Serum thyrotrophin at baseline predicts the natural course of subclinical hyperthyroidism

Evaluating the progression to abnormal thyrotropin in euthyroid preconception women: a population-based study

BACKGROUND

Abnormal preconception thyrotropin levels were associated with fecundability and adverse fetomaternal outcomes, however, little is known regarding the natural change of serum thyrotropin in euthyroid preconception women. Thus, we performed a population-based study to evaluate the progression to abnormal thyrotropin in euthyroid preconception women.

METHODS

This retrospective cohort study used data from the National Free Prepregnancy Checkups Project (NFPCP) collected between 2010 and 2020. Female Han Chinese participants aged 20-49 years who had two repeated NFPCP participations with a time interval of 1.5-3.0 years, confirmed non-pregnant status within this duration, and normal thyrotropin levels during their first participation were included for the analysis of thyrotropin abnormalities during the second NFPCP examination. Data were analyzed between June 1 and October 1, 2023.

RESULTS

This study included 186,095 euthyroid women of reproductive age (mean ± SD, 26.72 ± 4.70 years) whose preconception thyrotropin levels were between 0.37 and 4.87 mIU/L. The median follow-up time was 2.13 (IQR, 1.85-2.54) years. A total of 8,497 (4.57%) women developed abnormal thyrotropin, including 4,118 (2.21%) subnormal thyrotropin and 4,379 (2.35%) supranormal thyrotropin. Compared with the reference group (thyrotropin 1.01-2.00 mIU/L), the lower baseline thyrotropin group had greater risk of developing subnormal thyrotropin, and the higher baseline thyrotropin group had greater risk of developing supranormal thyrotropin. Moreover, the restricted cubic spline analysis revealed a U-shaped dose-response association of baseline thyrotropin levels or thyrotropin multiples of the median (MOM) levels against risk of subnormal thyrotropin in the follow-up, and a J-shaped dose-response association against risk of supranormal thyrotropin levels in the follow-up. We further found that baseline thyrotropin outside of 1.43-1.93 mIU/L or baseline thyrotropin MOM outside 0.59-1.36 would hava a higher risk of developing of abnormal thyrotropin.

CONCLUSIONS

Both low and high baseline thyrotropin were associated with a significantly increased risk of developing abnormal thyrotropin outcomes. The optimal preconception baseline thyrotropin levels may be between 1.43 mIU/L and 1.93 mIU/L or baseline thyrotropin MoM between 0.59 and 1.36 to minimize progression toward abnormal thyrotropin after 1.5-3.0 years. These findings may help with counseling of preconception thyroid function monitoring.

A machine learning-assisted system to predict thyrotoxicosis using patients' heart rate monitoring data: a retrospective cohort study

Previous studies have shown a correlation between resting heart rate (HR) measured by wearable devices and serum free thyroxine concentration in patients with thyroid dysfunction. We have developed a machine learning (ML)-assisted system that uses HR data collected from wearable devices to predict the occurrence of thyrotoxicosis in patients. HR monitoring data were collected using a wearable device for a period of 4 months in 175 patients with thyroid dysfunction. During this period, 3 or 4 thyroid function tests (TFTs) were performed on each patient at intervals of at least one month. The HR data collected during the 10 days prior to each TFT were paired with the corresponding TFT results, resulting in a total of 662 pairs of data. Our ML-assisted system predicted thyrotoxicosis of a patient at a given time point based on HR data and their HR-TFT data pair at another time point. Our ML-assisted system divided the 662 cases into either thyrotoxicosis and non-thyrotoxicosis and the performance was calculated based on the TFT results. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of our system for predicting thyrotoxicosis were 86.14%, 85.92%, 52.41%, and 97.18%, respectively. When subclinical thyrotoxicosis was excluded from the analysis, the sensitivity, specificity, PPV, and NPV of our system for predicting thyrotoxicosis were 86.14%, 98.28%, 94.57%, and 95.32%, respectively. Our ML-assisted system used the change in mean, relative standard deviation, skewness, and kurtosis of HR while sleeping, and the Jensen-Shannon divergence of sleep HR and TFT distribution as major parameters for predicting thyrotoxicosis. Our ML-assisted system has demonstrated reasonably accurate predictions of thyrotoxicosis in patients with thyroid dysfunction, and the accuracy could be further improved by gathering more data. This predictive system has the potential to monitor the thyroid function status of patients with thyroid dysfunction by collecting heart rate data, and to determine the optimal timing for blood tests and treatment intervention.

Management of thyroid dysfunction and thyroid nodules in the ageing patient

Thyroid dysfunction is a common endocrine disorder in the general population, with a reported prevalence of 10-15%. However, this rate is even higher in older adults, with an estimated prevalence of ≈25% in some populations. Since elderly patients usually present more comorbidities than younger individuals, thyroid dysfunction may carry a synergistic negative health impact, mainly due to increased cardiovascular disease risk. Moreover, thyroid dysfunction in the elderly can be more difficult to diagnose due to its subtle or even asymptomatic clinical presentation, and the interpretation of thyroid function tests may be affected by drugs that interfere with thyroid function or by the coexistence of several diseases. On the other hand, thyroid nodules are also a prevalent condition in older adults, and its incidence increases with age. The assessment and management of thyroid nodules in the ageing patient should take into account several factors, as risk stratification, thyroid cancer biology, patient´s overall health, comorbidities, treatment preferences, and goals of care. In this review article, we summarize the current knowledge on the pathophysiology, diagnosis, and therapeutic management of thyroid dysfunction in elderly patients and we also review how to identify and manage thyroid nodules in this population.

The management and metabolic characterization: hyperthyroidism and hypothyroidism

Hyperthyroidism and hypothyroidism are common diseases resulting from thyroid dysfunction, and are simple to diagnose and treat. The traditional treatment for hypothyroidism is thyroid hormone replacement therapy. The traditional treatments for hyperthyroidism include antithyroid drug, iodine radiotherapy, and surgery. Thyroid disease can be fatal in severe cases if untreated. Current statistical reference ranges used for diagnosis based on relevant biochemical parameters have been debated, and insufficient treatment can result in long-term thyroid hormone deficiency, which is associated with increased risk of cardiovascular disease and persistent symptoms. In contrast, overtreatment can result in heart disease and osteoporosis, particularly in older people and pregnant women. Therefore, under- or over-treatment should be avoided and treatment regimens should be monitored closely. A significant proportion of patients who achieve biochemical treatment goals still complain of significant symptoms. Systematic literature review was performed through the Embase (Elsevier), PubMed and Web of Science databases, and studies summarized evidence regarding treatment and management of hypothyroidism and hyperthyroidism, and reviewed clinical practice guidelines. We also reviewed the latest research on the metabolic mechanisms of hyperthyroidism and hypothyroidism, which contributed to understanding of thyroid diseases in the clinic. A reliable algorithm is needed to management, assessment, and treatment patients with hyperthyroidism and hypothyroidism, which can not only improve management efficiency, but also providing a broad application. In addition, the thyroid disorder showed a lipid metabolism tissue specificity in the Ventromedial Hypothalamus, and effect oxidative stress and energy metabolism of whole body. This review summarizes an algorithm for thyroid disease and the latest pathogenesis that would be useful to generalist and subspecialty physicians and others providing care for patients with this condition.

Approach to the Patient With a Suppressed TSH

Subclinical hyperthyroidism (SCH) is a laboratory diagnosis defined by a serum thyrotropin (TSH) concentration below the reference range (< 0.4 mU/L in most assays), and a free thyroxine (FT4) and 3,5,3'-triiodothyronine levels (FT3) in the reference range. Many patients diagnosed with SCH will be clinically euthyroid while others may present with manifestations characteristic of thyroid hormone excess, such as tachycardia, tremor, intolerance to heat, bone density loss, or weight loss. In addition to the laboratory abnormalities, patient factors such as age, symptoms, and underlying heart and bone disease are used to stratify patients for the risk of adverse outcomes and determine the appropriate treatment. Evaluation should include repeat thyroid function tests to document persistent TSH suppression, investigation of the underlying cause, as well as evaluation of the patient's risk of adverse outcomes in the setting of a subnormal TSH. Persistent SCH has been associated with an increased risk of a range of adverse events, including cardiovascular events such as atrial fibrillation and heart failure, bone loss and fracture, and in some studies, cognitive decline. Despite the consistent association of these adverse events with SCH, prospective studies showing improved outcomes with treatment remain limited. Management options include observation without active therapy, radioactive iodine ablation of the thyroid, antithyroid medication, thyroid surgery, or radiofrequency ablation, as appropriate for the patient and clinical setting. The choice of therapy should be guided by the underlying etiology of disease, patient factors, and the risks and benefits of each treatment option.

Association Between Subclinical Thyroid Dysfunction and Fracture Risk

IMPORTANCE

Clinical hyperthyroidism accelerates bone resorption without compensatory bone formation, reducing bone density and increasing the risk of fracture. The association between subclinical hyperthyroidism and fracture risk is less clear.

OBJECTIVE

To investigate the association of endogenous subclinical thyroid dysfunction and fracture risk, independent of clinical confounders.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study included 10 946 participants from the Atherosclerosis Risk in Communities Study, an ongoing prospective cohort study of community-dwelling individuals conducted from 1987-1989 through December 31, 2019, in Washington County, Maryland; Forsyth County, North Carolina; Jackson, Mississippi; and the suburbs of Minneapolis, Minnesota. Participants were not taking thyroid medications and had no history of fractures.

EXPOSURES

Thyrotropin and free thyroxine levels were measured at visit 2 (1990-1992). Subclinical hyperthyroidism was defined as a thyrotropin level lower than 0.56 mIU/L, subclinical hypothyroidism as a thyrotropin level higher than 5.1 mIU/L, and euthyroidism as a thyrotropin level of 0.56 to 5.1 mIU/L, with normal free thyroxine levels from 0.85 to 1.4 ng/dL.

MAIN OUTCOMES AND MEASURES

Incident fracture was ascertained using hospitalization discharge codes through 2019 and linkage to inpatient and outpatient Medicare claims through 2018.

RESULTS

Of 10 946 participants (54.3% women; mean [SD] age, 57 [5.7] years), 93.0% had euthyroidism, 2.6% had subclinical hyperthyroidism, and 4.4% had subclinical hypothyroidism. During a median follow-up of 21 years (IQR, 13.0-27.3 years), there were 3556 incident fractures (167.1 per 10 000 person-years). The adjusted hazard ratios of fracture were 1.34 (95% CI, 1.09-1.65) for those with subclinical hyperthyroidism and 0.90 (95% CI, 0.77-1.05) for those with subclinical hypothyroidism compared with individuals with euthyroidism. Among those with normal free thyroxine levels, thyrotropin levels in the lower-than-normal range were significantly associated with higher fracture-related hospitalization risk; fracture risk was greater among individuals with thyrotropin concentrations below 0.56 mIU/L.

CONCLUSIONS AND RELEVANCE

This community-based cohort study suggests that subclinical hyperthyroidism was an independent risk factor associated with fracture. The increased risk for fracture among individuals with a thyrotropin level lower than 0.56 mIU/L highlights a potential role for more aggressive screening and monitoring of patients with subclinical hyperthyroidism to prevent bone mineral disease.

Decision Making in Subclinical Thyroid Disease

Subclinical thyroid disease is frequently encountered in clinic practice. Although overt thyroid dysfunction has been associated with adverse clinical outcomes, uncertainty remains about the implications of subclinical thyroid disease. Available data suggest that subclinical hypothyroidism may be associated with increased risk of cardiovascular disease and death. Despite this finding, treatment with thyroid hormone has not been consistently demonstrated to reduce cardiovascular risk. Subclinical hyperthyroidism has been associated with increased risk of atrial fibrillation and osteoporosis, but the association with cardiovascular disease and death is uncertain. The decision to treat depends on the degree of thyroid-stimulating hormone suppression and underlying comorbidities.

Changes in Serum Thyroid Function Predict Cognitive Decline in the Very Old: Longitudinal Findings from the Newcastle 85+ Study

Background: Low serum thyrotropin (TSH) has been associated with an increased risk of cognitive impairment in observational studies of older individuals, but the mechanism underlying this is unclear. We investigated the association between changes in thyroid status and cognitive impairment in very old adults, using prospective data from the Newcastle 85+ study. Method: A cohort of 85-year-old individuals was assessed for health status and thyroid function. Complete data from a comprehensive multidimensional measure of health and repeat thyroid function were available for 642 participants with normal free thyroid hormones and TSH levels ranging between 0.1 and 10 mU/L. Cognitive performance, assessed using Mini-Mental State Examination (MMSE) and Cognitive Drug Research battery was examined by using linear mixed, logistic regression, and Cox proportional hazard models in relation to baseline and 3-year changes in serum TSH, free thyroxine (fT4), and free triiodothyronine (fT3). Results: Over 3 years, declining serum TSH was associated with reductions in fT4 and fT3, and an increased risk of incident cognitive impairment by 5 years (odds ratio1.77 [95% confidence interval: 1.19-2.61]; p = 0.004). A greater reduction in MMSE score was associated with larger TSH decline, at 3 (p = 0.001) and 5 years (p < 0.001), respectively. Steady fT4 concentrations were found in participants with rising TSH. Conclusions: In contrast to physiological expectation, in this group of 85-year-olds, a declining serum TSH was associated with reductions in free thyroid hormones over time. A decreasing serum TSH trajectory over time anticipated cognitive decline in later life. Declining TSH concentrations are a biomarker for cognitive impairment in later life.

Current approach to surgical management of hyperthyroidism

Hyperthyroidism is a set of disorders that involve excess synthesis and secretion of thyroid hormones by the thyroid gland, which leads to thyrotoxicosis. The most common forms of hyperthyroidism include diffuse toxic goiter (Graves' disease), toxic multinodular goiter (Plummer disease), and a solitary toxic adenoma. The most reliable screening measure of thyroid function is the thyroid-stimulating hormone (TSH) level. Options for treatment of hyperthyroidism include: antithyroid drugs, radioactive iodine therapy (the preferred treatment of hyperthyroidism among US thyroid specialists), or thyroidectomy. Massive thyroid enlargement with compressive symptoms, a suspicious nodule, Graves' orbitopathy, and patient preference are indications for surgical treatment of thyrotoxicosis. This paper reviews the current literature and controversies on the surgical approach to the management of hyperthyroidism.

[The thyroid gland in old age : Physiology and pathology]

In healthy older people the metabolism of thyroid hormones is physiologically altered and can possibly even actively contribute to longevity. This should also be taken into consideration in the treatment of diseases of the thyroid and principally also for younger patients. For example, with progressing age comorbidities become more prevalent and especially in cardiovascular diseases, hyperthyroidism is less well tolerated, and should be treated more aggressively. Benign multinodular goiter also becomes more prevalent in old age and should be surgically treated when causing mechanical symptoms. The treatment concept for malignant diseases should be adapted to the holistic situation of the patient but principally in the same manner as in younger patients. Old and very old patients also benefit from adequate, risk-adapted treatment of thyroid gland diseases so that appropriate diagnostics and clarification are meaningful, regardless of age.

The association of thyroid stimulation hormone levels with incident ischemic heart disease, incident stroke, and all-cause mortality

PURPOSE

Thyroid dysfunction may affect the risk of cardiovascular disease and mortality through effects on myocardial and vascular tissue and metabolism. Levels of thyroid stimulating hormone (TSH) indicates thyroid function. We aimed to assess the association between TSH-levels and incident ischemic heart disease (IHD), incident stroke, and all-cause mortality.

METHODS

We included 13,865 participants (18-71 years, 51.6% women) from five cohort studies conducted during 1974-2008 were included. TSH was measured at the baseline examination and classified as <0.4; 0.4-2.5 (ref.); 2.5-5.0; 5.0-10, or >10 mU/l. Incident IHD, incident stroke, and all-cause mortality were identified in registries until ultimo 2013. Data were analysed by multivariate Cox regression with age as underlying time axis. Results from the individual cohorts were pooled by random-effects meta-analysis.

RESULTS

The crude incidence rate was for IHD 7.8 cases/1000 person years (PY); stroke 5.4 cases/1000 PY; and all-cause mortality 11.3 deaths/1000 PY (mean follow-up: 14 years). Analyses showed no statistically significant associations between TSH-levels and incident IHD or incident stroke in the partly or fully adjusted models. There was a statistically significant association between TSH of 2.5-5 mU/l and all-cause mortality (hazard ratio 1.145 (95% CI 1.004-1.306) compared with TSH of 0.4-2.5 mU/l in the fully adjusted model.

CONCLUSION

The results do not provide evidence of a harmful effect of decreased or increased TSH on IHD or stroke in the general population. However, there is some indication of an elevated risk for all-cause mortality with TSH 2.5-5 mU/l compared with 0.4-2.5 mU/l.

Alemtuzumab-induced thyroid events in multiple sclerosis: a systematic review and meta-analysis

PURPOSE

Autoimmune thyroid events (ATEs) are common side effects after alemtuzumab (ALZ) therapy in patients with multiple sclerosis (MS). Our purpose was to reach more robust evidence on prevalence and outcome of the spectrum of alemtuzumab-induced autoimmune thyroid events in patients with multiple sclerosis.

METHODS

PubMed and Scopus were systematically searched through July 2019. Studies dealing with patients without personal history of thyroid dysfunctions and affected by MS treated with ALZ and reporting ATEs were selected. Data on prevalence and outcome of ATEs were extracted. A proportion of meta-analysis with random-effects model was performed.

RESULTS

Considering the overall pooled number of 1362 MS patients treated with ALZ (seven included studies), a 33% prevalence of newly diagnosed ATEs was recorded. Among all ATEs, Graves' disease (GD) was the most represented [63% of cases, 95% confidence interval (CI) 52-74%], followed by Hashimoto thyroiditis (15%, 95% CI 10-22%). Interestingly, GD showed a fluctuating course in 15% of cases (95% CI 8-25%). Of all GD, 12% (95% CI 2-42%) likely had spontaneous remission, 56% (95% CI 34-76%) required only antithyroid drugs, 22% (95% CI 13-32%) needed additional RAI, and 11% (95% CI 0.9-29%) underwent definitive surgery.

CONCLUSION

Among different categories of ATEs, Graves' hyperthyroidism was the most common thyroid dysfunction, occurring in more than half of cases. Antithyroid drugs should represent the first-line treatment for ALZ-induced GD patients. However, alemtuzumab-induced GD could not be considered as having a more favourable outcome than conventional GD, given the substantial chance to encounter a fluctuating and unpredictable course.

Thyroid disease in the perimenopause and postmenopause period

The interpretation of thyroid function tests should be cautiously made during the perimenopause and postmenopause period bearing in mind that physiologic changes do exist in this group of women in terms of secretion and metabolism of thyrotropin and thyroid hormones. Moreover the incidence of thyroid disorders increases in postmenopausal and elderly women. There is no consensus for screening postmenopausal women even though there is well-known evidence about the effect of thyroid status on cognitive function, cardiovascular risk, bone turnover, and longevity. The diagnosis of any thyroid disorder is challenging in these patients because the symptoms are more subtle and attributed to menopausal symptoms. Management requires more attention in this population than that of younger groups, because high doses of L-thyroxine can lead to cardiac complications and increased bone turnover. Furthermore radio-iodine is preferred in treatment of hyperthyroidism in older patients. The risk of nodular thyroid disease and thyroid cancers increases in this group. Although the diagnostic approach is the same as for young patients, the risk of surgery is high and disease prognosis is worse. Women with any form of thyroid disease should be treated according to the current guidelines. Decision for menopausal hormonal therapy should be individualized regardless of the concomitant presence of thyroid disorders.

Global epidemiology of hyperthyroidism and hypothyroidism

Thyroid hormones are essential for growth, neuronal development, reproduction and regulation of energy metabolism. Hypothyroidism and hyperthyroidism are common conditions with potentially devastating health consequences that affect all populations worldwide. Iodine nutrition is a key determinant of thyroid disease risk; however, other factors, such as ageing, smoking status, genetic susceptibility, ethnicity, endocrine disruptors and the advent of novel therapeutics, including immune checkpoint inhibitors, also influence thyroid disease epidemiology. In the developed world, the prevalence of undiagnosed thyroid disease is likely falling owing to widespread thyroid function testing and relatively low thresholds for treatment initiation. However, continued vigilance against iodine deficiency remains essential in developed countries, particularly in Europe. In this report, we review the global incidence and prevalence of hyperthyroidism and hypothyroidism, highlighting geographical differences and the effect of environmental factors, such as iodine supplementation, on these data. We also highlight the pressing need for detailed epidemiological surveys of thyroid dysfunction and iodine status in developing countries.

Incidence of thyroid dysfunction in an Iranian adult population: the predictor role of thyroid autoantibodies: results from a prospective population-based cohort study

Background

The prevalence of thyroid dysfunction is high in Isfahan, an area of iodine sufficient in Iran. The aim of this study is to investigate the incidence of thyroid dysfunctions in adults of metropolitan Isfahan and to determine the role of thyroid autoantibodies.

Methods

In a population-based cohort study in 2006–2011, we measured TSH, T4, T3, thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TgAb) in 618 out of 2254 people who were euthyroid in 2006. The incidence rates per 1000 person-year (pr) were calculated. The odds ratio (OR), relative risk (RR), and 95% confidence interval (95% CI) were calculated based on logistic regression to quantify the potential predictors of thyroid dysfunction. The receiver-operator characteristic (ROC) analysis along with area under the curve (AUC) was used to determine the optimal cutoff values for baseline TPOAb and TgAb as predictors of thyroid dysfunction.

Results

Within a 6-year follow-up, the incidence rate of hypothyroidism was 3.3 in women and 2.1 in men while the incidence rate of hyperthyroidism was 3.8 in women and none in men per 1000 (person-year). A cutoff value of TPOAb at 38 IU/mL was obtained to differentiate the patients with hypothyroidism and hyperthyroidism, with specificity of 0.75 and sensitivity of 0.76, and AUC (CI 95%) of 0.882 (0.743–1.02), P = 0.01 and 0.817 (0.600–1.035) P = 0.033, respectively. There is a statistically significant association of hypothyroidism and hyperthyroidism with positive TPOAb [RR (CI 95%): 1.99 (1.27–3.13) and 2.20 (1.23–3.95), respectively].

Conclusions

The incidence rate of thyroid dysfunction is high in Isfahan, and higher TPOAb concentration is its strong predictor.

MANAGEMENT OF ENDOCRINE DISEASE: Subclinical thyrotoxicosis: prevalence, causes and choice of therapy

Subclinical thyrotoxicosis is a condition affecting up to 10% of the population in some studies. We have reviewed literature and identified studies describing prevalences, causes and outcomes of this condition. Treatment should be considered in all subjects if this biochemical abnormality is persistent, especially in case of symptoms of thyrotoxicosis or in the presence of any complication. In particular, treatment should be offered in those subclinically thyrotoxic patients with a sustained serum TSH below 0.1 U/L. However it is important to recognise that there are no large controlled intervention studies in the field and thus there is no high quality evidence to guide treatment recommendations. In particular, there is no evidence for therapy and there is weak evidence of harm from thyrotoxicosis if serum TSH is in the 0.1-0.4 IU/L range. In this review, we describe the different causes of subclinical thyrotoxicosis, and how treatment should be tailored to the specific cause. We advocate radioactive iodine treatment to be the first-line treatment in majority of patients suffering from subclinical thyrotoxicosis due to multinodular toxic goitre and solitary toxic adenoma, but we do generally not recommend it as the first-line treatment in patients suffering from subclinical Graves' hyperthyroidism. Such patients may benefit mostly from antithyroid drug therapy. Subclinical thyrotoxicosis in early pregnancy should in general be observed, not treated. Moreover, we advocate a general restriction of therapy in cases where no specific cause for the presumed thyroid hyperactivity has been proven.

2016 American Thyroid Association Guidelines for Diagnosis and Management of Hyperthyroidism and Other Causes of Thyrotoxicosis

BACKGROUND

Thyrotoxicosis has multiple etiologies, manifestations, and potential therapies. Appropriate treatment requires an accurate diagnosis and is influenced by coexisting medical conditions and patient preference. This document describes evidence-based clinical guidelines for the management of thyrotoxicosis that would be useful to generalist and subspecialty physicians and others providing care for patients with this condition.

METHODS

The American Thyroid Association (ATA) previously cosponsored guidelines for the management of thyrotoxicosis that were published in 2011. Considerable new literature has been published since then, and the ATA felt updated evidence-based guidelines were needed. The association assembled a task force of expert clinicians who authored this report. They examined relevant literature using a systematic PubMed search supplemented with additional published materials. An evidence-based medicine approach that incorporated the knowledge and experience of the panel was used to update the 2011 text and recommendations. The strength of the recommendations and the quality of evidence supporting them were rated according to the approach recommended by the Grading of Recommendations, Assessment, Development, and Evaluation Group.

RESULTS

Clinical topics addressed include the initial evaluation and management of thyrotoxicosis; management of Graves' hyperthyroidism using radioactive iodine, antithyroid drugs, or surgery; management of toxic multinodular goiter or toxic adenoma using radioactive iodine or surgery; Graves' disease in children, adolescents, or pregnant patients; subclinical hyperthyroidism; hyperthyroidism in patients with Graves' orbitopathy; and management of other miscellaneous causes of thyrotoxicosis. New paradigms since publication of the 2011 guidelines are presented for the evaluation of the etiology of thyrotoxicosis, the management of Graves' hyperthyroidism with antithyroid drugs, the management of pregnant hyperthyroid patients, and the preparation of patients for thyroid surgery. The sections on less common causes of thyrotoxicosis have been expanded.

CONCLUSIONS

One hundred twenty-four evidence-based recommendations were developed to aid in the care of patients with thyrotoxicosis and to share what the task force believes is current, rational, and optimal medical practice.

Thyroid function testing in an inpatient mental health unit

OBJECTIVE

Thyroid function tests are a common screening investigation for patients admitted to a psychiatric inpatient unit.

METHOD

This study aimed to retrospectively assess the clinical utility of routine thyroid function testing performed on newly admitted psychiatric patients over a 4-year period in Victoria, Australia via chart review of all abnormal results identified.

RESULTS

Our retrospective audit revealed only two cases where identification of thyroid dysfunction informed patient management. In each case, the patient had a known history of thyroid disease. In this audit period, 893 patients required screening to yield one clinically relevant abnormal result, costing AU$24,975.57.

CONCLUSION

Such low clinical utility does not support routine admission thyroid function tests for psychiatric inpatients. We conclude that thyroid function tests should only be performed where the history and clinical signs suggest a likely contribution of thyroid dysfunction to the psychiatric presentation.

The Natural History of Subclinical Hyperthyroidism in Graves' Disease: The Rule of Thirds

BACKGROUND

There is little information regarding the natural history of subclinical hyperthyroidism (SH) due to Graves' disease (GD).

METHODS

A prospective analysis was conducted of patients with SH due to GD between 2007 and 2013 with at least 12 months of follow-up. SH was diagnosed if serum thyrotropin (TSH) was below the laboratory reference range (0.4-4.0 mIU/L) and when thyroid hormones were normal. GD was confirmed by either a raised TSH receptor antibody (TRAb) level or uniform uptake on Technetium scan.

RESULTS

Forty-four patients (89% female, 16% current smokers, and 5% with active Graves' orbitopathy) were diagnosed with SH due to GD. Over the follow-up period (median 32 months), approximately one third (34%) of the cohort progressed to overt hyperthyroidism, one third (34%) normalized their thyroid function, slightly less than one third (30%) remained in the SH state, while one person became hypothyroid. Multivariate regression analysis showed that older age and positive antithyroid peroxidase (TPO) antibody status had a positive association with risk of progression to overt hyperthyroidism, with hazard ratios of 1.06 ([confidence interval (CI) 1.02-1.10], p < 0.01) per year and 10.15 ([CI 1.83-56.23], p < 0.01), respectively, independent of other risk factors including, smoking, TRAb levels at diagnosis, and sex.

CONCLUSIONS

A third each of patients with SH due to GD progress, normalize, or remain in the SH state. Older people and those with positive anti-TPO antibodies have a higher risk of progression of the disease. These novel data need to be verified and confirmed in larger cohorts and over longer periods of follow-up.

Does low-normal serum TSH level adversely impact cognition in elderly adults and might methimazole therapy improve outcomes?

Serum thyroid stimulating hormone (TSH) levels increase with age. This elevation has been associated with better outcomes in very elderly subjects; however, little is known about the relationship between TSH below the lower limit of the reference range and health-related outcomes. Here, we investigated the association between cognitive impairment or depressive symptoms and low-normal serum TSH (<1.0 μIU/mL, in the reference range) in elderly subjects and whether the use of methimazole in subjects without dementia but with low-normal TSH could affect cognition or depressive symptoms. From 293 healthy adults ≥65 years old with normal TSH included in the sectional phase, only subjects without dementia were prospectively analyzed: 1) TSH ≥1.0 μIU/mL (observation; untreated); 2) TSH <1.0 μIU/mL (observation; untreated); and 3) TSH <1.0 μIU/mL (methimazole therapy). Cognition was assessed, using the Mini Mental State Examination (MMSE) and depressive symptoms (at MMSE ≥ 13) by the Geriatric Depression Scale (GDS). Age >80 years was the sole independent factor associated with dementia (OR=2.89; confidence interval [CI] 1.72-4.86; p<0.01). Prospectively, 93 completed follow-up, with 7.5% (7) receiving methimazole intervention. Untreated subjects with lower TSH showed the greatest declines in MMSE scores during follow-up that was not observed in those with serum TSH ≥1.0 μIU/mL. Lower MMSE score reductions were associated with elderly subjects receiving methimazole. There were no significant changes in depressive symptoms and GDS scores among those with serum TSH <1.0 μIU/mL. In this study, low-normal TSH was not associated with higher prevalence of dementia. However, in elderly subjects without dementia, low TSH was associated with worsening cognition.

The 2015 European Thyroid Association Guidelines on Diagnosis and Treatment of Endogenous Subclinical Hyperthyroidism

Endogenous subclinical hyperthyroidism (SHyper) is caused by Graves' disease, autonomously functioning thyroid nodules and multinodular goitre. Its diagnosis is based on a persistently subnormal serum thyroid-stimulating hormone (TSH) level with free thyroid hormone levels within their respective reference intervals. In 2014 the European Thyroid Association Executive Committee, given the controversies regarding the treatment of Endo SHyper, formed a task force to develop clinical practice guidelines based on the principles of evidence-based medicine. The task force recognized that recent meta-analyses, including those based on large prospective cohort studies, indicate that SHyper is associated with increased risk of coronary heart disease mortality, incident atrial fibrillation, heart failure, fractures and excess mortality in patients with serum TSH levels <0.1 mIU/l (grade 2 SHyper). Therefore, despite the absence of randomized prospective trials, there is evidence that treatment is indicated in patients older than 65 years with grade 2 SHyper to potentially avoid these serious cardiovascular events, fractures and the risk of progression to overt hyperthyroidism. Treatment could be considered in patients older than 65 years with TSH levels 0.1-0.39 mIU/l (grade 1 SHyper) because of their increased risk of atrial fibrillation, and might also be reasonable in younger (<65 years) symptomatic patients with grade 2 SHyper because of the risk of progression, especially in the presence of symptoms and/or underlying risk factors or co-morbidity. Finally, the task force concluded that there are no data to support treating SHyper in younger asymptomatic patients with grade 1 SHyper. These patients should be followed without treatment due to the low risk of progression to overt hyperthyroidism and the weaker evidence for adverse health outcomes.

Subclinical thyroid dysfunction and the risk for fractures: a systematic review and meta-analysis

BACKGROUND

Data on the association between subclinical thyroid dysfunction and fractures conflict.

PURPOSE

To assess the risk for hip and nonspine fractures associated with subclinical thyroid dysfunction among prospective cohorts.

DATA SOURCES

Search of MEDLINE and EMBASE (1946 to 16 March 2014) and reference lists of retrieved articles without language restriction.

STUDY SELECTION

Two physicians screened and identified prospective cohorts that measured thyroid function and followed participants to assess fracture outcomes.

DATA EXTRACTION

One reviewer extracted data using a standardized protocol, and another verified data. Both reviewers independently assessed methodological quality of the studies.

DATA SYNTHESIS

The 7 population-based cohorts of heterogeneous quality included 50,245 participants with 1966 hip and 3281 nonspine fractures. In random-effects models that included the 5 higher-quality studies, the pooled adjusted hazard ratios (HRs) of participants with subclinical hyperthyroidism versus euthyrodism were 1.38 (95% CI, 0.92 to 2.07) for hip fractures and 1.20 (CI, 0.83 to 1.72) for nonspine fractures without statistical heterogeneity (P = 0.82 and 0.52, respectively; I2= 0%). Pooled estimates for the 7 cohorts were 1.26 (CI, 0.96 to 1.65) for hip fractures and 1.16 (CI, 0.95 to 1.42) for nonspine fractures. When thyroxine recipients were excluded, the HRs for participants with subclinical hyperthyroidism were 2.16 (CI, 0.87 to 5.37) for hip fractures and 1.43 (CI, 0.73 to 2.78) for nonspine fractures. For participants with subclinical hypothyroidism, HRs from higher-quality studies were 1.12 (CI, 0.83 to 1.51) for hip fractures and 1.04 (CI, 0.76 to 1.42) for nonspine fractures (P for heterogeneity = 0.69 and 0.88, respectively; I2 = 0%).

LIMITATIONS

Selective reporting cannot be excluded. Adjustment for potential common confounders varied and was not adequately done across all studies.

CONCLUSION

Subclinical hyperthyroidism might be associated with an increased risk for hip and nonspine fractures, but additional large, high-quality studies are needed.

PRIMARY FUNDING SOURCE

Swiss National Science Foundation.

Subclinical hyperthyroidism when presenting as initial manifestation of juvenile Hashimoto's thyroiditis: first report on its natural history

BACKGROUND

Due to the lack of specific pediatric studies, no data are available about natural history of endogenous subclinical hyperthyroidism (SH) in childhood.

AIMS

(a) To investigate for the first time the natural history of SH [suppressed thyrotropin (TSH) and normal free thyroxine free thyroxine (FT4) levels] when presenting as initial manifestation of Hashimoto's thyroiditis (HT) in childhood (group A); (b) to compare spontaneous evolution of HT-related SH with that observed in age-matched patients with HT-related frank hyperthyroidism (suppressed TSH and elevated FT4 levels), i.e., Hashitoxicosis Htx (group B).

RESULTS

In the 11 patients of group A, TSH normalization spontaneously occurred 1-24 months after diagnosis, while in the 10 patients of group B it occurred 3-9 months after diagnosis, with no differences between the 2 groups in terms of time interval from entry to TSH normalization. In group A, this time interval was related to baseline thyroid peroxidase antibodies (r=0.78, p = 0.04). During follow-up, eight patients of each group remained euthyroid, whereas two became hypothyroid (in both groups) and one developed Graves' disease (in group A).

CONCLUSION

(a) HT should be included among the causes of endogenous SH in pediatric age; (b) in children with HT-related SH, spontaneous normalization of TSH levels occurs within the first 24 months after diagnosis, as well as in age-matched patients with Htx; (c) in both these conditions, a further deterioration of thyroid function might re-present in some patients during follow-up; (d) Ht-related SH and Htx might be possibly seen as different biochemical stages along the same continuum.

The aging thyroid

PURPOSE OF REVIEW

As life expectancy increases and population age advances, diagnosis and treatment of diseases common in the geriatric population assume an increasingly important role in modern medicine. In the last few years, the emergence of age-specific reference ranges for thyroid-stimulating hormone (TSH) has added to the complexity of diagnosis of thyroid dysfunction in this age group, especially in the 'subclinical' category.

RECENT FINDINGS

The recent studies confirm an increase in population TSH distribution with age, both in cross-sectional and longitudinal studies. Conclusive evidence about adverse cardiovascular, metabolic, and cognitive consequences of subclinical hypothyroidism in the elderly remains elusive. The transient nature of subtle degrees of thyroid dysfunction in a significant proportion of elderly patients has also been reproduced in the recent publications.

SUMMARY

A growing body of literature in the last few years, reviewed here, highlights the importance of employing additional caution before assigning diagnoses of hypothyroidism or hyperthyroidism to elderly patients and initiation of treatment modalities that can have long-lasting effects.

A prospective study of thyroid function, bone loss, and fractures in older men: The MrOS study

Excess thyroid hormone is associated with increased bone loss and fracture risk in older women, but few data exist for men. We sought to determine if thyroid function is independently associated with bone loss and fracture risk in older men. Data were analyzed from the Osteoporotic Fractures in Men (MrOS) study, a cohort of community-dwelling U.S. men aged 65 years and older. Using a case-cohort design, fasting baseline serum archived at -80°C was assayed for thyroid-stimulating hormone (thyrotropin) (TSH) and free thyroxine (FT4) in 397 men with confirmed nonspine fracture, including 157 hip fractures, and 1420 randomly selected men without fracture. TSH and FT4 were analyzed as continuous variables and as thyroid function categories (subclinical hyperthyroid, euthyroid, and subclinical hypothyroid). Hip dual-energy X-ray absorptiometry (DXA) (Hologic QDR4500) was measured at baseline and after a mean follow-up of 4.6 years. Incident nonspine fractures were centrally adjudicated. Bone loss was evaluated with multivariate regression methods and fractures risk was evaluated using hazard models that accounted for the case-cohort sampling, adjusted for age, clinic-site, body mass index (BMI), race, physical activity, corticosteroid use, smoking, alcohol intake, and thyroid medication use. In fully adjusted analyses, TSH was not associated with risk of nonspine fracture (relative hazard [RH] 0.92 per SD decrease in TSH; 95% confidence interval [CI], 0.74-1.14), but was significantly associated with risk of hip fracture (RH 1.31; 95% CI, 1.01-1.71), which persisted among normal range TSH values (RH 1.21; 95% CI, 1.00-1.47). There was no association between TSH or FT4 and bone loss, and fracture risk did not differ significantly by thyroid function category. We conclude that although neither TSH nor FT4 are associated with bone loss, lower serum TSH may be associated with an increased risk of hip fractures in older men.