Resistance To Thyroid Hormone Research Articles

Effective TRIAC treatment of a THRβ-mutated patient with thyroid hormone resistance.

Resistance to thyroid hormone (RTH) is a rare autosomal dominant disease characterized by an alteration of thyroid hormone negative feedback, usually as a consequence of a mutation in the thyroid hormone receptor-b gene (THRβ). It is characterized by high variability of clinical manifestations, ranging from isolated abnormal thyroid function tests without symptoms to severe and impaired clinical conditions. Here we report the case of a woman who was diagnosed with RTHβ when she was 35 years old and was treated with 3,5,3-triiodiothyroacetic acid (TRIAC) because of the onset of clinical symptoms of hyperthyroidism. This therapy has been effective in controlling thyrotoxicosis for 5 years. After this time the patient developed an autoimmune hyperthyroidism, with TSH receptor autoantibodies appearance, which caused a loss of efficacy of the drug in controlling the disease. The development of different pathophysiological mechanisms of thyrotoxicosis, as in this case, could be the reason for both variability of disease manifestations and of loss of response to drug therapy.

Correlation Between Impaired Sensitivity to Thyroid Hormones and Serum Uric Acid in Female Patients With Obesity and After Laparoscopic Sleeve Gastrectomy

ObjectiveAn alterable risk factor for hyperuricemia is obesity. Additionally, obese people may have a moderate form of acquired resistance to thyroid hormones. Thyrotropin, thyroid hormones, and obesity all interact subtly. However, the connection between thyroid hormone sensitivity and hyperuricemia in obese patients both before and after laparoscopic sleeve gastrectomy (LSG) has not yet been clarified. The objective of our study was to investigate the connection between impaired thyroid hormone sensitivity and elevated uric acid (UA) levels before and after LSG. MethodsIn total, 1054 euthyroid patients with obesity (481 male, 573 female), 248 (143 female patients) of whom underwent subsequent LSG, were enrolled in this retrospective study. Anthropometric measurements and thyroid hormone and UA levels were taken before and 3 months after LSG. ResultsFemale patients with obesity with impaired sensitivity to thyroid hormones had higher UA levels (P for trend <.01). The odds ratio of the fourth vs first quartile of thyroid feedback quantile index, thyrotropin, and thyrotropin-thyroxine resistance index were 4.285 (confidence interval: 1.360-13.507), 3.700 (confidence interval: 1.276-10.729), and 2.839 (confidence interval: 1.014-7.948), respectively, with robust relationships with female hyperuricemia (all P < .05). However, there was only a positive correlation between the decline in UA levels and thyroid feedback quantile index, thyrotropin, and thyrotropin-thyroxine resistance index in female patients following LSG. ConclusionFemale hyperuricemia is correlated with higher thyroid hormone resistance index scores. Resistance to thyroid hormones was greatly improved by LSG. The decrease in UA levels after surgery is correlated with the improvement of thyroid hormone resistance after LSG.

Resistance to thyroid hormone and nonfunctioning pituitary microadenoma in a 13-year-old boy with THRB mutation.

Resistance to thyroid hormone (RTH) is a rare syndrome characterized by elevated serum free iodothyronines levels and non-suppressed thyroid stimulating hormones (TSH). The most common cause of RTH is heterozygous pathogenic mutations in thyroid hormone receptor β gene (THRB). Because of the similarities in biochemical profiles, differential diagnosis between RTHβ and TSH-secreting pituitary adenoma (TSHoma) is important, and accurate RTHβ diagnosis is essential to prevent inappropriate treatment. A 13-year-old boy was referred to our hospital for a microadenoma and uncontrolled hyperthyroidism despite use of methimazole for more than one year. He suffered from thyrotoxic clinical features and elevated serum T3 and fT4, and normal ranges for TSH and other pituitary hormones were noted. TSH receptor antibody was undetectable, and pituitary MRI revealed a 3mm-sized microadenoma. A TRH stimulation test showed normal TSH response, and the TSH-α-subunit level was not elevated, which is consistent with RTH. The patient was diagnosed with RTHβ and coexistent non-functioning pituitary microadenoma based on identification of a heterozygous mutation, c.1021C>G (p.Leu341Val), in THRB. Methimazole treatment was stopped, and a β-adrenergic blocking agent was started, subsequently thyrotoxic symptoms were relieved. Currently, only one pediatric case diagnosed with RTH and TSHoma has been reported so far, and this case is the first to report a pediatric case of coexistence of RTH and non-functioning pituitary microadenoma. Also, this case shows that inappropriate secretion of thyroid hormones requires careful clinical diagnosis to avoid unnecessary and potentially harmful management.

A case report: TSh-oma in patient with Down syndrome

Tsh-oma or Thyrotropinoma is a condition in which there is a pituitary adenoma that secretes TSH in an autonomous fashion, resulting in hyperthyroidism with its clinical aspects and complications. It is a very a rare condition comprising less than 0.1% of pituitary adenomas. The diagnosis and evaluation of Tsh-oma are challenging, as the clinical manifestations and the biochemical profile resemble the thyroid hormone resistance syndromes. Therefore, a high index of suspicion is required. Down syndrome is a chromosomal disease (trisomy 21) manifested in clinical, physical, and developmental impacts on affected persons. It is associated with thyroid autoimmune diseases and thyroid hypoplasia (congenital hypothyroidism) however, to our knowledge, there have been no described cases in the literature where Down syndrome was associated with a TSH-secreting pituitary adenoma. We hereby present a 34-year-old male known to have Down syndrome who was found to have a thyroid disorder (Tsh-oma) different from the known thyroid disorders linked to Down syndrome.

Concurrent &lt;i&gt;THRB&lt;/i&gt; and &lt;i&gt;DUOX2&lt;/i&gt; variants in a patient detected via newborn screening for congenital hypothyroidism: a case of resistance to thyroid hormone

Concurrent &lt;i&gt;THRB&lt;/i&gt; and &lt;i&gt;DUOX2&lt;/i&gt; variants in a patient detected via newborn screening for congenital hypothyroidism: a case of resistance to thyroid hormone

Thyroid Hormone Resistance Syndrome: From Molecular Mechanisms to Its Potential Contribution to Hypertension.

Thyroid hormone resistance (THR) is a rare inherited disorder that affects approximately one in every 40,000 live births. This condition arises from a mutation in the thyroid hormone receptor β, leading to reduced responsiveness of target tissues. It can result in a combination of hypothyroidism and hyperthyroidism symptoms in different tissues. The thyroid hormone is crucial for controlling blood pressure, and even small changes in its levels can have an effect on vascular resistance, cardiac performance, and heart rhythm. Both hypo- and hyperthyroidism have been associated with elevated blood pressure, underscoring the significant link between thyroid hormone sensitivity and vascular function. Considering thyroid hormone sensitivity is essential in clinical practice, particularly when managing patients with hypertension, to ensure personalized and effective treatment approaches. Monitoring thyroid function is essential during the diagnosis of hypertension, as thyroid dysfunction can often be corrected to normalize blood pressure. It's crucial to distinguish between essential hypertension and hypertension associated with a thyroid abnormality in THR. The mechanisms behind the development of hypertension in THR include reduced nitric oxide production, dysregulation of the renin-angiotensin-aldosterone system, impaired endothelial function, and mutations in the deiodinases. Physicians shouldunderstand the underlying mechanisms of THR and identify new therapeutic targets for hypertension in THR.

Thyroid hormone resistance: Diagnostic challenges and management

Thyroid hormone resistance: Diagnostic challenges and management

A case of thyroid hormone resistance with hyperthyroidism

A case of thyroid hormone resistance with hyperthyroidism

Tiratricol inhibits yellow fever virus replication through targeting viral RNA-dependent RNA polymerase of NS5

Yellow fever virus (YFV) infection is a major public concern that threatens a large population in South America and Africa. No specific antiviral drugs are available for treating yellow fever. Here, we report that tiratricol (triiodothyroacetic acid, TRIAC), a clinically approved drug used to treat thyroid hormone resistance syndrome (THRS), is a potent YFV inhibitor both in host cells and in animal models.An in vitro study demonstrates that TRIAC remarkably suppresses viral RNA synthesis and protein expression in a dose-dependent manner in human hepatoma cell lines (Huh-7) with an EC50 value of 2.07 μM and a CC50 value of 385.77 μM respectively. The surface plasmon resonance assay and molecular docking analysis indicate that TRIAC hinders viral replication by binding to the RNA-dependent RNA polymerase (RdRp) domain of viral nonstructural protein NS5, probably through interacting with the active sites of RdRp.The inhibitory effect of TRIAC in vivo is also confirmed in 3-week old C57BL/6 mice challenged with YFV infection, from which the survival of the mice as well as lesions and infection in their tissues and serum issignificantly promoted following oral administration of TRIAC (0.2 mg/kg/day). Additionally, TRIAC shows a broad-spectrum antiviral activity against multiple flaviviruses such as TBEV, WNV,ZIKV, andJEV in vitro. Our data demonstrate that the TH analogue TRIAC is an effective anti-YFV compound and may act as a potential therapeutic candidate for the treatment of YFV infection if its clinical importance is determined in patients in future.

SAT504 Thyroidal Pax de Deux: 2 Cases of Resistance to Thyroid Hormone and Coexisting Thyroid Disease

Abstract Disclosure: S.V. Ribeiro: None. T. Moreno: None. A. Varela: None. P. Freitas: None. D.M. Carvalho: None. Resistance to thyroid hormone (RTH) is a rare clinical syndrome defined by hyposensitivity to thyroid hormone (TH) and characterized by elevated TH levels in the absence of TSH suppression. In most subjects with RTH, treatment is not required as tissue resistance is adequately compensated for by an increase in the endogenous supply of TH. This is not the case in patients with limited thyroidal reserve. Here we describe the clinical features of two unrelated patients with RTH and coexisting thyroid disease. Patient 1 was an 18-year-old female medical student referred to our consultation from Pediatrics. She had been diagnosed with autoimmune thyroiditis at age of 7 following the development of an obvious goiter. By then her thyroid-function tests (TFT) showed elevated TSH (8.75 µIU/mL, NR 0.41-3.67) and a normal free T4 (1.3 ng/dL, NR 0.82-1.76). She tested positive for the presence of antibodies to thyroperoxidase and thyroglobulin. The cytological findings on aspiration biopsy were consistent with Hashimoto’s thyroiditis. Throughout the years, despite levothyroxine supplementation she displayed systematically elevated TSH and normal FT4. The results of a thyrotropin stimulation test were normal. The suspicious of erratic compliance to therapy was raised.Follow-up at our outpatient clinic confirmed requirement for unusually high replacement doses of levothyroxine in order to maintain TSH within normal limits at expense of elevated FT4 and FT3 levels, suggesting the possibility of RTH. She was found with a THRβ c.1292T&amp;gt;C p.(Iso431Thr) heterozygous mutation. She remains clinically euthyroid under supplementation. Patient 2 was an asymptomatic 54-year-old female who consulted us for further evaluation of a thyroid nodule. Thyroid-FT showed an elevated FT3, at 3.86 μg/dL (NR, 1.75 to 3.71), an elevated FT4 at 1.86 ng/dL (NR 0.70 to 1.48), and a normal TSH level at 1.55 µIU/mL (NR, 0.40 to 4.50). A diffuse goiter was revealed by scintigraphy and the ultrasound showed no relevant findings. A diagnosis of RTH was genetically confirmed (THRβ c.1707C&amp;gt;G p.(P453A)). After a 6-year follow-up, she was diagnosed with supraventricular tachyarrhythmia for which she was started on amiodarone. Shortly after, her TFT revealed elevated TSH that normalized a few months after amiodarone withdrawal. Three years later, she was admitted to the intensive care unit due to cardiogenic shock attributed to tachycardia-induced cardiomyopathy and restarted on amiodarone. Her subsequent TFT showed elevated TSH (42.07 µIU/mL), with decreasing levels of TH (FT3 2.02 μg/dL, FT4 1.06 ng/dL). A diagnosis of amiodarone-induced hypothyroidism was made and levothyroxine supplementation was initiated and adjusted considering the patient’s symptoms. These cases show that the coexistence of RTH with other thyroidal disease can make diagnosis and management challenging and requires awareness and long-term follow-up. Presentation Date: Saturday, June 17, 2023

FRI496 A Rare Case Of Thyroid Hormone Resistance Beta

Abstract Disclosure: H.K. Rai: None. R.M. Pradhan: None. A. Chaudhuri: None. Background: Genetic mutation in the thyroid hormone receptor leads to the reduced affinity of hormone binding; thus, causing thyroid hormone resistance. It is characterized by a wide range of phenotypic variations and subsequent diagnostic and treatment challenges. Here, we present a case of resistance to the thyroid hormone Beta, with a rare genetic abnormality, that was misdiagnosed as hyperthyroidism. Case: A 46-year-old woman diagnosed with hyperthyroidism s/p RAIA resulting in hypothyroidism on levothyroxine therapy (112mcg daily, weight: 55kg), presented with ten pounds of weight gain, constipation, and cold intolerance for the past six months. TFTs were as follows: TSH: 6.493 mcUnits/ml (normal: 0.400-5.00 mcUnits/ml), and free T4: 1.83 ng/dL (normal: 0.80-1.80 ng/dL). The patient was clinically hypothyroid despite having an elevated FT4 and TSH level. She was also on metoprolol succinate 25 mg daily for sinus tachycardia for the past 1 year. Upon inquiring about further details, the patient informed that at the age of 22, she had significant weight loss, palpitations, and anxiety, but also reported dry skin. The patient was seen by multiple endocrinologists and was provided with contradictory diagnoses. She had RAI scan which was significant for increased uptake and subsequently underwent RAIA. The patient was seen by multiple physicians in the past, levothyroxine dose was adjusted on various occasions but her TFTs never normalized. Post-ablation, she continued to require a higher than the weight-based dose of levothyroxine. Upon review of family history, the patient reported that her father, sister, and daughter had a similar pattern of TFTs with elevated FT4 and TSH values. All of them had palpitations and anxiety that were not severe enough to seek medical care. Family history was also significant for ADHD and hyperlipidemia present in the daughter and father. All affected family members have short stature. The levothyroxine dose was slowly titrated based on the clinical presentation. She was euthyroid with 150 mcg daily of levothyroxine with TSH of 4.869 mcUnits/ml and free T4: 1.85 ng/dl. Given her presentation and suspicion of thyroid hormone resistance, we decided to proceed with genetic testing. The result was positive for the THRB (Resistance to thyroid hormone beta) variant c.904A&amp;gt;G.p.(IIe302Val), which is classified as a variant of uncertain significance, as there is currently insufficient evidence to support its disease-causing role. However, there is a strong association between the gene and the patient's phenotype. Conclusion: The distinctive feature of RTH beta is high levels of free T4 while TSH concentration is normal or elevated, with a combination of hypothyroid and hyperthyroid symptoms. Such patients are often misdiagnosed. We herein describe a novel pathogenic RTH beta gene variant causing thyroid hormone resistance that needs to be further explored. Presentation: Friday, June 16, 2023

FRI479 Resistance To Thyroid Hormone Due To Thyroid Hormone Receptor Alpha (THRA) Gene Mutation

Abstract Disclosure: J.O. Abdelkarim: None. S. Parveen: None. M.G. Jakoby: None. J. Fleischer: None. Introduction: Resistance to thyroid hormone (RTH) is a heritable disorder characterized by diminished response to triiodothyronine (T3). Most cases of RTH are due to mutations in the thyroid hormone receptor beta (THRB) gene (“RTH-beta”). Mutations in thyroid hormone receptor alpha (THRA) gene appear to be a rare cause of RTH (“RTH-alpha”), with the first case reported in 2012. We present a case of RTH-alpha in a patient confirmed to have a pathogenic THRA mutation. Clinical Case: A 38-year-old Caucasian male was referred to genetic clinic due to mild developmental delay, dyscalculia and mild autism spectrum disorder. He was born at term by uncomplicated spontaneous vaginal delivery. Parents first noticed developmental delays at age 5 y, though no evaluation occurred during childhood. As an adult, the patient completed seminary studies and was employed as a Catholic priest. An intellectual disability gene panel revealed a pathogenic variant of the THRA gene (c.1151G&amp;gt;A p.R384H). Both parents tested negative for the mutation. Examination was notable for obesity (183 cm, 186 kg, BMI 55.5), macrocephaly, hypertelorism, pectus excavatum and small hands with short digits. No thyroid anatomic thyroid abnormalities were appreciated on neck examination or ultrasonography. TSH was 1.860 mIU/L (0.358-3.740), free T4 0.71 ng/dL (0.76-1.46), and free T3 3.2 pg/mL (2.2-4.0). The patient had no symptoms of hypothyroidism, and supplemental thyroid hormone was deferred. Discussion: There are 29 reported THRA gene mutations and 32 cases of RTH-alpha reported in the peer reviewed literature. Common clinical features include mild-to-moderate intellectual impairment, low basal metabolic rate (BMR), mild skeletal dysplasia, normocytic anemia, bradycardia, consistent with high expression of THRA in brain, heart, gastrointestinal tract, skeletal muscle, and bone. TSH is normal to slightly increased, free T4 is low to low normal, and free T3 is normal to modestly elevated. This is the third reported case of the c.1151G&amp;gt;A missense mutation resulting in an arginine to histidine substitution at codon 384. Thyroid function tests conform to the pattern described for other cases of RTH-alpha. Like the other two patients with the R384H mutation, developmental delays occurred, though intellectual manifestations mitigated with time and the patient completed seminary studies without difficulty. Mitigation of phenotype with age has been reported in RTH-alpha mice with the R384C missense mutation. Short stature did not occur in this patient or the other R384H cases. Unlike other patients, this patient did not experience anemia or constipation. Macrocephaly is a common feature of the three R384H cases, but the patient’s other skeletal manifestations (e.g. pectus excavatum) were not reported. This case demonstrates the difficulty of recognizing THR-alpha and extends our understanding of the R384H phenotype. Presentation: Friday, June 16, 2023

SAT482 A Case of Falsely Elevated Free T4 and Free T3 Levels Caused by Human Anti Mouse Antibodies.

Abstract Disclosure: I.J. Romao: None. M.H. Shanik: None. Introduction: When there are clinical and biochemical discrepancies with thyroid function tests immunoassay interference should be considered (1). Human anti mouse antibodies (HAMA) are antibodies found in humans that react with immunoglobulins in mice and are used as diagnostic reagents for laboratory measurements. The presence of HAMA most commonly causes a false elevation of thyroid stimulating hormone but can also increase Free T4 and Free T3 levels. Case presentation: A 31 year old woman presented for evaluation of elevated Free T4 and Free T3 levels. For several weeks she complained of feeling neck soreness and palpitations. She had a recent infection and low-grade fever. She also felt pressure behind her eyes. She had a history of anxiety and took Xanax as needed, multivitamin and probiotic. Cousin had thyroid disease. On exam her blood pressure was 138/86, heart rate 80, respiratory rate 12, weight 149 lbs., height 5’5”. Her thyroid was firm and not tender. She had a thyroid ultrasound that showed a homogenous gland with no discrete nodules. TSH was 1.3 uIU/mL (0.27-4.2), Total T4 10.4 ug/dL (4.5 – 12), Free T4 4.6 ng/dL (0.9-1.7), Total T3 1.6 ng/mL (0.8-2.0), Free T3 10.1 pg/mL (2.0-4.4). C reactive protein, erythrocyte sedimentation and interleukin 6 levels were in the normal range. Thyroid peroxidase antibodies and thyroglobulin antibodies were elevated. The differential diagnosis included thyroiditis, pituitary tumor producing thyroid stimulating hormone and thyroid hormone resistance. She did not have a thyroid uptake and scan because she had small children at home. To rule out a pituitary adenoma she had a pituitary MRI that showed a normal small pituitary gland. The test for resistance to thyroid hormone mutation analysis was negative. Over a few months she had some clinical improvement, and her thyroid function tests remained the same which would not be consistent with thyroiditis. HAMA level was checked to evaluate for immunoassay interference with thyroid function tests. The HAMA level was elevated at greater than 600 ng/mL (0-188). Free T4 by equilibrium dialysis was normal at 1.6 ng/dL (1.1 – 2.4). Conclusion: HAMA can cause falsely elevated Free T4 and Free T3 levels. It is important to suspect immunoassay interference when there are inconsistencies in the clinical presentation and thyroid function tests. Identifying the presence of elevated HAMA can prevent misdiagnosis and inappropriate patient management. 1. Favresse J, Burlacu MC, Maiter D, Gruson D. Interferences with thyroid immunoassays: Clinical implications and detection algorithm. Endocrine Reviews. 2018. Pages 830-850. Presentation Date: Saturday, June 17, 2023

FRI476 Asymptomatic Thyrotropin-secreting Pituitary Microadenoma With Biochemical Secondary Hyperthyroidism: A Diagnostic Conundrum

Abstract Disclosure: G. Al-Naqeeb: None. R. Ghosh: None. P. Veeraraghavan: None. C. Cochran: None. J. Klubo-Gwiezdzinska: None. S. Gubbi: None. Background: Thyrotropin (TSH)-secreting pituitary adenomas (TSHAs) are often macroadenomas (&amp;gt;1 cm), and clinically present with secondary hyperthyroidism (SH), but clinically silent microTSHAs (&amp;lt;1 cm) with only biochemical SH pose a diagnostic challenge. Clinical Case: A 49-year-old, healthy male was referred to our center for evaluation of abnormal thyroid function tests (TFTs). Immunoassay (IA) measurements at an outside hospital had identified elevated free T4 (FT4), and an inappropriately normal TSH, and a pituitary magnetic resonance imaging (MRI) had noted an 8mm x 7mm non-invasive adenoma. The patient denied hyperthyroidism symptoms, medication/herbal supplement intake, radiation exposure, headaches, vision changes, and thyroid/pituitary disorders, or abnormal TFTs in relatives. Physical exam revealed no signs and symptoms of hyperthyroidism. No thyromegaly or cervical lymphadenopathy was felt. IA profile at our institute was consistent with an SH pattern [TSH: 3.32 mIU/L (NL: 0.4 - 4.7); FT4: 3 ng/dL (NL: 0.9 - 1.7); total T4: 14.5 mcg/dL (NL: 4.5 - 11.7); triiodothyronine: 266.6 ng/dL (NL: 80 - 200)], with similar values on repeat measurement. Equilibrium dialysis technique also yielded an elevated FT4 value. TSH-receptor, anti-thyroid peroxidase, and anti-thyroglobulin (Tg) antibody (Ab) titers, serum Tg, and thyroid binding globulin levels were normal. Dilution studies ruled out heterophile Ab interference. Familial dysalbuminemic hyperthyroxinemia was unlikely given the elevated FT4 values. Genetic testing revealed a normal THRB gene, thereby ruling out thyroid hormone resistance. THRA gene was not tested due to absence of behavioral or hearing issues. Markers of hyperthyroidism, including angiotensin converting enzyme, carotene, apolipoproteins, and osteocalcin levels were normal, except for an elevated sex hormone binding globulin of 104 nmol/L (NL: 11 - 78). Biochemical evaluation of other pituitary axes was normal. However, an elevated alpha sub-unit fraction (ASF) was noted on two separate measurements. Sonogram revealed a heterogeneous, hypervascular thyroid. Bone densitometry, echocardiogram, and Holter monitor studies were normal. The combination of biochemical SH, elevated ASF, pituitary adenoma, and exclusion of other etiologies causing SH pattern established the diagnosis of TSHA. An active surveillance approach was implemented. A pituitary MRI done 18 months later showed minimal (2mm in one axis) increase in the adenoma size, and the patient continued to demonstrate biochemical SH but remained asymptomatic. Conclusion: MicroTSHAs can present with asymptomatic SH. In this situation, excluding other biochemical SH etiologies is crucial to prevent unnecessary invasive procedures. But once TSHA diagnosis is established, due to the risk of tumor growth leading to symptomatic SH or mass effects, active surveillance is warranted. Presentation: Friday, June 16, 2023

FRI532 Thyroid Hormone Resistance: A Possible New Variant In The THRB Gene

Abstract Disclosure: A. Siddiqui: None. Z. Khan: None. T. Ahmed: None. K. Selk: None. Background: Resistance to the Thyroid Hormone (RTH) is caused by reduced target tissue response to thyroid hormone, resulting in the loss of the normal feedback mechanism that suppresses secretion of thyrotropin (TSH). Most cases of RTH are familial, usually inherited in an autosomal dominant manner, with over 100 different pathogenic variants having been described. Clinical Case: A 45-year-old male with history of attention deficit disorder presented for management of hypothyroidism. The patient was Anti-TPO positive, consistent with Hashimoto's thyroiditis and he was treated with varying doses of levothyroxine. Labs on 100 mcg levothyroxine showed a TSH of 7.07 (0.35-4.94 uIU/mL), free t4 1.86 (0.7-1.48 ng/dL), and free t3 4.41 (2.3-4.2 pg/mL). This initially prompted concern for a TSHoma. An alpha subunit level was found to be 0.3 ng/dL and pituitary MRI was within normal limits. Given continued persistent thyroid hormone elevations, further testing for human anti-mouse antibody interference was performed and also unrevealing. The patient continued to report feeling tired and fatigued, with multiple joint pains and inability to focus or concentrate. His levothyroxine was increased to 125 mcg per day. However, even after the adjustment, he still did not notice any change in his symptoms. A trial of addition of liothyronine 5mcg daily was also performed but he self-discontinued this as he did note any improvement. Overall, his findings were highly suspicious for thyroid hormone resistance. Genetic testing for a thyroid hormone resistance beta (THRB) mutation was performed. Direct sequence analysis of the coding region and splice-sites of the THRB gene identified one copy of the c.1368G&amp;gt;T (p.Leu456Phe) variant of uncertain significance. Analysis of this variant using bioinformatics tools for the prediction of the effect of amino acid changes on protein structure and function yielded predictions that this variant is damaging. However, the THRB c.1368G&amp;gt;T (p.Leu456Phe) variant has not been described in online databases or published literature. It also has not been reported in large, multi-ethnic general populations. Conclusion: This is the first case to our knowledge demonstrating the THRB c.1368G&amp;gt;T (p.Leu456Phe) variant gene as likely giving rise to RTH. Further testing of family members has been recommended to help clarify the clinical significance of this finding. Presentation: Friday, June 16, 2023

Cardiovascular Morbidity and Mortality Is Higher in Patients with Thyroid Hormone Resistance β Syndrome than in the General Population

Cardiovascular Morbidity and Mortality Is Higher in Patients with Thyroid Hormone Resistance β Syndrome than in the General Population

Disfunzioni tiroidee mascherate all’interno dei range di normalità

Thyroid function plays a crucial role in metabolic homeostasis, in the regulation of blood pressure, energy expenditure and in glucose and lipid metabolism. Thyroid alteration patterns, particularly hypothyroidism, are widely known to be associated with metabolic syndrome. However, more recently, different thyroid hormone release patterns have shown not to fit within the classic definitions of hypothyroidism or hyperthyroidism, patterns in which hormone levels may often be within the normal range. A condition defined as thyroid hormone resistance syndrome has been identified as a state characterized by thyroid hormones within the upper limits of the normal range but with normal to high TSH levels. In fact, many studies have shown an association between this condition and pathologies such as obesity, metabolic syndrome, diabetes and NAFLD. Recent studies have hypothesized that thyroid hormone resistance might be present in patients with disabilities, therefore they also investigated whether and how all those conditions may influence one another. Furthermore, given the important role that TSH and thyroid hormones play in the development of various diseases, and the consequent implications for the health system, the creation of reliable algorithms that support the interpretation of thyroid homeostasis in the clinical setting is therefore pivotal.

Lack of thyroid hormone receptor beta is not detrimental for non-alcoholic steatohepatitis progression

Agonists for thyroid hormone receptor β (TRβ) show promise in preclinical studies and clinical trials to improve non-alcoholic fatty liver disease. A recent study on human livers, however, revealed reduced TRβ expression in non-alcoholic steatohepatitis (NASH), indicating a developing thyroid hormone resistance, which could constitute a major obstacle for those agonists. Using a rapid NASH paradigm combining choline-deficient high-fat diet and thermoneutrality, we confirm that TRβ declines during disease progression in mice similar to humans. Contrary to expectations, mice lacking TRβ showed less liver fibrosis, and NASH marker genes were not elevated. Conversely, increasing TRβ expression in wild-type NASH mice using liver-targeted gene therapy did not improve histology, gene expression, or metabolic parameters, indicating that TRβ receptor levels are of minor relevance for NASH development and progression in our model, and suggest that liver-rather than isoform-specificity might be more relevant for NASH treatment with thyroid hormone receptor agonists.

Association between serum vitamin D levels and sensitivity to thyroid hormone indices: a cross-sectional observational study in NHANES 2007-2012.

We designed this study to determine whether there is a link between vitamin D levels and sensitivity to thyroid hormone and to provide a new perspective for studying the relationship between vitamin D and thyroid disease. Our study included 8,126 participators from the National Health and Nutrition Examination Survey (NHANES) database between 2007 and 2012. We used weighted multiple linear regression models to enquire the connection between serum vitamin D levels and thyroid hormone sensitivity indicators, including the following: Thyroid-stimulating hormone index (TSHI), Free Triiodothyronine/Free thyroxine (FT3/FT4), Thyroid Feedback Quantile-based Index (TFQI), and Thyrotroph Thyroxine Resistance Index (TT4RI). Finally, we used constrained cubic splines to explore possible nonlinear relationships. All data cleaning and statistical analyses were performed using R software. The final Results were reached after adjusting for various confounding factors. We found a U-shaped relationship between TFQI and serum vitamin D, and the lowest TFQI appeared when the serum vitamin D concentration was 25.77ng/ml. However, an inverse U-shaped relationship was found between FT3/FT4 and vitamin D levels. When the serum vitamin D concentration was 25.43ng/ml, the ratio of FT3/FT4 was the highest. In the US population, our study concluded that FTQI and FT3/FT4 were U-shaped or inverse-U-shaped with serum vitamin D levels respectively after several adjustments. Therefore, FTQI and FT3/FT4 are considered indicators of the complex relationship between thyroid hormone resistance and vitamin D metabolism. In the future, more complex prospective investigations are needed to confirm these findings and find a causal link between them.

A Historical Reflection on Scientific Advances in Understanding Thyroid Hormone Action.

Background: Thyroid hormone (TH) has actions in every tissue of the body and is essential for normal development, as well as having important actions in the adult. The earliest markers of TH action that were identified and monitored clinically, even before TH could be measured in serum, included oxygen consumption, basal metabolic rate, serum cholesterol, and deep tendon reflex time. Cellular, rodent, amphibian, zebrafish, and human models have been used to study TH action. Summary: Early studies of the mechanism of TH action focused on saturable-specific triiodothyronine (T3) nuclear binding and direct actions of T3 that altered protein expression. Additional effects of TH were recognized on mitochondria, stimulation of ion transport, especially the sodium potassium ATPase, augmentation of adrenergic signaling, role as a neurotransmitter, and direct plasma membrane effects. The cloning of the thyroid hormone receptor (THR) genes in 1986 and report of the THR crystal structure in 1995 produced rapid progress in understanding the mechanism of TH nuclear action, as well as the development of modified THR ligands. These findings revealed nuances of TH signaling, including the role of nuclear receptor coactivators and corepressors, repression of positively stimulated genes by the unliganded receptor, THR isoform-specific actions of TRα (THRA) and TRβ (THRB), and THR binding DNA as a heterodimer with retinoid-x-receptor (RXR) for genes positively regulated by TH. The identification of genetic disorders of TH transport and signaling, especially Resistance to Thyroid Hormone (RTH) and monocarboxylate transporter 8 (Mct8) defects, has been highly informative with respect to the mechanism of TH action. Conclusions: The impact of THR isoform, post-translational modifications, receptor cofactors, DNA response element, and selective TH tissue uptake, on TH action, have clinical implications for diagnosing and treating thyroid disease. Additionally, these findings have led to the development of novel TH and TH analogue therapies for metabolic, neurological, and cardiovascular diseases.