The epidemiology of thyrotoxicosis in New Zealand: incidence and geographical distribution in north Canterbury, 1983-1985

Incidence of hyperthyroidism in patients with bipolar or schizoaffective disorder with or without lithium: 21-year follow-up from the LiSIE retrospective cohort study

BACKGROUND

Lithium-associated hyperthyroidism is much rarer than lithium-associated hypothyroidism. Yet, it may be of substantial clinical significance for affected individuals. For instance, lithium-associated hyperthyroidism could destabilise mood, mimic manic episodes and impact physical health. Only few studies have explored incidence rates of lithium-associated hyperthyroidism. Even fewer studies have compared incidence rates according to lithium exposure history.

OBJECTIVES

To determine the impact of lithium treatment on the incidence rate of hyperthyroidism in patients with bipolar or schizoaffective disorder and assess its aetiology.

DESIGN

This study is part of the LiSIE (Lithium - Study into Effects and Side Effects) retrospective cohort study.

METHODS

Between 1997 and 2017, patients in the Swedish region of Norrbotten with a diagnosis of bipolar or schizoaffective disorder were screened for all episodes of overt hyperthyroidism in form of thyrotoxicosis or thyroiditis. Incidence rates of episodes of hyperthyroidism per 1000 person-years (PY) were compared in relation to lithium exposure; concurrent, previous, or no exposure ever (lithium-naïve patients).

RESULTS

In 1562 patients, we identified 16 episodes of hyperthyroidism corresponding to an incidence rate of 0.88 episodes per 1000 PY. Ninety-four percent of episodes had occurred in women. Patients who had concurrently been exposed to lithium, had an incidence rate of 1.35 episodes per 1000 PY. Patients who had previously been exposed to lithium had an incidence rate of 0.79 per 1000 PY. Patients who had never been exposed to lithium had an incidence rate of 0.47 per 1000 PY. There were no significant differences in the risk ratios for patients with concurrent or previous exposure compared with lithium-naïve patients, neither for hyperthyroidism overall, thyrotoxicosis, or thyroiditis.

CONCLUSION

Lithium-associated hyperthyroidism seems uncommon. The risk of hyperthyroidism does not seem significantly higher in patients with current or previous lithium exposure than in lithium-naïve patients.

Graves' disease

Graves' disease (GD) is an autoimmune disease that primarily affects the thyroid gland. It is the most common cause of hyperthyroidism and occurs at all ages but especially in women of reproductive age. Graves' hyperthyroidism is caused by autoantibodies to the thyroid-stimulating hormone receptor (TSHR) that act as agonists and induce excessive thyroid hormone secretion, releasing the thyroid gland from pituitary control. TSHR autoantibodies also underlie Graves' orbitopathy (GO) and pretibial myxoedema. Additionally, the pathophysiology of GO (and likely pretibial myxoedema) involves the synergism of insulin-like growth factor 1 receptor (IGF1R) with TSHR autoantibodies, causing retro-orbital tissue expansion and inflammation. Although the aetiology of GD remains unknown, evidence indicates a strong genetic component combined with random potential environmental insults in an immunologically susceptible individual. The treatment of GD has not changed substantially for many years and remains a choice between antithyroid drugs, radioiodine or surgery. However, antithyroid drug use can cause drug-induced embryopathy in pregnancy, radioiodine therapy can exacerbate GO and surgery can result in hypoparathyroidism or laryngeal nerve damage. Therefore, future studies should focus on improved drug management, and a number of important advances are on the horizon.

Thyrotoxicosis in an Indigenous New Zealand Population - a Prospective Observational Study

Background

Reported international incidence rates of thyrotoxicosis vary markedly, ranging from 6 to 93 cases per 100 000 per annum. Along with population demographics, exposures, and study design factors, ethnicity is increasingly being recognized as a potential factor influencing incidence. This study aimed to document the epidemiology and clinical presentation of thyrotoxicosis for Māori, the indigenous population in New Zealand.

Methods

A prospective study of adult patients presenting with a first diagnosis of thyrotoxicosis between January 2013 and October 2014 to a single New Zealand center. Demographic data were collected, and detailed clinical assessment performed.

Results

With 375 patients, an incidence rate of thyrotoxicosis of 73.0 per 100 000 per annum was identified. Of these, 353 (94.1%) participated in the study. The median age of the cohort was 47 years, 81% were female, and 58% had Graves disease. The overall incidence of thyrotoxicosis for Māori, the indigenous people of New Zealand, was higher than non-Māori (123.9 vs 57.3 per 100 000 per annum). Rates of both Graves disease and toxic multinodular goiter were higher in Māori as compared to non-Māori (incidence rate ratios of 1.9 [1.4, 2.6] and 5.3 [3.4, 8.3], respectively), with this increase being maintained after controlling for age, deprivation, and smoking.

Conclusions

Māori, the indigenous people of New Zealand, have an increased incidence of thyrotoxicosis compared to non-Māori and, in particular, toxic multinodular goiter. A greater understanding of the epidemiology of thyrotoxicosis in other indigenous and marginalized ethnic groups may help to optimize therapeutic pathways, equitable care and outcomes.

An Adolescent Female with Bipolar Disorder Presenting with Lithium-Induced Hyperthyroidism

Lithium therapy has been associated with several endocrine disorders including thyroid dysfunction, diabetes insipidus, and hyperparathyroidism. While its suppressive effect on thyroid function is well known, it is very rare to observe lithium-induced hyperthyroidism especially in the pediatric population. Here, we describe a case of lithium-induced hyperthyroidism in an adolescent female with bipolar disorder. The patient is a 17-year-old female who was treated with lithium for bipolar disorder and presented with symptoms and laboratory findings consistent with hyperthyroidism. Since thyroid autoantibodies were negative, thyroid dysfunction was attributed to lithium toxicity. Indeed, her clinical and biochemical hyperthyroid state resolved after stopping lithium therapy. Lithium-associated hyperthyroidism can occur in the pediatric population. We propose close monitoring of thyroid hormone levels in children on lithium therapy.

Inequitable Long-Term Outcomes for an Indigenous Population After Definitive Treatment of Patients With Graves Disease

BACKGROUND

Māori, the indigenous people of Aotearoa/New Zealand, have an increased incidence of Graves disease and often require more than one radioiodine (RAI) dose, raising the question as to whether surgery may be preferable in this population. However, there is a lack of outcome data after definitive therapy in an indigenous population.

AIM

To assess ethnic differences in thyroid status after definitive therapy for Graves disease.

METHODS

Single-center retrospective review of patients treated by RAI or thyroidectomy from 1 December 2001 to 31 March 2013. TSH levels at 1, 2, 5, and 10 years after treatment were recorded.

RESULTS

A total of 798 patients were included: 589 received RAI, and 209 underwent surgery. Overall, 48% of patients were euthyroid at 1 year after definitive treatment, and 63.5% were euthyroid by 10 years. Māori were less likely to be euthyroid when compared with Europeans at all time points (e.g., 29.7% vs 57.3% at 1 year and 52.2% vs 70.9% at 10 years, P < 0.0005). Māori were more likely to receive more than one dose of RAI compared with Europeans (30.2% vs 14.2%, P < 0.0005). Persistent thyrotoxicosis at 1 year after RAI was seen in 25.8% of Māori compared with 8.3% of Europeans (P < 0.0005).

CONCLUSIONS

Māori have lower rates of optimal thyroid levels than their European counterparts at all time points studied. Early disparity was associated with a higher RAI failure rate. Late differences were due to higher rates of untreated hypothyroidism. Overall, euthyroid rates were low, indicating the need for improvement in care, particularly for indigenous peoples.

Effect of lithium on thyroid function in adolescents with mood disorder

BACKGROUND

The purpose of the study was to determine thyroid gland volume and the frequency of thyroid dysfunction by using ultrasonography and laboratory parameters (TSH, T3, and T4) in long term lithium treated adolescent patients with mood disorder.

METHODOLOGY

In a cross-sectional study, we performed ultrasonography and thyroid function test in 30 adolescent patients on long-term lithium treatment for mood disorder. Patients with adequate serum lithium levels for one year or more were taken for the study. Ultrasonography examinations of thyroid gland and thyroid function test were performed in these patients. Patients who were on other mood stabilizers were taken up as controls.

RESULT

The thyroid stimulating hormone (TSH) levels and ultrasonographically measured thyroid volume were significantly higher in patients receiving lithium in comparison to patients with other mood stabilizers. A significant positive correlation was found between total thyroid volume and TSH levels.

CONCLUSION

Adolescent mood disorder patients on long term lithium therapy have increased thyroid volume and isolated increases in serum TSH levels compared to those on other mood stabilizers.

Race/Ethnicity and the prevalence of thyrotoxicosis in young Americans

BACKGROUND

Race/ethnicity may be a newly recognized risk factor for Graves' disease.

OBJECTIVE

The aim of this study was to examine the prevalence of thyrotoxicosis by race/ethnicity in Americans aged 12-49 years using three National Health and Nutritional Examination Surveys (NHANES).

METHODS

Data were analyzed from 17,939 participants in NHANES III (1988-1994), NHANES 1999-2002, and NHANES 2007-2010 with available thyroid function test results. Thyrotoxicosis was defined as a serum thyrotropin (TSH) of ≤0.1 mIU/L or subjects taking methimazole or propylthiouracil, and overt thyrotoxicosis was defined as high serum thyroxine and a serum TSH of ≤0.1 mIU/L. Logistic regression was performed accounting for the complex sampling design of NHANES, and the results from all three NHANES surveys were combined using a random-effects model.

RESULTS

There were 75 study participants with point prevalent thyrotoxicosis, representing a pooled prevalence of 0.4% for Americans aged 12-49 years. Prevalent thyrotoxicosis was nearly three times more likely in non-Hispanic black subjects compared with non-Hispanic whites (OR=2.9 [CI 1.5-5.7]), while there was no difference between the prevalence of thyrotoxicosis in Mexican Americans compared to non-Hispanic whites (OR=1.2 [CI 0.6-2.4]; I2 for heterogeneity=0% for both). Among 27 patients with overt thyrotoxicosis, the odds ratio was 8.7 [CI 0.7-112.6] for non-Hispanic blacks and 4.6 [CI 0.4-59.3] for Mexican Americans compared with non-Hispanic whites.

CONCLUSIONS

The results suggest there are race/ethnicity differences in the prevalence of thyrotoxicosis. Future studies should address whether these differences are due to heritable factors, environmental exposures, or a combination of both.

Role of genetic and non-genetic factors in the etiology of Graves' disease

In spite of the advancements in understanding the pathogenic mechanisms of Graves' disease (GD), its ultimate cause remains elusive. The majority of investigators agree that GD is likely a multifactorial disease, due to a complex interplay of genetic and non-genetic factors that lead to the loss of immune tolerance to thyroid antigens and to the initiation of a sustained autoimmune reaction. Twin and family studies support a role of genetic factors, among which the HLA complex, CD40, CTLA-4, PTPN22, FCRL3, thyroglobulin, and the TSH receptor may be involved. Among non-genetic factors, iodine, infections, psychological stress, gender, smoking, thyroid damage, vitamin D, selenium, immune modulating agents, and periods of immune reconstitution may contribute the development of the diseases. Here we review in detail the respective role of genetic and non-genetic factors in the etiology of GD, taking advantage of the great bulk of data generated especially over the past 30 years.

Safety of AS03-adjuvanted inactivated split virion A(H1N1)pdm09 and H5N1 influenza virus vaccines administered to adults: pooled analysis of 28 clinical trials

Clinical trials have shown that AS03-adjuvanted H5N1 and A(H1N1)pdm09 vaccines are highly immunogenic, although with an increased reactogenicity profile relative to non-adjuvanted vaccines in terms of the incidence of common injection site and systemic adverse events (AEs). We evaluated pooled safety data from 22,521 adults who had received an AS03-adjuvanted H5N1 or A(H1N1)pdm09 influenza or control vaccine with the purpose to identify medically-attended AEs (MAEs), including subsets of serious AEs (SAEs), potentially immune-mediated diseases (pIMDs), and AEs of special interest (AESI), and to explore a potential association of these AEs with the administration of an AS03-adjuvanted influenza vaccine. For participants who had received an AS03-adjuvanted vaccine, the relative risks (RRs) for experiencing a MAE or a SAE compared to control group (participants who had received a non-adjuvanted vaccine or saline placebo) were 1.0 (95% confidence interval [CI]: 0.9; 1.1) and 1.1 (95% CI: 0.9; 1.4), respectively. The overall RRs for experiencing an AESI or a pIMD (AS03-adjuvanted vaccine/control) were 1.2 (95% CI: 0.9; 1.6) and 1.7 (95% CI: 0.8; 3.8), respectively. Thirty-8 participants in the AS03-adjuvanted vaccine group had a pIMD reported after vaccine administration, yielding an incidence rate (IR) of 351.9 (95% CI: 249.1; 483.1) per 100,000 person-years. The estimated IRs in the AS03-adjuvanted vaccine group were greater than the literature reported rates for: facial paresis/VIIth nerve paralysis, celiac disease, thrombocytopenia and ulcerative colitis. These results do not support an association between AS03-adjuvanted H5N1 and A(H1N1)pdm09 vaccines and the AEs collected in the trials included in the analysis.

A prevalence of thyroid disorder in Western part of Nepal

BACKGROUND

Nepal is an endemic area with regards to iodine deficiency, as well as a nutritional iodine deficiency is thought to be prevalent in all the Himalayan, sub-Himalayan and the Terai regions of Nepal. Thyroid dysfunction is a major public health problem among the Nepalese population.

OBJECTIVES

The objective of this study was to find out the prevalence of thyroid dysfunction among the patients who attended the Charak Hospital, Pokhara, Nepal.

MATERIALS AND METHODS

A hospital based study was undertaken by using the data which was retrieved from the thyroid function tests, which included free T3, free T4 and TSH, from the register which was maintained in the Department of Biochemistry of the Charak Hospital, Pokhara, Nepal, from 1(st) January, 2011 to 30th December, 2012. Descriptive statistics and testing of the hypothesis were used for the analysis by using the EPI INFO and the SPSS version 16 softwares.

RESULTS

The total number of cases was 1504, which included 23.20% males and 76.80% females. The prevalence of thyroid dysfunction was 17.42%. Females had more thyroid dysfunction than the males. Hypothyroidism (2.26%) and subclinical hypothyroidism (10.50%) had higher prevalences as compared to hyperthyroidism (1.59%) and subclinical hyperthyroidism (3.05%) in the western region of Nepal. A higher prevalence of the thyroid dysfunction was observed in the subjects who ages were above 41-50 years.

CONCLUSION

Females and people of advanced ages were more vulnerable to thyroid dysfunction in the population. Hypothyroidism and subclinical hypothyroidism were preponderant, followed by subclinical hyperthyroidism.

The incidence and prevalence of thyroid autoimmunity

The thyroid gland is the most common organ affected by autoimmune disease. Other autoimmune diseases, most notably type 1 diabetes mellitus, are increasing in incidence. It is unknown whether autoimmune thyroid diseases are following the same pattern. This review summarizes studies of autoimmune thyroid disease incidence and prevalence since 1950, not only for these measures of occurrences, but also for commenting on identified risk factors for thyroid autoimmunity. We find that incidence of autoimmune thyroid disease is currently higher than in historic series although the studies are so variable in design, patient population, disease definition, and laboratory methods that it is impossible to tell whether this difference is real. Further research is required to assess the possibility of changing disease patterns of autoimmune thyroid disease as opposed to simple changes in diagnostic thresholds.

The incidence of thyroid function abnormalities and natural course of subclinical thyroid disorders, Tehran, I.R. Iran

BACKGROUND

Despite the high prevalence of thyroid dysfunction, the epidemiology and natural course of these disorders have not been identified yet.

AIM

The present survey was conducted to determine the incidence of thyroid dysfunction and natural course of subclinical thyroid disorders in an urban community of Tehran, I.R. Iran.

SUBJECTS AND METHODS

Serum TSH and thyroperoxidase antibody (TPOAb) were measured at baseline and after 6.7 yr from a sample of 1999 randomly selected subjects aged≥20 yr, participants of the Tehran Lipid and Glucose Study (TLGS). Median TSH value and 2.5, 5, 95, and 97.5 TSH percentiles were determined at baseline using data obtained from 808 negative TPOAb subjects with no history of any thyroid disease or surgery, goiter, nodule, taking thyroid hormone preparations or anti-thyroid drugs. In those with abnormal TSH level, total T4 and T3 uptake were measured and free T4 index was calculated.

RESULTS

Normal TSH reference range was 0.4-5.8 μU/ml according to the 2.5 and 97.5 TSH percentiles. The incidence rates of thyroid function abnormalities in 1000 subjects per year were as follows: clinical hypothyroidism: 0.28 in women and 0.21 in men; subclinical hypothyroidism: 11.59 in women and 4.69 in men; clinical hyperthyroidism: 1.4 in women and 0.21 in men; and subclinical hyperthyroidism: 5.72 in women and 3.62 in men. A significant increase was found in the frequency of positive TPOAb in women from 15.9 to 17.7% (p=0.006). Of 8 women with subclinical hypothyroidism at baseline, 5 remained unchanged, 1 became normal, and 1 developed clinical hypothyroidism at followup. Two women with subclinical hyperthyroidism normalized at follow-up. Of 2 men with subclinical hypothyroidism at baseline, 1 remained unchanged, whereas the other progressed to clinical hypothyroidism.

CONCLUSION

After a 6.7 yr follow-up significant increase in the incidence of subclinical thyroid disorders was observed in both men and women, as compared to overt thyroid dysfunction. Increase in the prevalence of TPOAb positivity was observed only in women.

Incidence of hyperthyroidism in Sweden

INTRODUCTION

The incidence of hyperthyroidism has been reported in various countries to be 23-93/100,000 inhabitants per year. This extended study has evaluated the incidence for ~40% of the Swedish population of 9 million inhabitants. Sweden is considered to be iodine sufficient country.

METHODS

All patients including children, who were newly diagnosed with overt hyperthyroidism in the years 2003-2005, were prospectively registered in a multicenter study. The inclusion criteria are as follows: clinical symptoms and/or signs of hyperthyroidism with plasma TSH concentration below 0.2 mIE/l and increased plasma levels of free/total triiodothyronine and/or free/total thyroxine. Patients with relapse of hyperthyroidism or thyroiditis were not included. The diagnosis of Graves' disease (GD), toxic multinodular goiter (TMNG) and solitary toxic adenoma (STA), smoking, initial treatment, occurrence of thyroid-associated eye symptoms/signs, and demographic data were registered.

RESULTS

A total of 2916 patients were diagnosed with de novo hyperthyroidism showing the total incidence of 27.6/100,000 inhabitants per year. The incidence of GD was 21.0/100,000 and toxic nodular goiter (TNG=STA+TMNG) occurred in 692 patients, corresponding to an annual incidence of 6.5/100,000. The incidence was higher in women compared with men (4.2:1). Seventy-five percent of the patients were diagnosed with GD, in whom thyroid-associated eye symptoms/signs occurred during diagnosis in every fifth patient. Geographical differences were observed.

CONCLUSION

The incidence of hyperthyroidism in Sweden is in a lower range compared with international reports. Seventy-five percent of patients with hyperthyroidism had GD and 20% of them had thyroid-associated eye symptoms/signs during diagnosis. The observed geographical differences require further studies.

Minimal impact of excess iodate intake on thyroid hormones and selenium status in older New Zealanders

OBJECTIVE

Iodine deficiency has re-emerged in New Zealand, while selenium status has improved. The aim of this study was to investigate the effects of excess iodine intake as iodate on thyroid and selenium status.

METHODS

In a randomized controlled trial on older people (mean±s.d. 73±4.8 years; n=143), two groups received >50  mg iodine as iodate/day for 8 weeks because of supplement formulation error, either with 100  μg selenium (Se+highI) or without selenium (highI). Four other groups received 80  μg iodine as iodate/day with selenium (Se+lowI) or without selenium (lowI), selenium alone (Se+), or placebo. Thyroid hormones, selenium status, and median urinary iodine concentration (MUIC) were compared at weeks 0, 8, and 4 weeks post-supplementation.

RESULTS

MUIC increased nine- and six-fold in Se+highI and highI groups, decreasing to baseline by week 12. Plasma selenium increased in selenium-supplemented groups (P<0.001). The level of increase in whole blood glutathione peroxidase (WBGPx) in the Se+highI group was smaller than Se+ (P=0.020) and Se+lowI (P=0.007) groups. The decrease in WBGPX in the highI group was greater than other non-selenium-supplemented groups, but differences were not significant. Ten of 43 participants exposed to excess iodate showed elevated TSH (hypothyroidism) at week 8. In all but two, TSH had returned to normal by week 12. In three participants, TSH decreased to <0.10  mIU/l (hyperthyroidism) at week 8, remaining low at week 12.

CONCLUSIONS

Excess iodate induced hypothyroidism in some participants and hyperthyroidism in others. Most abnormalities disappeared after 4 weeks. Excess iodate reduced WBGPx activity and resulted in smaller increases in WBGPx after selenium supplementation.

Transient psychosis due to painless thyroiditis in a patient with anxiety disorder: a case report

Introduction

There are few reports on thyrotoxic psychosis caused by diseases other than Graves' disease or toxic nodular goiter.

Case presentation

A 64-year-old Japanese woman was treated for anxiety disorder in our clinic for 10 years. She had five episodes of transient psychosis during the first five years. When she developed psychosis without neck pain 10 years after her first visit, a laboratory reexamination revealed that she had subclinical hyperthyroidism, and tested positive for antithyroid autoantibodies, negative for thyroid stimulating hormone receptor antibody and had decreased radioactive iodine uptake. She was diagnosed as having painless thyroiditis. The hyperthyroidism disappeared within a month, and the psychosis lasted for three months.

Conclusion

To the best of our knowledge, this is the first report of psychosis due to painless thyroiditis-induced hyperthyroidism. Physical symptoms of painless thyroiditis are often so mild that careful differential diagnosis is necessary in the cases of transient psychosis.

Epidemiology of subtypes of hyperthyroidism in Denmark: a population-based study

OBJECTIVE

Few population-based studies have described the epidemiology of subtypes of hyperthyroidism.

DESIGN

A prospective population-based study, monitoring two well-defined Danish cohorts in Aalborg with moderate iodine deficiency (n=311 102) and Copenhagen with only mild iodine deficiency (n=227 632).

METHODS

A laboratory monitoring system identified subjects with thyroid function tests suggesting overt hyperthyroidism (low s-TSH combined with high s-thyroxine or s-triiodothyronine). For all subjects, we collected information on medical history, thyroid scintigraphy and thyroid hormone receptor antibody (TRAb) measurement. Information was used to disprove or verify primary overt hyperthyroidism and to subclassify hyperthyroidism into nosological disorders.

RESULTS

From 1997 to 2000 (2 027 208 person-years of observation), we verified 1682 new cases of overt hyperthyroidism. The overall standardized incidence rate (SIR) per 100 000 person-years was 81.6, and was higher in Aalborg compared with Copenhagen (96.7 vs 60.0, P<0.001), giving an SIR ratio (SIRR (95% confidence interval (CI))) between moderate versus mild iodine-deficient areas of 1.6 (1.4-1.8). Nosological types of hyperthyroidism (percentage/SIRR (95% CI)): multinodular toxic goitre (MNTG) 44.1%/1.9 (1.6-2.2), Graves' disease (GD) 37.6%/1.2 (0.99-1.4), solitary toxic adenoma (STA) 5.7%/2.4 (1.3-3.5), 'mixed type' hyperthyroidism (TRAb-positive, scintigraphicly multinodular) 5.4%/6.0 (3.0-12), subacute thyroiditis 2.3%/0.9 (0.4-1.4), postpartum thyroid dysfunction 2.2%/1.6 (0.8-3.0), amiodarone-associated hyperthyroidism 0.8%/7.1 (1.1-65), hyperthyroidism after thyroid radiation 0.7%/12.3 (0.8-50), lithium-associated hyperthyroidism 0.7%/0.97 (0.4-4.8) and hyperthyroidism caused by various other factors 0.7%. Lifetime risk for overt hyperthyroidism was 10.5%/6.5%/2.4% (females/all/males).

CONCLUSION

Hyperthyroidism was common in Denmark with MNTG and GD as dominating entities. The higher incidence of hyperthyroidism in the most iodine-deficient region was caused by higher frequency of MNTG, 'mixed-type', STA and amiodarone-associated hyperthyroidism.

Incidence of thyrotoxicosis in childhood: a national population based study in the UK and Ireland

OBJECTIVE

To measure the UK and Ireland incidence of childhood (<15 years) thyrotoxicosis and to describe the presenting features.

CONTEXT

Incidence data on thyrotoxicosis in childhood are not available for the UK and Ireland. Recent studies have reported an apparent increase in cases in Europe.

DESIGN

A national prospective surveillance study for 12 months from September 2004, co-ordinated by The British Paediatric Surveillance Unit (BPSU).

PATIENTS AND MEASUREMENTS

All paediatricians across the UK and Ireland were requested monthly to report new cases. Details of presenting features were then obtained by questionnaire.

RESULTS

One hundred ten cases of acquired childhood thyrotoxicosis were identified in the UK and Ireland. The incidence of acquired thyrotoxicosis was 0.9 per 100,000 <15 years olds in the UK and Ireland, (95% CI: 0.8-1.1). Autoimmune thyrotoxicosis accounted for 96% of cases. There was an increasing incidence with age in each sex. Females have a significantly higher incidence than males in the 10- to 14-year age group. A variety of presenting symptoms were reported: weight loss (64%), fatigue/tiredness (54%), change in behaviour' (50%) and heat intolerance (47%). 4.5 % cases were asymptomatic. The commonest signs were goitre (78%) and tremor (58%). There were no cases of thyroid storm.

CONCLUSIONS

This national population survey defines the incidence of thyrotoxicosis in children in the UK and Ireland during 2004-2005, which was lower than expected in comparison with other European studies. The survey illustrates contemporary presenting characteristics of the disease.

The incidence of autoimmune thyroid disease: a systematic review of the literature

OBJECTIVE

To undertake a systematic review of literature published between 1980 and 2008 on the incidence of autoimmune thyroid disease.

DESIGN

All relevant papers found through searches of Medline, EMBASE and ScienceDirect were critically appraised and an assessment was made of the reliability of the reported incidence data.

RESULTS

The reported incidence of autoimmune hypothyroidism varied between 2.2/100 000/year (males) and 498.4/100 000/year (females) and for autoimmune hyperthyroidism, incidence ranged from 0.70/100 000/year (Black males) to 99/100 000/year (Caucasian females). Higher incidence rates were found in women compared to men for all types of autoimmune thyroid disease. The majority of studies included in the review investigated Caucasian populations mainly from Scandinavia, Spain, the UK and the USA. It is possible that nonautoimmune cases were included in the incidence rates reported here, which would give an overestimation in the incidence rates of autoimmune disease presented.

CONCLUSION

To our knowledge this is the most comprehensive systematic review of autoimmune thyroid disease conducted in the past two decades. Studies of incidence of autoimmune thyroid disease have only been conducted in a small number of mainly western countries. Our best estimates of the incidence of hypothyroidism is 350/100 000/year in women and 80/100 000/year in men; the incidence of hyperthyroidism is 80/100 000/year in women and 8/100 000/year in men.

Joint genetic susceptibility to type 1 diabetes and autoimmune thyroiditis: from epidemiology to mechanisms

Type 1 diabetes (T1D) and autoimmune thyroid diseases (AITD) frequently occur together within families and in the same individual. The co-occurrence of T1D and AITD in the same patient is one of the variants of the autoimmune polyglandular syndrome type 3 [APS3 variant (APS3v)]. Epidemiological data point to a strong genetic influence on the shared susceptibility to T1D and AITD. Recently, significant progress has been made in our understanding of the genetic association between T1D and AITD. At least three genes have been confirmed as major joint susceptibility genes for T1D and AITD: human leukocyte antigen class II, cytotoxic T-lymphocyte antigen 4 (CTLA-4), and protein tyrosine phosphatase non-receptor type 22. Moreover, the first whole genome linkage study has been recently completed, and additional genes will soon be identified. Not unexpectedly, all the joint genes for T1D and AITD identified so far are involved in immune regulation, specifically in the presentation of antigenic peptides to T cells. One of the lessons learned from the analysis of the joint susceptibility genes for T1D and AITD is that subset analysis is a key to dissecting the etiology of complex diseases. One of the best demonstrations of the power of subset analysis is the CTLA-4 gene in T1D. Although CTLA-4 showed very weak association with T1D, when analyzed in the subset of patients with both T1D and AITD, the genetic effect of CTLA-4 was significantly stronger. Gene-gene and genetic-epigenetic interactions most likely play a role in the shared genetic susceptibility to T1D and AITD. Dissecting these mechanisms will lead to a better understanding of the etiology of T1D and AITD, as well as autoimmunity in general.

Incidence of hyperthyroidism in Stockholm, Sweden, 2003-2005

OBJECTIVES

To investigate the incidence of hyperthyroidism in Stockholm County, in those patients who were diagnosed with hyperthyroidism for the first time during the years 2003-2005.

DESIGN

All new cases of hyperthyroidism > or = 18 years of age were prospectively registered to calculate the total incidence of hyperthyroidism, as well as the incidence of the subgroups: Graves' disease (GD), toxic multinodular goitre and solitary toxic adenoma (STA). Eight specialized units/hospitals in Stockholm County participated in the registration. The participating physicians were all specialists in medical endocrinology, oncology, nuclear medicine or surgery.

RESULTS

During a 3-year period, 1431 new patients of hyperthyroidism were diagnosed in a well-defined adult population (> 18 years of age) of in average 1,457,036 inhabitants. This corresponds to a mean annual incidence of hyperthyroidism of 32.7/100,000. The incidence of GD was 24.5/100,000 per year, toxic nodular goitre was 3.3/100,000 per year and STA was 4.9/100,000 per year.

CONCLUSIONS

The total incidence of hyperthyroidism in Stockholm County was found to be 32.7/100,000 per year, of which 75% had GD. There were a higher percentage of smokers among the patients with hyperthyroidism compared with the overall population in Stockholm, but no difference in the frequency of smoking between patients with GD and toxic nodular goitre.

Increasing prevalence and incidence of thyroid disease in Tayside, Scotland: the Thyroid Epidemiology Audit and Research Study (TEARS)

OBJECTIVE

We aimed to describe the changing incidence of thyroid disease in a population-based study in Tayside, Scotland (population 390 000) between 1994 and 2001.

DESIGN

A retrospective, data-linkage, population-based study measuring the incidence and prevalence of thyroid disease.

PATIENTS

All patients with newly diagnosed, treated and stable thyroid disease in Tayside were identified by electronic linkage of six datasets, including all regional biochemistry data, hospital admissions, deaths and a thyroid follow-up register.

RESULTS

The overall prevalence of thyroid dysfunction has increased from 2.3% to 3.8% (1994-2001). The prevalence of ever having had hyperthyroidism increased from 0.86% to 1.26% in females and 0.17% to 0.24% in males (P < 0.0001 for both). The standardized incidence of hyperthyroidism increased from 0.68 to 0.87 per 1000 females/year, representing a 6.3% annual increase (P < 0.0001). The prevalence of primary hypothyroidism increased from 3.12% to 5.14% in females and 0.51% to 0.88% in males (P < 0.0001 for both). The standardized incidence of primary hypothyroidism did not change and varied between 3.90 and 4.89 per 1000 females/year over the 8 years. Incidence of hypothyroidism in males increased from 0.65 to 1.01 per 1000 males/year (P = 0.0017). Mean age at diagnosis of primary hypothyroidism declined in females from 1994 to 2001.

CONCLUSIONS

The prevalence of primary hypothyroidism and previous hyperthyroidism has increased in Tayside, Scotland. This is partly due to an increasing incidence of disease, increased ascertainment and earlier diagnosis of disease. This will result in an increased workload for endocrinologists and general practitioners.

Results of surgery for toxic multinodular goiter

PURPOSE

We analyzed the clinical and histological features of patients operated on for toxic multinodular goiter (TMG) to determine the clinical profile and evaluate the surgical results.

METHODS

We reviewed 672 patients who underwent surgery for multinodular goiter (MG), 112 (17%) of whom had hyperthyroidism, and analyzed the epidemiological, clinical, and surgical variables.

RESULTS

The patients with TMG tended to be older than those with nontoxic MG, with a greater evolution time of the goiter and a higher rate of positive antithyroid antibodies. In the multivariate analysis, the only feature characteristic of TMG, as opposed to nontoxic MG, was the evolution time. Morbidity was 34%, representative of the fact that that most of the patients were seen before the establishment of our endocrine surgical unit. The hyperthyroid symptoms resolved in all patients, but 4 of 17 patients who underwent partial surgical resection showed signs of relapse within a follow-up period of 98 +/- 71 months.

CONCLUSIONS

TMG is characterized by a long evolution time and is most effectively treated by total thyroidectomy, which achieves complete remission from symptoms, without relapse, and is necessary if there is associated carcinoma. However, the incidence of complications may be high if this procedure is not carried out by surgeons with experience in endocrine surgery.

A cluster of thyrotoxicosis associated with consumption of a soy milk product

OBJECTIVE

To determine whether a New Zealand cluster of thyrotoxicosis with low uptake on scintiscan was associated with soy milk consumption.

METHOD

A case-control study was conducted, with controls matched by age, sex, and region.

RESULTS

All cases (5/5) and one control (1/30) consumed soy milk before the index date. The cases all drank a brand of soy milk that had unexpectedly high levels of iodine. In a simple unmatched unadjusted analysis, the lower bound of the 95% confidence interval for the odds ratio was 19.

CONCLUSION

This cluster was associated with consumption of a soy milk product. The thyrotoxicosis was probably due to iodine-induced thyrotoxicosis.

IMPLICATIONS

This investigation raises issues about quality control in manufacturing processes and the monitoring of food products for their safety. It also raises issues about public and health professional awareness of the potential health effects from food additives in some processed foods.

Thyrotropin-stimulated DNA synthesis and thyroglobulin expression in normal and hyperthyroid feline thyrocytes in monolayer culture

Feline hyperthyroidism is a common, spontaneous disease in older cats that is similar clinically and histopathologically to human toxic multinodular goiter (TNG). In this study, the functional response of feline normal thyroid (NT) and hyperthyroid (HT) cells grown in monolayer culture to thyrotropin (TSH) was determined. Basal levels of DNA synthesis were similar in NT and HT cells. TSH stimulated concentration-dependent DNA synthesis in NT and HT cells, with maximal stimulation seen at 1 and 10 mU/mL TSH in NT and HT cells, respectively. HT cells had higher basal levels of thyroglobulin (Tg) expression. TSH stimulated Tg expression in NT and HT cells in a concentration-dependent fashion, with maximal activity at 0.5 and 5 mU/mL TSH, respectively. These results demonstrate that NT and HT cells in monolayer culture exhibit growth and functional responses to TSH. HT cells have higher basal Tg expression than NT cells and require higher TSH concentrations to stimulate DNA synthesis and Tg expression, two measures of thyroid cell activation. These data support the idea that feline hyperthyroidism is caused by cell abnormalities, resulting in dysregulated growth and hormone synthesis, and emphasize its importance as an animal model for TNG.

Multivariate analysis of risk factors for feline hyperthyroidism in New Zealand

AIM

To search for putative risk factors for feline hyperthyroidism in New Zealand, using a case-control study.

METHODS

A questionnaire-based case-control study involving the owners of 375 cats in New Zealand (125 hyperthyroid cats, 125 randomly selected control cats, and 125 age- and sex-matched control cats) was conducted to examine associations between potential risk factors and occurrence of feline hyperthyroidism. Data were collected between December 1996 and February 1998, relative to cat and owner demography and medical history, cats' indoor and outdoor environments, and cats' diets. A range of statistical techniques was employed to analyse the data, including descriptive analyses, univariate logistic regression for each variable and multivariate stepwise forward logistic regression.

RESULTS

Multivariate analysis revealed that affected cats were more likely to be female (odds ratio (OR)=3.3; 95% confidence interval (CI)=1.2-9.0) and older than unaffected random control cats. Purebred cats were at a much lower risk of being diagnosed as hyperthyroid than were domestic short- and long-haired cats (OR=0.01; 95% CI=0.001-0.20). If more than one cat was present in a household, hyperthyroidism was less likely to be identified (OR=0.15; 95% CI=0.05-0.44) compared with single-cat households. Hyperthyroid cats were 6.6 times more likely (95% CI=1.8-23.9) to be reported to sleep predominantly on the floor than control cats. Cats whose bedding was regularly treated with anti-flea products appeared to be at a considerably higher risk for hyperthyroidism (OR=57.6; 95% CI=3.8-->200); and, to a lesser extent, so were cats living in households where fly sprays were reported to be used regularly (OR=3.3; 95% CI=1.2-9.3). The interaction between drinking water from puddles and regular use of organic garden fertilisers, such as compost or animal manure, was associated with a 5.3-fold (95% CI=1.1-25.6) increase in the risk of cats being diagnosed with the disease. Hyperthyroid cats were twice as likely (95% CI=0.3-12.9) to have eaten at least half of their daily food requirements as canned commercial cat food compared with unaffected cats. Cats exposed to a variety of flavours of canned cat food were more likely to be diagnosed with hyperthyroidism than were those fed only one flavour (OR=3.8; 95% CI=1.5-9.6). The presence of dental disorders was associated with a 5.5-fold increase in the risk of being diagnosed as hyperthyroid and this association was independent of the cat's age (95% CI=1.7-17.5).

CONCLUSIONS

The results of this study support and extend those in several earlier reports and show that cats in New Zealand are, in many respects, similar to cats in Europe and North America in terms of their susceptibility to hyperthyroidism. The finding that female cats are predisposed to hyperthyroidism is at variance with most previously published work. It remains unclear which, if any, of the identified disease associations are causal, so further studies of this increasingly prevalent feline endocrinopathy are warranted.

Seasonal variation in relapse rate of graves' disease after thionamide drug treatment

OBJECTIVE

Controversy abounds on the issue of seasonal variation in new onset of Graves' disease, partly due to the difficulty of precisely dating the exact start of symptoms. To address the possible relationship between climatic changes and disease activity from a different perspective, we reviewed time of relapse during regular follow-up after successful drug treatment with thionamides.

DESIGN

Retrospective analysis of a case series in a university clinic.

PATIENTS AND MEASUREMENTS

We consecutively registered patients who experienced re-emergence of hyperthyroidism between 1992 and 2001 after successful antithyroid drug therapy. Excluded were subjects with superimposing painless thyroiditis, in postpartum, on immunomodulatory drugs, or off thionamides prematurely on their own volition.

RESULTS

Fifty-two patients recurred 2 to 36 months after drug cessation. The frequency was higher in spring and summer (March to August) than in autumn and winter (September to February). With a new coated-tube radioreceptor assay, TSH binding inhibitor immunoglobulin activity was detected in sera from 87.5% of the reworsened patients.

CONCLUSIONS

Graves' disease tends to relapse more frequently in spring and summer. Further clinical studies are warranted to clarify underlying mechanism (s) for this seasonal variation.

Searching for the autoimmune thyroid disease susceptibility genes: from gene mapping to gene function

The autoimmune thyroid diseases (AITD) are complex diseases that are caused by an interaction between susceptibility genes and environmental triggers. Genetic susceptibility, in combination with external factors (e.g., dietary iodine), is believed to initiate the autoimmune response to thyroid antigens. Abundant epidemiological data, including family and twin studies, point to a strong genetic influence on the development of AITD. Various techniques have been used to identify the genes contributing to the etiology of AITD, including candidate gene analysis and whole genome screening. These studies have enabled the identification of several loci (genetic regions) that are linked with AITD, and in some of these loci putative AITD susceptibility genes have been identified. Some of these genes/loci are unique to Graves' disease (GD) and Hashimoto's thyroiditis (HT), and some are common to both diseases, indicating that there is a shared genetic susceptibility to GD and HT. The putative GD and HT susceptibility genes include both immune modifying genes (e.g., human leukocyte antigen, cytotoxic T lymphocyte antigen-4) and thyroid-specific genes (e.g., TSH receptor, thyroglobulin). Most likely these loci interact, and their interactions may influence disease phenotype and severity. It is hoped that in the near future additional AITD susceptibility genes will be identified and the mechanisms by which they induce AITD will be unraveled.

Cutaneous manifestations of endocrine disorders: a guide for dermatologists

Dermatologists may commonly see skin lesions that reflect an underlying endocrine disorder. Identifying the endocrinopathy is very important, so that patients can receive corrective rather than symptomatic treatment. Skin diseases with underlying endocrine pathology include: thyrotoxicosis; hypothyroidism; Cushing syndrome; Addison disease; acromegaly; hyperandrogenism; hypopituitarism; primary hyperparathyroidism; hypoparathyroidism; pseudohypoparathyroidism and manifestations of diabetes mellitus. Thyrotoxicosis may lead to multiple cutaneous manifestations, including hair loss, pretibial myxedema, onycholysis and acropachy. In patients with hypothyroidism, there is hair loss, the skin is cold and pale, with myxedematous changes, mainly in the hands and in the periorbital region. The striking features of Cushing syndrome are centripetal obesity, moon facies, buffalo hump, supraclavicular fat pads, and abdominal striae. In Addison disease, the skin is hyperpigmented, mostly on the face, neck and back of the hands. Virtually all patients with acromegaly have acral and soft tissue overgrowth, with characteristic findings, like macrognathia and enlarged hands and feet. The skin is thickened, and facial features are coarser. Conditions leading to hyperandrogenism in females present as acne, hirsutism and signs of virilization (temporal balding, clitoromegaly).A prominent feature of hypopituitarism is a pallor of the skin with a yellowish tinge. The skin is also thinner, resulting in fine wrinkling around the eyes and mouth, making the patient look older. Primary hyperparathyroidism is rarely associated with pruritus and chronic urticaria. In hypoparathyroidism, the skin is dry, scaly and puffy. Nails become brittle and hair is coarse and sparse. Pseudohypoparathyroidism may have a special somatic phenotype known as Albright osteodystrophy. This consists of short stature, short neck, brachydactyly and subcutaneous calcifications. Some of the cutaneous manifestations of diabetes mellitus include necrobiosis lipoidica diabeticorum, diabetic dermopathy, scleredema adultorum and acanthosis nigricans.

Thyrotoxicosis among Hanford, Washington, Downwinders: a community-based health survey

Sixty cases of thyrotoxicosis (including hyperthyroidism, Graves' disease, and toxic goiter), an unexpectedly large number compared with general population data, were reported in a voluntary health survey that included a period of approximately 50 yr, with 801 self-defined "Downwinders" who had lived near the Hanford, Washington, nuclear facility. In another self-selected group of medical patients (n = 423) who were examined over the same time period, only 2 cases of thyrotoxicosis were identified. Evidence is presented that suggests that the effects of bias from self-selection likely did not account for the magnitude of the apparent excess of thyrotoxicosis cases in the present study population. The findings are consistent with those of other studies, as well as with the hypothesis of an association of thyrotoxicosis with exposures to radioiodine.

Association between lithium use and thyrotoxicosis caused by silent thyroiditis

OBJECTIVE

To determine the incidence of silent thyroiditis in lithium users and characterize lithium-associated thyrotoxicosis.

DESIGN

Retrospective record review.

PATIENTS

400 consecutive patients (300 with Graves' disease and 100 with silent thyroiditis) who underwent radioiodine scanning of the thyroid.

MEASUREMENTS

Odds of lithium exposure.

RESULTS

The odds of lithium exposure were increased 4.7-fold in patients with silent thyroiditis compared with those with Graves' disease (95% CI: 1.3, 17). Lithium-associated silent thyroiditis occurred with an incidence rate of approximately 1.3 cases per 1000 person-years, and lithium-associated thyrotoxicosis occurred with an incidence rate of approximately 2.7 cases per 1000 person-years, higher than the reported incidence rates of silent thyroiditis (< 0.03-0.28 cases per 1000 person-years) and of thyrotoxicosis (0.8-1.2 cases per 1000 person-years) in the general population.

CONCLUSION

Thyrotoxicosis caused by silent thyroiditis might be associated with lithium use.

An unusual case of inappropriate secretion of thyrotropin: neoplastic or nonneoplastic?

OBJECTIVE

To report an unusual case that illustrates the difficulties in distinguishing neoplastic (nIST) from nonneoplastic inappropriate secretion of thyrotropin (nnIST).

METHODS

We describe clinical, biochemical, genetic analysis, and magnetic resonance imaging (MRI) results in a patient with hyperthyroidism due to IST, and we review the related literature.

RESULTS

The patient demonstrated overt clinical and biochemical hyperthyroidism with inappropriately increased thyrotropin levels, which failed to respond to thyrotropin-releasing hormone (TRH) stimulation. Sex hormone-binding globulin (SHBG) levels were in the hyperthyroid range. Alpha subunit levels were normal, as was the alpha subunit/thyrotropin molar ratio. MRI of the pituitary was negative for tumor during a 2-year period, and octreotide scan was also negative for sellar uptake. Basal oxygen consumption was abnormally increased. Genetic analysis failed to reveal mutations of the thyroid receptor b gene. The patient responded well to radioiodine ablation of his thyroid.

CONCLUSION

This patient had clinical symptoms of hyperthyroidism associated with some features characteristic of nIST (increased level of SHBG, lack of thyrotropin response to TRH stimulation, absence of thyroid receptor b mutations) and others typical of nnIST (normal alpha subunit and its molar ratio to thyrotropin, absence of tumor on sellar imaging). Close follow-up with periodic MRI of the sella is important because of the possible existence of a small pituitary tumor, which may become apparent at a later date. Therapy to control symptoms is important. Hormone replacement, if needed, should be adjusted to maintain clinical euthyroidism, guided by free thyroxine levels.

Absence of seasonal variation in Graves disease

PURPOSE

To determine whether there is an identifiable pattern of seasonal variation in the onset of symptoms of orbitopathy and thyrotoxicosis in patients with Graves disease.

METHODS

This retrospective, noncomparative case series reviewed 305 randomly selected office records of patients referred to one author (M.K.) for evaluation of Graves orbitopathy between July 1990 and June 1998. All patients met inclusion criteria for the diagnosis of Graves orbitopathy. During initial evaluation for orbitopathy, patients identified the date of onset of orbital symptoms as well as the earliest date of either onset of thyroid symptoms or documented thyroid abnormality. Patients were excluded from analysis of seasonal variation if they could not recall the month of symptom onset or were euthyroid. The onset of orbital symptoms and identification of dysthyroid state were analyzed by calendar month and season. The chronological relationship of the development of orbital and thyroid symptoms was evaluated.

RESULTS

No significant seasonal variation appeared in the onset of orbital symptoms or identification of dysthyroidism. Out of 148 patients, 115 (78%) developed symptoms of orbital disease within 18 months of the identification of dysthyroidism. The most common presenting orbital symptoms were swelling of the lid or prominence of the globe.

CONCLUSIONS

This study fails to provide evidence for a seasonal influence on the incidence of Graves disease and the associated orbitopathy.

Toxic nodular goiter. Toxic adenoma and toxic multinodular goiter

Solitary toxic adenoma and toxic multinodular goiter are very common forms of thyrotoxicosis around the world. Advances in molecular biology and genetics have led to new insights into the pathogenesis of these disorders. Current theories on autonomy in the thyroid are discussed in this article. The therapeutic roles of surgery, radioiodine ablation, and percutaneous ethanol administration also are reviewed.

The significant increase in incidence of Graves' disease in eastern Serbia during the civil war in the former Yugoslavia (1992 to 1995)

The incidence of Graves' disease for the last 25 years in eastern Serbia (Yugoslavia), Timok Region is reported. Registration of all Graves' disease patients was conducted in the Endocrinology-Thyroid Unit of Nuclear Medicine Service, Medical Center Zajecar. Timok Region has a population of 315,000 people in seven counties. From 1971 to 1980 an average of 16 new patients per year were registered; from 1981 to 1990 an average of 33 patients per year were registered; in 1995 the number reached 100, and in 1996 there were 148 newly registered patients. Some of the possible factors influencing this significant annual increase of autoimmune hyperthyroidism are discussed.

The genetic susceptibility to Graves' disease

Graves' disease (GD) develops as a result of a complex interaction between genetic susceptibility genes and likely environmental factors. Most epidemiological data support an important genetic contribution to the development of GD. The concordance rate of GD in monozygotic twins is 30-60% and in dizygotic twins 3-9%, and thyroid autoantibodies have been reported in up to 50% of the siblings of patients with GD. For many years now, HLA studies have consistently shown an increased frequency of HLA-DR3 in Caucasian patients with GD; but with only a risk ratio of 3-5. However, recent advances in human genome mapping techniques have enabled the study of many other candidate genes. Of these additional, non-HLA genes, only CTLA-4 has been consistently found to be associated with GD. Using a linkage based approach which only detects highly significant susceptibility genes we have recently reported preliminary results which demonstrated that a marker located approximately 25 cM from the TSH receptor gene on chromosome 14q31 is linked to GD and in the same vicinity as the IDDM-11 locus. Such results, if confirmed, may signal the presence of a gene family related to endocrine autoimmunity on chromosome 14q31.

Epidemiology and estimated population burden of selected autoimmune diseases in the United States

Autoimmune diseases cause significant and chronic morbidity and disability. The actual number of persons in the United States that are affected by autoimmune diseases and the resultant magnitude of their impact on the public's health are limited to a few specific diseases. In order to understand the clinical, public health and economic importance of these diseases it is necessary to have estimates of incidence and prevalence rates in the population. In this analysis, we estimate the number of persons affected by 24 autoimmune diseases in the United States by applying mean weighted prevalence and incidence rates obtained from published articles to U. S. Census data. The study was restricted to 24 autoimmune predefined diseases for which there was direct or indirect evidence for autoimmune pathogenesis. Subsequently, we used computerized search software and ancestry searching (bibliographies) to conduct a comprehensive search of articles published from 1965 to the present. Eligible studies included those which adhered to standard disease definitions and which included population-based estimates of incidence or prevalence rates. Mean weighted incidence and prevalence rates were calculated from eligible published studies with greater weight proportionately given to larger studies. The mean rates were then applied to the U.S. Census population figures to estimate the number of persons currently afflicted with each disease and the number of new cases occurring each year in the United States. Only U.S. and European studies were used to estimate prevalence and incidence rates when there were at least six eligible studies available for a disease. When there were fewer than six studies, all available studies were included, regardless of country of origin. The number of eligible incidence and prevalence studies found in the literature varied considerably between the 24 autoimmune diseases selected. The largest number of eligible prevalence studies were conducted on multiple sclerosis (MS), rheumatoid arthritis, and systemic lupus erythematosus (SLE) (>/=23), followed by insulin-dependent diabetes (IDDM), myasthenia gravis, primary biliary cirrhosis, and scleroderma (>/=7). There were only one to four eligible studies done on 11 other diseases, and no prevalence studies on 6 diseases. Incidence studies were less frequent but the largest number of studies were conducted on IDDM (n = 37) and MS (n = 28), followed by Graves' disease/hyperthyroidism, glomerulonephritis, primary biliary cirrhosis, rheumatic fever, rheumatoid arthritis, scleroderma, and SLE (>/=9). On the other 11 diseases, there were one to six eligible studies, and no studies on 5 diseases. There were no eligible incidence or prevalence studies on Goodpasture's syndrome, idiopathic thrombocytopenia purpura, or relapsing polychondritis. Overall we estimate that 8,511,845 persons in the United States or approximately 1 in 31 Americans are currently afflicted with one of these autoimmune diseases. The diseases with the highest prevalence rates were Graves'/hyperthyroidism, IDDM, pernicious anemia, rheumatoid arthritis, thyroiditis, and vitiligo, comprising an estimated 7,939, 280 people or 93% of the total number estimated. Glomerulonephritis, MS, and SLE added an estimated 323,232 people. The prevalence of the other diseases reviewed were rare, less than 5.14/100,000. Most diseases were more common in women. From the incidence data we estimate that 237,203 Americans will develop an autoimmune disease in 1996 and that approximately 1,186,015 new cases of these autoimmune diseases occur in the United States every 5 years. Women were at 2.7 times greater risk than men to acquire an autoimmune disease. After reviewing the medical literature for incidence and prevalence rates of 24 autoimmune diseases, we conclude that many autoimmune diseases are infrequently studied by epidemiologists. As a result the total burden of disease may be an underestimate. (ABSTRACT TRUNCATED)

Seasonal variation in the diagnosis of Graves' disease

OBJECTIVE

Heat intolerance is a well known symptom of Graves' disease. Therefore, it is possible that increased ambient temperature could influence the recognition of Graves' disease by unmasking or enhancing the symptom of heat intolerance. Our aim was to determine if there is a seasonal variation in the diagnosis of Graves' disease.

DESIGN

A retrospective study.

SETTING

A county hospital and clinic.

PATIENTS

Two hundred and seven patients with Graves' disease diagnosed from 1985 to 1992.

RESULTS

A high correlation was found between the temperature and the number of cases of Graves' disease diagnosed. A larger proportion of patients (68%) was diagnosed during the warmer half of the year, May-October, than during the cooler half. The peak incidence of the diagnosis occurred in May, when 17.4% of the patients were diagnosed. Although the peak average monthly temperature occurs in July, the month of May corresponds to the time of the year when the temperature is making its largest positive change in the month-to-month variation.

CONCLUSIONS

Seasonal variations in the temperature can affect the incidence of the diagnosis of Graves' disease. The diagnosis is more common during the months of higher temperature.

Lithium associated thyrotoxicosis: a report of 14 cases, with statistical analysis of incidence

OBJECTIVE

Lithium is known to cause goitre and hypothyroidism, and has been associated less commonly with hyperthyroidism. We report a series of 14 patients with lithium associated thyrotoxicosis (LiAT), and have used epidemiological data to assess the association between long-term lithium treatment and the development of thyrotoxicosis.

DESIGN

Information for this retrospective study was obtained from records of patients attending the thyroid clinic between 1973 and 1991. Statistical analysis of the association between long-term lithium treatment and incidence of thyrotoxicosis was made using local thyrotoxicosis incidence figures and lithium prescription data.

MEASUREMENTS

Investigations included 99mTc pertechnetate thyroid scans, and blood analyses to measure serum T4, serum T3, free T4 index, and thyroid microsomal and thyroglobulin antibody titres.

RESULTS

During the 18-year period there were 14 patients with LiAT. This number of cases of thyrotoxicosis occurring in patients on lithium was more than three times greater than that predicted from local thyrotoxicosis incidence rates (P < 0.05). Scintiscans were obtained for 13 patients: 8 had toxic diffuse goitre, 2 toxic multinodular goitre, 1 toxic uninodular goitre, and 2 had a lack of visualization consistent with 'painless thyroiditis'. Nine patients received a course of carbimazole and 6 of these remain in remission. Six patients have received 131I therapy. Eight patients have become hypothyroid at follow-up (5 post 131I, 1 following a course of carbimazole, and the 2 with 'painless thyroiditis').

CONCLUSIONS

Statistical analysis has shown that long-term lithium therapy is associated with an increased risk of thyrotoxicosis. LiAT is a heterogeneous condition with differing underlying thyroid pathologies and the mechanisms remain uncertain. The management of LiAT should initially be with antithyroid medication, and 131I therapy should be given only to patients who do not obtain long-term remission.

Increased incidence of thyrotoxicosis after iodine supplementation in an iodine sufficient area

The aim of this study was to determine the incidence rate of thyrotoxicosis (TT) before and during dietary-iodine supplementation in an iodine-sufficient area.

POPULATION

the study was carried out in Vigo, South Galicia (northwest of Spain), from January 1977 to December 1989. The mean population throughout the study period was 267,330 inhabitants (47% males and 53% females). From January 1985, a mandatory consumption of iodinized salt on the whole population started in Galicia. This region was considered as an iodine-deficient area but Vigo is an iodine-sufficient area.

MEASUREMENTS

all newly diagnosed TT cases in Vigo city within the study period were included in this study. Diagnosis of TT was based on the clinical manifestations, an elevated level of T4 and suppressed TSH values. The difference between diffuse and nodular forms of goiter was assessed by scintigraphy. The average incidence rate (AIR) was determined in two periods, before (period A, 1977-1984) and during (period B, 1985-1989) iodine supplementation.

RESULTS

the AIR throughout the whole study period was 4.89 new cases per 100,000 population, 95% confidence limits 4.16 to 5.63; AIR was 1.34 for males and 8.03 for females. AIR in period B was significantly higher with respect to period A, 7.68 and 3.10 per 100,000 respectively. The confidence interval for the difference was from -20.4 to 30.1, p < 0.05. The increase of the incidence of TT was comprised of both nodular and diffuse goiters.

CONCLUSIONS

dietary iodinesupplementation in iodine-sufficient areas may induce an increase of the incidence of TT.(ABSTRACT TRUNCATED AT 250 WORDS)