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.

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.

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

BACKGROUND

Individuals with resistance to thyroid hormone owing to mutations in the thyroid hormone receptor β gene (RTHβ) 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 RTHβ, followed-up in UK endocrine clinics.

METHODS

In a retrospective cohort design, we linked genetically confirmed patients with RTHβ 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 RTHβ with all-cause mortality and cardiovascular events.

FINDINGS

We identified 61 patients with a genetic diagnosis of RTHβ 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 RTHβ 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.

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.

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.

Thyroid Autoimmunity and Dysfunction in Sri Lankan Children and Adolescents After 22 Years of Sustained Universal Salt Iodization

Background: Sri Lanka introduced universal salt iodization (USI) in 1995 after which we demonstrated a high thyroglobulin antibody (TgAb) prevalence in 1998. However, it is unclear whether thyroid autoimmunity persists in the long term in populations exposed to sustained USI and whether such populations have an excess of thyroid dysfunction. We evaluated the prevalence of thyroid autoantibodies and dysfunction in Sri Lankan children and adolescents after more than two decades of sustained USI. Methods: We selected 10- to 18-year-old subjects of both sexes (randomized cluster sampling) from all 9 provinces of Sri Lanka in this cross-sectional study. Blood, urine, and anthropometric data were collected and thyroid ultrasound scans were performed. Validated statistical methods were used to derive local population-specific reference ranges for all thyroid parameters. We also measured urine iodine concentration (UIC), salt, and water iodine concentrations. Results: Blood and urine samples from 2507 and 2473 subjects respectively, and ultrasound scans from 882 subjects were analyzed. Population-derived upper limits for thyroid peroxidase antibody (TPOAb) and TgAb, and reference ranges for triiodothyronine, thyroxine, and thyrotropin (total and age-year-related groups) were significantly different from manufacturer's reference ranges. Using these derived ranges, the prevalence of TPOAb was 10.3% and TgAb was 6.4%. Of the TPOAb-positive subjects, TPOAb were of low concentration in 66.2% (1-3 times the upper limit of the reference range [ULRR]) and showed the strongest association with subclinical hypothyroidism (SCH) at the highest concentrations (>4 ULRR). The prevalence of SCH was 3%. Median UIC (interquartile range) was 138.5 μg/L (79.4-219.0) with regional variability, and median thyroglobulin was 8.3 ng/mL (4.1-13.5). Goiter prevalence was 0.6% and 1.93% (thyroid volume compared to age and body surface area, respectively). Salt and water iodine concentrations were satisfactory. Conclusions: Sri Lanka has safely and effectively implemented USI with good sources of iodine, leading to sustained iodine sufficiency over more than two decades. The early postiodization TgAb surge (42.1%) has settled (6.4%), and despite a persistently high TPOAb prevalence (10.3%), SCH prevalence remains low (3%). Further studies should be undertaken to monitor thyroid autoimmune dysfunction in Sri Lankan children, using age-specific, population-derived reference ranges.

Method-dependent variation in TSH and FT4 reference intervals in pregnancy: A systematic review

BACKGROUND

Gestational TSH and FT4 reference intervals may differ according to assay method, but the extent of variation is unclear and has not been systematically evaluated. We conducted a systematic review of published studies on TSH and FT4 reference intervals in pregnancy. Our aim was to quantify method-related differences in gestation reference intervals, across four commonly used assay methods, Abbott, Beckman, Roche and Siemens.

METHODS

We searched the literature for relevant studies, published between January 2000 and December 2020, in healthy pregnant women without thyroid antibodies or disease. For each study, we extracted trimester-specific reference intervals (2.5-97.5 percentiles) for TSH and FT4 as well as the manufacturer-provided reference interval for the corresponding non-pregnant population.

RESULTS

TSH reference intervals showed a wide range of study-to-study differences with upper limits ranging from 2.33 to 8.30 mU/L. FT4 lower limits ranged from 4.40 to 13.93 pmol/L, with consistently lower reference intervals observed with the Beckman method. Differences between non-pregnant and first trimester reference intervals were highly variable, and for most studies, the TSH upper limit in the first trimester could not be predicted or extrapolated from non-pregnant values.

CONCLUSIONS

Our study confirms significant intra- and intermethod disparities in gestational thyroid hormone reference intervals. The relationship between pregnant and non-pregnant values is inconsistent and does not support the existing practice in many laboratories of extrapolating gestation references from non-pregnant values. Laboratories should invest in deriving method-specific gestation reference intervals for their population.

Asymmetry indicates more severe and active disease in Graves' orbitopathy: results from a prospective cross-sectional multicentre study

PURPOSE

Patients with Graves' orbitopathy can present with asymmetric disease. The aim of this study was to identify clinical characteristics that distinguish asymmetric from unilateral and symmetric Graves' orbitopathy.

METHODS

This was a multi-centre study of new referrals to 13 European Group on Graves' Orbitopathy (EUGOGO) tertiary centres. New patients presenting over a 4 month period with a diagnosis of Graves' orbitopathy were included. Patient demographics were collected and a clinical examination was performed based on a previously published protocol. Patients were categorized as having asymmetric, symmetric, and unilateral Graves' orbitopathy. The distribution of clinical characteristics among the three groups was documented.

RESULTS

The asymmetric group (n = 83), was older than the symmetric (n = 157) group [mean age 50.9 years (SD 13.9) vs 45.8 (SD 13.5), p = 0.019], had a lower female to male ratio than the symmetric and unilateral (n = 29) groups (1.6 vs 5.0 vs 8.7, p < 0.001), had more active disease than the symmetric and unilateral groups [mean linical Activity Score 3.0 (SD 1.6) vs 1.7 (SD 1.7), p < 0.001 vs 1.3 (SD 1.4), p < 0.001] and significantly more severe disease than the symmetric and unilateral groups, as measured by the Total Eye Score [mean 8.8 (SD 6.6) vs 5.3 (SD 4.4), p < 0.001, vs 2.7 (SD 2.1), p < 0.001].

CONCLUSION

Older age, lower female to male ratio, more severe, and more active disease cluster around asymmetric Graves' orbitopathy. Asymmetry appears to be a marker of more severe and more active disease than other presentations. This simple clinical parameter present at first presentation to tertiary centres may be valuable to clinicians who manage such patients.

Current controversies in the management of Graves' hyperthyroidism

Introduction: The management of Graves' disease centers on the use of effective and well-established therapies, namely thionamide antithyroid drugs, radioactive iodine, and thyroidectomy. Optimal treatment strategies are however controversial and vary significantly across centers.Areas covered: This review addresses specific controversies in Graves' disease management including the choice of primary therapy, the approach to women planning pregnancy, and optimal strategies for antithyroid drug and radioiodine therapy.Expert opinion: Important considerations in choosing therapy include treatment efficacy, adverse effects, patient convenience, and resource settings. Recent data suggest that early and effective control of hyperthyroidism is key to improving cardiovascular morbidity and mortality. Studies addressing cancer risk in radioiodine-treated patients face methodological challenges and require clarification in appropriately designed studies. Remission rates with antithyroid drugs are comparable when thionamides are used alone (titration-regimen) or in combination with levothyroxine (block and replace) and can be optimized by extending treatment for at least 12-18 months. Fixed and calculated radioiodine activity regimens are both effective but entail a trade-off between convenience and precision in the administered activity. Optimal preconception strategies are still evolving but ablative treatment in advance of pregnancy offers the most pragmatic means of reducing adverse effects of hyperthyroidism in subsequent pregnancy.

Safety of antithyroid drugs in pregnancy: update and therapy implications

Introduction: The thionamide antithyroid drugs, methimazole (MMI), its pro-drug derivative carbimazole (CMZ), and propylthiouracil (PTU) are the mainstay of treatment for hyperthyroidism in pregnancy. However, antithyroid drugs carry risks of adverse effects that can affect fetal and maternal well-being.Areas covered: This review provides an update on the safety of antithyroid drugs in pregnancy, focusing on the most serious concerns of severe liver disease and congenital anomalies.Expert opinion: PTU-induced liver disease is uncommon but can run a catastrophic course in pregnancy with a risk of liver failure and threats to maternal or fetal survival. Acute pancreatitis is a relatively rare occurrence that has been linked to thionamide use in a handful of reports in non-pregnant individuals. Observational studies on the risk of birth defects with antithyroid drug exposure in pregnancy overall show an increase in birth defect risk with exposure to CMZ/MMI, and to a lesser extent, PTU. Further studies are required to determine whether the currently recommended approach of switching between thionamide drugs in pregnancy improves outcomes. Ultimately, a preventative strategy of offering definitive therapy to hyperthyroid women of childbearing potential offers the best approach to truly reduce the risks of antithyroid drug adverse effects in pregnancy.

Should radioiodine now be first line treatment for Graves' disease?

Background

Radioiodine represents a cost-effective treatment option for Graves’ disease. In the UK, it is traditionally reserved for patients who relapse after initial thionamide therapy. In a change from current practice, the new guidelines of the National Institute for Health and Care Excellence (NICE) recommends that radioiodine should now be first line therapy for Graves’ disease. However, the safety of radioiodine with respect to long-term mortality risk has been the subject of recent debate. This analysis examines evidence from treatment related mortality studies in hyperthyroidism and discusses their implications for future Graves’ disease treatment strategies.

Main body

Some studies have suggested an excess mortality in radioiodine treated cohorts compared to the background population. In particular, a recent observational study reported a modest increase in cancer-related mortality in hyperthyroid patients exposed to radioiodine. The interpretation of these studies is however constrained by study designs that lacked thionamide control groups or information on thyroid status and so could not distinguish the effect of treatment from disease. Two studies have shown survival advantages of radioiodine over thionamide therapy, but these benefits were only seen when radioiodine was successful in controlling hyperthyroidism. Notably, increased mortality was associated with uncontrolled hyperthyroidism irrespective of therapy modality.

Conclusions

Early radioiodine treatment will potentially reduce mortality and should be offered to patients with severe disease. However, thionamides are still suitable for patients with milder disease, contraindications to radioiodine, or individuals who choose to avoid permanent hypothyroidism. Ultimately, a patient individualised approach that prioritises early and sustained control of hyperthyroidism will improve long-term outcomes regardless of the therapy modality used.

Primary therapy of Graves' disease and cardiovascular morbidity and mortality: a linked-record cohort study

BACKGROUND

Graves' disease is routinely treated with antithyroid drugs, radioiodine, or surgery, but whether the choice of initial therapy influences long-term outcomes is uncertain. We evaluated cardiovascular morbidity and mortality according to the method and effectiveness of primary therapy in Graves' disease.

METHODS

In this retrospective cohort study, we identified patients with hyperthyroidism, diagnosed between Jan 1, 1998, and Dec 31, 2013, from a thyroid-stimulating hormone (TSH)-receptor antibody (TRAb) test register in south Wales, UK, and imported their clinical data into the All-Wales Secure Anonymised Information Linkage (SAIL) Databank (Swansea University, Swansea, UK). Patients with Graves' disease, defined by positive TRAb tests, were selected for the study, and their clinical data were linked with outcomes in SAIL. We had no exclusion criteria. Patients were matched by age and sex to a control population (1:4) in the SAIL database. Patients were grouped by treatment within 1 year of diagnosis into the antithyroid drug group, radioiodine with resolved hyperthyroidism group (radioiodine group A), or radioiodine with unresolved hyperthyroidism group (radioiodine group B). We used landmark Kaplan-Meier and Cox regression models to analyse the association of treatment with the primary outcome of all-cause mortality and the secondary outcome of major adverse cardiovascular events (myocardial infarction, heart failure, ischaemic stroke, or death) with the landmark set at 1 year after diagnosis. We analysed the association between outcomes and concentration of TSH using Cox regression and outcomes and free thyroxine (FT4) concentration using restricted cubic-spline regression models.

FINDINGS

We extracted patient-level data on 4189 patients (3414 [81·5%] females and 775 [18·5%] males) with Graves' disease and 16 756 controls (13 656 [81·5%] females and 3100 [18·5%] males). In landmark analyses, 3587 patients were in the antithyroid drug group, 250 were in radioiodine group A, 182 were in radioiodine group B. Patients had increased all-cause mortality compared with controls (hazard ratio [HR] 1·22, 95% CI 1·05-1·42). Compared with patients in the antithyroid drug group, mortality was lower among those in radioiodine group A (HR 0·50, 95% CI 0·29-0·85), but not for those in radioiodine group B (HR 1·51, 95% CI 0·96-2·37). Persistently low TSH concentrations at 1 year after diagnosis were associated with increased mortality independent of treatment method (HR 1·55, 95% CI 1·08-2·24). Spline regressions showed a positive non-linear relationship between FT4 concentrations at 1 year and all-cause mortality.

INTERPRETATION

Regardless of the method of treatment, early and effective control of hyperthyroidism among patients with Graves' disease is associated with improved survival compared with less effective control. Rapid and sustained control of hyperthyroidism should be prioritised in the management of Graves' disease and early definitive treatment with radioiodine should be offered to patients who are unlikely to achieve remission with antithyroid drugs alone.

FUNDING

National Institute for Social Care and Health Research, Wales.

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.

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.

Attitudes and perceptions of health professionals towards management of hypothyroidism in general practice: a qualitative interview study

OBJECTIVE

To explore the attitudes and perceptions of health professionals towards management of hypothyroidism that contributes to the suboptimal treatment of hypothyroidism in general practice.

DESIGN

A qualitative interview study using semistructured interviews.

PARTICIPANTS

Sixteen participants were interviewed between March and August 2016 comprising nine general practitioners (GPs), four pharmacists, two practice nurses and one nurse practitioner.

SETTING

General practice and community pharmacies in the counties of Northumberland, Tyne and Wear, Stockton-on-Tees and North Cumbria, North of England, UK.

METHOD

A grounded-theory approach was used to generate themes from interviews, which were underpinned by the theory of planned behaviour to give explanation to the data.

RESULTS

Although health professionals felt that hypothyroidism was easy to manage, GPs and nurses generally revealed inadequate knowledge of medication interactions and levothyroxine pharmacokinetics. Pharmacists felt limited in the advice that they provide to patients due to lack of access to patient records. Most GPs and nurses followed local guidelines, and relied on blood tests over clinical symptoms to adjust levothyroxine dose. The information exchanged between professional and patient was usually restricted by time and often centred on symptoms rather than patient education. Health professionals felt that incorrect levothyroxine adherence was the main reason behind suboptimal treatment, although other factors such as comorbidity and concomitant medication were mentioned. Enablers perceived by health professionals to improve the management of hypothyroidism included continuity of care, blood test reminders, system alerts for interfering medications and prescription renewal, and accessible blood tests and levothyroxine prescriptions for patients.

CONCLUSION

There is a significant health professional behavioural component to the management of hypothyroidism. Addressing the differences in patient and professional knowledge and perceptions could reduce the barriers to optimal treatment, while continuity of care and increased involvement of pharmacists and practice nurses would help to promote optimal thyroid replacement.

Current challenges in the pharmacological management of thyroid dysfunction in pregnancy

INTRODUCTION

Thyroid dysfunction is common in pregnancy and has adverse fetal and maternal health consequences. A number of challenges in the management of gestational thyroid dysfunction remain unresolved including uncertainties in optimal thresholds for correction of hypothyroidism and strategies for pharmacological management of hyperthyroidism. Areas covered: We addressed key challenges and areas of uncertainty in the management of thyroid dysfunction in pregnancy. Expert commentary: Gestational thyroid hormone reference intervals vary according to population ethnicity, iodine nutrition, and assay method and each population should derive trimester specific reference intervals for use in pregnancy. Subclinical hypothyroidism and isolated hypothyroxinaemia are common in pregnancy but there is no consensus on the benefits of correcting these conditions. Although observational studies show potential benefits of levothyroxine on child neurocognitive function these benefits are have not been supported by two controlled trials. Carbimazole should be avoided in the first trimester of pregnancy due to risk of congenital anomalies but recent studies would suggest that this risk is present to a lesser magnitude with propylthiouracil. Current international guidelines recommend the use of propylthiouracil in the first trimester and switching to carbimazole for the remainder of pregnancy but the benefits and practicalities of this approach is unproven.

Current trends in antithyroid drug treatment of Graves' disease

INTRODUCTION

Graves' hyperthyroidism is associated with significant morbidity and mortality risk. The thionamides, methimazole, its pro-drug derivative carbimazole, and propylthiouracil, remain a cornerstone of management. Yet despite decades of use, optimal strategies for maximising treatment response and curtailing adverse effect risk remains uncertain.

AREAS COVERED

We reviewed the current literature on the evidence based medical management of Graves' disease. Specifically, we evaluated current approaches to the use of thionamides, adjunctive therapies, and potential novel agents for controlling Graves' hyperthyroidism.

EXPERT OPINION

Primary medical therapy is successful in less than 50% of cases and so careful selection of patients for medical treatment based on a combination of pathological and pragmatic considerations is essential. Carbimazole or methimazole is the treatment of choice in the non-pregnant population driven by its more favourable pharmacokinetic and adverse effect profile over propylthiouracil. In pregnancy the choice of treatment is less straightforward and an approach that minimises undue fetal exposure to all thionamides should be adopted. Additional data is needed on the value of adjunctive therapies including potassium perchlorate, iodides, glucocorticoids, lithium, and cholestyramine. Novel agents directed against pathogenetic targets including TSH receptor blocking monoclonal antibodies and small molecule antagonists may hold promise for the future.

Thyroid antibody-negative euthyroid Graves' ophthalmopathy

TSH receptor antibodies (TRAbs) are the pathological hallmark of Graves' disease, present in nearly all patients with the disease. Euthyroid Graves' ophthalmopathy (EGO) is a well-recognized clinical entity, but its occurrence in patients with negative TRAbs is a potential source of diagnostic confusion. A 66-year-old female presented to our endocrinology clinic with right eye pain and diplopia in the absence of thyroid dysfunction. TRAbs were negative, as measured with a highly sensitive third(-)generation thyrotropin-binding inhibitory immunoglobulin (TBII) ELISA assay. CT and MRI scans of the orbit showed asymmetrical thickening of the inferior rectus muscles but no other inflammatory or malignant orbital pathology. Graves' ophthalmopathy (GO) was diagnosed on the basis of the clinical and radiological features, and she underwent surgical recession of the inferior rectus muscle with complete resolution of the diplopia and orbital pain. She remained euthyroid over the course of follow-up but ultimately developed overt clinical and biochemical hyperthyroidism, 24 months after the initial presentation. By this time, she had developed positive TRAb as well as thyroid peroxidase antibodies. She responded to treatment with thionamides and remains euthyroid. This case highlights the potential for negative thyroid-specific autoantibodies in the presentation of EGO and underscores the variable temporal relationship between the clinical expression of thyroid dysfunction and orbital disease in the natural evolution of Graves' disease.

LEARNING POINTS

Euthyroid Graves' ophthalmopathy can present initially with negative thyroid-specific autoantibodies.Patients with suggestive symptoms of ophthalmopathy should be carefully evaluated for GO with imaging studies even when thyroid function and autoantibodies are normal.Patients with EGO can develop thyroid dysfunction within 4 years of follow-up underpinning the need for long-term follow-up and continued patient and physician vigilance in patients who have been treated for EGO.

Predicting malignancy in thyroid nodules: feasibility of a predictive model integrating clinical, biochemical, and ultrasound characteristics

Background

Although the majority of thyroid nodules are benign the process of excluding malignancy is challenging and sometimes involves unnecessary surgical procedures. We explored the development of a predictive model for malignancy in thyroid nodules by integrating a combination of simple demographic, biochemical, and ultrasound characteristics.

Methods

Retrospective case-record review.

We reviewed records of patients with thyroid nodules referred to our institution from 2004 to 2011 (n = 536; female 84 %, mean age 51 years). All malignancy was proven histologically while benign disease was either confirmed histologically, or on cytology with minimum 36-month observation period. We focused on the following predictors: age, sex, smoking status, thyroid hormones (FT4 and TSH) and nodule characteristics on ultrasound. Variables were included in a multivariate logistic regression and bootstrap analyses were used to confirm results.

Results

Independent predictors of malignancy in the fully adjusted model were TSH (OR 1.53, 95 % CI 1.10, 2.12, p = 0.01), male gender (OR 3.45, 95 % CI 1.33, 8.92, p = 0.01), microcalcifications (OR 6.32, 95 % CI 2.82, 14.1, p < 0.001), and irregular nodule margins (OR 5.45, 95 % CI 1.61, 18.6, p = 0.006) Bootstrap analyses strengthened these associations and a parsimonious analysis consisting of these variables and age-group demonstrated an area under the curve of 0.77. A predictive score was sensitive (86.9 %) at low scores and highly specific (94.87 %) at higher scores for distinguishing benign from malignant disease.

Conclusions

A predictive model for malignancy using a combination of clinical, biochemical, and radiological characteristics may support clinicians in reducing unnecessary invasive procedures in patients with thyroid nodules.

Electronic supplementary material

The online version of this article (doi:10.1186/s13044-016-0033-y) contains supplementary material, which is available to authorized users.

Thyroxine replacement: a clinical endocrinologist's viewpoint

BACKGROUND

Hypothyroidism affects 2-5% of the general population. Patients with uncorrected disease suffer significant morbidity and have an increased risk of cardiovascular disease and neurocognitive impairment. Levothyroxine, the treatment of choice, is inexpensive, easy to administer and in most cases restores well-being while normalizing thyroid function. However, 30-50% of individuals on levothyroxine are either over-treated or under-treated and others remain dissatisfied with treatment despite achieving thyroid hormone concentrations within the laboratory reference interval.

METHODS

This review is based on a systematic search of the literature for controlled trials, systematic reviews, guideline papers and cohort studies addressing best practice in thyroid hormone replacement.

RESULTS

Recent decades have seen improvements in patient management strategies driven by a better appreciation of levothyroxine pharmacokinetics. However, aspects of therapy such as the optimal timing of medication, strategies to overcome treatment non-adherence and target thyroid stimulating hormone concentrations in pregnancy and in patients with differentiated thyroid cancer remain challenging. Furthermore, there is now a substantial body of literature on common genetic variations in the deiodinases and thyroid hormone transporters and their role in the local regulation of thyroid hormone delivery. The benefits of combination therapy with liothyronine and levothyroxine are uncertain, and while it is theoretically probable that subsets of genetically predisposed individuals will benefit from combination therapy the existing evidence is as yet limited.

CONCLUSION

Despite the availability of thyroid hormone replacement for more than a century, there are still substantial challenges in practice and opportunities to improve treatment outcomes.

Resistant hypertension with adrenal nodule: are we removing the right gland?

Resistant hypertension is often difficult to treat and may be associated with underlying primary aldosteronism (PA). We describe the case of an elderly gentleman who presented with severe and resistant hypertension and was found to have a left adrenal incidentaloma during evaluation but had aldosterone excess secondary to unilateral adrenal hyperplasia (UAH) of the contralateral gland, which needed surgical intervention. A 65-year-old gentleman was evaluated for uncontrolled high blood pressure (BP) in spite of taking four antihypertensive medications. The high BP was confirmed on a 24-h ambulatory reading, and further biochemical evaluation showed an elevated serum aldosterone renin ratio (ARR) (1577 pmol/l per ng per ml per h). Radiological evaluation showed an adrenal nodule (15 mm) in the left adrenal gland but an adrenal vein sampling demonstrated a lateralization towards the opposite site favouring the right adrenal to be the source of excess aldosterone. A laparoscopic right adrenalectomy was performed and the histology of the gland confirmed nodular hyperplasia. Following surgery, the patient's BP improved remarkably although he remained on antihypertensives and under regular endocrine follow-up. PA remains the most common form of secondary and difficult-to-treat hypertension. Investigations may reveal incidental adrenal lesions, which may not be the actual source of excess aldosterone, but UAH may be a contributor and may coexist and amenable to surgical treatment. An adrenal vein sampling should be undertaken for correct lateralization of the source, otherwise a correctable diagnosis may be missed and the incorrect adrenal gland may be removed.

Should All Women Be Screened for Thyroid Dysfunction in Pregnancy?

The subject of universal thyroid screening in pregnancy generates impassioned debate. Thyroid dysfunction is common, has significant adverse implications for fetal and maternal well-being, is readily detectable and can be effectively and inexpensively treated. Furthermore, the currently recommended case-finding strategy does not identify a substantially proportion of women with thyroid dysfunction thus favoring universal screening. On the other hand subclinical thyroid dysfunction forms the bulk of gestational thyroid disorders and the paucity of high-level evidence to support correction of these asymptomatic biochemical abnormalities weighs against universal screening. This review critically appraises the literature, examines the pros and cons of universal thyroid screening in pregnancy, highlighting the now strong case for implementing universal screening and explores strategies for its implementation.

Prognostic significance of thyroglobulin antibody epitopes in differentiated thyroid cancer

CONTEXT

Thyroglobulin antibodies (TgAbs) are surrogate markers of disease recurrence or persistence in differentiated thyroid cancer (DTC). However, the prognostic significance of TgAb heterogeneity in DTC has not been investigated.

OBJECTIVE

To evaluate the relationship between TgAb epitope specificities and clinical outcomes in DTC patients.

DESIGN

We studied 61 TgAb-positive patients with DTC, post-thyroidectomy and remnant ablation (7 males, 54 females; age-range 16-80 years, median follow-up duration 8.9 years). TgAb epitope reactivities were mapped using a panel of 10 thyroglobulin (Tg) monoclonal antibodies delineating six antigenic Tg clusters in competitive ELISA studies. Sera from 45 patients with Hashimoto's thyroiditis (HT) and 22 TgAb-positive healthy subjects served as autoimmune and healthy controls. Tg was measured by immunoradiometric assay (IRMA), electrochemiluminescence immunoassay (ECLIA), and RIA, while TgAbs was measured by ELISA and ECLIA methods.

RESULTS

Samples from 26 DTC patients showed TgAb epitope restriction similar to HT patients, while 35 patients exhibited nonspecific reactivity comparable to healthy controls. DTC patients with epitope restriction had higher rates of recurrent/persistent disease (81% vs 17%, P < .001), higher median TgAb concentration (887.0 vs 82.0 kIU/L; P < .001), and a higher prevalence of thyroid lymphocytic infiltration (71.4% vs 26.8%; P < .001) compared to patients with nonspecific reactivity. Samples with epitope restriction also had a lower median Tg-IRMA/RIA ratio (3.0% vs 36.0%; P < .001) denoting greater degrees of Tg assay interference.

CONCLUSIONS

TgAb epitope restriction is associated with a less favorable prognosis than nonspecific reactivity in DTC patients. TgAb epitope specificities may have prognostic value in DTC.

Maternal perchlorate levels in women with borderline thyroid function during pregnancy and the cognitive development of their offspring: data from the Controlled Antenatal Thyroid Study

OBJECTIVE

Thyroid dysfunction is associated with impaired cognitive development. Perchlorate decreases thyroidal iodine uptake, potentially reducing thyroid hormone production. It is unclear whether perchlorate exposure in early life affects neurodevelopment.

DESIGN

Historical cohort analysis.

PATIENTS

From 2002 to 2006, 21,846 women at gestational age <16 weeks recruited from antenatal clinics in Cardiff, UK and Turin, Italy were enrolled in the Controlled Antenatal Thyroid Screening Study (CATS). We undertook a retrospective analysis of 487 mother-child pairs in mothers who were hypothyroid/hypothyroxinemic during pregnancy and analyzed whether first trimester maternal perchlorate levels in the highest 10% of the study population were associated with increased odds of offspring IQ being in the lowest 10% at 3 years of age.

MAIN OUTCOME MEASURES

Maternal urinary perchlorate, offspring IQ.

RESULTS

Urine perchlorate was detectable in all women (median 2.58 μg/L); iodine levels were low (median 72 μg/L). Maternal perchlorate levels in the highest 10% of the population increased the odds of offspring IQ being in the lowest 10% OR = 3.14 (95% CI 1.38, 7.13) P = .006 with a greater negative impact observed on verbal OR = 3.14 (95% CI 1.42, 6.90) P = .005 than performance IQ. Maternal levothyroxine therapy did not reduce the negative impact of perchlorate on offspring IQ.

CONCLUSIONS

This is the first study using individual-level patient data to study maternal perchlorate exposure and offspring neurodevelopment and suggests that high-end maternal perchlorate levels in hypothyroid/hypothyroxinemic pregnant women have an adverse effect on offspring cognitive development, not affected by maternal levothyroxine therapy. These results require replication in additional studies, including in the euthyroid population.

TSH levels and risk of miscarriage in women on long-term levothyroxine: a community-based study

CONTEXT

Thyroid dysfunction is associated with adverse obstetric outcomes, but there is limited information on pregnancy outcomes in women established on levothyroxine.

OBJECTIVE

The objective of the study was to determine the relationship between TSH levels and pregnancy outcomes in levothyroxine-treated women in a large community-based database.

DESIGN

This was a historical cohort analysis.

PATIENTS

Individuals with a first prescription of levothyroxine from 2001 through 2009 (n = 55 501) were identified from the UK General Practice Research Database (population 5 million). Of these, we identified 7978 women of child-bearing age (18-45 y) and 1013 pregnancies in which levothyroxine had been initiated at least 6 months before conception.

MAIN OUTCOME MEASURES

TSH, miscarriage/delivery status, and obstetric outcomes were measured.

RESULTS

Forty-six percent of levothyroxine-treated women aged 18-45 years had a TSH level greater than 2.5 mU/L (recommended upper level in the first trimester). Among pregnant women who had their TSH measured in the first trimester, 62.8% had a TSH level greater than 2.5 mU/L, with 7.4% greater than 10 mU/L. Women with TSH greater than 2.5 mU/L in the first trimester had an increased risk of miscarriage compared with women with TSH 0.2-2.5 mU/L after adjusting for age, year of pregnancy, diabetes, and social class (P = .008). The risk of miscarriage was increased in women with TSH 4.51-10 mU/L [odds ratio (OR) 1.80, 95% confidence interval (CI) 1.03, 3.14)] and TSH greater than 10 mU/L (OR 3.95, 95% CI 1.87, 8.37) but not with TSH 2.51-4.5 mU/L (OR 1.09, 95% CI 0.61, 1.93).

CONCLUSIONS

The majority of levothyroxine-treated women have early gestational TSH levels above the recommended targets (>2.5 mU/L) with a strong risk of miscarriage at levels exceeding 4.5 mU/L. There is an urgent need to improve the adequacy of thyroid hormone replacement in early pregnancy.

Therapy of endocrine disease: Impact of iodine supplementation in mild-to-moderate iodine deficiency: systematic review and meta-analysis

BACKGROUND

Although the detrimental effects of severe iodine deficiency are well recognised, the benefits of correcting mild-to-moderate iodine deficiency are uncertain.

OBJECTIVES

We undertook a systematic review of the impact of iodine supplementation in populations with mild-to-moderate iodine deficiency.

METHODS

We searched Medline and the Cochrane library for relevant articles published between January 1966 and April 2013, which investigated the effect of iodine supplementation on maternal and newborn thyroid function, infant neurodevelopment and cognitive performance in school-age children. The quality of studies was graded and eligible trials were evaluated in the meta-analysis.

RESULTS

Nine randomised controlled trials (RCTs) and eight observational studies met the inclusion criteria. Controlled trials on infant neurodevelopment were lacking; gestational iodine supplementation reduced maternal thyroid volume and serum thyroglobulin and in some studies prevented a rise in serum thyroid-stimulating hormone. None of the intervention trials recorded an excess frequency of thyroid dysfunction in contrast to observational studies. A pooled analysis of two RCTs which measured cognitive function in school-age children showed modest benefits of iodine supplementation on perceptual reasoning (standardised mean difference (SMD) 0.55; 95% CI 0.05, 1.04; P=0.03) and global cognitive index (SMD 0.27; 95% CI 0.10, 0.44; P=0.002) with significant heterogeneity between studies.

CONCLUSION

Iodine supplementation improves some maternal thyroid indices and may benefit aspects of cognitive function in school-age children, even in marginally iodine-deficient areas. Further large prospective controlled studies are urgently required to clarify these findings and quantify the risk/benefits of iodine supplementation in regions previously believed to be iodine sufficient such as the UK.

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.

Recent trends in the incidence, geographical distribution, and survival from thyroid cancer in Wales, 1985-2010

BACKGROUND

Previous studies of thyroid cancer incidence in Wales have given varying results with suggestions of an excess of cases in geographic areas that were previously exposed to the radioactive fallout from the 1986 Chernobyl nuclear reactor incident. Our objective in this study was to provide an up-to-date comprehensive analysis of time trends in the incidence, geographical distribution, and survival from thyroid cancer in Wales.

METHODS

We identified thyroid cancer cases, registered from 1985 through 2010 in the Welsh Cancer Intelligence and Surveillance Unit (WCISU). Age standardized rates were determined from the European standard population. A Poisson regression model was fitted to assess temporal trends and rate ratios (RRs) and confidence intervals (CIs) were determined and compared across consecutive time periods: 1985-1997 and 1998-2010. Standardized incidence ratios were calculated for each of the 22 local authority areas. Relative survival and Kaplan-Meier curves were computed to analyze all cause and thyroid cancer-specific survival.

RESULTS

A total of 1747 thyroid cancer cases were registered from 1985 to 2010. Age standardized incidence rates were 2.8 and 1.2 per 100,000 population per year for females and males respectively. Incidence rates increased with time (RR 1.3 [CI 1.2-1.5], p < 0.001; 1998-2010 vs. 1985-1997). The incidence of papillary cancer increased progressively over the study period (RR 2.22 [CI 1.91-2.57], p < 0.001; 1998-2010 vs. 1985-1997), while rates for other (nonpapillary) histological subtypes remained static (RR 0.95 [CI 0.84-1.08], p = 0.45; 1998-2010 vs. 1985-1997). We identified two geographical areas of increased incidence, but the spatial distribution of cases was inconsistent with exposure to radioactive fallout. Five-year relative survival from all-cause mortality improved from 74.2 [CI 66.8-80.1] in 1985-1989 to 82.6 [CI 77.1-86.9] in 2000-2004, but remained poor for patients over the age of 65 years (p < 0.001, > 65 years vs. 15-64 years) and patients with anaplastic thyroid cancer (p < 0.001; anaplastic vs. other histological varieties).

CONCLUSIONS

The incidence of thyroid cancer has increased in Wales, predominantly due to an increase in papillary cancers. The current geographical distribution of cases does not support a radiation effect in the region. Survival has remained poor for patients over the age of 65 years and those with anaplastic carcinoma.

Declining vision: saved by a tracheostomy

A 37-year-old woman presented to our hospital with a history of headaches, blurred vision and declining visual acuity. She had a history of obstructive sleep apnoea associated with Treacher Collins syndrome, a rare congenital disorder characterised by craniofacial deformities and obstruction of the upper airways. On funduscopy we noted bilateral papilloedema and retinal haemorrhages. A CT scan of the brain excluded a space occupying lesion and contrast-enhanced CT did not show evidence of venous sinus thrombosis. The cerebrospinal fluid opening pressure on lumbar puncture was normal. We made a diagnosis of visual loss and papilloedema secondary to chronic CO2 retention from obstructive sleep apnoea. Her vision and headaches improved remarkably following a permanent tracheostomy. This case highlights the association between obstructive sleep apnoea and papilloedema and shows that the associated visual loss can ultimately be restored with a tracheostomy.

Trends in hospital admissions with diabetic ketoacidosis in Wales, 1999-2010

We determined the incidence of diabetic ketoacidosis in Wales using nationwide hospital discharge data. Ketoacidosis admission rate was 24 per 100,000 person years and increased progressively from 1999 to 2010. The highest incidence was seen in 10-29 year olds, highlighting the need for targeted prevention in this age-group.

Serum thyrotrophin at baseline predicts the natural course of subclinical hyperthyroidism

OBJECTIVE

Optimal therapeutic strategies for subclinical hyperthyroidism are undecided. Overt disease develops in a minority of cases, but the risk factors for progression remain unclear. We examined whether a baseline thyrotrophin (TSH) predicted progression to overt hyperthyroidism in asymptomatic individuals with subclinical hyperthyroidism.

DESIGN, PATIENTS AND MEASUREMENTS

This was a retrospective study of 323 patients with subclinical hyperthyroidism seen in our institution from 2003 to 2010 (mean age 71 years, males 26·9%, females 73·1%, mean follow-up duration 32 months, range 6-93 months). Serum TSH and free thyroxine (FT4) were documented at baseline and during follow-up. After excluding individuals with nonthyroid causes of low TSH, patients were grouped according to initial TSH as: TSH 0·10-0·39 mU/l (grade I) and TSH < 0·10 mU/l (grade II).

RESULTS

Only 38 patients (11·8%) developed overt hyperthyroidism with annual progression rates of 0·6-3·7%. Most patients reverted to normal thyroid status (31·6%) or remained subclinically hyperthyroid (56·7%). Progression to frank hyperthyroidism was higher in grade II than in grade I patients (20·3% vs 6·8%, P < 0·001, Chi square test). Kaplan-Meier curves showed faster progression rates in grade II than grade I (P < 0·001, log rank test). In stepwise multivariate Cox regression analysis, TSH < 0·1 mU/l was associated with overt hyperthyroidism (hazard ratio 3·4, confidence interval 1·6-7·0), whereas age, gender, FT4 and aetiological diagnosis were not associated with hyperthyroidism.

CONCLUSIONS

Thyrotrophin predicts overt hyperthyroidism in asymptomatic individuals with subclinical hyperthyroidism. Patients with TSH < 0·10 mU/l have a higher risk of progressing to hyperthyroidism than those with TSH 0·10-0·39 mU/l.

Adequacy of thyroid hormone replacement in a general population

BACKGROUND

Suboptimal thyroid hormone replacement may carry harmful health consequences.

AIMS

Our objectives were to determine the prevalence and factors associated with inadequate replacement in patients receiving treatment with levothyroxine.

DESIGN

Retrospective general practice audit.

METHODS

We identified levothyroxine users through electronic searches of primary care records in all 11 practices within a county borough. The adequacy of thyroid hormone replacement was determined from the current serum, serum thyrotropin (TSH) as: (i) adequate replacement (normal TSH; 0.4-4.0 mU/l); (ii) over replacement (low TSH; <0.4 mU/l); and (iii) under replacement (high TSH; >4.0 mU/l).

RESULTS

Out of a registered patient population of 58 567, we identified 1037 patients who were first included in the hypothyroidism disease register between January 2004 and December 2009 (mean age 62.4 ± 15.9 years; female 85.9%, male 14.1%). Inadequate replacement was seen in 385 patients (37.2%), comprising 205 patients (19.8%) with over replacement and 180 patients (17.4%) with under replacement. Step-wise logistic regression showed that the factors associated with under replacement were male gender [odds ratio (OR) 2.85, confidence interval (CI) 1.86-4.38; P < 0.001 and younger age (OR 0.88, CI 0.80-0.98; P = 0.02 per 10 year increase in age) while longer duration of treatment was associated with over-treatment (OR 1.06, CI 1.01-1.10). A thyroid function test was performed in the preceding 12 months in 914 patients (88.1%) and appropriate dose adjustments had been made in 81.0% (312/385) of patients with abnormal results.

CONCLUSION

Despite frequent monitoring and dose adjustment activities, inadequate thyroid hormone replacement remained a problem in over a third of levothyroxine users in this population.

Thyroid dysfunction in pregnancy: optimizing fetal and maternal outcomes

Recent decades have seen a growing awareness of the threat posed by thyroid dysfunction in pregnancy on maternal, fetal and neonatal well-being. Uncontrolled hypothyroidism and hyperthyroidism are associated with adverse obstetrics and fetal outcomes and also affect neurointellectual development in the offspring. Excellent outcomes are, however, achievable with appropriate management. An understanding of the changes in thyroid hormone economy in pregnancy is crucial to the evaluation of thyroid status in pregnant patients with thyroid dysfunction. Furthermore, a balance must be maintained between the control of maternal disease and the requirements of the developing fetus. Careful monitoring of patients in a multidisciplinary care setting, and appropriate adjustments of treatment, is essential throughout pregnancy and the puerperium. In this special report we summarize best practice in the management of thyroid dysfunction in pregnancy.

Thyroid dysfunction in patients with diabetes: clinical implications and screening strategies

BACKGROUND

Patients with diabetes mellitus are at an increased risk of thyroid disease. The frequency of thyroid dysfunction in diabetic patients is higher than that of the general population and up to a third of patients with type-1 diabetes (T1DM) ultimately develop thyroid dysfunction. Unrecognised thyroid dysfunction may impair metabolic control and add to cardiovascular disease risk in diabetic patients.

AIMS

Our aims were to review the current literature on the association between thyroid dysfunction and diabetes mellitus, to highlight relevant clinical implications, and to examine present thyroid disease screening strategies in routine diabetes care.

RESULTS

The pleiotropic effects of thyroid hormones on various metabolic processes are now better understood. Uncontrolled hyperthyroidism in diabetic patients may trigger hyperglycaemic emergencies while recurrent hypoglycaemic episodes have been reported in diabetic patients with hypothyroidism. Furthermore, thyroid dysfunction may amplify cardiovascular disease risk in diabetic patients through inter-relationships with dyslipidaemia, insulin resistance and vascular endothelial dysfunction. However, the significance of subclinical degrees of thyroid dysfunction remains to be clarified. While these developments have implications for diabetic patients a consensus is yet to be reached on optimal thyroid screening strategies in diabetes management.

CONCLUSIONS

The increased frequency of thyroid dysfunction in diabetic patients and its likely deleterious effects on cardiovascular and metabolic function calls for a systematic approach to thyroid disease screening in diabetes. Routine annual thyroid testing should be targeted at diabetic patients at risk of thyroid dysfunction such as patients with T1DM, positive thyroid autoantibodies or high-normal TSH concentrations.

Can a random serum cortisol reduce the need for short synacthen tests in acute medical admissions?

BACKGROUND

Short synacthen tests (SSTs) are frequently performed in medical inpatients with suspected adrenocortical insufficiency. The utility of a random or baseline serum cortisol in this setting is unclear. We determined random cortisol thresholds that safely preclude SSTs in acute medical admissions.

METHODS

We analysed SSTs in acute non-critically ill general medical patients (n = 166, median age 66, range 15-94 y; men 48%, women 52%). The SST was defined according to the 30-min cortisol as 'pass' (>550 nmol/L) or 'fail' (< or =550 nmol/L). Receiver operating characteristics (ROC) curves were generated to determine the predictive value of the basal cortisol for a failed SST.

RESULTS

Of 166 SSTs, a pass was seen in 127 (76.5%) tests, while 39 (23.5%) tests failed the SST. ROC curves showed that no single cut-off point of the baseline cortisol was adequately both sensitive and specific for failing the SST despite a good overall predictive value (area under curve 0.94; 95% confidence interval 0.89-0.98). A basal cortisol <420 nmol/L had 100% sensitivity and 54% specificity for failing the SST, while a basal cortisol <142 nmol/L had 100% specificity and 35% sensitivity. Restricting the SST to patients with a basal cortisol <420 nmol/L would have prevented 44% of SSTs while correctly identifying all patients who failed the SST.

CONCLUSION

A baseline serum cortisol may prevent unnecessary SSTs in medical inpatients with suspected adrenocortical insufficiency. However, SSTs are still indicated in patients with random cortisol <420 nmol/L, or where the suspicion of adrenal insufficiency is compelling.

Insulin therapy in type 2 diabetes: insulin analogue mix 50, a potential role in reducing postprandial hyperglycaemia and cardiovascular disease

IMPORTANCE OF THE FIELD

Postprandial hyperglycaemia is becoming topical, with studies suggesting a link to cardiovascular disease. Recently, a number of new therapies for the treatment of type 2 diabetes have become available.

AREAS COVERED IN THIS REVIEW

This review looks at the evidence for the potential role of insulin analogue mix 50 to reduce postprandial hyperglycaemia and cardiovascular disease.

SEARCH STRATEGY

Medline and Embase databases were searched using the MeSH terms to identify relevant studies from 1980 to 2009. Both original articles and reviews were extracted. Published reference lists were also examined. MeSH terms used for literature searching: human insulins, insulin analogues, insulin analogue mix 50, glycaemia, postprandial glucose, fasting glucose, type 2 diabetes, type 1 diabetes, cardiovascular disease.

WHAT THE READER WILL GAIN

The reader is presented with evidence discussing the importance of postprandial hyperglycaemia and studies comparing different insulin regimes and in particular insulin analogue mix 50 and its potential to reduce postprandial glucose surges and reduce cardiovascular disease.

TAKE-HOME MESSAGE

Insulin analogue mix 50 is a viable therapeutic option in a sub-group of patients with type 2 diabetes.

The utility of radioiodine uptake and thyroid scintigraphy in the diagnosis and management of hyperthyroidism

BACKGROUND AND OBJECTIVES

The value and practice of thyroid radionuclide imaging in the diagnosis and management of hyperthyroidism is unsettled. Our objectives were to determine the influence of thyroid uptake and scintigraphy on the diagnosis of hyperthyroidism and the prediction of outcome following radioiodine therapy.

PATIENTS AND DESIGN

We reviewed records and scintigraphic studies on 881 hyperthyroid patients carried out between 2000 and 2007. The agreement between the clinical and scintigraphic diagnosis was evaluated by kappa statistics. We determined the relationship between 4-h (123)I uptake and the outcome of (131)I treatment in 626 patients. A multiple logistic regression model was used to determine variables influencing treatment outcome in 1 year.

RESULTS

The diagnostic categories were Graves' disease (GD, n = 383), toxic multinodular goitre (n = 253), solitary toxic nodule (n = 164) and Graves' disease coexisting with nodules (n = 81). The mean age of the patients was 58 +/- 17, (M:F 160:721). There was good agreement between clinical and scintigraph diagnosis (K = 0.60, 95% CI 0.57-0.64, P < 0.001); and they were correctly matched in 74%; mismatched in 6% and indeterminate in 20% of patients. Treatment outcome was not associated with scintigraph diagnosis (P = 0.98) or radioiodine uptake at 4 h (P = 0.2). The use of antithyroid medications before treatment predicted treatment failure (odds ratio 2.0, 95% CI 1.2-3.6, P = 0.01).

CONCLUSION

Thyroid scintigraphy and uptake studies did not influence diagnosis or treatment outcomes in most cases of hyperthyroidism. Our findings in this retrospective study do not justify their routine use. Selective scanning will reduce cost and exposure to radioisotopes without compromising diagnostic accuracy or treatment outcomes.

Restricted thyroglobulin antibody epitope specificities in subjects with type 1 diabetes mellitus

OBJECTIVES

Following iodisation in Sri Lanka we observed a high prevalence of thyroglobulin antibodies (TgAbs) in type 1 diabetic (T1DM) patients. The clinical significance of these TgAbs is uncertain. We sought to obtain a detailed epitope analysis of TgAbs in T1DM patients recruited from diabetes clinics and to compare these with TgAb epitope specificities in patients with autoimmune thyroid disease (AITD) and healthy individuals in that country.

DESIGN AND METHODS

We used a panel of 10 Tg-MAbs in competitive ELISA reactions in a prospective study of subjects recruited from Colombo, to determine the epitopes recognised by TgAb-positive patients with T1DM (n=58, 34F:24M, median age 16 years), AITD patients (n=42, 33F:9M, median age 37 years) and healthy subjects (n=50, 39F:11M, median age 27 years). The outcomes were a comparison of reactivity with six Tg clusters (I-VI) in these subjects, and the relation of epitope specificity patterns with free thyroxine and TSH.

RESULTS

Patients with T1DM and AITD but not healthy control subjects preferentially recognised the immunodominant clusters, I, III and IV. Patients with these narrow epitope specificities had higher median TSH levels (1.60 vs 1.06; P=0.01), and were more frequently positive for antibodies to thyroid peroxidase than those with broad specificities (52.3 vs 7.1%; P=0.004).

CONCLUSIONS

The TgAb epitope specificities in euthyroid Sri Lankans with T1DM are similar to AITD patients. TgAb epitope studies may potentially identify T1DM patients at risk of thyroid dysfunction.