firmicutes were higher in the control group than in the hypothyroidism group. The serum C-reactive protein level, the weight gain during pregnancy, and the incidence of fetal distress were higher in the hypothyroidism group than in the control group. The QPCR results also showed the same changes of the intestinal microbiota in the two groups. There were significant differences in the oral and intestinal microbiota between pregnant women with hypothyroidism and normal pregnant women. The changes of microbiota is one of the factors influencing the occurrence and development of hypothyroidism during pregnancy.

Invited Review: Glucosinolates Might Result in Low Methane Emissions From Ruminants Fed Brassica Forages

Methane is formed from the microbial degradation of feeds in the digestive tract in ruminants. Methane emissions from ruminants not only result in a loss of feed energy but also contribute to global warming. Previous studies showed that brassica forages, such as forage rape, lead to less methane emitted per unit of dry matter intake than grass-based forages. Differences in rumen pH are proposed to partly explain these low emissions. Rumen microbial community differences are also observed, but the causes of these are unknown, although altered digesta flow has been proposed. This paper proposes a new mechanism underlying the lower methane emissions from sheep fed brassica forages. It is reported that feeding brassica forages to sheep can increase the concentration of free triiodothyronine (FT3) in serum, while the intramuscular injection of FT3 into sheep can reduce the mean retention time of digesta in the rumen. The short retention time of digesta is associated with low methane production. Glucosinolates (GSLs) are chemical components widely present in plants of the genus Brassica. After ruminants consume brassica forages, GSLs are broken down in the rumen. We hypothesize that GSLs or their breakdown products are absorbed into the blood and then may stimulate the secretion of thyroid hormone FT3 in ruminants, and the altered thyroid hormone concentration may change rumen physiology. As a consequence, the mean retention time of digesta in the rumen would be altered, resulting in a decrease in methane emissions. This hypothesis on mitigation mechanism is based on the manipulation of animal physiological parameters, which, if proven, will then support the expansion of this research area.

Weight gain following treatment of hyperthyroidism-A forgotten tale

Hyperthyroidism causes weight loss in the majority, but its effect is variable and 10% of patients gain weight. Its treatment usually leads to weight gain and some studies have reported an excess weight regain. However, there is considerable inter-individual variability and a differential effect on body weight by different treatments, with some studies reporting more weight increase with radioiodine, and perhaps surgery, compared with anti-thyroid drugs. The excess weight regain may relate to treatment-induced hypothyroidism. Furthermore, the transition from hyperthyroidism to euthyroidism may unmask, or exacerbate, the predisposition that some patients have towards obesity. Other risk factors commonly implicated for such weight increase include the severity of thyrotoxicosis at presentation and underlying Graves' disease. Conflicting data exist whether lean body mass or fat mass or both are increased post-therapy and whether such increments occur concurrently or in a sequential manner; this merits clarification. In any case, clinicians need to counsel their patients regarding this issue at presentation. Limited data on the effect of dietary interventions on weight changes with treatment of hyperthyroidism are encouraging in that they cause significantly lesser weight gain compared to standard care. More research is indicated on the impact of the treatment of hyperthyroidism on various anthropometric indices and the predisposing factors for any excessive weight gain. Regarding the impact of dietary management or other weight loss interventions, there is a need for well-designed and, ideally, controlled intervention studies.

Diarrhea as a form of presentation of medullary thyroid carcinoma

A case is presented of a 57-year-old man consulting for chronic diarrhea. Based on subsequent findings (thyroid nodule and metastases), the possibility of metastatic medullary thyroid carcinoma (MTC) was raised. Thyroidectomy allowed diagnosing a multicentric left lobe MTC. MTC is a rare cause of diarrhea, but should be considered, especially in the presence of signs or symptoms of alarm or nonresponse to empirical therapy.

Effects of breeding center, age and parasite burden on fecal triiodothyronine levels in forest musk deer

The objective of this study was to evaluate the effects of sex, breeding center and age on fecal triiodothyronine levels in captive forest musk deer Moschus berezovskii, and to explore the age-intensity model of gastrointestinal parasites. Furthermore, the association between fecal triiodothyronine levels and parasite egg shedding was also analyzed. We collected musk deer fecal samples from two breeding centers located in Shaanxi and Sichuan province, China. Enzyme-linked immunosorbent assays were utilized to estimate the fecal triiodothyronine concentrations and profiles, and fecal parasite eggs or oocysts were counted using the McMaster technique. Female deer from both breeding centers consistently showed higher triiodothyronine concentrations than those observed in males, which indicates that a distinct physiology pattern occurs by sex. The triiodothyronine concentration in Sichuan breeding center was significantly higher than that in Shaanxi center for both sexes, suggesting that differences in environment, diet and management practices are likely to affect the metabolism. In addition, a negative relationship between triiodothyronine concentrations and age was found (r = - 0.75, p < 0.001), and parasite egg shedding was also negatively associated with age (r = - 0.51, p < 0.001), by which we can infer that older animals evolves a more developed immune system. Finally, a positive association between parasite egg shedding and triiodothyronine levels was found, which could be explained by the additional energy metabolism resulting from parasitic infection. Results from this study might suggest metabolic and immunological adaptations in forest musk deer. These baseline data could be used to unveil metabolic status and establish parasite control strategies, which has great potential in captive population management as well as their general health evaluations.

Clinical Feasibility of Monitoring Resting Heart Rate Using a Wearable Activity Tracker in Patients With Thyrotoxicosis: Prospective Longitudinal Observational Study

Background

Symptoms and signs of thyrotoxicosis are nonspecific and assessing its clinical status is difficult with conventional physical examinations and history taking. Increased heart rate (HR) is one of the easiest signs to quantify this, and current wearable devices can monitor HR.

Objective

We assessed the association between thyroid function and resting HR measured by a wearable activity tracker (WD-rHR) and evaluated the clinical feasibility of using this method in patients with thyrotoxicosis.

Methods

Thirty patients with thyrotoxicosis and 10 controls were included in the study. Participants were instructed to use the wearable activity tracker during the study period so that activity and HR data could be collected. The primary study outcomes were verification of changes in WD-rHR during thyrotoxicosis treatment and associations between WD-rHR and thyroid function. Linear and logistic model generalized estimating equation analyses were performed and the results were compared to conventionally obtained resting HR during clinic visits (on-site resting HR) and the Hyperthyroidism Symptom Scale.

Results

WD-rHR was higher in thyrotoxic patients than in the control groups and decreased in association with improvement of thyrotoxicosis. A one standard deviation–increase of WD-rHR of about 11 beats per minute (bpm) was associated with the increase of serum free T4 levels (beta=.492, 95% CI 0.367-0.616, P<.001) and thyrotoxicosis risk (odds ratio [OR] 3.840, 95% CI 2.113-6.978, P<.001). Although the Hyperthyroidism Symptom Scale showed similar results with WD-rHR, a 1 SD-increase of on-site rHR (about 16 beats per minute) showed a relatively lower beta and OR (beta=.396, 95% CI 0.204-0.588, P<.001; OR 2.114, 95% CI 1.365-3.273, P<.001) compared with WD-rHR.

Conclusions

Heart rate data measured by a wearable device showed reasonable predictability of thyroid function. This simple, easy-to-measure parameter is clinically feasible and has the potential to manage thyroid dysfunction.

Trial Registration

ClinicalTrials.gov NCT03009357; https://clinicaltrials.gov/ct2/show/NCT03009357 (Archived by WebCite at http://www.webcitation.org/70h55Llyg)

Trends in treatments of thyroid disease following iodine fortification in Denmark: a nationwide register-based study

Background

Long-term iodine exposure may influence the frequency of thyroid disease treatments through fluctuations in thyroid diseases. Yet, the long-term fluctuations in thyroid disease treatments upon iodine fortification (IF) are not fully known. We aimed to examine the development in thyroid disease treatments in Denmark before and following the implementation of IF in 2000.

Methods

Nationwide data on antithyroid medication, thyroid hormone therapy, thyroid surgery, and radioiodine treatment were obtained from Danish registries. Negative binominal regression was applied to analyze annual changes in treatment rates adjusted for region of residence, sex, and age.

Results

Incidence of antithyroid medication transiently increased but fell and reached steady state from 2010 at an incidence rate ratio (RR) of 0.72 (95% confidence interval [CI] 0.67–0.77) compared to year 2000. Thyroid hormone therapy increased and reached steady state in 2010 at an incidence RR of 1.75 (95% CI 1.62–1.89) compared to year 2000. Thyroid surgery was constant except for higher rates in 2014–2015, and radioiodine treatment fluctuated with no apparent pattern.

Conclusion

Ten years after IF, a steady state was observed for incident antithyroid medication below the level at IF, and thyroid hormone therapy above the level at IF. Only small changes were observed in thyroid surgery and radioiodine treatment. In the same period, changes in diagnostic and treatment practices and lifestyle factors are likely to have occurred and should be considered when evaluating the effects of IF on treatment of thyroid diseases.

Flushing Disorders Associated with Gastrointestinal Symptoms: Part 1, Neuroendocrine Tumors, Mast Cell Disorders and Hyperbasophila

Flushing is the subjective sensation of warmth accompanied by visible cutaneous erythema occurring throughout the body with a predilection for the face, neck, pinnae, and upper trunk where the skin is thinnest and cutaneous vessels are superficially located and in greatest numbers. Flushing can be present in either a wet or dry form depending upon whether neural-mediated mechanisms are involved. Activation of the sympathetic nervous system results in wet flushing, accompanied by diaphoresis, due to concomitant stimulation of eccrine sweat glands. Wet flushing is caused by certain medications, panic disorder and paroxysmal extreme pain disorder (PEPD). Vasodilator mediated flushing due to the formation and release of a variety of biogenic amines, neuropeptides and phospholipid mediators such as histamine, serotonin and prostaglandins, respectively, typically presents as dry flushing where sweating is characteristically absent. Flushing occurring with neuroendocrine tumors accompanied by gastrointestinal symptoms is generally of the dry flushing variant, which may be an important clinical clue to the differential diagnosis. A number of primary diseases of the gastrointestinal tract cause flushing, and conversely extra-intestinal conditions are associated with flushing and gastrointestinal symptoms. Gastrointestinal findings vary and include one or more of the following non-specific symptoms such as abdominal pain, nausea, vomiting, diarrhea or constipation. The purpose of this review is to provide a focused comprehensive discussion on the presentation, pathophysiology, diagnostic evaluation and management of those diseases that arise from the gastrointestinal tract or other site that may cause gastrointestinal symptoms secondarily accompanied by flushing. This review is divided into two parts given the scope of conditions that cause flushing and affect the gastrointestinal tract: Part 1 covers neuroendocrine tumors (carcinoid, pheochromocytomas, vasoactive intestinal polypeptide, medullary carcinoma of the thyroid), polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, skin changes (POEMS), and conditions involving mast cells and basophils; while Part 2 covers dumping syndrome, mesenteric traction syndrome, rosacea, hyperthyroidism and thyroid storm, anaphylaxis, panic disorders, paroxysmal extreme pain disorder, and food, alcohol and medications.

Thyroid Dysfunction, Neurological Disorder and Immunosuppression as the Consequences of Long-term Combined Stress

Stress is a powerful modulator of neuroendocrine, behavioral, and immunological functions. So far, the molecular mechanisms of response to stressors still remain elusive. In the current study, after 10 days of repeated chronic stress (hot-dry environment and electric foot-shock), a murine model of combined-stress (CS) was created in the SPF Wistar rats. Meanwhile, we established an ulcerative-colitis (UC) rat model induced by 2,4,6-trinitrobenzene sulfonic acid (TNBS)/ethanol enema according to previous studies. The blood, hypothalamus, and colon tissues of these rats from CS, normal control (NC), UC and sham (SH) groups, were collected for further investigations. Comparing to the NC group, the serum levels of T3, T4, fT3 and fT4 were obviously decreased in the CS group after chronic stress, indicating that thyroid dysfunction was induced by long-term combined stress. Moreover, the application of RNA-seq and subsequent analyses revealed that neurological disorder and immunosuppression were also caused in the hypothalamus and colon tissues, respectively. Comparing with SH group, besides the induced colon inflammation, thyroid dysfuntion and neurological disorder were also produced in the UC group, suggesting that hypothalamic-pituitary-thyroid (HPT) axis and gastrointestinal system might not function in isolation, but rather, have intricate crosstalks.

Gut-thyroid axis and celiac disease

Autoimmune thyroiditis has an increased prevalence in patients with celiac disease and vice versa. The objective of the current review is to highlight the epidemiological, clinical, serological, pathological, pathophysiological, hormonal, genetic and immunological factors shared between the two entities. They might represent the two ends of the gut-thyroid axis where the cross-talks' pathways are still unravelled. New observations are reviewed, highlighting some gut-thyroid interrelated pathways that potentially might lead to new therapeutic strategies.

MAHMI database: a comprehensive MetaHit-based resource for the study of the mechanism of action of the human microbiota

The Mechanism of Action of the Human Microbiome (MAHMI) database is a unique resource that provides comprehensive information about the sequence of potential immunomodulatory and antiproliferative peptides encrypted in the proteins produced by the human gut microbiota. Currently, MAHMI database contains over 300 hundred million peptide entries, with detailed information about peptide sequence, sources and potential bioactivity. The reference peptide data section is curated manually by domain experts. The in silico peptide data section is populated automatically through the systematic processing of publicly available exoproteomes of the human microbiome. Bioactivity prediction is based on the global alignment of the automatically processed peptides with experimentally validated immunomodulatory and antiproliferative peptides, in the reference section. MAHMI provides researchers with a comparative tool for inspecting the potential immunomodulatory or antiproliferative bioactivity of new amino acidic sequences and identifying promising peptides to be further investigated. Moreover, researchers are welcome to submit new experimental evidence on peptide bioactivity, namely, empiric and structural data, as a proactive, expert means to keep the database updated and improve the implemented bioactivity prediction method. Bioactive peptides identified by MAHMI have a huge biotechnological potential, including the manipulation of aberrant immune responses and the design of new functional ingredients/foods based on the genetic sequences of the human microbiome. Hopefully, the resources provided by MAHMI will be useful to those researching gastrointestinal disorders of autoimmune and inflammatory nature, such as Inflammatory Bowel Diseases. MAHMI database is routinely updated and is available free of charge.

Database URL:http://mahmi.org/

Benign thyroid disease in pregnancy: A state of the art review

Thyroid dysfunction is the commonest endocrine disorder in pregnancy apart from diabetes. Thyroid hormones are essential for fetal brain development in the embryonic phase. Maternal thyroid dysfunction during pregnancy may have significant adverse maternal and fetal outcomes such as preterm delivery, preeclampsia, miscarriage and low birth weight. In this review we discuss the effect of thyroid disease on pregnancy and the current evidence on the management of different thyroid conditions in pregnancy and postpartum to improve fetal and neonatal outcomes, with special reference to existing guidelines on the topic which we dissect, critique and compare with each other. Overt hypothyroidism and hyperthyroidism should be treated appropriately in pregnancy, aiming to maintain euthyroidism. Subclinical hypothyroidism is often pragmatically treated with levothyroxine, although it has not been definitively proven whether this alters maternal or fetal outcomes. Subclinical hyperthyroidism does not usually require treatment and the possibility of non-thyroidal illness or gestational thyrotoxicosis should be considered. Autoimmune thyroid diseases tend to improve during pregnancy but commonly flare-up or emerge in the post-partum period. Accordingly, thyroid auto-antibodies tend to decrease with pregnancy progression. Postpartum thyroiditis should be managed based on the clinical symptoms rather than abnormal biochemical results.

Prevalence of Celiac Disease in Patients with Autoimmune Thyroid Disease: A Meta-Analysis

BACKGROUND

Several screening studies have indicated an increased prevalence of celiac disease (CD) among individuals with autoimmune thyroid disease (ATD), but estimates have varied substantially.

OBJECTIVE

The aim of this study was to examine the prevalence of CD in patients with ATD.

METHOD

A systematic review was conducted of articles published in PubMed Medline or EMBASE until September 2015. Non-English papers with English-language abstracts were also included, as were research abstracts without full text available when relevant data were included in the abstract. Search terms included "celiac disease" combined with "hypothyroidism" or "hyperthyroidism" or "thyroid disease." Fixed-effects inverse variance-weighted models were used. Meta-regression was used to examine heterogeneity in subgroups.

RESULTS

A pooled analysis, based on 6024 ATD patients, found a prevalence of biopsy-confirmed CD of 1.6% [confidence interval (CI) 1.3-1.9%]. Heterogeneity was large (I(2) = 70.7%). The prevalence was higher in children with ATD (6.2% [CI 4.0-8.4%]) than it was in adults (2.7%) or in studies examining both adults and children (1.0%). CD was also more prevalent in hyperthyroidism (2.6% [CI 0.7-4.4%]) than it was in hypothyroidism (1.4% [CI 1.0-1.9%]).

CONCLUSIONS

About 1/62 patients with ATD have biopsy-verified CD. It is argued that patients with ATD should be screened for CD, given this increased prevalence.

Clinical challenges in thyroid disease: Time for a new approach?

Thyroid disease is common, and the prevalence is rising. Traditional diagnosis and monitoring relies on thyroid stimulating hormone (TSH) levels. This does not always result in symptomatic improvement in hypothyroid symptoms, to the disappointment of both patients and physicians. A non-traditional therapeutic approach would include evaluation of GI function as well as a dietary history and micronutrient evaluation. This approach also includes assessment of thyroid peroxidase (TPO) antibodies, T3, T4, and reverse T3 levels, and in some cases may require specific T3 supplementation in addition to standard T4 therapy. Both high and low TSH levels on treatment are associated with particular medical risks. In the case of high TSH this is primarily cardiac, whereas for low TSH it is predominantly bone health. This article discusses these important clinical issues in more detail, with some practical tips especially for an approach to the "non-responders" to the current traditional therapeutic approach.