2013 ETA Guideline: Management of Subclinical Hypothyroidism

Clinical aspects of thyroid function during ageing

Globally, populations are ageing at a rapid rate. The increase in the number of older citizens is accompanied by an increased prevalence of thyroid dysfunction, one of the most common disorders in older people. However, the diagnosis of thyroid dysfunction in older people is hindered by several factors, including the scarcity of thyroid dysfunction symptoms in older people. We describe the physiological changes in thyroid function that occur with increasing age, focusing on literature regarding changes in thyroid function test results in older populations. We also discuss treatment considerations for clinical and subclinical thyroid dysfunction according to international guidelines for older people. Finally, we discuss the relationship between variations in thyroid function and common diseases of old age including cardiovascular disease, osteoporosis, cognitive impairment, and frailty and suggest directions for future research.

Relation of Subclinical Hypothyroidism is Associated With Cardiovascular Events and All-Cause Mortality in Adults With High Cardiovascular Risk

The aim of this study was to determine the association between subclinical hypothyroidism and cardiovascular (CVD) events, and mortality using the atherosclerotic CVD risk score. We carried out an observational study in a prospective cohort that was followed up for 12 years. The study included 3,021 participants aged ≥ 40 years at baseline from the Ansung cohort, part of the Korean Genome and Epidemiology Study. Cox regression models were constructed to evaluate the hazards ratio (HR) and 95% confidence interval (CI) for all-cause mortality and CVD events in groups classified according to thyroid status. Subgroup analysis was performed with a cut-off age of 65 years or 7.5% of the 10-year atherosclerotic CVD risk score. The subclinical hypothyroidism group in the highest quartile of thyroid-stimulating hormone (>6.57 mIU/L) had a significantly increased risk of all-cause mortality (HR 2.12, 95% CI 1.27 to 3.56) and CVD events (HR 1.92, 95% CI 1.21 to 3.04) compared with euthyroid participants. Subgroup analysis by CVD risk revealed that participants with high CVD risk only had a high risk of all-cause mortality (HR 2.18, 95% CI 1.22 to 3.87) and CVD events (HR 2.42, 95% CI 1.35 to 4.33). Further analysis showed that participants aged <65 years with high CVD risk had the highest risk of all-cause mortality (HR 3.50, 95% CI 1.50 to 8.16) and CVD events (HR 3.37, 95% CI 1.46 to 9.57). Our results demonstrated that high thyroid-stimulating hormone levels were associated with a greater risk of mortality and new CVD risks, particularly among subjects with high CVD risk.

Impact of Thyroid Hormone Therapy on Atherosclerosis in the Elderly With Subclinical Hypothyroidism: A Randomized Trial

CONTEXT

Subclinical hypothyroidism (SHypo) has been associated with atherosclerosis, but no conclusive clinical trials assessing the levothyroxine impact on carotid atherosclerosis exist.

OBJECTIVE

To assess the impact of treatment of SHypo with levothyroxine on carotid atherosclerosis.

DESIGN AND SETTING

Randomized, double-blind, placebo-controlled trial nested within the Thyroid Hormone Replacement for Subclinical Hypothyroidism trial.

PARTICIPANTS

Participants aged ≥65 years with SHypo [thyroid-stimulating hormone (TSH), 4.60 to 19.99 mIU/L; free thyroxine level within reference range].

INTERVENTION

Levothyroxine dose-titrated to achieve TSH normalization or placebo, including mock titrations.

MAIN OUTCOME MEASURES

Carotid intima media thickness (CIMT), maximum plaque thickness measured with ultrasound.

RESULTS

One hundred eighty-five participants (mean age 74.1 years, 47% women, 96 randomized to levothyroxine) underwent carotid ultrasound. Overall mean TSH ± SD was 6.35 ± 1.95 mIU/L at baseline and decreased to 3.55 ± 2.14 mIU/L with levothyroxine compared with 5.29 ± 2.21 mIU/L with placebo (P < 0.001). After a median treatment of 18.4 months (interquartile range 12.2 to 30.0 months), mean CIMT was 0.85 ± 0.14 mm under levothyroxine and 0.82 ± 0.13 mm under placebo [between-group difference = 0.02 mm; 95% CI, -0.01 to 0.06; P = 0.30]. The proportion of carotid plaque was similar (n = 135; 70.8% under levothyroxine and 75.3% under placebo; P = 0.46). Maximum carotid plaque thickness was 2.38 ± 0.92 mm under levothyroxine and 2.37 ± 0.91 mm under placebo (between-group difference -0.03; 95% CI, -0.34 to 0.29; P = 0.86). There were no significant interactions between levothyroxine treatment and mean CIMT, according to sex, baseline TSH (categories 4.6 to 6.9, 7.0 to 9.9, and ≥10 mIU/L), or established cardiovascular disease (all P for interaction ≥ 0.14).

CONCLUSION

Normalization of TSH with levothyroxine was associated with no difference in CIMT and carotid atherosclerosis in older persons with SHypo.

Reference intervals for thyrotropin in an area of Northern Italy: the Pordenone thyroid study (TRIPP)

PURPOSE

Thyrotropin (TSH) is the most accurate marker of thyroid dysfunction in the absence of pituitary or hypothalamic disease. Studies on TSH reference intervals (RIs) showed wide inter-individual variability and prompted an intense debate about the best estimation of TSH RIs.

DESIGN

We performed a population study on TSH RIs, using current data stored in the laboratory information system (LIS), at the Hospital Department of Laboratory Medicine, Pordenone (Italy), historically an area of mild-moderate iodine deficiency with a relatively high goiter prevalence.

METHODS

136,650 individuals constituted the final sample. A TSH immunoassay was performed on fasting serum samples with the Dimension Vista 1500 analyzer (Siemens Healthineers). We adopted the Kairisto's procedure to analyze TSH data downloaded by the LIS, applying the indirect strategy for deriving RIs.

RESULTS

TSH RIs of the entire population were 0.32-3.36 mIU/L with a distribution skewed towards higher values. RIs were 0.26-3.61 mIU/L for females, and 0.32-3.01 mIU/L for males. Unlike other studies, TSH median levels progressively decreased from 0-4 to 85-104 years in the overall population, both in male and in female subgroups, showing an inverse correlation between TSH and age in all groups.

CONCLUSIONS

This study is the first to analyze a high percentage (40%) of individuals from an ethnically homogenous Caucasian population. The results obtained emphasize the opportunity to define the TSH RIs according to age, gender and race, in addition to assay methods, and provide further insight about the possible role of iodine status.

Mild Hypothyroidism in Childhood: Who, When, and How Should Be Treated?

Mild hypothyroidism, also known as subclinical hypothyroidism (SH), is biochemically defined as serum TSH levels above the upper limit of the reference range, in the presence of normal serum concentrations of total T4 and free T4 (FT4). In the neonatal period, mild hypothyroidism can be defined by the presence of a TSH value between 6 and 20 mIU/L and normal FT4 levels. After the neonatal period, SH can be defined mild if TSH ranges between 4.5 and 10 mIU/L. The management of mild hypothyroidism in childhood is challenging. The major concern is to establish whether this condition should always be considered an expression of mild thyroid dysfunction. Indeed, the effects of untreated mild hypothyroidism are still not completely defined. In the neonatal period, concern exists about neurocognitive outcome; in children, although there is no clear evidence of alterations in growth or neurocognitive development, subtle cardiovascular abnormalities have been documented. Therefore, there is still uncertainty about the need of treatment across all ages, and the management should be based on the age of the child, the etiology, and the degree of TSH elevation, as well as on other patient factors. This review updates current evidences on diagnosis and management of mild hypothyroidism in childhood.

The Current Understanding of the Endocrine Effects From Immune Checkpoint Inhibitors and Recommendations for Management

Clinical trials in the past decade have established the antitumor effects of immune checkpoint inhibition as a revolutionary treatment for cancer. Namely, blocking antibodies to cytotoxic T-lymphocyte antigen 4 and programmed death 1 or its ligand have reached routine clinical use. Manipulation of the immune system is not without side effects, and autoimmune toxicities often known as immune-related adverse events (IRAEs) are observed. Endocrine IRAEs, such as hypophysitis, thyroid dysfunction, and insulin-dependent diabetes mellitus, can present with unique profiles that are not seen with the use of traditional chemotherapeutics. In this Review, we discuss the current hypotheses regarding the mechanism of these endocrinopathies and their clinical presentations. Further, we suggest guidelines and algorithms for patient management and future clinical trials to optimize the detection and treatment of immune checkpoint–related endocrinopathies.

Is only Thyroid Peroxidase Antibody Sufficient for Diagnosing Chronic Lymphocytic Thyroiditis?

Objectives:

Recently, only anti-thyroid peroxidase (anti-TPO) has been suggested as an autoantibody in the diagnosis of chronic lymphocytic thyroiditis (CLT). In contrast, anti-thyroglobulin (anti-Tg) positivity has also been reported to be important. To evaluate this relationship more clearly, we planned to retrospectively investigate the autoantibody levels of the patients who underwent thyroid surgery for various reasons and those with CLT in postoperative pathology.

Methods:

We evaluated 670 patients who underwent thyroid surgery (total/subtotal thyroidectomy) for various reasons at our hospital between January 2015 and March 2017. Patients with indications of Graves’ disease, toxic multinodular goiter, and all malignancies except for thyroid papillary carcinoma (TPC) were excluded. Eighty-nine patients whose pathology findings were compatible with CLT and preoperative thyroid autoantibodies were identified enrolled in to the study. Patients with absence and presence of thyroid antibodies were included in the seronegative CLT group and seropositive CLT group, respectively. In addition, patients were divided into thyroid papillary carcinoma (TPC) and benign groups.

Results:

According to the study criteria, 89 (83 females, six males) (mean age, 46.08±11.19 years) patients who had preoperatively identified autoantibodies were detected. Anti-TPO positivity was found in 47 (52.8%) cases, whereas anti-Tg positivity was found in 49 (55.1%). Only anti-TPO positivity was found in 18 (20.2%) cases, whereas only anti-Tg positivity was detected in 20 (22.5%). Twenty-two (24.7%) of the patients were seronegative. On comparing the seronegative and seropositive groups, seronegativity was more frequent in male patients (p=0.03). Thyroid-stimulating hormone was found to be significantly higher in the seropositive group (p=0.01). TPC was detected in 36 (40.4%) of all cases. No difference regarding age, thyroid function tests, and antibody levels was found between the benign and TPC groups.

Conclusion:

Although all of our cases were histopathologically diagnosed with CLT, serologically, 75.3% of thyroid autoimmunities could be shown when both antibodies were evaluated together. When only anti-TPO was considered, this rate decreased to 52.8%. Therefore, anti-Tg appears to be still important in showing autoimmunity. Prospective studies are needed to evaluate this relationship more clearly.

[Hypothyroidism-when and how to treat?]

The diagnosis of hypothyroidism is primarily based on clinical signs and symptoms as well as measurement of thyroid-stimulating hormone (TSH) concentration. Subclinical hypothyroidism is characterized by elevated TSH with normal serum free thyroxine (fT₄) and triiodothyronine (fT₃) levels, while in manifest hypothyroidism serum fT₄ and fT₃ levels are reduced. Common causes of primary hypothyroidism are autoimmune thyroiditis as well as therapeutic interventions, such as thyroid surgery or radioiodine therapy. Signs and symptoms of hypothyroidism include fatigue, bradycardia, constipation and cold intolerance. In subclinical hypothyroidism, symptoms may be absent. Initiation of levothyroxine (T₄) therapy not only depends on the level of TSH elevation, but also on other factors, such as patient age, presence of pregnancy or comorbidities. Treatment of patients with subclinical hypothyroidism is still a controversial topic. In general, thyroid hormone replacement therapy in non-pregnant adults ≤ 70 years is clearly indicated if the TSH concentration is >10 mU/l. Standard of care for treatment of hypothyroidism is T₄ monotherapy. The biochemical treatment goal for T₄ replacement in primary hypothyroidism is a TSH level within the reference range (0.4-4.0 mU/l). In contrast, in secondary hypothyroidism, serum fT₄ levels are the basis for adjusting thyroid hormone dosage. Inadequate replacement of T₄ resulting in subclinical or even manifest hyperthyroidism should urgently be avoided. T₄/liothyronine (T3) combination therapy is still a matter of debate and not recommended as standard therapy, but may be considered in patients with persistence of symptoms, despite optimal T₄ treatment, based on expert opinion.

Thyroid disorders in alemtuzumab-treated multiple sclerosis patients: a Belgian consensus on diagnosis and management

This paper deals with thyroid disease that can occur after treatment with alemtuzumab (humanized monoclonal anti-CD52) for relapsing–remitting multiple sclerosis (MS). The 5-year incidence of thyroid adverse events in phase 3 clinical trials is up to 40.7%. In most cases, the thyroid dysfunction is mild and easily manageable and only few serious thyroid adverse events have been reported. The need for patient education on the risk of thyroid dysfunction, as well as regular clinical and biochemical thyroid function screening is well described. However, practical clinical guidance in case of abnormal thyroid-related findings prior to or after alemtuzumab treatment is currently lacking. Therefore, a Belgian taskforce consisting of MS and thyroid experts was created in 2016, with the objective of issuing a clinical thyroid management algorithm based on available scientific evidence and personal experience with regard to alemtuzumab treatment-related thyroid adverse events.

MANAGEMENT OF ENDOCRINE DISEASE: Pitfalls on the replacement therapy for primary and central hypothyroidism in adults

Hypothyroidism is one of the most common hormone deficiencies in adults. Most of the cases, particularly those of overt hypothyroidism, are easily diagnosed and managed, with excellent outcomes if treated adequately. However, minor alterations of thyroid function determine nonspecific manifestations. Primary hypothyroidism due to chronic autoimmune thyroiditis is largely the most common cause of thyroid hormone deficiency. Central hypothyroidism is a rare and heterogeneous disorder characterized by decreased thyroid hormone secretion by an otherwise normal thyroid gland, due to lack of TSH. The standard treatment of primary and central hypothyroidism is hormone replacement therapy with levothyroxine sodium (LT4). Treatment guidelines of hypothyroidism recommend monotherapy with LT4 due to its efficacy, long-term experience, favorable side effect profile, ease of administration, good intestinal absorption, long serum half-life and low cost. Despite being easily treatable with a daily dose of LT4, many patients remain hypothyroid due to malabsorption syndromes, autoimmune gastritis, pancreatic and liver disorders, drug interactions, polymorphisms in DIO2 (iodothyronine deiodinase 2), high fiber diet, and more frequently, non-compliance to LT4 therapy. Compliance to levothyroxine treatment in hypothyroidism is compromised by daily and fasting schedule. Many adult patients remain hypothyroid due to all the above mentioned and many attempts to improve levothyroxine therapy compliance and absorption have been made.

Subclinical hypothyroidism: new trials, old caveats

The indications for levothyroxine replacement therapy for subclinical hypothyroidism (SH) remain a subject of debate, especially when prescribed for older adults. The results of the recent TRUST trial indicate that levothyroxine does not improve clinical symptom scores among elderly patients with SH. While there is much concern regarding the dilemma of introducing or withholding levothyroxine, less attention may be paid to the differential diagnosis of an elevated TSH level, which is the prerequisite for diagnosing SH. Herein, we review these issues facing endocrinologists and internists/generalists either in practice or in training. When a patient presents abnormal thyroid test results compatible with SH, a series of issues need to be addressed before the implementation of replacement therapy is considered: first, an isolated TSH elevation not linked to a primary thyroid pathology should be excluded; second, the persistent nature of the patient's TSH elevation and SH profile should be verified; third, SH symptoms and potential complications relevant for the specific patient should be documented; fourth, expectations from levothyroxine substitution therapy for SH in the specific patient should be clarified. Only then can the decision be made whether levothyroxine substitution should be introduced or not.

Predictive Factors of Nivolumab-induced Hypothyroidism in Patients with Non-small Cell Lung Cancer

BACKGROUND/AIM

Although immune checkpoint inhibitors play an important role in the therapy of lung cancer, they are associated with various immune-related adverse events and predictive factors of them are unclear. In this study, we investigated predictive factors of nivolumab-induced hypothyroidism which is one of the adverse events in patients with lung cancer.

PATIENTS AND METHODS

Patients with non-small-cell lung cancer who were administered nivolumab at our hospital between December 2015 and May 2016 were retrospectively enrolled. The thyroid-stimulating hormone, free triiodothyronine, free thyroxine, thyroid peroxidase (TPO) antibody, and thyroglobulin antibody levels of each patient were analyzed.

RESULTS

Of the 64 patients enrolled, 5 (7.8%) developed hypothyroidism after treatment with nivolumab. The TPO and thyroglobulin antibodies were significantly positive in patients who developed primary hypothyroidism.

CONCLUSION

TPO and thyroglobulin antibody levels at baseline may be predictive of hypothyroidism.

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.

Initial evaluation of thyroid dysfunction - Are simultaneous TSH and fT4 tests necessary?

Objective

Guidelines for thyroid function evaluation recommend testing TSH first, then assessing fT4 only if TSH is out of the reference range (two-step), but many clinicians initially request both TSH and fT4 (one-step). Given limitations of previous studies, we aimed to compare the two-step with the one-step approach in an unselected community-dwelling study population, and develop a prediction score based on clinical parameters that could identify at-risk patients for thyroid dysfunction.

Design

Cross-sectional analysis of the population-based Busselton Health Study.

Methods

We compared the two-step with the one-step approach, focusing on cases that would be missed by the two-step approach, i.e. those with normal TSH, but out-of-range fT4. We used likelihood ratio tests to identify demographic and clinical parameters associated with thyroid dysfunction and developed a clinical prediction score by using a beta-coefficient based scoring method.

Results

Following the two-step approach, 93.0% of all 4471 participants had normal TSH and would not need further testing. The two-step approach would have missed 3.8% of all participants (169 of 4471) with a normal TSH, but a fT4 outside the reference range. In 85% (144 of 169) of these cases, fT4 fell within 2 pmol/l of fT4 reference range limits, consistent with healthy outliers. The clinical prediction score that performed best excluded only 22.5% of participants from TSH testing.

Conclusion

The two-step approach may avoid measuring fT4 in as many as 93% of individuals with a very small risk of missing thyroid dysfunction. Our findings do not support the simultaneous initial measurement of both TSH and fT4.

Thyroid-stimulating hormone and adverse left ventricular remodeling following ST-segment elevation myocardial infarction

BACKGROUND

Adverse left ventricular remodeling is one of the major determinants of heart failure and mortality in patients surviving ST-segment elevation myocardial infarction (STEMI). The hypothalamic-pituitary-thyroid axis is a key cardiovascular regulator; however, the relationship between hypothalamic-pituitary-thyroid status and post-STEMI left ventricular remodeling is unclear. We aimed to investigate the association between thyroid-stimulating hormone concentrations and the development of left ventricular remodeling following reperfused STEMI.

METHODS

In this prospective observational study of 102 consecutive STEMI patients, thyroid-stimulating hormone levels were measured at the first day after infarction and 4 months thereafter. Cardiac magnetic resonance scans were performed within the first week as well as at 4 months follow-up to determine infarct characteristics, myocardial function and as primary endpoint left ventricular remodeling, defined as a 20% or greater increase in left ventricular end-diastolic volume.

RESULTS

Patients with left ventricular remodeling (n=15, 15%) showed significantly lower concentrations of baseline (1.20 [0.92-1.91] vs. 1.73 [1.30-2.60] mU/l; P=0.02) and follow-up (1.11 [0.86-1.28] vs. 1.51 [1.15-2.02] mU/l; P=0.002) thyroid-stimulating hormone. The association between baseline thyroid-stimulating hormone and left ventricular remodeling remained significant after adjustment for major clinical (peak high-sensitivity cardiac troponin T and C-reactive protein, heart rate; odds ratio (OR) 5.33, 95% confidence interval (CI) 1.52-18.63; P=0.01) and cardiac magnetic resonance predictors of left ventricular remodeling (infarct size, microvascular obstruction, ejection fraction; OR 4.59, 95% CI 1.36-15.55; P=0.01). Furthermore, chronic thyroid-stimulating hormone was related to left ventricular remodeling independently of chronic left ventricular remodeling correlates (infarct size, ejection fraction, left ventricular end-diastolic volume, left ventricular end-systolic volume; OR 9.22, 95% CI 1.69-50.22; P=0.01).

CONCLUSIONS

Baseline and chronic thyroid-stimulating hormone concentrations following STEMI were independently associated with left ventricular remodeling, proposing a novel pathophysiological axis in the development of post-STEMI left ventricular remodeling.

Diffuse Myocardial Injuries are Present in Subclinical Hypothyroidism: A Clinical Study Using Myocardial T1-mapping Quantification

Subclinical hypothyroidism (SHT) is a common disorder that may represent early thyroid dysfunction and is related to adverse cardiovascular events. However, myocardial injuries induced by SHT are difficult to detect. Our previous study demonstrated that the cardiac magnetic resonance (CMR) myocardial longitudinal relaxation time (T1) mapping technique is a useful tool for assessing diffuse myocardial injuries in overt hypothyroidism patients. This study was designed to detect whether diffuse myocardial injuries were present in SHT by using the T1 mapping technique. We found that SHT participants had significantly increased native T1 values within four segments of the left ventricle (all p < 0.01), especially patients with thyroid-stimulating hormone (TSH) levels ≥10 µIU/mL, compared with those in the controls. In addition, the native T1 values were negatively correlated with free thyroxine (FT4) (r = −0.476, p = 0.003) and were positively correlated with TSH (r = 0.489, p = 0.002). Furthermore, left ventricular diastolic function estimated by the peak filling rate (PFR) was significantly lower in patients with TSH levels ≥10 µIU/mL than that in the controls (p < 0.05). In conclusion, diffuse myocardial injuries were present in SHT, and T1 mapping may be a useful tool for evaluating mild myocardial injuries in SHT at an early stage. Our study is the first to confirm myocardial injuries in SHT patients using T1 mapping.

Trends in Costs of Thyroid Disease Treatment in Denmark during 1995-2015

BACKGROUND

Iodine fortification (IF) may contribute to changes in costs of thyroid disease treatment through changes in disease patterns. From a health economic perspective, assessment of the development in costs of thyroid disease treatment in the population is pertinent.

OBJECTIVES

To assess the trends in annual medicine and hospital costs of thyroid disease treatment during 1995-2015 in Denmark, i.e., before and after the introduction of mandatory IF in 2000.

METHODS

Information on treatments for thyroid disease (antithyroid medication, thyroid hormone therapy, thyroid surgery, and radioiodine treatment) was obtained from nationwide registers. Costs were valued at 2015 prices using sales prices for medicines and the Danish Diagnosis-Related Group (DRG) and Danish Ambulatory Grouping System (DAGS) tariffs of surgeries/radioiodine treatments. Results were adjusted for changes in population size and age and sex distribution.

RESULTS

The total direct medicine and hospital costs of thyroid disease treatment increased from EUR ∼190,000 per 100,000 persons in 1995 to EUR ∼270,000 per 100,000 persons in 2015. This was mainly due to linearly increased costs of thyroid hormone therapy and increased costs of thyroid surgery since 2008. Costs of antithyroid medication increased slightly and transiently after IF, while costs of radioiodine treatment remained constant. Costs of thyroid hormone therapy and thyroid surgery did not follow the development in the prevalence of hypothyroidism and structural thyroid diseases observed in concurrent studies.

CONCLUSION

The costs of total direct medicine and hospital costs for thyroid disease treatment in Denmark increased from 1995 to 2015. This is possibly due to several factors, e.g., changes in treatment practices, and the direct effect of IF alone remains to be estimated.

Subclinical hypothyroidism in children: is it always subclinical?

Aim of this commentary is to report current knowledges on the main clinical and metabolic abnormalities which might be observed in children with longstanding and untreated subclinical hypothyroidism (SH) and to comment the most recent views about natural evolution of thyroid function in the cases with either idiopathic or Hashimoto’s thyroiditis-related SH. On the basis of these preliminary remarks, the essential guidelines for an appropriate and tailored management of SH children are also proposed.

Hypothyroidism and the Heart

Hypothyroidism is a commonly encountered clinical condition with variable prevalence. It has profound effects on cardiac function that can impact cardiac contractility, vascular resistance, blood pressure, and heart rhythm. With this review, we aim to describe the effects of hypothyroidism and subclinical hypothyroidism on the heart. Additionally, we attempt to briefly describe how hypothyroid treatment affects cardiovascular parameters.

Effect of Levothyroxine on Blood Pressure in Patients With Subclinical Hypothyroidism: A Systematic Review and Meta-Analysis

Background: Patients with subclinical hypothyroidism (SCH) have elevated blood pressure, but the effect of levothyroxine (LT4) therapy on blood pressure among those patients is still unclear. This study aimed to assess whether LT4 therapy could reduce blood pressure in SCH patients through a systematic review and meta-analysis. Methods: PubMed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science were searched. Randomized controlled trials (RCTs) assessing the effect of LT4 therapy on blood pressure or prospective follow-up studies comparing the blood pressure level before and after LT4 treatment were included, and the mean difference of systolic blood pressure (SBP) or diastolic blood pressure (DBP) was pooled using random-effect meta-analysis. Results: Twenty-nine studies including 10 RCTs and 19 prospective follow-up studies were eligible for the analysis. Meta-analysis of 10 RCTs suggested that LT4 therapy could significantly reduce SBP in SCH patients by 2.48 mmHg (95% CI -4.63 to -0.33, P = 0.024). No heterogeneity was observed among these 10 RCTs (I² = 0%). Meta-analysis of the 19 prospective follow-up studies found that LT4 therapy significantly decreased SBP and DBP by 4.80 mmHg (95%CI -6.50 to -3.09, P < 0.001) and 2.74 mmHg (95%CI -4.06 to -1.43, P < 0.001), respectively. Conclusion: The findings suggest that LT4 replacement therapy can reduce blood pressure in SCH patients, which needs to be validated in more clinical trials with larger samples.

A Renewed Focus on the Association Between Thyroid Hormones and Lipid Metabolism

Thyroid dysfunction, manifesting as either overt or subclinical hypothyroidism, negatively affects lipid metabolism: this leads to hypercholesterolemia which progressively increases the risk for cardiovascular disease and, potentially, mortality. Hypercholesterolemia in hypothyroidism is mainly due to a reduction in low-density lipoprotein (LDL) receptor activity, this accompanied by concomitant diminishing control by triiodothyronine (T3) of sterol regulatory element-binding protein 2 (SREBP-2), which modulates cholesterol biosynthesis by regulating rate-limit degrading enzyme 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoA) activity. Recently, 3,5-diiodothyronine (T2), a natural thyroid hormone derivative, was found to repress the transcription factor carbohydrate-response element-binding protein (ChREBP) and also to be involved in lipid catabolism and lipogenesis, though via a different pathway than that of T3. While thyroid hormone could therapeutically reverse the dyslipidemic profile commonly occurring in hypothyroidism, it should be borne in mind that the potency of the effects may be age-and sex-dependent. Thyroid hormone administration possibly also sustains and enhances the efficacy of hypolipidemic drugs, such as statins, ezetimibe and proprotein convertase subtilisin/kexin type 9 (PCSK9), in patients with dyslipidemia and hypothyroidism.

Antibody-mediated thyroid dysfunction during T-cell checkpoint blockade in patients with non-small-cell lung cancer

Background

Programmed cell death protein-1 (PD-1) blockade therapies have demonstrated durable responses and prolonged survival in a variety of malignancies. Treatment is generally well tolerated although immune-related adverse events (irAEs) can occur. Autoimmune thyroid dysfunction is among the most common irAE, but an assessment of the clinical, mechanistic, and immunologic features has not been previously described.

Patient and methods

Patients with advanced non-small-cell lung cancer (NSCLC) treated with pembrolizumab at Memorial Sloan Kettering Cancer Center (n = 51) as part of KEYNOTE-001 (NCT01295827) were included. Thyroid function test and anti-thyroid antibodies were assessed prospectively at each study visit, beginning before the first treatment. Frequency of development of thyroid dysfunction, association with anti-thyroid antibodies, clinical course, and relationship with progression-free survival and overall survival to treatment with pembrolizumab was evaluated.

Results

Of 51 patients treated, 3 were hypothyroid and 48 were not at baseline. Ten of 48 [21%, 95% confidence interval (CI) 10% to 35%] patients developed thyroid dysfunction requiring thyroid replacement. Anti-thyroid antibodies were present in 8 of 10 patients who developed thyroid dysfunction, compared with 3 of 38 who did not (80% versus 8%, P < 0.0001). Thyroid dysfunction occurred early (median, 42 days) in the pembrolizumab course, and a majority (6 of 10 patients) experienced brief, transient hyperthyroidism preceding the onset of hypothyroidism; no persistent hyperthyroidism occurred. Both hyperthyroidism and hypothyroidism were largely asymptomatic. Overall survival with pembrolizumab was significantly longer in subjects who developed thyroid dysfunction (hazard ratio, 0.29; 95% CI 0.09-0.94; P = 0.04).

Conclusions

Thyroid dysfunction during pembrolizumab treatment of NSCLC is common and is characterized by early-onset, frequently preceded by transient hyperthyroidism, closely associated with anti-thyroid antibodies, and may be associated with improved outcomes. The presence of antibody-mediated toxicity in T-cell-directed therapy suggests an under-recognized impact of PD-1 biology in modulating humoral immunity.

Prevalence of treated hypothyroidism in the community: Analysis from general practices in North-East England with implications for the United Kingdom

OBJECTIVE

Hypothyroidism is more frequently diagnosed in women and older individuals. It has been suggested that the prevalence of hypothyroidism and the number of prescriptions for thyroid hormones are increasing. However, despite hypothyroidism being a common medical condition, contemporary data on prevalence, particularly across the various age groups, is limited.

DESIGN

Information regarding number of individuals diagnosed with treated hypothyroidism (defined as patients prescribed levothyroxine) across ten General Practices (total population of 66 843) in the North-East of England in 2016 was obtained in an anonymized manner. Total as well as age group-specific point prevalence rates were calculated. In addition, corresponding population data for the United Kingdom were acquired, and national total and age-specific hypothyroidism prevalence rates were estimated.

RESULTS

The overall prevalence of hypothyroidism in this community sample was 4.5% (n = 3004). Prevalence increased across the age groups from 0.1% in children aged 0-10 years to 15.1% in those aged more than 90 years. After adjusting for demographic differences between the North-East England and UK populations, it is estimated that the total UK-wide prevalence of hypothyroidism in 2016 is 3.6%; affecting more than 2.3 million individuals including nearly 800 000 individuals aged >70 years.

CONCLUSIONS

Hypothyroidism affects millions of individuals in the UK and is currently a prevalent diagnosis in more than 1 in 10 individuals aged above 70 years. As the population ages this number is likely to increase. The clinical and economic effects of current management strategies for hypothyroidism, particularly in the older population, need to be evaluated.

Pre-admission TSH levels predict long-term mortality in adults treated for hypothyroidism

CONTEXT

Limited data is available regarding the association between pre-admission thyroid function and prognosis of hospitalized patients treated for hypothyroidism.

OBJECTIVE

Evaluate an association between thyroid stimulating hormone (TSH) levels and mortality in hospitalized levothyroxine-treated patients.

DESIGN AND SETTING

Observational data of patients admitted to medical wards between 2011 and 2013. TSH levels obtained up to 180 days prior to admission were stratified as follows: low (≤0.5 mIU/L), normal (0.5-5 mIU/L), high (>5 mIU/L).

PATIENTS

Patients aged 60-80 years with available thyroid function tests were matched with controls without hypothyroidism.

MAIN OUTCOME

All-cause mortality up to 66-months following discharge.

RESULTS

One thousand and fifty seven patients (73% females, mean (SD) age 71 ± 6 years) were matched with controls without hypothyroidism. Mean hospital stay and in-hospital mortality were not different between groups. Mortality risk at the end-of-follow-up was 41% (438/1057) and 37% (392/1057) for patients with and without hypothyroidism (p < 0.05). TSH levels were classified as follows: low, 84 patients (8%); normal, 667 patients (63%); high, 306 patients (29%). Length of hospitalization and in-hospital mortality were not different between TSH categories. Mortality risk at the end-of-follow-up was 30, 39, and 50% with low, normal and elevated TSH, respectively. Adjusted hazard ratio (95% CI) of mortality at the end-of-follow-up was of 2.2 (1.2-3.8) for high vs. low TSH levels, and 1.4 (1.1-1.9) for high vs. normal TSH levels.

CONCLUSION

In treated hypothyroid adult patients, increased TSH up to 6 months prior to admission is associated with increased mortality. Treatment should aim at achieving euthyroidism to improve survival.

Hypothyroidism in hospitalized elderly patients: a sign of worse prognosis

PURPOSE

Overt hypothyroidism has adverse clinical consequences and might worsen prognosis in critically ill elderly patients. However, the difficult interpretation of thyroid function tests (TFT) due to non-thyroidal illness (NTI) has led to discouragement of screening for thyroid dysfunction. Our aim was to determine the prevalence of TFT compatible with hypothyroidism and to study its influence on mortality among hospitalized elderly patients.

METHODS

In this prospective study we consecutively included all patients ≥60 years admitted by the Internal Medicine Department to the hospital ward (n = 451) of the Cesar Milstein Hospital in Buenos Aires, Argentina. TFT were done on day 1 and 8. Thyroid function categories were defined as overt and subclinical hypothyroidism, overt and subclinical hyperthyroidism, euthyroidism and NTI. Stage of chronic kidney disease (CKD), Adult Comorbidity Evaluation (ACE)-27, and intra-hospital mortality were recorded. The association between mortality and TFT categories was studied by Cox regression.

RESULTS

Out of 451 patients (77.0 ± 7.9 years, 54% females) 76% were categorized as NTI, 4% as overt hypothyroid, 10% as subclinical hypothyroid, 1% as subclinical hyperthyroid and 9% as euthyroid. Overt hypothyroid patients showed significantly higher mortality than the rest of the groups (25%, p < 0.05) while ACE-27 was similar among all of them (p = 0.658). In addition, patients within the overt hypothyroid category showed a higher mortality rate than NTI in a model adjusted by Stage 5-CKD, ACE-27, sex and age [HR 3.1 (1.14-8.41), p < 0.026].

CONCLUSION

Overt hypothyroidism during hospitalization was associated with elevated mortality. Further studies would reveal if TFT alterations compatible with hypothyroidism should be diagnosed/treated in hospitalized elderly patients.

Evaluation of thyroid test utilization through analysis of population-level data

BACKGROUND

Inappropriate laboratory test utilization can result in unnecessary patient testing and increased healthcare costs. While several thyroid function tests are available, thyroid-stimulating hormone (TSH) is recommended as the first-line test for investigating and monitoring thyroid dysfunction. We evaluate thyroid test utilization in Northern Alberta in terms of testing patterns, frequencies, and reflex cutpoints.

METHODS

This retrospective study analyzed thyroid test requests from January to December 2014. Each request was designated as appropriate or potentially inappropriate as per clinical practice guidelines and Choosing Wisely recommendations, and the frequencies of each testing pattern were calculated. Sub-analysis was performed to categorize testing patterns based on physician specialty. The number of test requests per patient was determined to assess the appropriateness of testing frequency. Receiver operating characteristic (ROC) curves were generated to define optimal TSH cutpoints for automatic reflex to FT4 testing.

RESULTS

Of 752,217 test requests, approximately 10% were potentially inappropriate in terms of testing patterns. Free thyroxine (FT4) and free triiodothyronine (FT3) requested with TSH accounted for 59% of all potentially inappropriate test requests, and 49% of requests from endocrinologists (ENDO) were potentially inappropriate, occurring most frequently among those with less experience. Excessive testing frequencies were observed in 869 patients, accounting for 9382 test requests. Adjustment of our TSH reflex cutpoint would significantly increase specificity for identifying a low FT4 without compromising sensitivity.

CONCLUSIONS

This study suggests that questionable testing patterns, excessive testing frequencies, and suboptimal reflexive testing cutpoints contribute to inappropriate thyroid test utilization.

Subclinical Hypothyroidism and Its Association with Increased Cardiovascular Mortality

Thyroid hormones play an important role in regulating different metabolism functions and multiple organs' performance. Changes in the thyroid hormone axis can lead to profound effects on the stability of vital organs and systems, especially the cardiovascular system. Hypothyroidism is classified according to the clinical presentation as overt and subclinical. There is some evidence supporting the benefits of thyroxine hormone replacement for subclinical hypothyroidism on cardiovascular mortality outcomes. However, the clinical relevance of measuring and treating high thyroid-stimulating hormone (TSH) levels in newly diagnosed heart failure patients with preserved ejection fraction requires further study. In this report, we review the current evidence regarding the prognostic significance of subclinical hypothyroidism in heart failure patients with preserved ejection fraction.

Subclinical Hypothyroidism - Whether and When To Start Treatment?

Subclinical hypothyroidism represents a state with increased values of thyroid stimulating hormone (TSH) and normal values of thyroxine (T4) and triiodothyronine (T3). The disorder is asymptomatic, and the diagnosis is made based on the results of laboratory findings when the level of TSH reaches values above 4.0 mU/l. It is still subject to debate whether patients with subclinical hypothyroidism are at increased risk of cardiovascular disease, neuropsychiatric and neuromuscular disorders. Studies have shown that the appearance of general symptoms and complications are more common in patients whose values of TSH are above 10 mU/l. Therefore, the initiation of therapy with levothyroxine, which is the foundation of substitution therapy, is advised in patients whose TSH is >10 mU/l. As for patients whose values of TSH are from 4.0 to 10.0 mU/l and who make up 90% of the patients with subclinical hypothyroidism, further research is needed to determine the effects of the disorder and levothyroxine therapy on the health. Until then, the introduction of the substitution therapy in patients with TSH which is <10 mU/l should be considered in the case of the presence of general symptoms, anti-thyroid antibodies, increased lipids and other risk factors, goitre, pregnancy, ovarian dysfunction and infertility.

Physical performance in newly diagnosed hypothyroidism: a pilot study

OBJECTIVE

Hypothyroidism is complicated by neuromuscular symptoms (myalgias, slowness of movements, and tiredness) and signs (easy fatigability and cramps), which may have a negative impact on general well-being and quality of life. In a pilot, prospective, controlled study, we investigated the features of muscle dysfunction in hypothyroidism by disease questionnaire, biochemical measures, and physical performance tests.

MATERIALS AND METHODS

Fifty-seven consecutive patients with newly diagnosed hypothyroidism were enrolled, 27 subclinical (S-Hypo) and 30 overt (O-Hypo). A series of 30 euthyroid subjects, with similar demographic characteristics, served as controls. Patients were administered a short disease questionnaire and underwent laboratory exams and standardized physical tests, both at baseline and after restoration of biochemical euthyroidism.

RESULTS

Compared to euthyroid controls, the O-Hypo group showed significantly higher prevalence of neuromuscular symptoms and significantly higher serum creatine phosphokinase (CPK) levels (p value < 0.0001). S-Hypo had slightly higher CPK levels and prevalence of neuromuscular symptoms than controls. Both S-Hypo and O-Hypo patients performed worse than controls in the six-minute walking test. Differences between patients and controls in handgrip strength test and timed chair standing test failed to reach statistical significance (although a trend was noticeable), possibly due to the small sample size. In O-Hypo, an inverse correlation was found between CPK levels and the handgrip strength test (p value < 0.001). Restoration of euthyroidism was associated with normalization of questionnaire responses, six-minute walking test, as well as serum CPK levels.

CONCLUSION

In addition to neuromuscular symptoms, hypothyroidism is associated with abnormalities of physical performance. The six-minute walking test is the most valuable test to assess this aspect. In the pilot study, levothyroxine therapy could reverse muscle functional abnormalities.

MANAGEMENT OF ENDOCRINE DISEASE: l-Thyroxine replacement therapy in the frail elderly: a challenge in clinical practice

The number of elderly people, mostly aged over 85 years (the 'oldest old'), is increasing worldwide. As a consequence, accompanying morbidity and disability have been increasing, and frailty, defined as an age-related condition of decline of physiological reserves and vulnerability, represents an emerging problem. Caring for older frail people may represent a challenge, since the elderly differ significantly from younger adults in terms of comorbidity, polypharmacy, pharmacokinetics and greater vulnerability to adverse drug reactions. Specific criteria of therapeutic appropriateness and modified goals of care are needed in such patients, also in endocrine care settings. Indeed, thyroid dysfunctions are among the most common conditions in older, multimorbid populations. The prevalence of overt and subclinical hypothyroidism is as high as 20% and thyroid hormone prescription is common in the elderly, with a trend toward levothyroxine treatment of more marginal degrees of hypothyroidism. In addition, older patients have the highest rate of overtreatment during replacement therapy and are more susceptible to developing adverse effects from thyroid hormone excess. Recently, results of a multicentric randomized controlled trial, the TRUST-IEMO collaboration trial, added further insights to the debated question of whether and when levothyroxine treatment is required and if it is beneficial in the elderly. With this in mind, we revised the relevant literature on the impact of thyroid dysfunction and replacement therapy among older people, with the aim to better define indications, benefits and risks of l-T4 replacement therapy in the frail elderly.

The Relationship between Subclinical Thyroid Disease and Cardiovascular Disease Risk Score in Koreans

Subclinical hyperthyroidism and subclinical hypothyroidism are characterized by abnormal thyroid stimulating hormone (TSH) with normal free thyroxine. Subclinical thyroid diseases, to date, have received less attention compared with other thyroid diseases since they are asymptomatic. This study aimed to verify the association between subclinical thyroid diseases and cardiovascular diseases (CVDs) risk score in the Korean population. This was a population-based cohort study using data collected from 3,722 subjects (aged ≥ 30 years) during the 6th Korea National Health and Nutrition Examination Survey (KNHANES VI; 2013-2015). Gender-specific Framingham risk scores were calculated to identify the association between subclinical thyroid diseases and 10-year CVD risk score. Complex survey, with consideration of sampling weight, was analyzed using generalized linear models after stratification by gender. The TSH reference range was between 0.61 and 6.91 mIU/L in this study. TSH showed a positive association with the 10-year CVD risk score only in the female population (P = 0.001). There were significant differences in the least squares means of 10-year CVD risk score by the effect of subclinical hypothyroidism compared with euthyroidism (normal group) in females, after adjusting for body mass index, white blood cell, and urine iodine (P = 0.006 and Bonferroni corrected P = 0.012). In conclusion, subclinical hypothyroidism is associated with increased 10-year CVD risk score in the female Korean population aged 30 years or more. Therefore, we recommend to clinically checkup major CVD risk factors in female patients with subclinical hypothyroidism aged 30 years or more.

Dyslipidemia in subclinical hypothyroidism requires assessment of small dense low density lipoprotein cholesterol (sdLDL-C)

BACKGROUND

Usually both hypothyroidism and hyperthyroidism are related to the cardiovascular and cerebrovascular disease development. The relationship between subclinical hypothyroidism has been widely investigated but the findings remain controversial. The aim of the present study was to evaluate the lipid profile in patients with subclinical hypothyroidism (SHypo) in comparison to controls and to determine the association of SHypo and dyslipidemia in attempt to find importance of small dense low-density lipoprotein cholesterol (sdLDL-C) in atherosclerosis.

MATERIAL AND METHODS

In this study we included 100 women, aged 30 to 70 years that were divided into subgroups according to their age. According to the values of levels of thyroid hormones they were divided into euthyroid (control) group (n = 64) and (newly discovered) subclinical hypothyroidism (SHypo) group (n = 36). A high-sensitivity C-reactive protein (hs-CRP) and lipid profile, including small dense low-density lipoprotein cholesterol (sdLDL-C) were determined. Body weight and height were measured and BMI calculated. History of the current illness, medication, alcohol consumption and cigarettes smoking were noted.

RESULTS

Changed lipid profile as well as elevated triglycerides and sdLDL-C were observed in the group with subclinical hypothyroidism compared to the control group.

CONCLUSIONS

It is important to determine serum lipid levels, especially serum sdLDL-C levels at an early stage of subclinical hypothyroidism, since they represent atherogenic LDL particles and are better indicators for dyslipidaemia in subclinical hypothyroidism and the development of atherosclerosis with potential complications such as cardiovascular and cerebrovascular diseases.

Hypothyroidism

Hypothyroidism is a common condition of thyroid hormone deficiency, which is readily diagnosed and managed but potentially fatal in severe cases if untreated. The definition of hypothyroidism is based on statistical reference ranges of the relevant biochemical parameters and is increasingly a matter of debate. Clinical manifestations of hypothyroidism range from life threatening to no signs or symptoms. The most common symptoms in adults are fatigue, lethargy, cold intolerance, weight gain, constipation, change in voice, and dry skin, but clinical presentation can differ with age and sex, among other factors. The standard treatment is thyroid hormone replacement therapy with levothyroxine. However, a substantial proportion of patients who reach biochemical treatment targets have persistent complaints. In this Seminar, we discuss the epidemiology, causes, and symptoms of hypothyroidism; summarise evidence on diagnosis, long-term risk, treatment, and management; and highlight future directions for research.

Evaluation of Daily Blood Pressure Alteration in Subclinical Hypothyroidism

BACKGROUND

Subclinical hypothyroidism is the most common thyroid dysfunction in the general population. The relationship between overt thyroid dysfunction and hypertension is generally understood. Besides high blood pressure, non-dipper hypertension is known to increase cardiovascular risk. Our aim is to investigate daily blood pressure changes and the frequency of non-dipping patterns in patients with subclinical hypothyroidism.

METHODS

Forty-nine patients without hypertension with subclinical hypothyroidism were compared with 50 healthy sex- and age-matched controls using ambulatory blood pressure monitoring.

RESULTS

Thyroid-stimulating hormone (TSH) levels were significantly higher in the subclinic hypothyroidism group, and there was no difference between free triiodothyronine (FT3) and free thyroxine (FT4) levels which could be predicted as a result of the study design. Levels of mean diastolic, daytime diastolic, nighttime diastolic and nighttime systolic blood pressure were significantly higher in the subclinic hypothyroidism group (p = 0.001 for mean, daytime and nighttime diastolic and p = 0.01 for nighttime systolic). Diastolic non-dipping occurred more frequently in the subclinic hypothyroidism group [subclinical hypothyroidism group 24 patients (49%), control group 13 patients (26%), p = 0.01]. On multivariate analysis, subclinical hypothyroidism was independently associated with diastolic non-dipping (95% confidence interval 1.162-8.053, odds ratio 1.182, p = 0.024).

CONCLUSIONS

Our study found that both the frequency of diastolic non-dipping pattern and diastolic blood pressure increase with subclinical hypothyroidism. Therfore, it would appear that searching for non-dipping pattern can add valuable information for patients with subclinical hypothyroidism.

The lipid-lowering effect of levothyroxine in patients with subclinical hypothyroidism: A systematic review and meta-analysis of randomized controlled trials

OBJECTIVES

Dyslipidaemia is common in patients with subclinical hypothyroidism (SCH). To date, there is no universal agreement regarding the lipid-lowering effect of substitution treatment with L-T4 in patients with SCH. We aimed to clarify the effect by conducting this systematic review and meta-analysis of randomized controlled trials (RCTs).

DESIGN

We systematically searched PubMed, the Cochrane Library, ClinicalTrials.gov and EMBASE for RCTs comparing substitution treatment to placebo treatment or observation. We focused on the primary outcomes of changes from baseline of total, low-density lipoprotein and high-density lipoprotein cholesterol (TC, LDL-C and HLD-C) and triglycerides. Subgroup analyses were performed, assessing the effect of treatment duration, disease severity and ethnicity on the occurrence of discrepancy.

RESULTS

Twelve trials, with 940 participants, were eligible for analysis. Compared with the control group, levothyroxine substitution yielded a mean reduction in TC (-0.29 mmol/L, [-0.42 to -0.16]) and LDL-C (-0.22 mmol/L, [-0.36 to -0.09]), with no significant effects on HDL-C (-0.04 mmol/L, [-0.08 to 0.01]) or triglycerides (-0.04 mmol/L, [-0.08 to 0.00]). Trials in which only patients with mild SCH (thyrotropin <10 mIU/L) were enrolled showed equivalent effects. The lowering effects were weaker, but still significant, in long-term treatment (>6 months) compared with short-term treatment (≤6 months) for TC (-0.19 mmol/L [-0.35, -0.03] vs -0.50 mmol/L [-0.68, -0.31], P=.047) and LDL-C (-0.09 mmol/L [-0.16, -0.02] vs -0.46 mmol/L [-0.68, -0.25], P=.006).

CONCLUSIONS

Levothyroxine treatment has clear benefits on TC and LDL-C in SCH patients, including those with mild SCH.

Subclinical Hypothyroidism: Frequency, clinical presentations and treatment indications

Objective:

To determine the frequency, modes of clinical presentation and indications for replacement therapy in a cohort of patients with subclinical hypothyroidism (SCH).

Methods:

This study was conducted at the Endocrine and Diabetes Unit of Jinnah Postgraduate Medical Centre from September 2007 – October 2015. This was a retrospective chart analysis of prospectively collected data in whichthe medical records of 4448 patients who had presented to the Endocrine Clinic from 2007 to 2015 were reviewed. A total of 2760 (62.05%) patients were diagnosed withthyroid disorders, whereas 260 (9.42%) patients had SCH. The SCH patients were between the age of 12 to 70 years; TSH was> 4mIU/l with normal levels of FT3 and FT4. Patients were enrolled using a predesigned structured proforma. Those having chronic systemic diseases were excluded from this study. SPSS 13 was used to evaluate the data.

Results:

Femalepatients comprised93.8% (244 patients) of those with SCH, whereas only 6.2% (16 patients) were male. Common presenting symptoms were, lethargy in 146 patients (56.2%); increase in weight in 102 patients (39.2%) and menstrual irregularities in 90 patients (34.6%). TSH level of < 10mIU/l (4 - 10) was seen in 177 patients (68.1%) and 83 patients (31.9%) had TSH ≥ 10mU/l. Thyroxine was given to 183 (70.4%) of these patients. Common treatment indications were TSH of ≥ 10, which was seen in 83 patients (31.9%), subfertility in 32 patients (12.3%), troublesome symptoms suggestive of hypothyroidism in 31 patients (11.9%) and high titers of antibodies in 23 patients (8.8%).

Conclusion:

SCH is frequently seen in our population, with most patients complaining of lethargy. The most common treatment indications were a TSH ≥ 10mIU/l, whereas troublesome symptoms of hypothyroidism and subfertility were the common treatment indications in patients who had a TSH of < 10mIU/l.

Thyroid Hormone Therapy for Older Adults with Subclinical Hypothyroidism

BACKGROUND

The use of levothyroxine to treat subclinical hypothyroidism is controversial. We aimed to determine whether levothyroxine provided clinical benefits in older persons with this condition.

METHODS

We conducted a double-blind, randomized, placebo-controlled, parallel-group trial involving 737 adults who were at least 65 years of age and who had persisting subclinical hypothyroidism (thyrotropin level, 4.60 to 19.99 mIU per liter; free thyroxine level within the reference range). A total of 368 patients were assigned to receive levothyroxine (at a starting dose of 50 μg daily, or 25 μg if the body weight was <50 kg or the patient had coronary heart disease), with dose adjustment according to the thyrotropin level; 369 patients were assigned to receive placebo with mock dose adjustment. The two primary outcomes were the change in the Hypothyroid Symptoms score and Tiredness score on a thyroid-related quality-of-life questionnaire at 1 year (range of each scale is 0 to 100, with higher scores indicating more symptoms or tiredness, respectively; minimum clinically important difference, 9 points).

RESULTS

The mean age of the patients was 74.4 years, and 396 patients (53.7%) were women. The mean (±SD) thyrotropin level was 6.40±2.01 mIU per liter at baseline; at 1 year, this level had decreased to 5.48 mIU per liter in the placebo group, as compared with 3.63 mIU per liter in the levothyroxine group (P<0.001), at a median dose of 50 μg. We found no differences in the mean change at 1 year in the Hypothyroid Symptoms score (0.2±15.3 in the placebo group and 0.2±14.4 in the levothyroxine group; between-group difference, 0.0; 95% confidence interval [CI], -2.0 to 2.1) or the Tiredness score (3.2±17.7 and 3.8±18.4, respectively; between-group difference, 0.4; 95% CI, -2.1 to 2.9). No beneficial effects of levothyroxine were seen on secondary-outcome measures. There was no significant excess of serious adverse events prespecified as being of special interest.

CONCLUSIONS

Levothyroxine provided no apparent benefits in older persons with subclinical hypothyroidism. (Funded by European Union FP7 and others; TRUST ClinicalTrials.gov number, NCT01660126 .).

Latent Hypothyroidism in Adults

BACKGROUND

The prevalence of latent/subclinical hypothyroidism is between 3% and 10%, according to epidemiologic studies that have been carried out in the USA, the United Kingdom, and Denmark. As persons with latent hypo - thyroidism are often asymptomatic, the diagnosis is often made incidentally in routine laboratory testing.

METHODS

This review is based on a selective search in PubMed for publications on the diagnosis and treatment of latent hypothyroidism. All pertinent articles and guidelines published from 1 January 2000 to 31 July 2016 were included.

RESULTS

The diagnosis of latent hypothyroidism is generally assigned after repeated measurement of a TSH concentration above 4.0 mU/L in a person whose fT4 concentration is in the normal range. The most common cause is autoimmune thyroiditis, which can be detected by a test for autoantibodies. L-thyroxin supplementation is a controversial matter: its purpose is to prevent the development of overt hypothyroidism, but there is a danger of overtreatment, which increases the risk of fracture. To date, no benefit of L-thyroxin supplementation has been demonstrated with respect to morbidity and mortality, health-related quality of life, mental health, cognitive function, or reduction of overweight. There is, however, evidence of a beneficial effect on cardiac function in women, and on the vascular system. At present, treatment is generally considered indicated only if the TSH level exceeds 10.0 mU/L.

CONCLUSION

Limited data are available on the relevant clinical endpoints and undesired side effects of supplementation therapy. Physicians should advise patients about the indications for such treatment on an individual basis after due consideration of the risks and benefits.