Current utility of first-line FT4 and TSH in screening for central hypothyroidism.

BACKGROUND: Thyroid testing strategies vary across laboratories. First-line combined thyroid stimulating hormone (TSH) and freeT4 (FT4) have historically been preferred by many laboratories as this detects individuals with undiagnosed central hypothyroidism who can be missed with a first-line TSH-only strategy. However, an up-to-date evaluation of the utility of this approach is lacking. OBJECTIVES: We investigated the clinical utility of first-line TSH and FT4 in the detection of central hypothyroidism in current day practice. DESIGN, PATIENTS, AND MEASUREMENTS: The All-Wales laboratory information system was queried to identify thyroid function tests in patients aged ≥16 years with decreased FT4 and inappropriate TSH (low-FT4). The 1-year incidence of low-FT4 was determined using mid-year population data. Clinical information of patients with low-FT4 was reviewed to determine causes of low-FT4 and the incidence of central hypothyroidism. RESULTS: The incidence of low-FT4 varied according to FT4 assay method (range: 98-301 cases/100,000 population/year). Fifteen new cases of central hypothyroidism were detected in two health boards, equivalent to 2 cases/100,000 population/year. Positive predictive value of low-FT4 for central hypothyroidism was 2%-4%. In a cross-section of primary care patients, low-FT4 was detected in 0.5% of all thyroid tests with assay-related differences in detection rates. CONCLUSIONS: Although low-FT4 is a common laboratory finding, the incidence of central hypothyroidism remains rare. With the currently increased rates of thyroid testing and increased use of medications that decrease FT4, low-FT4 has a much lower predictive value for central hypothyroidism than previously reported. Thyroid screening strategies will need to balance the yield from first line TSH and FT4 testing with the cost of investigating individuals with non-pathological laboratory abnormalities.

Use of liothyronine (T3) in hypothyroidism: Joint British Thyroid Association/Society for endocrinology consensus statement.

Persistent symptoms in patients treated for hypothyroidism are common. Despite more than 20 years of debate, the use of liothyronine for this indication remains controversial, as numerous randomised trials have failed to show a benefit of treatment regimens that combine liothyronine (T3) with levothyroxine over levothyroxine monotherapy. This consensus statement attempts to provide practical guidance to clinicians faced with patients who have persistent symptoms during thyroid hormone replacement therapy. It applies to non-pregnant adults and is focussed on care delivered within the UK National Health Service, although it may be relevant in other healthcare environments. The statement emphasises several key clinical practice points for patients dissatisfied with treatment for hypothyroidism. Firstly, it is important to establish a diagnosis of overt hypothyroidism; patients with persistent symptoms during thyroid hormone replacement but with no clear biochemical evidence of overt hypothyroidism should first have a trial without thyroid hormone replacement. In those with established overt hypothyroidism, levothyroxine doses should be optimised aiming for a TSH in the 0.3-2.0 mU/L range for 3 to 6 months before a therapeutic response can be assessed. In some patients, it may be acceptable to have serum TSH below reference range (e.g. 0.1-0.3 mU/L), but not fully suppressed in the long term. We suggest that for some patients with confirmed overt hypothyroidism and persistent symptoms who have had adequate treatment with levothyroxine and in whom other comorbidities have been excluded, a trial of liothyronine/levothyroxine combined therapy may be warranted. The decision to start treatment with liothyronine should be a shared decision between patient and clinician. However, individual clinicians should not feel obliged to start liothyronine or to continue liothyronine medication provided by other health care practitioners or accessed without medical advice, if they judge this not to be in the patient's best interest.

Late offspring effects of antenatal thyroid screening.

BACKGROUND: Thyroid dysfunction in pregnancy is associated with adverse offspring outcomes and recent birth-cohort studies suggest that even mild degrees of thyroid dysfunction may be linked with a range of late cognitive and behavioural effects in childhood and adolescence. SOURCES OF DATA: This review summarizes recent literature of observational studies and critically appraises randomized controlled trials (RCTs) of antenatal thyroid screening and Levothyroxine intervention. AREAS OF AGREEMENT: Overt hypothyroidism and hyperthyroidism carry significant risks for unfavourable offspring outcomes and should be appropriately corrected in pregnancy. AREAS OF CONTROVERSY: The significance of subclinical hypothyroidism and hypothyroxinaemia is still unclear. Meta-analyses of birth-cohort studies show associations of maternal subclinical hypothyroidism and hypothyroxinaemia with intellectual deficits, attention deficit hyperactivity disorder (ADHD) and autism spectrum disorders, while hyperthyroidism and high-normal FT4 were linked with ADHD. RCTs have shown no benefits of screening on neurodevelopmental outcomes although Levothyroxine could have been initiated too late in pregnancy in these trials. GROWING POINTS: A small number of studies have shown inconsistent associations of maternal thyroid dysfunction with offspring cardiometabolic indices including blood pressure and body weight. Correction of maternal thyroid dysfunction was, however, associated with favourable long-term metabolic profiles in mothers, including lipid profiles, fat mass and body mass index. Antenatal thyroid screening may therefore present opportunities for optimizing a wider range of outcomes than envisaged. AREAS FOR DEVELOPING RESEARCH: Future trials with early antenatal thyroid screening and intervention are necessary to clarify the impact of screening on late offspring and maternal effects.

Antithyroid drug therapy in pregnancy and risk of congenital anomalies: Systematic review and meta-analysis.

OBJECTIVES: The risk of congenital anomalies following in utero exposure to thionamide antithyroid drugs (ATDs) is unresolved. Observational studies are contradictory and existing meta-analyses predate and preclude more recent studies. We undertook an updated meta-analysis of congenital anomaly risk in women exposed to carbimazole or methimazole (CMZ/MMI), propylthiouracil (PTU), or untreated hyperthyroidism in pregnancy. METHODS: We searched Medline, Embase, and the Cochrane database for articles published up till August 2021. We pooled separate crude and adjusted risk estimates using random effects models and subgroup analyses to address heterogeneity. RESULTS: We identified 16 cohort studies comprising 5957, 15,785, and 15,666 exposures to CMZ/MMI, PTU, and untreated hyperthyroidism, respectively. Compared to nondisease controls, adjusted risk ratio (RR) and 95% confidence intervals (95% CIs) for congenital anomalies was increased for CMZ/MMI (RR, 1.28; 95% CI, 1.06-1.54) and PTU (RR, 1.16; 95% CI, 1.08-1.25). Crude risk for CMZ/MMI was increased relative to PTU (RR, 1.20; 95% CI, 1.01-1.43). Increased risk was also seen with exposure to both CMZ/MMI and PTU, that is, women who switched ATDs in pregnancy (RR, 1.51; 95% CI, 1.14-1.99). However, the timing of ATD switch was highly variable and included prepregnancy switches in some studies. The excess number of anomalies per 1000 live births was 17.2 for patients exposed to CMZ/MMI, 9.8, for PTU exposure, and 31.4 for exposure to both CMZ/MMI and PTU. Risk in the untreated group did not differ from control or ATD groups. The untreated group was however highly heterogeneous in terms of thyroid status. Subgroup analysis showed more positive associations in studies with >500 exposures and up to 1-year follow-up. CONCLUSIONS: ATD therapy carries a small risk of congenital anomalies which is higher for CMZ/MMI than for PTU and does not appear to be reduced by switching ATDs in pregnancy. Due to key limitations in the available data, further studies will be required to clarify the risks associated with untreated hyperthyroidism and with switching ATDs in pregnancy.

Trends in costs and prescribing for liothyronine and levothyroxine in England and wales 2011-2020.

INTRODUCTION: Recent prescribing policies in England and Wales have imposed significant restrictions on liothyronine prescribing in general practice driven by the prohibitive costs and uncertain benefits of liothyronine in the management of hypothyroidism. However, the impact of these policies on liothyronine usage and costs is still unclear. METHODS: Data were downloaded from the NHS monthly General Practice Prescribing Data in England and from the Comparative Analysis System for Prescribing Audit (CASPA) in Wales for 2011-2020. Trends over the period in amount and costs of levothyroxine and liothyronine prescribing were analysed. RESULTS: The total medication costs per year for England Wales for hypothyroidism rose from £60.8 million to £129.8 million in 2015-16 and have since reduced to £88.4 million. Levothyroxine prescriptions have been growing above the population growth rate at 0.7%/annum in England and 1.1% in Wales. The costs/patient/year for liothyronine rose from £550 to £3000 in 2015-16 and has since fallen to £2500. Use of liothyronine as a percentage of levothyroxine started to fall in 2015-16 at 7%/annum in England and 3% in Wales. Nevertheless, 0.5% of levothyroxine-treated patients continue to receive liothyronine. All Clinical Commission Groups (CCGs) in England continue to have at least one liothyronine prescribing practice and 48.5% of English general practices prescribed liothyronine in 2019-20. CONCLUSION: In spite of strenuous attempts to limit prescribing of liothyronine in general practice, a significant number of patients continue to receive this therapy. The price differential of liothyronine vs levothyroxine should be examined again in light of the continuing use of liothyronine.

Liothyronine and levothyroxine prescribing in England: A comprehensive survey and evaluation.

INTRODUCTION: The approach to thyroid hormone replacement varies across centres, but the extent and determinants of variation is unclear. We evaluated geographical variation in levothyroxine (LT4) and liothyronine (LT3) prescribing across General Practices in England and analysed the relationship of prescribing patterns to clinical and socioeconomic factors. METHODS: Data was downloaded from the NHS monthly General Practice Prescribing Data in England for the period 2011-2020. RESULTS: The study covered a population of 19.4 million women over 30 years of age, attending 6,660 GP practices and being provided with 33.7 million prescriptions of LT4 and LT3 at a total cost of £90million/year. Overall, 0.5% of levothyroxine treated patients continue to receive liothyronine. All Clinical Commission Groups (CCGs) in England continue to have at least one liothyronine prescribing practice and 48.5% of English general practices prescribed liothyronine in 2019-2020. Factors strongly influencing more levothyroxine prescribing (model accounted for 62% of variance) were the CCG to which the practice belonged and the proportion of people with diabetes registered on the practice list plus antidepressant prescribing, with socioeconomic disadvantage associated with less levothyroxine prescribing. Whereas factors that were associated with increased levels of liothyronine prescribing (model accounted for 17% of variance), were antidepressant prescribing and % of type 2 diabetes mellitus individuals achieving HbA1c control of 58 mmol/mol or less. Factors that were associated with reduced levels of liothyronine prescribing included smoking and higher obesity rates. CONCLUSION: In spite of strenuous attempts to limit prescribing of liothyronine in general practice a significant number of patients continue to receive this therapy, although there is significant geographical variation in the prescribing of this as for levothyroxine, with specific general practice and CCG-related factors influencing prescribing of both levothyroxine and liothyronine across England.

Is there a role for natural desiccated thyroid in the treatment of levothyroxine unresponsive hypothyroidism? Results from a consecutive case series.

INTRODUCTION: Some levothyroxine unresponsive individuals with hypothyroidism are prescribed a natural desiccated thyroid (NDT) preparation such as Armour Thyroid® or ERFA Thyroid® . These contain a mixture of levothyroxine and liothyronine in a fixed ratio. We evaluated the response to NDT in individuals at a single endocrine centre in terms of how the change from levothyroxine to NDT impacted on their lives in relation to quality of life (QOL) and thyroid symptoms. METHODS: The ThyPRO39 (thyroid symptomatology) and EQ-5D-5L-related QoL/EQ5D5L (generic QOL) questionnaires were administered to 31 consecutive patients who had been initiated on NDT, before initiating treatment/6 months later. RESULTS: There were 28 women and 3 men. The dose range of NDT was 60-180 mg daily. Age range was 26-77 years with length of time since diagnosis with hypothyroidism ranging from 2 to 40 years. One person discontinued the NDT because of lack of response; two because of cardiac symptoms. EQ-5D-5L utility increased from a mean (SD) of 0.214 (0.338) at baseline, to 0.606 (0.248) after 6 months; corresponding to a difference of 0.392 (95% CI 0.241-0.542), t = 6.82, P < .001. EQ-VAS scores increased from 33.4 (17.2) to 71.1 (17.5), a difference of 37.7 (95% CI 25.2-50.2), t = -4.9, P < .001. ThyPRO scores showed consistent fall across all domains with the composite QoL-impact Score improving from 68.3 (95% CI 60.9-75.7) to 25.2 (95% CI 18.7-31.7), a difference of 43.1 (95% CI 33-53.2) (t = 5.6, P < .001). CONCLUSION: Significant symptomatic benefit and improvement in QOL was experienced by people with a history of levothyroxine unresponsive hypothyroidism treated with NDT, suggesting the need for further evaluation of NDT in this context.

PITUITARY IMAGING BY MRI AND ITS CORRELATION WITH BIOCHEMICAL PARAMETERS IN THE EVALUATION OF MEN WITH HYPOGONADOTROPIC HYPOGONADISM.

Objective: A significant ambiguity still remains about which patient deserves a magnetic resonance imaging (MRI) scan of the pituitary during evaluation of hypogonadotropic hypogonadism (HH) in men. Methods: Retrospective case series of 175 men with HH referred over 6 years. Results: A total of 49.7% of men had total testosterone (TT) levels lower than the Endocrine Society threshold of 5.2 nmol/L. One-hundred forty-two patients (81.2%) had normal appearance of pituitary MRI, whereas others had different spectrum of abnormalities (empty sella [n = 16], macroadenoma [n = 8], microadenoma [n = 8], and pituitary cyst [n = 1]). In men with TT in the lowest quartile, MRI pituitary findings were not significantly different from men in the remaining quartiles (P = .50). Patients with raised prolactin had higher number of abnormal MRI findings (38.9% vs. 13.7%; P = .0014) and adenomatous lesions (macro and micro) (27.8% vs. 4.3%; P = .01) in comparison to men with normal prolactin. The prolactin levels (median [interquartile range]) were highest in men with macroadenomas in both groups (9,950 [915]; P = .007 and 300 [68.0] mU/L; P = .02, respectively), with concomitant lower levels of other pituitary hormones. Multivariate logistic regression showed an association of abnormal pituitary MRI with insulin-like growth factor 1 (IGF-1) standard deviation score (SDS) (odds ratio [OR], 1.78 [95% confidence interval (CI), 1.15 to 2.77]; P = .009) and prolactin (OR, 1.00 [95% CI, 1.00 to 1.03]; P = .01). Conclusion: MRI of the pituitary is not warranted in all patients with HH, as the yield of identifiable abnormalities is quite low. Anatomic lesions are likely to be present only when low levels of TT (<5.2 nmol/L) are found concomitantly with high levels of prolactin and/or low IGF-1 SDS. Abbreviations: CI = confidence interval; FT4 = free thyroxine; GH = growth hormone; HH = hypogonadotropic hypogonadism; IGF-1 = insulin-like growth factor; LH = luteinizing hormone; MRI = magnetic resonance imaging; OR = odds ratio; SDS = standard deviation score; TSH = thyroid-stimulating hormone; TT = total testosterone.

Preconception management of thyroid dysfunction.

Uncorrected thyroid dysfunction in pregnancy has well-recognized deleterious effects on foetal and maternal health. The early gestation period is one of the critical foetal vulnerability during which maternal thyroid dysfunction may have lasting repercussions. Accordingly, a pragmatic preconception strategy is key for ensuring optimal thyroid disease outcomes in pregnancy. Preconception planning in women with hypothyroidism should pre-empt and mirror the adaptive changes in the thyroid gland by careful levothyroxine dose adjustments to ensure adequate foetal thyroid hormone delivery in pregnancy. In hyperthyroidism, the goal of preconception therapy is to control hyperthyroidism while curtailing the unwanted side effects of foetal and maternal exposure to antithyroid drugs. Thus, pregnancy should be deferred until a stable euthyroid state is achieved, and definitive therapy with radioiodine or surgery should be considered in women with Graves' disease planning future pregnancy. Women with active disease who are imminently trying to conceive should be switched to propylthiouracil either preconception or at conception in order to minimize the risk of birth defects from carbimazole or methimazole exposure. Optimal strategies for women with borderline states of thyroid dysfunction namely subclinical hypothyroidism, isolated hypothyroxinaemia and thyroid autoimmunity remain uncertain due to the dearth of controlled interventional trials. Future trial designs should aspire to recruit and initiate therapy before conception or as early as possible in pregnancy.

SEASONAL VARIATION OF VITAMIN D AND SERUM THYROTROPIN LEVELS AND ITS RELATIONSHIP IN A EUTHYROID CAUCASIAN POPULATION.

OBJECTIVE: It is unclear whether seasonal variations in vitamin D concentrations affect the hypothalamo-pituitary-thyroid axis. We investigated the seasonal variability of vitamin D and serum thyrotropin (TSH) levels and their interrelationship. METHODS: Analysis of 401 patients referred with nonspecific symptoms of tiredness who had simultaneous measurements of 25-hydroxyvitamin D3 (25[OH]D3) and thyroid function. Patients were categorized according to the season of blood sampling and their vitamin D status. RESULTS: 25(OH)D3 levels were higher in spring-summer season compared to autumn-winter (47.9 ± 22.2 nmol/L vs. 42.8 ± 21.8 nmol/L; P = .02). Higher median (interquartile range) TSH levels were found in autumn-winter (1.9 [1.2] mU/L vs. 1.8 [1.1] mU/L; P = .10). Across different seasons, 25(OH)D3 levels were observed to be higher in lower quartiles of TSH, and the inverse relationship was maintained uniformly in the higher quartiles of TSH. An independent inverse relationship could be established between 25(OH)D3 levels and TSH by regression analysis across both season groups (autumn-winter: r = -0.0248; P<.00001 and spring-summer: r = -0.0209; P<.00001). We also observed that TSH varied according to 25(OH)D3 status, with higher TSH found in patients with vitamin D insufficiency or deficiency in comparison to patients who had sufficient or optimal levels across different seasons. CONCLUSION: Our study shows seasonal variability in 25(OH)D3 production and TSH secretion in euthyroid subjects and that an inverse relationship exists between them. Further studies are needed to see if vitamin D replacement would be beneficial in patients with borderline thyroid function abnormalities. ABBREVIATIONS: 25(OH)D2 = 25-hydroxyvitamin D2; 25(OH)D3 = 25-hydroxyvitamin D3; AITD = autoimmune thyroid disease; FT4 = free thyroxine; TFT = thyroid function test; TSH = thyrotropin; UVB = ultraviolet B.

Management of primary hypothyroidism: statement by the British Thyroid Association Executive Committee.

The management of primary hypothyroidism with levothyroxine (L-T4) is simple, effective and safe, and most patients report improved well-being on initiation of treatment. However, a proportion of individuals continue to suffer with symptoms despite achieving adequate biochemical correction. The management of such individuals has been the subject of controversy and of considerable public interest. The American Thyroid Association (ATA) and the European Thyroid Association (ETA) have recently published guidelines on the diagnosis and management of hypothyroidism. These guidelines have been based on extensive reviews of the medical literature and include sections on the role of combination therapy with L-T4 and liothyronine (L-T3) in individuals who are persistently dissatisfied with L-T4 therapy. This position statement by the British Thyroid Association (BTA) summarises the key points in these guidelines and makes recommendations on the management of primary hypothyroidism based on the current literature, review of the published positions of the ETA and ATA, and in line with best principles of good medical practice. The statement is endorsed by the Association of Clinical Biochemistry, (ACB), British Thyroid Foundation, (BTF), Royal College of Physicians (RCP) and Society for Endocrinology (SFE).

Recent trends in thyroid surgery in Wales.

INTRODUCTION: Our objective was to analyse trends in thyroid surgery in Wales over a recent 12-year period. METHODS: Details of patients who underwent thyroid surgery across Wales from 1999 to 2010 were analysed from the Patient Episodes Database for Wales [n = 6570, 83% (5429) female, 86% (5634) benign thyroid disease]. We determined age-adjusted thyroidectomy rates from the European standard population and a Poisson regression model was fitted to assess temporal trends. Joinpoint regression was used to calculate annual percentage change (APC) in thyroidectomy rates. RESULTS: An increase in thyroidectomy rates was observed for malignant disease [APC 4.5, 95% confidence interval (CI) 1.6-7.5] while surgery rates for benign disease declined over the period (APC -3.2, 95% CI -5.1 to -1.3). The use of total thyroidectomy rose from 17% (599/3501) in 1999-2004 to 30% (912/3069) in 2005-2010 (p < 0.001). Total thyroidectomies were performed in a higher proportion of males than females [26% (291/1141) vs. 22% (1220/5429), p = 0.03] and in a greater percentage of patients with malignant disease than benign [36% (337/936) vs. 21% (1174/5634), p < 0.001). General surgeons undertook 83% of thyroid surgery but with a growing involvement of ENT surgeons. Regional disparities were seen in the type of surgery offered to patients with benign thyroid disease. CONCLUSION: The use of total thyroidectomy for benign and malignant thyroid disease has risen in Wales. The increase in surgeries performed for malignancy would support a rising incidence of thyroid cancer in the region. Regional disparities in choice of surgery for benign disease require further exploration.

Controlled Antenatal Thyroid Screening Study III: Effects of gestational thyroid status on adolescent brain morphology.

CONTEXT: Children born to mothers with gestational hypo- or hyperthyroidism may have increased risk of adverse neurodevelopmental outcomes. However, the effects of maternal thyroid status on offspring brain development are unclear. OBJECTIVE: To establish whether adolescent brain morphology is affected by suboptimal gestational thyroid function (SGTF). DESIGN AND SETTING: The Controlled Antenatal Thyroid Screening (CATS) study randomized mothers with SGTF to levothyroxine or no supplementation from ∼12 weeks' gestation. At age 9, children born to mothers who were over-treated with levothyroxine had a higher risk of conduct and hyperactivity traits. For the current CATS III study, children underwent neuroimaging studies, including T1-weighted structural magnetic resonance imaging (MRI). PARTICIPANTS: A total of 85 children aged 11-16 years had usable T1-weighted MRI data (exposed to untreated SGTF (n=21), normal GTF (n=24), or treated SGTF (optimally-treated (n=21), over-treated (n=20)). MAIN OUTCOME MEASURES: Primary outcome: to examine the association of SGTF and its treatment with global brain volumes. Secondary and exploratory outcomes: to investigate the association of maternal TSH and free T4 levels with global and subregional brain volumes. Results were adjusted for age, sex and pubertal scores. RESULTS: There were no significant differences in global brain volumetric measures between groups, including total gray matter volume (p=0.373). Weak positive correlations were found between maternal TSH, but not FT4, levels and several brain volumes, but these did not survive testing for multiple comparisons. CONCLUSIONS: We found no evidence that SGTF was associated with differences in adolescent brain morphology, and no impact of levothyroxine supplementation.

Non-thionamide antithyroid drug options in Graves' hyperthyroidism.

INTRODUCTION: The thionamide anti-thyroid drugs namely carbimazole, methimazole, and propylthiouracil, have been the predominant therapy modality for Graves' hyperthyroidism for over 60 years. Although these agents have proven efficacy and favorable side-effect profiles, non-thionamide alternatives are occasionally indicated in patients who are intolerant or unresponsive to thionamides alone. This review examines the available non-thionamide drug options for the control of Graves' hyperthyroidism and summarizes their clinical utility, efficacy, and limitations. AREAS COVERED: We reviewed existing literature on mechanisms, therapeutic utility, and side-effect profiles of non-thionamide anti-thyroid drugs. Established non-thionamide agents act on various phases of the synthesis, release, and metabolism of thyroid hormones and comprise historical agents such as iodine compounds and potassium perchlorate as well as drug repurposing candidates like lithium, glucocorticoids, beta-blockers, and cholestyramine. Novel experimental agents in development target key players in Graves' disease pathogenesis including B-cell depletors (Rituximab), CD40 blockers (Iscalimab), TSH-receptor antagonists, blocking antibodies, and immune-modifying peptides. EXPERT OPINION: Non-thionamide anti-thyroid drugs are useful alternatives in Graves' hyperthyroidism and more clinical trials are needed to establish their safety and long-term efficacy in hyperthyroidism control. Ultimately, the promise for a cure will lie in novel approaches that target the well-established immunopathogenesis of Graves' disease.

Preconception Management of Hyperthyroidism and Thyroid Status in Subsequent Pregnancy: A Population-Based Cohort Study.

CONTEXT: Optimal thyroid status in pregnancy is essential in reducing the risk of adverse outcomes. The management of hyperthyroidism in women of reproductive age poses unique challenges and it is unclear how preconception treatment strategies impact on thyroid status in subsequent pregnancy. OBJECTIVE: We aimed to determine trends in the management of hyperthyroidism before and during pregnancy and to assess the impact of different preconception treatment strategies on maternal thyroid status. METHODS: We utilized the Clinical Practice Research Datalink database to evaluate all females aged 15-45 years with a clinical diagnosis of hyperthyroidism and a subsequent pregnancy (January 2000 to December 2017). We compared thyroid status in pregnancy according to preconception treatment, namely, (1) antithyroid drugs up to or beyond pregnancy onset, (2) definitive treatment with thyroidectomy or radioiodine before pregnancy, and (3) no treatment at pregnancy onset. RESULTS: Our study cohort comprised 4712 pregnancies. Thyrotropin (TSH) was measured in only 53.1% of pregnancies, of which 28.1% showed suboptimal thyroid status (TSH >4.0 mU/L or TSH <0.1 mU/L plus FT4 >reference range). Pregnancies with prior definitive treatment were more likely to have suboptimal thyroid status compared with pregnancies starting during antithyroid drug treatment (odds ratio 4.72, 95% CI 3.50-6.36). A steady decline in the use of definitive treatment before pregnancy was observed from 2000 to 2017. One-third (32.6%) of first trimester carbimazole-exposed pregnancies were switched to propylthiouracil while 6.0% of propylthiouracil-exposed pregnancies switched to carbimazole. CONCLUSION: The management of women with hyperthyroidism who become pregnant is suboptimal, particularly in those with preconception definitive treatment, and needs urgent improvement. Better thyroid monitoring and prenatal counseling are needed to optimize thyroid status, reduce teratogenic drug exposure, and ultimately reduce the risk of adverse pregnancy outcomes.

Age-related variation in thyroid function - a narrative review highlighting important implications for research and clinical practice.

BACKGROUND: Thyroid hormones are key determinants of health and well-being. Normal thyroid function is defined according to the standard 95% confidence interval of the disease-free population. Such standard laboratory reference intervals are widely applied in research and clinical practice, irrespective of age. However, thyroid hormones vary with age and current reference intervals may not be appropriate across all age groups. In this review, we summarize the recent literature on age-related variation in thyroid function and discuss important implications of such variation for research and clinical practice. MAIN TEXT: There is now substantial evidence that normal thyroid status changes with age throughout the course of life. Thyroid stimulating hormone (TSH) concentrations are higher at the extremes of life and show a U-shaped longitudinal trend in iodine sufficient Caucasian populations. Free triiodothyronine (FT3) levels fall with age and appear to play a role in pubertal development, during which it shows a strong relationship with fat mass. Furthermore, the aging process exerts differential effects on the health consequences of thyroid hormone variations. Older individuals with declining thyroid function appear to have survival advantages compared to individuals with normal or high-normal thyroid function. In contrast younger or middle-aged individuals with low-normal thyroid function suffer an increased risk of adverse cardiovascular and metabolic outcomes while those with high-normal function have adverse bone outcomes including osteoporosis and fractures. CONCLUSION: Thyroid hormone reference intervals have differential effects across age groups. Current reference ranges could potentially lead to inappropriate treatment in older individuals but on the other hand could result in missed opportunities for risk factor modification in the younger and middle-aged groups. Further studies are now needed to determine the validity of age-appropriate reference intervals and to understand the impact of thyroid hormone variations in younger individuals.

Cardiovascular morbidity and mortality in patients in Wales, UK with resistance to thyroid hormone ß (RTHß): a linked-record cohort study.

BACKGROUND: Individuals with resistance to thyroid hormone owing to mutations in the thyroid hormone receptor ß gene (RTHß) exhibit impaired tissue sensitivity to thyroid hormones, but retain sensitivity in cardiac tissue. Long-term health and survival outcomes in this rare disorder have not been evaluated. We investigated all-cause mortality and cardiovascular event risk in a cohort of patients with RTHß, followed-up in UK endocrine clinics. METHODS: In a retrospective cohort design, we linked genetically confirmed patients with RTHß and age-matched and sex-matched population controls to outcomes in datasets within the Welsh Secure Anonymised Information Linkage (SAIL) Databank. Kaplan-Meier and Cox regression models analysed associations of RTHß with all-cause mortality and cardiovascular events. FINDINGS: We identified 61 patients with a genetic diagnosis of RTHß between Jan 1, 1997, and Dec 31, 2019, and matched them with 2750 controls. Compared with controls, patients exhibited increased risks for all-cause mortality (hazard ratio [HR] 2·84, 95% CI 1·59-5·08), atrial fibrillation (10·56, 4·72-23·63), heart failure (HR 6·35, 95% CI 2·26-17·86), and major adverse cardiovascular events (MACE), comprising cardiovascular death, acute myocardial infarction, heart failure, or strokes (HR 3·49, 95% CI 2·04-5·99). The median age of first occurrence of any adverse event was 11 years earlier in patients (56 years, 95% CI 44-65) compared with controls (67 years, 65-70). Cubic spline analyses showed positive associations between FT4 concentrations at diagnosis and mortality or MACE, with FT4 concentration of 30 pmol/L or greater conferring increased risk. Compared with no intervention, treatment with antithyroid drugs, surgery or radioiodine gland ablation, or thyroxine did not control thyroid hormone excess. INTERPRETATION: We have documented reduced survival and increased cardiovascular morbidity in a cohort of patients with RTHß for the first time. These outcomes might be driven by lifelong cardiac exposure to thyroid hormone excess; and effective therapies, targeting hormone resistant pathways, could potentially curtail this risk. FUNDING: Royal College of Physicians, Wellcome Trust Investigator Award, and NIHR Cambridge Biomedical Research Centre.

Designing a combined liothyronine (LT3), L- thyroxine (LT4) trial in symptomatic hypothyroid subjects on LT4 - the importance of patient selection, choice of LT3 and trial design.

Approximately 10%-15% of subjects with hypothyroidism on L-thyroxine (LT4) alone have persistent symptoms affecting their quality of life (QoL). Although the cause is unclear, there is evidence that "tissue T3 lack" may be responsible. If so, combining liothyronine (LT3) with LT4 would be helpful. However, randomized controlled trials (RCT), have not established greater efficacy for the LT3 + LT4 combination in these subjects than for LT4 alone. While the trial design may have been responsible, the use of unphysiological, short-acting LT3 preparations and non-thyroid-specific patient-reported outcome measures (PROMs) may have contributed. We recommend attention to the following aspects of trial design for future RCTs of LT3 + LT4 compared to LT4 alone: (a) Subject selection-(i) measurable symptoms (disadvantages should be recognized); (ii) using a validated thyroid specific PROM such as ThyPRO39 or the Composite scale derived from it; (iii) those taking over 1.2 µg/day or 100 µg/day (for pragmatic reasons) of LT4 defining a population likely without intrinsic thyroid activity who depend on exogenous LT4; (iv) recruiting a preponderance of subjects with autoimmune thyroiditis increasing generalisability; and (v) those with a high symptom load with a greater response to combination therapy e.g. those with the deiodinase 2 polymorphism. (b) The use of physiological LT3 preparations producing pharmacokinetic similarities to T3 profiles in unaffected subjects: two long-acting LT3 preparations are currently available and must be tested in phase 2b/3 RCTs. (c) The superiority of a crossover design in limiting numbers and costs while maintaining statistical power and ensuring that all subjects experienced the investigative medication.

Gut Microbiome Associated With Graves Disease and Graves Orbitopathy: The INDIGO Multicenter European Study.

CONTEXT: Gut bacteria can influence host immune responses but little is known about their role in tolerance-loss mechanisms in Graves disease (GD; hyperthyroidism caused by autoantibodies, TRAb, to the thyrotropin receptor, TSHR) and its progression to Graves orbitopathy (GO). OBJECTIVE: This work aimed to compare the fecal microbiota in GD patients, with GO of varying severity, and healthy controls (HCs). METHODS: Patients were recruited from 4 European countries (105 GD patients, 41 HCs) for an observational study with cross-sectional and longitudinal components. RESULTS: At recruitment, when patients were hyperthyroid and TRAb positive, Actinobacteria were significantly increased and Bacteroidetes significantly decreased in GD/GO compared with HCs. The Firmicutes to Bacteroidetes (F:B) ratio was significantly higher in GD/GO than in HCs. Differential abundance of 15 genera was observed in patients, being most skewed in mild GO. Bacteroides displayed positive and negative correlations with TSH and free thyroxine, respectively, and was also significantly associated with smoking in GO; smoking is a risk factor for GO but not GD. Longitudinal analyses revealed that the presence of certain bacteria (Clostridiales) at diagnosis correlated with the persistence of TRAb more than 200 days after commencing antithyroid drug treatment. CONCLUSION: The increased F:B ratio observed in GD/GO mirrors our finding in a murine model comparing TSHR-immunized with control mice. We defined a microbiome signature and identified changes associated with autoimmunity as distinct from those due to hyperthyroidism. Persistence of TRAb is predictive of relapse; identification of these patients at diagnosis, via their microbiome, could improve management with potential to eradicate Clostridiales.