The epidemiology of thyroid disease and implications for screening

Learning the thyroid examination--a multimodality intervention for internal medicine residents

BACKGROUND

Many physicians have inadequate physical diagnosis skills and cannot detect thyroid abnormalities on physical examination.

PURPOSE

To evaluate a multimodality intervention to improve thyroid examination skills using a prospective controlled trial in first-year residents enrolled in an academic internal medicine program.

METHODS

The intervention group received a 60-minute educational session during which an endocrinologist described anatomical landmarks, thyroid abnormalities, and examination techniques using a slide show, computerized animation, videotape, and live demonstration on a volunteer with goiter. Residents examined a normal and a goitrous thyroid under the observation of a preceptor and received an evidence-based handout on the thyroid examination. The control group received no specific intervention. Examination technique and identification of thyroid abnormalities were blindly assessed in 2 stations of an objective structured clinical examination (OSCE).

RESULTS

Of the 19 residents in the intervention group and the 20 in the control group, 6 (32%) and 3 (15%), respectively, observed the neck for thyroid abnormalities (P = 0.3), 17 (90%) and 16 (80%) used proper hand position (P = 0.7), and 13 (68%) and 15 (75%) had the patient swallow while the neck was palpated (P = 0.7). There was a significant difference in the mean scores based on thyroid physical findings during the OSCE between the intervention and control groups (100 vs. 52.5 [maximal possible score = 200], P = 0.047).

CONCLUSION

A 1-hour multimodality learning session furthered the ability of first-year internal medicine residents to detect thyroid abnormalities.

Thyroid function and anti-thyroid antibodies in MS patients screened for interferon treatment. A multicenter study

Interferon beta (IFNB) treatment for multiple sclerosis (MS) has been associated with thyroid disorders (TD), in particular in patients with subclinical TD or anti-thyroid (AT) autoantibodies (autoAb) before starting treatment. TD and AT autoAb frequency was reported increased in MS. To determine whether MS patients have subclinical thyroid function abnormalities or anti-thyroid autoimmunity predisposing to develop TD, we performed a prospective multicenter screening of thyroid function and autoimmunity in 152 relapsing-remitting (RR) MS patients selected to receive IFNB treatment and in 437 healthy normothyroidal controls. Thyroid-related hormones and anti-thyroid microsomal antigen (anti-TMA) autoAb were tested with sensitive immunoradiometric or chromatographic assays. Cases were stratified for different progressively decreasing or increasing cutoff values of thyroid-stimulating hormone (TSH) (0.3, 0.2, 0.1, 3 and 5 mIU/l), and odds ratios (OR) with 95% confidence intervals (CI) calculated using logistic regression adjusted for gender, age, and anti-TMA autoAb positivity. The frequency of cases below or above the TSH cutoff values was not significantly different in MS patients and controls, and the risk to have an abnormal TSH level was not significantly increased in MS patients (OR ranging 0.37-0.84; CI, 0.05-3.01), even if anti-TMA autoAb positive (OR ranging 0.35-0.85; CI, 0.04-3.00). Frequencies of subclinical hypothyroidism and of anti-TMA autoAb positivity were, however, trending higher in MS men (ranging 5-7%) than in controls (3%). MS patients do not have an increased risk of subtle thyroid function abnormalities, subclinical TD, or anti-TMA autoAb positivity that may predispose to develop thyroid dysfunction during IFNB treatment. The positive trend for subclinical hypothyroidism and anti-TMA autoAb positivity, however, advises a longitudinal study of thyroid function and autoimmunity during IFNB treatment to see whether patients with baseline subclinical thyroid dysfunction develop clinically significant alteration during treatment.

Evaluation of chronic urticaria in patients with Hashimoto thyroiditis

The coincidence of Hashimoto thyroiditis (HT) and chronic idiopathic urticaria (CIU) is a commonly observed phenomenon in western New York. Previous literature suggested that there may be a direct relationship between them. We undertook these studies to determine whether humoral or cell-mediated mechanisms might link HT and CIU. Skin biopsies from patients with CIU, with or without HT, were indistinguishable by light microscopy. No immune complex deposition was observed, although only the skin from patients with CIU and HT contained perivascular fibrin deposits. Similarly, immunohistochemical studies evaluating cellular expression of CD3, CD4, CD8, CD20, and CD68 failed to differentiate between CIU with or without HT. Analysis of Vbeta restriction in thyroid tissue of patients with HT and the skin of patients with CIU and HT by in situ polymerase chain reaction failed to reveal any oligoclonal T-lymphocyte subpopulations. In contrast, only patients with CIU and HT had anti-FcepsilonRI antibodies in their sera that could induce degranulation of normal basophils. Some sera from patients with CIU and HT caused degranulation of normal basophils in the absence of anti-FceRI. The factor causing basophil degranulation in these sera was not determined. Patients with CIU and HT failed to improve clinically with thyroid replacement therapy. All CIU patients were equally well managed with symptomatic therapies. In conclusion, HT likely represents a marker of other autoimmunity, rather than being a direct causative agent in CIU. Management of CIU, with or without HT and with or without anti-FceRI antibodies, should be the same. Future studies will have to examine whether cell-mediated responses participate in CIU, especially in association with HT.

Evaluation of the patient with a suspected thyroid disorder

The principal types of thyroid disorders described herein can be recognized and evaluated clinically and biochemically by the obstetrician/gynecologist. Most patients with diffuse goiter should be referred for further evaluation and an RAI scan arranged while this consultation is awaited. Patients with solitary thyroid nodules should be referred for FNAB. Primary hypothyroidism without significant goiter can be treated without specialist referral, except in patients at high risk for ischemic coronary disease or arrhythmia. Primary hyperthyroidism, apart from subacute and postpartum thyroiditis, should be referred for specialist evaluation and definitive therapy. An RAI scan and uptake should be ordered, and beta-blocker therapy can be initiated as interim therapy in symptomatic patients. Patients with secondary (i.e., hypothalamic- or pituitary-based) thyroid dysfunction should always be referred for evaluation and treatment of the primary intracranial cause. There are several causes of abnormal thyroid function tests in apparently euthyroid patients, and the clinical context often provides important evidence of their nature. Clinical judgment is an important factor in knowing when to arrange specialist consultation.

Fine-needle aspiration biopsy of the thyroid

The routine use of thyroid FNAB caused profound changes in the management of thyroid nodules. FNAB allows a prompt identification and treatment of thyroid malignancies and avoids unnecessary surgery in patients with benign lesions, improving quality of life in patients with thyroid nodules. Furthermore, FNAB provides guidance for the type of surgery and reduces costs of care. On average, standard FNAB is nondiagnostic in 25% to 40% of cases, which include inadequate specimens and indeterminate (suspicious) diagnoses. In addition, a small percentage of false-negative diagnoses occur, which are unavoidable and raise concern of a late diagnosis of cancer. To minimize the limitations of FNAB, every center should reach and maintain a high standard of expertise in all of the steps of smear preparation and interpretation. Alternative modes of sampling or sample preparation may result in a reduction of nondiagnostic samples and better accuracy. Every center should set up clinical guidelines tailored to their own FNAB results and including the evaluation of clinical data. More work is needed to increase the accuracy of FNAB in suspicious cases. Toward this goal a variety of molecular markers have been evaluated; although none of them are ideal, some are promising. More studies need to be carried out in larger series to further evaluate the accuracy of these markers in identifying specific cancer histotypes within the group of suspicious lesions. It is hoped that, in the near future, the routine use of a combination of these markers will cost-effectively improve the diagnosis of malignant nodules classified as suspicious on traditional cytology. Statistical methods such as bayesian analysis or neural networks can be advantageously used to integrate different relevant information derived from family and personal history, clinical data, cytologic results, and evaluation of molecular markers.

High frequency of incidental diagnosis of extrathyroidal neoplastic diseases at the fine-needle aspiration biopsy of laterocervical lymph nodes in patients with thyroid nodules

This study was undertaken to evaluate the frequency of the incidental diagnosis of extrathyroidal lymph node diseases at ultrasound-guided fine-needle aspiration biopsy/cytology (FNAB/C) being done to check the presence of metastatic thyroid cancer in 30 subjects with thyroid nodule (TN) and enlarged cervical lymph nodes (CLN). The patients in whom cytology suggested the presence of malignancy in the TN or in the CLN underwent surgical removal for histologic diagnosis. The spectrum of diseases revealed by this survey included: (1) 10 benign diseases including 1 case of Piringer-Kuchinka lymphadenitis with benign TN; (2) 10 metastatic thyroid cancers (2 anaplastic and 8 papillary cancers); (3) 3 benign TN associated with metastatic invasion of cervical lymph nodes from lung (2 cases) and breast (1 case) cancer; (4) 1 Hodgkin's lymphoma of the cervical lymph nodes with hyperplastic TN; (5) 3 nodal lymphomas with benign thyroid nodule and 2 cases of thyroid lymphoma with nodal invasion; and (6) 1 nodal sarcoidosis with benign TN. The results of this study demonstrate that important neoplastic and hematologic diseases affecting the cervical lymph nodes may frequently be incidentally detected using ultrasonography (US) and FNAB/C in the diagnostic procedure for thyroid nodule.

Low birth weight is not associated with clinically overt thyroid disease: a population based twin case-control study

OBJECTIVE

In recent years low birth weight has been proposed as a risk factor for the development of several chronic diseases in adult life, including diabetes and subclinical autoimmune thyroid disease. The association could, however, also be due to genetic or environmental factors affecting both birth weight and adverse health outcomes in adult life. Moreover, it is at present unknown whether or not low birth weight is associated with an increased risk of developing clinically overt thyroid disease. The aim of the present study was to investigate the impact of birth weight and several other birth characteristics on the development of clinically overt thyroid disease.

DESIGN

A twin case-control study of same sex twin pairs.

PATIENTS

One hundred and thirty-one same sex twin pairs (262 twin individuals) discordant for clinically overt thyroid disease, ascertained from a population based nation-wide twin register.

MEASUREMENTS

Information about birth weight, birth length, birth order (first vs. second born), and prematurity was obtained from the original midwife records.

RESULTS

Forty-nine twin pairs were discordant for clinically overt autoimmune thyroid disease (Graves' disease = 35 and Hashimoto's thyroiditis = 14) and 82 pairs were discordant for overt nonautoimmune thyroid disease (Simple goitre = 79 and toxic nodular goitre = 3). Overall, there was no difference in birth weights between probands and the healthy co-twins in monozygotic (MZ, n = 39) or in dizygotic (DZ, n = 92) pairs (MZ: mean +/- SE: 2619 +/- 93 g vs. 2553 +/- 89 g, P = 0.40; DZ: 2576 +/- 45 g vs. 2585 +/- 49, P = 0.86). By means of logistic regression, the impact of other birth characteristics such as birth length, birth order (first vs. second born), and prematurity was tested. None of the variables reached statistical significance. Subdividing the twin pairs into those discordant for clinically overt Graves' disease, Hashimoto's thyroiditis, and nonautoimmune thyroid disease did not change the results.

CONCLUSIONS

This is the first study of the effect of birth weight and other birth characteristics on the subsequent development of clinically overt thyroid disease in which maternal, socioeconomic, and to a high degree, genetic factors have been controlled for. Our study did not show any effect of birth weight or any of the other birth characteristics on the risk of developing clinically overt autoimmune or nonautoimmune thyroid disease.

Management of the nontoxic multinodular goitre: a European questionnaire study

BACKGROUND AND OBJECTIVE

The optimum management strategy for the patient with a multinodular nontoxic goitre is still a matter of debate. Our aim was to assess the attitudes towards management of such patients throughout Europe by means of a questionnaire.

DESIGN

The questionnaire was circulated to all clinician members of the European Thyroid Association (ETA). A case report was followed by diagnostic investigations and choice of therapy in the index case (a 42-year-old woman with an irregular nontender bilaterally enlarged thyroid of 50-80 g and no clinical suspicion of malignancy). Eleven variations of the basic case report were proposed in order to evaluate the impact on management of each alteration.

SUBJECTS AND METHODS

One hundred and sixty-seven members replied to the letter, and 120 individuals from 22 countries completed the questionnaire (corresponding to approximately two-thirds of the clinical members of the ETA).

RESULTS

Based on the index case, serum TSH was the routine choice of 100%, and serum free T4/T4-index was included by 74%. Serum TPO autoantibodies, Tg autoantibodies and calcitonin were measured by 65%, 49% and 32%, respectively. The median number of blood tests used was four (range 1-11). Considerable intercountry variations were seen in the preferred imaging methods. Ninety-one percent of the clinicians would use at least one imaging modality. Ultrasound (US) was used by 84%, thyroid scintigraphy by 76%, and both methods by 69%. US had first priority (53% vs. 19% for scintigraphy). If scintigraphy was performed, fine-needle aspiration cytology was routinely used by 17% (inhomogeneous uptake) and 95% (dominant 'cold' area), and 63% used US-guidance. L-T4 treatment was supported by 52% of the clinicians, iodine supplementation by 4%, radioiodine by 6% and surgery by 10%. In the case of a suppressed serum TSH, radioiodine treatment was preferred by 44%, while surgery was the favoured recommendation in four clinical variations with a large goitre or suspicion of malignancy. Marked differences between the countries were suggested by L-T4 therapy being the dominant treatment in Italy, France and Germany in contrast to the prevailing use of radioiodine in Denmark and a wait and see policy in the UK.

CONCLUSIONS

Fundamental differences between European countries exist as regards diagnosis and treatment of the multinodular nontoxic goitre suggesting difficulties in reaching a consensus.

Population screening for autoimmune thyroid disease

Whether or not healthy adults in the community would benefit from screening for autoimmune thyroid disease is controversial. Although the prevalence of unsuspected overt thyroid disease is low, a significant proportion of subjects tested will have evidence of mild thyroid failure or excess. This article assesses whether subclinical thyroid disease is of sufficient clinical importance to warrant screening and, once detected and confirmed, to justify therapy. Population screening for autoimmune thyroid disease is assessed against recently revised screening criteria, using data from epidemiologic studies. Recommendations are proposed that may be applied in any iodine-replete community.

Genetic and environmental factors in the aetiology of simple goitre

The aetiology of simple goitre, affecting up to 5% of a population in iodine-sufficient areas and over 10% in endemic areas, is incompletely understood. It is generally believed that the development of simple goitre, whether endemic or sporadic, depends on complex interactions between genetic, environmental and endogenous factors. The importance of genetic factors is evident from the clustering of simple goitre within families and from a higher concordance rate for goitre in monozygotic than in dizygotic twins. Recently, studies assessing the role of specific candidate genes or genetic markers in the aetiology of simple goitre have given conflicting data in various families. However, there may well be single genes playing a major role within certain families, eg the thyroglobulin (Tg) gene, the thyroid-stimulating hormone receptor (TSHR) gene, the Na+/I- symporter (NIS) gene, and the multinodular goitre marker 1 (MNG1) on chromosome 14, but the genes will vary from family to family. In addition, family and twin studies also indicate a modest to major role for environmental factors in the aetiology of simple goitre. Clearly, iodine deficiency and cigarette smoking are the most important environmental risk factors associated with the genesis of simple goitre. Other suggested risk factors include naturally occurring goitrogens, emotional stress and certain drugs and infections. Ongoing studies focus on whole-genome screening in multiplex families as well as on large population-based case-control studies. However, the possibility that simple goitre is a heterogeneous disease without a single well-defined genotype and phenotype should be left open.

Thyroid incidentalomas. Prevalence, diagnosis, significance, and management

Thyroid incidentalomas are common, always impalpable, often less than 1.5 cm in size, and frequently benign. The authors recommend that low-risk patients with incidentalomas be followed up with clinical palpation in 6 to 12 months and not be subjected to routine testing with US-FNA. In the authors' strategy, fine-needle aspiration is reserved for an impalpable nodule and is performed under ultrasonographic guidance in the high-risk group of patients in whom either the imaging features or the clinical history is worrisome for malignancy. It does not seem necessary, practical, or cost-effective to perform biopsy or to excise surgically all impalpable nodules. Because of the high prevalence of thyroid incidentalomas, most of which are benign, a nonsurgical approach is logical.

Disclosing subclinical thyroid disease. An approach to mild laboratory abnormalities and vague or absent symptoms

Patients with subclinical thyroid disease often have no apparent symptoms or only nonspecific complaints. However, increasing evidence that early disease is associated with behavioral, psychiatric, biochemical, and organ-specific abnormalities has led several specialty organizations to publish or modify position papers. Serum TSH testing is the most sensitive method of identifying early thyroid dysfunction. It should be considered in patients who have risk factors for mild thyroid failure, have symptoms that could be related to thyroid disease, or are taking exogenous thyroid hormone. T4 therapy should be strongly considered in patients with a TSH level of 10 mIU/L or more. If observation is elected in asymptomatic patients with lesser TSH elevation, periodic measurements are advised. In patients with TSH suppression who are taking thyroid hormone, the dose should be lowered. If the TSH level is decreased because of endogenous suppression and free-T4 and T3 levels are normal, options include observation and treatment with an antithyroid drug or thyroid ablation. Early therapy should be considered in older patients and those with heart disease or nodular thyroid disease. The goal of all treatment methods should be to keep the TSH level in the normal range.

Thyroid nodules and cancer. When to wait and watch, when to refer

Thyroid nodules, a common problem in clinical practice, are usually benign; only about 5% of these nodules harbor malignancy. The first step in evaluation is measurement of serum TSH levels. When the TSH value is suppressed, a hyperfunctioning nodule is likely, and scintigraphy may be helpful for confirming the diagnosis. Because thyroid cancer is extremely rare in "hot" nodules, such a finding is reassuring. Observation alone or treatment with radioiodine is a reasonable alternative to surgery in many of these patients. Fine-needle aspiration biopsy is the single most important procedure for differentiating benign from malignant thyroid nodules, and its role in evaluation and management of nodular thyroid disease cannot be overemphasized. Ultrasound, scintigraphy, and radioiodine scanning, together with measurement of various tumor markers, are useful adjuncts in the preoperative and postoperative management of patients with thyroid cancer. A carefully thought-out management plan can help reduce the risk of unnecessary surgery in these patients.

Protocols for the preoperative selection of palpable thyroid nodules: review and progress

Modern protocols for the management of patients with palpable thyroid nodules agree that fine-needle aspiration is the first examination to be performed. However, they differ very much in the role attributed to scintigraphy and ultrasound examinations. In some protocols, these two techniques are not considered, whereas in others they are recommended at the end of the diagnostic workup to select for surgery those nodules with nondiagnostic or suspect fine-needle aspiration biopsy results. We report original data and literature showing that such use of scintigraphy and ultrasonography is not cost effective. Furthermore, we report original data showing that large-needle aspiration biopsy can be used to select for surgery those nodules with nondiagnostic or suspect results after fine-needle aspiration. Consequently, we suggest a new protocol for the preoperative selection of palpable thyroid nodules.

Association of MS with thyroid disorders

A controlled prospective study was conducted to determine whether thyroid disorders are present with increased frequency in patients with MS. We found that thyroid disorders were at least three times more common in women with MS than in female controls. This was accounted for mainly by the prevalence of hypothyroidism among the female MS patients. Because hypothyroidism is usually due to Hashimoto's thyroiditis, its association with MS may support the hypothesis of autoimmune pathogenesis for MS. Our findings might have therapeutic implications because interferon treatment can induce antithyroid antibodies and thyroiditis.

Subclinical hyperthyroidism

Subclinical hyperthyroidism is defined as a situation where the levels of the peripheral thyroid hormones are normal but serum thyrotropin (TSH) is low. It is not a rare finding; rates between 0.2% and 11.8% have been reported in different groups, according to age, sex, etc. The etiology is usually the same as that of overt hyperthyroidism. The health implications include general symptoms, effects on the cardiovascular system, and decreased bone density. The increased frequency of atrial fibrillation and the increased mortality reported are especially serious. It is not clear whether subclinical hyperthyroidism should be treated or not. Most authors conclude that treatment is required in selected cases or in special circumstances.

The influence of hypothyroidism and thyroid replacement therapy on stimulated parotid flow rates

OBJECTIVE

The purpose of this study was to determine, through use of cross-sectional and longitudinal data, whether hypothyroidism and its treatment with thyroid hormones have a significant effect on the production of stimulated parotid flow rates.

STUDY DESIGN

From the Baltimore Longitudinal Study of Aging (NIA, NIH), subjects with hypothyroidism taking and not taking thyroid replacement therapy were evaluated for the production of 2% citrate-stimulated parotid saliva in a cross-sectional and longitudinal investigation. Comparisons were made with nonmedicated healthy control subjects.

RESULTS

Cross-sectional analyses revealed that stimulated parotid flow rates were not significantly different between healthy controls, subjects with hypothyroidism on thyroid replacement therapy, and subjects with hypothyroidism not on thyroid replacement therapy. In general, longitudinal analyses revealed no significant differences over time in stimulated parotid flow rates between healthy controls and subjects with hypothyroidism.

CONCLUSIONS

Hypothyroidism and the concomitant use of thyroid replacement therapy do not cause significant changes in the production of stimulated parotid saliva.

Autoimmune events during interferon beta-1b treatment for multiple sclerosis

Autoimmune events, although rarely reported during interferon beta-1b (IFNB) treatment of relapsing-remitting (RR) multiple sclerosis (MS), may be more frequent than expected due to the many immunologic abnormalities associated with this disease. We report the prospective two-year follow-up of autoimmune events in 40 RR MS patients treated with IFNB and in 21 untreated MS controls. Thyroid and liver function and serum level of 12 autoantibodies (autoAbs) against organ- (thyroid, gastric, pancreatic) and non-organ-specific antigens were serially monitored. In contrast to control patients, autoAbs (anti-nuclear, -smooth muscle or -thyroid antigens) were detected in 13 IFNB-treated patients, and these were associated with thyroid or liver function alteration in many cases. Persistent autoimmune thyroid dysfunction occurred in three IFNB-treated patients, all of whom were women with a familial history of thyroid disease or baseline anti-thyroid autoAb positivity. For improvement of the MS relapse rate, thyroid dysfunction was adequately treated without stopping IFNB. Liver function alteration (17 IFNB-treated patients, associated with non-organ-specific autoAbs in four) was transient and did not require IFNB treatment to be stopped, with the exception of one patient who was already suffering from a drug-induced hepatopathy at baseline. During the IFNB treatment of MS, several autoimmune events may occur, indicating that thyroid and liver function and autoAbs must be carefully monitored.

Low incidence rate of overt hypothyroidism compared with hyperthyroidism in an area with moderately low iodine intake

In areas with relatively high iodine intake, the incidence rate of hypothyroidism is several-fold higher than that of hyperthyroidism. Recently, we found a similarly high prevalence rate of subclinical hypothyroidism compared with hyperthyroidism in a high iodine intake area, while a relatively low prevalence of subclinical hypothyroidism was observed in a low iodine intake area. In the present study we compared the incidence rate (newly diagnosed in primary care and at hospital) of overt hypothyroidism with that of hyperthyroidism in a well-defined geographical area in Jutland, Denmark, with an iodine intake around 60 microg/day. The number of personsxyears studied was 569,108. Data on hyperthyroidism have been published previously. The overall incidence of hypothyroidism was 13.5/100,000 per year (F/M 22.9/3.6), hyperthyroidism 38.7/100.000 per year (F/M 63.0/13.0). The incidence of hypothyroidism was steadily increasing with age up to 80/100,000 per year in subjects older than 70 years of age, but apart from congenital hypothyroidism it was lower than that of hyperthyroidism at all ages. The majority of patients (79%) was diagnosed to have spontaneous autoimmune hypothyroidism (16% with goiter, 84% with no thyroid visible or palpable). In conclusion, in an area with moderately low iodine intake, hypothyroidism was considerably less common than hyperthyroidism. This is in contrast to findings in high iodine intake areas. The iodine intake of an area seems to be of major importance for the pattern of thyroid disorders observed.

The systematic screening and management of hypothyroidism and hyperthyroidism during pregnancy

Altogether, thyroid function abnormalities during pregnancy can affect up to 10% of all women. The high prevalence of both hypo- and hyperthyroidism, the obstetrical repercussions associated with thyroid dysfunction in the mothers, as well as the potential role of maternal thyroid dysfunction as an influence on fetal development constitute solid arguments for a further increase of our knowledge of the pathophysiological processes underlying the alterations of thyroid function related to the pregnant state. In this review, the focus will be on the most clinically relevant aspects associated with hypothyroidism [autoimmune thyroid disorders (AITDs), subfertility, risk of miscarriage, risk of hypothyroidism in women with AITD and treatment of hypothyroid women] and with hyperthyroidism (clinical presentations during pregnancy, Graves' disease and its management, fetal hyperthyroidism in women with antithyroid-stimulating hormone receptor antibodies and gestational transient thyrotoxicosis associated with human chorionic gonadotropin stimulation of the maternal thyroid gland). I also propose a global strategy for the systematic screening of hypo- and hyperthyroidism in the pregnant state.

Chronic recurrent stress due to panic disorder does not precipitate Graves' disease

A role of psychic stress in precipitating hyperthyroid Graves' disease has been suggested, but the evidence in support of this pathogenetic mechanism is conflicting. In this study we investigated the possible occurrence of Graves' disease in patients with panic disorder, a psychiatric condition characterized by recurrent endogenous stress. The study group included 87 consecutive patients suffering from panic disorder since 1 to 30 years: 17 males (mean age 31.3, range 26-43 years) and 70 females (mean age 37.6, range 15-73 years). Two hundred and sixty-two normal subjects with no present or past history of psychiatric disorder served as controls. Patients were submitted to a full evaluation of the thyroid that included physical examination, assays for free thyroid hormones, TSH, thyroglobulin (TgAb), thyroperoxidase (TPOAb) and TSH receptor (TRAb) antibodies, and thyroid echography. The prevalence of circulating TgAb and/or TPOAb in patients with panic disorder did not differ from that in the control group. Twelve patients with panic disorder (13.7%) had circulating TgAb and/or TPOAb, but none had TRAb. Three out of 12 patients with thyroid antibodies, indicating a genetic susceptibility to autoimmune thyroid disease, had a family history of clinical thyroid autoimmunity, and 4 of them had a hypoechogenic pattern of the thyroid at ultrasound suggesting autoimmune thyroiditis. None of the patients with panic disorder had a previous history of hyperthyroidism. On examination, clinical hyperthyroidism or endocrine ophthalmopathy were not found in any of them. A small goiter was appreciated by palpation in 16 patients (18.3%). Free thyroid hormones and TSH were within the normal range in all patients but one: a 55-year old lady with normal serum free thyroid hormones and undetectable TSH. During an 18-month follow-up she did not develop hyperthyroidism and her TSH spontaneously returned in the normal range. Considering the individual duration of panic disorder, evidence for previous or present Graves' hyperthyroidism was not found for a total of 478 patient-years of exposure to recurrent endogenous stress in the whole study group, and for a total of 39 patient-years in patients with a genetic susceptibility to autoimmune thyroid disease. In conclusion, we found that recurrent endogenous stress did not precipitate Graves' hyperthyroidism in a series of 87 patients with panic disorder, encompassing a total of 478 patient-years of exposure to stress. Failure to activate the hypothalamic-pituitary-adrenal axis by endogenous stress due to panic disorder as opposed to exogenous stress due to life-events might explain why panic disorder does not precipitate Graves' hyperthyroidism.