The association between TSH and thyroid hormones in the normal or subclinical dysfunction range with left ventricular diastolic dysfunction.

Thyroid hormones modulate the cardiovascular system. However, the effects of subclinical thyroid dysfunction and euthyroidism on cardiac function remain unclear. We investigated the association between left ventricular (LV) diastolic dysfunction and subclinical thyroid dysfunction or thyroid hormones within the reference range. This cross-sectional study included 26,289 participants (22,197 euthyroid, 3,671 with subclinical hypothyroidism, and 421 with subclinical thyrotoxicosis) who underwent regular health check-ups in the Republic of Korea. Individuals with thyroid stimulating hormone (TSH) levels > 4.2 µIU/mL and normal free thyroxine (FT4, 0.78-1.85 ng/dL) and triiodothyronine (T3, 76-190 ng/dL) levels were defined as having subclinical hypothyroidism. Individuals with serum TSH levels < 0.4 µIU/mL and normal FT4 and T3 levels were defined as having subclinical thyrotoxicosis. The cardiac structure and function were evaluated using echocardiography. LV diastolic dysfunction with normal ejection fraction (EF) was defined as follows: EF of > 50% and (a) E/e' ratio > 15, or (b) E/e' ratio of 8-15 and left atrial volume index ≥ 34 mL/m2. Subclinical hypothyroidism was significantly associated with cardiac indices regarding LV diastolic dysfunction. The odds of having LV diastolic dysfunction was also increased in participants with subclinical hypothyroidism (adjusted odds ratio [AOR] 1.36, 95% confidence interval [CI], 1.01-1.89) compared to euthyroid participants. Subclinical thyrotoxicosis was not associated with LV diastolic dysfunction. Among the thyroid hormones, only serum T3 was significantly and inversely associated with LV diastolic dysfunction even within the normal range. Subclinical hypothyroidism was significantly associated with LV diastolic dysfunction, whereas subclinical thyrotoxicosis was not. Serum T3 is a relatively important contributor to LV diastolic dysfunction compared to TSH or FT4.

Fighting thyrotoxicosis with therapeutic plasma exchange: A case report.

Thyrotoxicosis is the clinical condition resulting from an excess of thyroid hormones for any reason. The main causes are Graves-Basedow disease, toxic multinodular goitre and toxic adenoma. The medical treatment to control thyroid function includes antithyroid drugs, beta blockers, iodine solutions, corticosteroids and cholestyramine. Although therapeutic plasma exchange is not generally part of the therapy, it is an alternative as a preliminary stage before the definitive treatment. This procedure makes it possible to eliminate T4, T3, TSI, cytokines and amiodarone. In most cases, more than one cycle is necessary, either daily or every three days, until clinical improvement is observed. The effect on thyrotoxicosis is temporary, with an approximate duration of 24-48h. This approach has been proposed as a safe and effective alternative when the medical treatment is contraindicated or not effective, and when there is multiple organ failure or emergency surgery is required.

[The association between baseline TPOAb and/or TgAb positivity and thyroid immune-related adverse events in patients with malignancies following treatment with immune checkpoint inhibitors].

Objective: To investigate the association between positive anti-thyroid peroxidase antibody (TPOAb) and/or anti-thyroglobulin antibody (TgAb) and the occurrence of thyroid immune-related adverse events (irAEs) in patients with malignant tumors who treated with immune checkpoint inhibitors (ICIs). Methods: A case-control study. A total of 116 patients with malignant tumor who received ICIs treatment and underwent thyroid function evaluation at Peking Union Medical College Hospital from January 2017 to April 2023 were enrolled retrospectively, including 77 males and 39 females, with a median age of (M(Q1, Q3)) 63.0 (55.0, 70.0) years. The patients were divided into the euthyroid group (n=58) and the thyroid irAEs group (n=58) according to whether thyroid irAEs occurred after ICIs treatment. The clinical characteristics and baseline anti-thyroid antibodies associated with the occurrence of thyroid irAEs after ICIs treatment in patients with malignant tumors were evaluated. Variables with statistical significance in univariate analysis were included in multivariate logistic regression model to analyze the risk factors for thyroid irAEs in patients with malignant tumors who received ICIs treatment. Results: In irAEs group, therewore 4 (3.4%) cases of clinical thyrotoxicosis, 23(19.8%) cases of subclinical thyrotoxicosis, 23 (19.8%) cases of clinical hypothyroidism, and 8(6.9%) cases of subclinical hypothyroidism. The positive rate of anti-thyroid antibodies at baseline in the thyrioid irAEs group was higher than that in the euthyroid group［16/58（27.6%）vs 3/58（5.2%），P=0.001］. After at least one course of ICIs treatment, the incidence of thyroid irAEs in patients with positive anti-thyroid antibodies at baseline was 84.2% (16/19), whereas it was 43.3% (42/97) in patients with negative anti-thyroid antibodies(P=0.001). Univariate logistic regression analysis showed that gender (OR=2.812, 95%CI:1.257-6.293), baseline thyroid autoantibodies were positive (OR=6.984, 95%CI: 1.909-25.547), baseline TgAb positivity (OR=8.909, 95%CI: 1.923-41.280), and baseline TPOAb positivity (OR=7.304, 95%CI: 1.555-34.308) were associated with thyroid irAEs (all P<0.05). Multivariate logistic regression analysis indicated that baseline TgAb positivity (OR=7.637, 95%CI: 1.617-36.072) was a risk factor for thyroid irAEs (P=0.01). Conclusions: The incidence of thyroid irAEs is higher in patients who are positive for baseline TPOAb and/or TgAb compared to those who are negative for TPOAb and TgAb. Patients with positive TgAb at baseline are at high risk of developing thyroid irAEs.

Evaluation of the safety profile of the quadrivalent vaccine against human papillomavirus in the risk of developing autoimmune, neurological, and hematological diseases in adolescent women in Colombia.

BACKGROUND: Cervical cancer eradication is one of the main goals for 2030 by the World Health Organization, which can only be achieved with high vaccination rates against Human Papilloma Virus. In Colombia, more and better scientific evidence is required to increase confidence in vaccination. The objective of this study is to evaluate the safety profile of the quadrivalent vaccine against HPV in the risk of developing autoimmune, neurological, and hematological diseases in adolescent women in Colombia. METHODS: We designed a cohort study based on national HPV vaccination records and incident diagnostic data for the diseases of special interest during 2012 and 2021. We included adolescent women between 9 and 19 years old and compared vaccinated and non-vaccinated cohorts using an Inverse Probability of Treatment Weighting (IPWT) method for each scenario disease and follow-up period (180 and 360 days). FINDINGS: The Odds Ratio (OR) of developing diseases of interest was estimated during two follow up periods, 180 and 360 days after the follow-up index date (Vaccination Day). The OR for developing rheumatoid arthritis was 4·4; CI95% (1·74 - 11·14), juvenile idiopathic arthritis was 2·76 IC95% (1·50 - 5·11), idiopathic thrombocytopenic purpura was 2·54 IC95% (1·28 - 5·02) and thyrotoxicosis was 2·86 IC95% (1·03 - 7·95), when comparing the vaccinated versus unvaccinated population. However, the temporal distribution of cases incident did not reveal a clear difference between the cohorts, since the rate of appearance of new cases has a constant linear behavior for the two groups. INTERPRETATION: For rheumatoid arthritis, juvenile idiopathic arthritis, idiopathic thrombocytopenic purpura, and thyrotoxicosis; the application of the vaccine had an effect on the development of the disease. Nevertheless, our results should be interpreted with caution and be further studied, considering that the biological plausibility of the events occurred without a clear temporal pattern in relation to the exposure to the vaccine.

Using Bedside Spectral Doppler Ultrasound for the Assessment of Patients With Thyrotoxicosis.

OBJECTIVE: To assess the bedside utility of Spectral Doppler Ultrasound (SDUS) in the initial evaluation of patients presenting with thyrotoxicosis. METHODS: This is a retrospective cross-sectional study of patients diagnosed with thyrotoxicosis at an academic outpatient endocrinology clinic from August 2019 to November 2022. The thyroid arteries' peak systolic velocities (PSV) were measured bilaterally using SDUS. PSV ≥40 cm/s in at least a single thyroid artery was considered a reasonable cut-off for Graves' disease and PSV of perinodular artery ≥ 25 cm/s for toxic adenoma. RESULTS: We identified 73 patients. Mean age ± standard deviation 45.2 ± 16.4 years, 54 (74.0%) were female, 49 (67.1%) were Caucasian, 23 (31.5%) were African American, and 1 (1.4%) was Asian. The confirmed diagnoses were 48 (65.8%) Graves' disease, 13 (17.8%) thyroiditis, four (5.5%) toxic adenoma, four (5.5%) amiodarone-induced thyroiditis type 2, 1 (1.4%) toxic multinodular goiter, 1 (1.4%) had an unremarkable repeat thyroid function testing, and two (2.7%) were unconfirmed. Diagnosis based on the SDUS initial assessment was accurate in 65 (89.0%) of the patients, and it was conclusive and confirmatory during the initial encounter in 55 (75.3%) of the patients before additional testing. A thyroid scan was obtained in nine (12.3%) patients. Incorrectly diagnosed patients were observed in two patients of each of the following categories: Graves' disease, thyroiditis, toxic adenoma, and unconfirmed diagnoses. CONCLUSIONS: SDUS can be a valuable, efficient, and cost-effective bedside tool in the initial assessment of patients presenting with thyrotoxicosis.

Paraneoplastic Hyperthyroidism Secondary to a Chemotherapy-Induced Surge in ß-hCG in a Patient with Non-Seminomatous Germ Cell Tumor.

Thyrotoxicosis as the presenting syndrome of an underlying ß-hCG-secreting malignancy is well described. It has been previously theorized, but not reported, that the surge of ß-hCG secondary to chemotherapy induction may inadvertently trigger thyrotoxicosis. After thorough review, this is the first documented case of such event in peer-reviewed medical literature published in the English language. This is a case of a 21-year-old male with stage IIIc non-seminomatous germ cell tumor who developed paraneoplastic hyperthyroidism within 4 days of the first cycle of chemotherapy. Management considerations are suggested based on this case and review of the literature.

Retracting the thyroid matters: Who develops asymptomatic transient thyrotoxicosis after parathyroidectomy.

BACKGROUND: Hyperthyroidism after parathyroidectomy is not a well-understood complication. We sought to determine the incidence and risk factors of hyperthyroidism after parathyroidectomy. MATERIALS AND METHODS: This is a prospective study of 91 patients undergoing parathyroidectomy. Pre- and post-operative thyroid-stimulating hormone(TSH) and free thyroxine(T4) levels at two-week follow-ups were collected. Bivariate analyses were conducted to compare demographics, laboratory results, and intraoperative findings between patients with normal and suppressed post-parathyroidectomy TSH. RESULTS: Twenty-two(24.2 â€‹%) patients had suppressed TSH after parathyroidectomy and 2(2.2 â€‹%) reported symptoms of hyperthyroidism. All hyperthyroidism resolved within 6 weeks. No patients required medical treatment. Compared to the normal TSH group, the suppressed TSH group had significantly more bilateral explorations(91.0 â€‹% vs. 58.0 â€‹%, p â€‹= â€‹0.006), and superior parathyroid resections(95.5 â€‹% vs. 65.2 â€‹%, p â€‹= â€‹0.006). CONCLUSION: Transient hyperthyroidism is common following parathyroidectomy, which is likely associated with intraoperative thyroid manipulation. Gentle retraction of thyroid glands in parathyroidectomy is warranted, especially during superior parathyroid gland resection.

Amiodarone-induced thyrotoxicosis: Should surgery be considered?

Amiodarone is the most widely prescribed antiarrhythmic drug worldwide, but induces thyrotoxicosis or hypothyroidism in 15 to 20% of patients. Hyperthyroidism is less frequent than hypothyroidism, and two types of thyrotoxicosis are distinguished according to presence of underlying thyroid disease. Diagnosis is made in case of low TSH and high levels of T3 and T4. Initial treatment is based on anti-thyroid drugs and/or glucocorticoids. Some patients do not respond to medication, which increases the time spent with hyperthyroidism. A long interval between diagnosis and euthyroidism and low left ventricular ejection fraction (LVEF) are predictive of major adverse cardiovascular events. Here, after describing the current state of knowledge of amiodarone-induced thyrotoxicosis, we analyze the literature on the impact of surgery. We suggest that early surgery should be the first option in case of ineffective medical treatment or LVEF<40%. In expert centers, surgical morbidity is no longer different than in other indications for thyroidectomy.

Comparison of pathophysiology in subclinical hyperthyroidism with different etiologies.

Subclinical hyperthyroidism (SHyper) is defined as normal levels of free thyroxine (fT4) and free triiodothyronine (fT3) with suppressed levels of TSH. Previous studies have reported the individual pathophysiology of endogenous SHyper patients and athyreotic patients receiving TSH suppression therapy with levothyroxine; however, apparently no studies have compared the two conditions. Five-hundred-forty untreated endogenous SHyper patients and 1,024 patients receiving TSH suppression therapy who underwent total thyroidectomy for papillary thyroid carcinoma were sampled. Thyroid hormone profiles and peripheral indices related to thyrotoxicosis were investigated in endogenous SHyper patients, athyreotic patients receiving TSH suppression therapy, and healthy participants. Endogenous SHyper patients showed significantly higher thyroid hormone levels (fT4 [p < 0.001] and fT3 [p < 0.001]), and peripheral indices showed a significant tendency towards thyrotoxicosis (strong TSH suppression: alkaline phosphatase [ALP, p < 0.001], creatinine [Cre, p < 0.001], pulse rate [p < 0.05]; and mild TSH suppression: Cre [p < 0.05]) than healthy participants. In contrast, athyreotic patients receiving TSH suppression therapy showed a significant tendency towards thyrotoxicosis than healthy participants only when TSH was strongly suppressed (fT3 [p < 0.001] and Cre [p < 0.001]). Endogenous SHyper patients showed significantly higher fT3 levels (p < 0.001) than athyreotic patients receiving TSH suppression therapy; however, there was a significant tendency towards thyrotoxicosis only when TSH was strongly suppressed (ALP [p < 0.05] and pulse rate [p < 0.05]). The effects of endogenous SHyper and TSH suppression therapy on target organ function are different. Although the serum thyroid hormone profile is similar to that of the thyrotoxic state, athyreotic patients receiving TSH suppression therapy with mildly suppressed serum TSH levels are not thyrotoxic.

Exploring synthesis as a vital cognitive skill in complex clinical diagnosis.

Clinicians employ two main cognitive approaches for diagnoses, depending on their expertise. Novices typically use linear hypothetico-deductive methods, while experts rely more on intuitive pattern recognition. These closely correspond to System 1 and System 2 thinking described in behavioral economics. We propose that complex cases additionally require the cognitive skill of synthesis, to visualize and understand the connections between various elements. To illustrate the concept, we describe a 60-year-old individual with a 6 h history of chest pain, fever, cough, accompanying chronic heart failure, atrial fibrillation, COPD, thyrotoxicosis, and ischemic heart disease. Faced with such a scenario, a bedside approach adapted by clinicians is to generate a list of individual diagnoses or pathways of pathogenesis, and address them individually. For example, this cluster could include: smoking causing COPD, IHD leading to chest pain and heart failure, and thyrotoxicosis causing atrial fibrillation (AF). However, other interconnections across pathways could be considered: smoking contributing to IHD; COPD exacerbating heart failure; IHD and pneumonia triggering atrial fibrillation; thyrotoxicosis and AF, independently worsening heart failure; COPD causing hypoxemia and worsening ventricular function. The second cluster of explanation offers a richer network of relationships and connections across disorders and pathways of pathogenesis. This cognitive process of creatively identifying these relationships is synthesis, described in Bloom's taxonomy of the cognitive domain. It is a crucial skill required for visualizing a comprehensive and holistic view of a patient. The concept of synthesis as a cognitive skill in clinical reasoning warrants further exploration.

Hyperthyroidism.

Thyrotoxicosis causes a variety of symptoms and adverse health outcomes. Hyperthyroidism refers to increased thyroid hormone synthesis and secretion, most commonly from Graves' disease or toxic nodular goitre, whereas thyroiditis (typically autoimmune, viral, or drug induced) causes thyrotoxicosis without hyperthyroidism. The diagnosis is based on suppressed serum concentrations of thyroid-stimulating hormone (TSH), accompanied by free thyroxine and total or free tri-iodothyronine concentrations, which are raised (overt hyperthyroidism) or within range (subclinical hyperthyroidism). The underlying cause is determined by clinical assessment, detection of TSH-receptor antibodies and, if necessary, radionuclide thyroid scintigraphy. Treatment options for hyperthyroidism include antithyroid drugs, radioactive iodine, and thyroidectomy, whereas thyroiditis is managed symptomatically or with glucocorticoid therapy. In Graves' disease, first-line treatment is a 12-18-month course of antithyroid drugs, whereas for goitre, radioactive iodine or surgery are preferred for toxic nodules or goitres. Evidence also supports long-term treatment with antithyroid drugs as an option for patients with Graves' disease and toxic nodular goitre.

Thyroid abscess associated with thyrotoxicosis caused by Yersinia enterocolitica subsp. palearctica in a patient with follicular adenoma of the thyroid gland.

BACKGROUND: Yersinia enterocolitica is a gram-negative zoonotic bacterial pathogen that is typically transmitted via the fecal-oral route. The most common clinical manifestation of a Y. enterocolitica infection is self-limited gastroenteritis. Although various extraintestinal manifestations of Y. enterocolitica infection have been reported, there are no reports of thyroid abscesses. CASE PRESENTATION: An 89-year-old Japanese man with follicular adenoma of the left thyroid gland was admitted to our hospital with a 2-day history of fever and left neck pain. Laboratory tests revealed low levels of thyroid stimulating hormone and elevated levels of free thyroxine 4. Contrast-enhanced computed tomography showed low-attenuation areas with peripheral enhancement in the left thyroid gland. He was diagnosed with thyroid abscess and thyrotoxicosis, and treatment with intravenous piperacillin-tazobactam was initiated after collecting blood, drainage fluid, and stool samples. The isolated Gram-negative rod bacteria from blood and drainage fluid cultures was confirmed to be Y. enterocolitica. He was diagnosed with thyroid abscess and thyrotoxicosis due to be Y. enterocolitica subsp. palearctica. The piperacillin-tazobactam was replaced with levofloxacin. CONCLUSION: We report a novel case of a thyroid abscess associated with thyrotoxicosis caused by Y. enterocolitica subsp. palearctica in a patient with a follicular thyroid adenoma.

In Vivo Evaluation of the Pharmacokinetic Interaction between Levothyroxine and Amiodarone in Rat Plasma: Evaluation of Importance of Therapeutic Drug Monitoring during Co-Therapy.

Amiodarone-induced thyrotoxicosis (AIT) is a common condition in patients who are receiving amiodarone for cardiac arrhythmia. This risk is elevated in iodine-deficient regions. Levothyroxine is the standard treatment for patients with hypothyroidism. This investigation is concerned with the evaluation of the possible pharmacokinetic interaction between amiodarone and levothyroxine upon co-therapy in rats and to investigate the cause of thyrotoxicosis. A selective, sensitive and precise RP-HPLC method was developed for the simultaneous determination of levothyroxine and amiodarone in rat plasma. A stationary phase of C18 Xterra RP column and a mobile phase consisting of acetonitrile: acidified water with 0.1% trifluoracetic acid (pH = 4.8) with gradient elution were used. The experiment was conducted at ambient temperature with flow rate of 1.5 mL/min for the chromatographic separation and quantitation of the investigated drugs. Protein precipitation with methanol was applied for the analysis of the two drugs in rat plasma. The method was linear over concentration range of 5-200 µg/mL for both levothyroxine and amiodarone. The European Medicines Agency guideline was applied for the validation of the developed bioanalytical method. The method was successfully applied to in vivo pharmacokinetic study in which levothyroxine and amiodarone were quantified in plasma of rats after receiving an oral dose of levothyroxine and amiodarone. After the calculation of the pharmacokinetic parameters, a statistical analysis was performed to elucidate the existence of significant difference between test and control groups in rats. The combination of levothyroxine and amiodarone significantly decreased levothyroxine bioavailability in rats, making the therapeutic drug monitoring mandatory in patients receiving levothyroxine and amiodarone. In addition, the increased clearance of levothyroxine upon the co-administration with amiodarone may explain the reported hypothyroidism.

Incidence of Endocrine-Related Dysfunction in Patients Treated with New Immune Checkpoint Inhibitors: A Meta-Analysis and Comprehensive Review.

BACKGRUOUND: This study investigated the incidence of endocrine immune-related adverse events (irAEs) for recently developed immune checkpoint inhibitor (ICI) drugs. METHODS: We collected studies on newly developed ICI drugs using PubMed/Medline, Embase, and Cochrane Library from inception through January 31, 2023. Among ICI drugs, nivolumab, pembrolizumab, and ipilimumab were excluded from the new ICI drugs because many papers on endocrine-related side effects have already been published. RESULTS: A total of 44,595 patients from 177 studies were included in this analysis. The incidence of hypothyroidism was 10.1% (95% confidence interval [CI], 8.9% to 11.4%), thyrotoxicosis was 4.6% (95% CI, 3.8% to 5.7%), hypophysitis was 0.8% (95% CI, 0.5% to 1.1%), adrenal insufficiency was 0.9% (95% CI, 0.7% to 1.1%), and hyperglycemia was 2.3% (95% CI, 1.6% to 3.4%). Hypothyroidism and thyrotoxicosis occurred most frequently with programmed cell death protein-1 (PD-1) inhibitors (13.7% and 7.5%, respectively). The rate of endocrine side effects for the combination of a programmed death-ligand 1 inhibitor (durvalumab) and cytotoxic T lymphocyte-associated antigen 4 inhibitor (tremelimumab) was higher than that of monotherapy. In a meta-analysis, the combination of tremelimumab and durvalumab had a 9- to 10-fold higher risk of pituitary and adrenal-related side effects than durvalumab alone. CONCLUSION: Newly developed PD-1 inhibitors had a high incidence of thyroid-related irAEs, and combined treatment with durvalumab and tremelimumab increased the risk of pituitary- and adrenal-related irAEs. Based on these facts, it is necessary to predict the endocrine side effects corresponding to each ICI drug, diagnose and treat them appropriately, and try to reduce the morbidity and mortality of patients.

Psychosis secondary to thyrotoxicosis that persisted post-thyroidectomy: a case report.

BACKGROUND: This case report is of a patient with psychosis secondary to thyrotoxicosis that persisted and reemerged after definitive treatment of thyroidectomy, which is a unique occurrence in the literature. CASE PRESENTATION: This patient is a male between 30 and 35 years of age with a history of Graves Disease and no past psychiatric history who was admitted to the hospital due to psychosis secondary to thyrotoxicosis. The thyrotoxicosis was treated with surgical removal, but the psychotic symptoms persisted after surgery and normalization of standard thyroid functional measures. The symptoms were of sufficient significance for inpatient psychiatric hospitalization, a rare occurrence. Ultimately after an extended stay in the psychiatric unit, the patient's symptoms stabilized with a second-generation antipsychotic, and the patient was discharged from the psychiatric unit. CONCLUSION: This case is evidence that the link between psychosis and hyperthyroidism is still poorly understood due to the patient's psychotic symptoms persisting after the definitive treatment of thyroidectomy and the fact that it required anti-psychotic medications for normalization.

Thyrotoxicosis as a rare presentation in acute suppurative thyroiditis: a case report.

BACKGROUND: Acute suppurative thyroiditis is a rare and potentially life-threatening disease. A few cases of acute suppurative thyroiditis associated with thyrotoxicosis have been reported in adults. We report a case of acute suppurative thyroiditis that was associated with thyrotoxicosis. CASE PRESENTATION: We report the case of a 49-year-old Iranian female presented with a painful neck swelling for a week. Computed tomography showed a well-defined gas-filled collection in the left thyroid lobe with an enhancing margin. The patient underwent two-phase surgery, first left thyroid abscess drainage and then total thyroidectomy. The result of histopathology examination was multinodular goiter with abscess formation without malignancy. CONCLUSION: Abscess formation and thyrotoxicosis is a very rare condition that occurs at the same time in acute suppurative thyroiditis. Despite antibiotic therapy being the first line of treatment, surgery is also required when antibiotic therapy fails.

Hyperthyroidism: A Review.

Importance: Overt hyperthyroidism, defined as suppressed thyrotropin (previously thyroid-stimulating hormone) and high concentration of triiodothyronine (T3) and/or free thyroxine (FT4), affects approximately 0.2% to 1.4% of people worldwide. Subclinical hyperthyroidism, defined as low concentrations of thyrotropin and normal concentrations of T3 and FT4, affects approximately 0.7% to 1.4% of people worldwide. Untreated hyperthyroidism can cause cardiac arrhythmias, heart failure, osteoporosis, and adverse pregnancy outcomes. It may lead to unintentional weight loss and is associated with increased mortality. Observations: The most common cause of hyperthyroidism is Graves disease, with a global prevalence of 2% in women and 0.5% in men. Other causes of hyperthyroidism and thyrotoxicosis include toxic nodules and the thyrotoxic phase of thyroiditis. Common symptoms of thyrotoxicosis include anxiety, insomnia, palpitations, unintentional weight loss, diarrhea, and heat intolerance. Patients with Graves disease may have a diffusely enlarged thyroid gland, stare, or exophthalmos on examination. Patients with toxic nodules (ie, in which thyroid nodules develop autonomous function) may have symptoms from local compression of structures in the neck by the thyroid gland, such as dysphagia, orthopnea, or voice changes. Etiology can typically be established based on clinical presentation, thyroid function tests, and thyrotropin-receptor antibody status. Thyroid scintigraphy is recommended if thyroid nodules are present or the etiology is unclear. Thyrotoxicosis from thyroiditis may be observed if symptomatic or treated with supportive care. Treatment options for overt hyperthyroidism from autonomous thyroid nodules or Graves disease include antithyroid drugs, radioactive iodine ablation, and surgery. Treatment for subclinical hyperthyroidism is recommended for patients at highest risk of osteoporosis and cardiovascular disease, such as those older than 65 years or with persistent serum thyrotropin level less than 0.1 mIU/L. Conclusions and Relevance: Hyperthyroidism affects 2.5% of adults worldwide and is associated with osteoporosis, heart disease, and increased mortality. First-line treatments are antithyroid drugs, thyroid surgery, and radioactive iodine treatment. Treatment choices should be individualized and patient centered.