Natural history of autoimmune thyroiditis

Predictivity of thyroid autoantibodies for the development of thyroid disorders in children and adolescents with Type 1 diabetes

AIMS

To investigate the prevalence of thyroid autoantibodies and their significance for the development of thyroid disorders in children and adolescents with Type 1 diabetes.

METHODS

Antibodies to thyroglobulin (anti-TG) and thyroperoxidase (anti-TPO) were measured in 216 patients (113 boys; median age 12.9 years (range 1-22 years)) with Type 1 diabetes (diabetes duration 2.5 years (0-14 years)) in a cross-sectional study. Sixteen patients with significantly elevated anti-TPO titres were followed longitudinally (6.0 years (4-13 years)) including the measurement of anti-TPO, anti-TG, T(3), T(4), thyroid-stimulating hormone (TSH) and ultrasound assessment.

RESULTS

Twenty-two patients (10.0%) had significantly elevated titres of anti-TPO, 19 (8.7%) of anti-TG and 13 (5.9%) of both autoantibodies. Girls had more frequently elevated anti-TPO antibodies than boys (P < 0.05). Eight of 16 patients (50%) developed thyroid disorders defined by a TSH elevation (> or = 4.5 microU/ml) and/or sonographic thyroid abnormalities during a median time of 3.5 years (2-6 years) after first detection of anti-TPO positivity. They were characterized by higher levels of anti-TPO (P = 0.001) and a more frequent coexistence of anti-TG antibodies (P = 0.002) than those with no development of thyroid disorder even after an observation period of 5.5 years (5-10 years).

CONCLUSIONS

Because 50% of children with diabetes and significant titres of anti-TPO develop thyroid problems within 3-4 years, examinations of thyroid antibodies should be performed yearly. In cases of significant antibody titres, thyroid function tests and ultrasound assessment are recommended in order to minimize the risk of undiagnosed hypothyroidism in these patients.

A 6-month randomized trial of thyroxine treatment in women with mild subclinical hypothyroidism

PURPOSE

The role of thyroxine replacement in subclinical hypothyroidism remains unclear. We performed a 6-month randomized, double-blind, placebo-controlled trial to evaluate the effects of thyroxine treatment for mild subclinical hypothyroidism, defined as a serum thyroid-stimulating hormone level between 5 to 10 microU/mL with a normal serum free thyroxine level (0.8-16 ng/dL).

SUBJECTS AND METHODS

We randomly assigned 40 women with mild subclinical hypothyroidism who had presented to their family practitioners to either thyroxine treatment (n = 23; 50 to 100 microg daily) or placebo (n = 17). Health-related quality of life (Hospital Anxiety and Depression scale, 30-item General Health Questionnaire), fasting lipid profiles, body weight, and resting energy expenditure were measured at baseline and 6 months.

RESULTS

The most common presenting symptoms were fatigue (n = 33 [83%]) and weight gain (n = 32 [80%]). At presentation, 20 women (50%) had elevated anxiety scores and 22 (56%) had elevated scores on the General Health Questionnaire. Thirty-five women completed the study. There were no significant differences in the changes from baseline to 6 months between women in the thyroxine group and the placebo group for any of the metabolic, lipid, or anthropometric variables measured, expressed as the mean change in the thyroxine group minus the mean change in the placebo group: body mass index, -0.3 kg/m(2) (95% confidence interval [CI]: -0.9 to 0.4 kg/m(2)); resting energy expenditure, -0.2 kcal/kg/24 h (95% CI: -1.3 to 1.0 kcal/kg/24 h); and low-density lipoprotein cholesterol, -4 mg/dL (95% CI: -23 to 15 mg/dL). There was a significant worsening in anxiety scores in the thyroxine group (scores increased in 8 of 20 women and were unchanged in 2 of 20) compared with the placebo group (scores increased in 1 of 14 women and were unchanged in 6 of 14; P = 0.03). CONCLUSIONS; We observed no clinically relevant benefits from 6 months of thyroxine treatment in women with mild subclinical hypothyroidism.

Ten-year follow-up of thyroid function in lithium patients

The objective of this paper was to study prospectively the course of clinically relevant thyroid dysfunction in a cohort of patients on long-term lithium treatment. Patients (N = 150) who had undergone a cross-sectional evaluation of their thyroid function in 1989, when they were at different stages of lithium treatment, were followed up for the presence of thyroid autoimmunity, hypothyroidism, and goiter during a further period of lithium exposure of up to ten years. The following annual rates of newly developed thyroid dysfunction were observed: autoimmunnity (1.4%), subclinical hypothyroidism (1.7%), and goiter (2.1%). Subjects with thyroid autoimmunity had a higher chance of requiring substitution treatment with levothyroxine for subclinical hypothyroidism compared with subjects with no evidence of thyroid autoimmunity (13/32 = 41% versus 7/118 = 6%). Subjects (N = 15) who were prescribed carbamazepine in addition to lithium showed a significant decrease of TSH concentrations. In patients already being treated with lithium for several years, the overall incidence of hypothyroidism, goiter, and thyroid autoimmunity were comparable with those reported for the general population. However, lithium exposure may represent an additional risk factor for hypothyroidism in women and/or in the presence of thyroid autoimmunity.

Management practices among primary care physicians and thyroid specialists in the care of hypothyroid patients

Prospective studies are not available to address various issues commonly encountered in the management of hypothyroid patients. We have conducted a case-based mail survey of American Thyroid Association (ATA) members and primary care providers (PCP) regarding hypothyroidism management issues. A majority of ATA members and a minority of PCPs used antithyroid antibody testing in the evaluation of hypothyroidism. Approximately 2/3 of all respondents indicated that they would treat patients with mild thyroid failure when antithyroid antibodies are negative; 77% of PCPs and 95% of ATA members recommended treatment when antibodies are positive. For a young patient with mild thyroid failure, 71% of ATA members would initiate a full levothyroxine (LT4) replacement dose of 1.6 microg/kg per day or slightly lower; PCPs were more likely to start with a low dose and titrate upwards. For a young patient with overt hypothyroidism, 42% of PCPs and 51% of ATA respondents recommended an initial full LT4 replacement dose. The majority of all respondents would start with a low LT4 dose and adjust the dose gradually in an elderly patient, regardless of the severity of thyroid hormone deficiency. More than 40% of ATA respondents chose a target thyrotropin (TSH) range of 0.5-2.0 microU/mL for a young patient while 39% favored a goal of 1.0-4.0 microU/mL for an elderly patient. PCPs more often chose a broader TSH goal of 0.5-5.0 microU/mL. In conclusion, the current practice patterns of PCPs and ATA members that were elicited in this survey differ significantly in regard to the evaluation and management of hypothyroidism.

Subclinical hypothyroidism: a review of neuropsychiatric aspects

The authors review current information about the prevalence, causes, course, and consequences of subclinical hypothyroidism. There is evidence that subclinical hypothyroidism may be associated with cognitive dysfunction, mood disturbance, and diminished response to standard psychiatric treatments. Recommendations are presented for the screening, evaluation and treatment of patients in whom subclinical hypothyroidism may be contributing to neuropsychiatric dysfunction.

Comparison of some different methods for analysis of thyroid autoantibodies: importance of thyroglobulin autoantibodies

Blood samples from 141 children and adolescents were used to evaluate differences between commercial kits and radioimmunoassay (RIA) methods for detecting thyroid autoantibodies. Thyroglobulin autoantibodies (Tg-Ab) were analyzed with a hemagglutination kit and a RIA; thyroid peroxidase autoantibodies (TPO-Ab) were measured with a gelagglutination assay and a RIA. The results of the antibody tests were compared with thyroid function tests (triiodothyronine [T3], thyroxine [T4], thyrotropin [TSH]) and with the results of ultrasound of the thyroid in antibody-positive patients. The correlation of antibody levels between the two methods was higher for TPO-Ab than for Tg-Ab. Moderate to high levels of TPO-Ab correlated to elevated TSH levels. Autoimmune thyroiditis (AIT) was found in 6 of the 141 children. The RIA-based thyroglobulin assay was the only test that identified autoantibodies in all 6 cases. In contrast, the hemagglutination kit thyroglobulin assay failed to identify 4 of the 6 AIT cases.

[Chronic autoimmune thyroiditis in the child]

OBJECTIVE

The aim of the study was to describe the clinical characteristics and long-term follow-up of a group of children with chronic autoimmune thyroiditis.

PATIENTS AND METHODS

Sixty children (age: 11.9 +/- 2.7 years) were studied in a retrospective analysis.

RESULTS

At diagnosis, 34 of the children were hypothyroid (compensated hypothyroidism, n = 15; true hypothyroidism, n = 19) and 26 euthyroid. Thyroid ultrasonography showed characteristic features of heterogenicity and/or hypoechogenicity in all patients. Other autoimmune diseases were found in ten subjects (17%) and 23% had a family history of thyroid disease. At the end of the follow-up, nine of 45 children (20% of the cases) followed up for at least one year (mean follow-up 4.4 +/- 3.7 years), demonstrated a change in thyroid function. Hypothyroidism was detected in two initially euthyroid patients. Among initially hypothyroid patients, seven (28%) recovered normal thyroid function, allowing L-thyroxine withdrawal for four weeks, after 1.5 to 8.4 years. No factor was found to be predictive of the course of the disease. All subjects treated with L-thyroxine for hypothyroidism reached normal final height.

CONCLUSION

The natural course of chronic lymphocytic thyroiditis is variable and unpredictable. Recovery from hypothyroidism does occur and can be aided by the L-thyroxine withdrawal test. The disease requires lifelong thyroid surveillance, especially in women during pregnancy, in order to avoid a potential adverse effect on the future child.

Clinical review 115: effect of thyroxine therapy on serum lipoproteins in patients with mild thyroid failure: a quantitative review of the literature

The objective of our study was to estimate the expected change in serum lipoprotein concentrations after treatment with T4 in patients with mild thyroid failure (i.e. subclinical hypothyroidism). Our data sources included MEDLINE, between January 1966 and May 1999, and review of references from relevant articles. There were 1,786 published studies identified, 461 abstracts reviewed, 74 articles retrieved, 24 articles evaluated against predetermined entry criteria, and 13 studies systematically reviewed and abstracted. All studies reported serum total cholesterol concentration changes during T4 treatment, 12 reported triglyceride changes, 10 reported high-density lipoprotein (HDL) cholesterol changes, and 9 reported low-density lipoprotein (LDL) cholesterol changes. There were 247 patients in 13 studies. The mean decrease in the serum total cholesterol concentration was -0.20 mmol/L (-7.9 mg/ dL), with a 95% confidence interval of -0.09 to -0.34. The decline in serum total cholesterol was directly proportional to its baseline concentration. Studies enrolling hypothyroid participants receiving suboptimal T4 doses reported significantly larger decreases in serum total cholesterol after thyroid-stimulating hormone normalization than studies enrolling previously untreated individuals with mild thyroid failure [-0.44 mmol/L (-17 mg/dL) vs. -0.14 mmol/L (-5.6 mg/dL), P = 0.05]. The change in serum LDL cholesterol concentration was -0.26 mmol/L (-10 mg/dL), with a 95% confidence interval of -0.12 to -0.41. Serum HDL and triglyceride concentrations showed no change. These results, although based on fewer than 250 patients, suggest that T4 therapy in individuals with mild thyroid failure lowers mean serum total and LDL cholesterol concentrations. The reduction in serum total cholesterol may be larger in individuals with higher pretreatment cholesterol levels and in hypothyroid individuals taking suboptimal T4 doses. There do not seem to be significant effects of T4 on serum HDL or triglyceride concentrations.

Prevalence of subclinical hypothyroidism in a population living in the Milan metropolitan area

Subclinical hypothyroidism is a condition characterized by increased levels of thyroid-stimulating hormone (TSH) associated with normal levels of free triiodothyronine (FT3) and free thyroxine (FT4). The exact prevalence of this condition in Italy is not known. The aim of this study was to assess the presence of subclinical hypothyroidism in 1001 subjects living in the Milan area (age 17-89) and apparently free from thyroid pathology. This sample which had applied to a large laboratory centre (Centro Diagnostico Italiano, Milano) for a routine check-up was seen from April to July 1996. A serum TSH assay was performed using a highly sensitive immunoenzymatic method, while an FT3 and FT4 assay was performed by means of a radioimmunologic method using commercial kits. The prevalence of subclinical hypothyroidism in the total population proved to be 4.7% (95% CI-Confidence Interval: 3.4-6.0). Sex stratification showed a prevalence of 6.1% in females and 3.4% in males. Prevalence in patients up to 65 was 4.2%. This value increased up to 8.0% in subjects over 65. By combining these variables, in females >65 prevalence increased to 11.3%. Overall, symptoms typical of overt hypothyroidism were found in 58.3% of patients suffering from subclinical hypothyroidism and in 39.9% of healthy subjects (p<0.02). The results of this study show that there is a significant presence (about 5%) of subclinical hypothyroidism in this population and that its frequency is more than doubled in women over 65. Early treatment might reduce the progression to overt hypothyroidism. The benefits of such a procedure were recently suggested by a decision making modelling approach applied to the Italian environment.

L-thyroxine prevents the bone-conserving effect of HRT in postmenopausal women with subclinical hypothyroidism

Hypothyroidism, which is a common disorder among postmenopausal women, may be associated with higher than average bone mineral content. Contrarily, treatment with L-thyroxine may cause a significant bone loss. The aim of our study was to evaluate the effects of hormone-replacement therapy (HRT) on bone density in women with subclinical hypothyroidism treated with L-thyroxine. A total of 73 postmenopausal women with thyroid-stimulating hormone (TSH) levels > 5 mU/l and normal free thyroxine values, who never used HRT or L-thyroxine, were divided into three groups according to the treatment given during a 3-year follow-up period: 34 women received only HRT; 20 women received HRT and L-thyroxine, and the remaining 19 women received neither medications. A euthyroid control group included 41 postmenopausal women with TSH levels between 0.5 and 1.5 mU/l, who were using HRT since the initial visit. Lumbar spine bone density measurements were performed at baseline and study termination. Taken as a whole, the hypothyroid women had a non-significant higher baseline bone mineral density (BMD) as compared to the euthyroid controls (1.068 +/- 0.19 g/cm2 vs. 1.024 +/- 0.15). After 3 years, both the euthyroid and hypothyroid women on HRT only had an increase in BMD (0.032 +/- 0.04 g/cm2 and 0.028 +/- 0.05 g/cm2, respectively; p < 0.001 for both, compared to baseline). Hypothyroid women using no medication had a decrease of 0.034 +/- 0.07 g/cm2 in BMD, and those receiving both HRT and L-thyroxine lost the most: 0.04 +/- 0.08 g/cm2 (p < 0.05 for both, compared to baseline). The addition of L-thyroxine thus prevented the beneficial effect of HRT on BMD. Thyroid hormone replacement is recommended only when overt symptoms of hormone deficiency occur. In such cases, a single bone-conserving treatment with HRT may not suffice.

Epidemiology of thyroid diseases in iodine sufficiency

Epidemiology of thyroid diseases in iodine-sufficient areas (ISA) deals with sporadic goiter, thyroid autoimmune diseases, and thyroid cancer. A comparison between the different studies performed is difficult because methods have changed over time and selection criteria and definitions such as prevalence or incidence were not used consistently by some authors. Sporadic goiter: in ISA, autoimmune processes play a major role in the development of sporadic goiter. In adults, sporadic diffuse goiter is most frequent in young women (16%), perhaps due to additional relative iodine deficiency especially in pregnancy, and declines with age (<10%). Sporadic nodular goiter increases from 5% in young women to 9% in older women. Autoimmune thyroid disease (AITD): thyroid autoantibodies (TAb) and histopathological lymphocytic infiltration of the thyroid is much more common in ISA (4.6% in women; 1.1% in men) than in iodine-deficient areas (IDA). The prevalence and incidence of hypothyroidism and hyperthyroidism varies, depending on whether overt and subclinical forms are included and whether newly or previously diagnosed dysfunction is considered. In an overview of the literature, the prevalence is 2 in 1000 for overt and 6 in 1000 for subclinical hyperthyroidism in ISA. The values for hypothyroidism are 5 in 1000 and 15 in 1000, respectively. Change from IDA to ISA: in former IDA, the percentage of hyperthyroidism increases up to 4 years after salt iodination. Whereas this effect is transient for Plummer's disease, a change from IDA to ISA seems to lead to a permanent increase in overt and subclinical Graves' disease. Thyroid cancer: most studies demonstrate that the histopathological types of thyroid cancer are different in IDA and ISA. There is a tendency toward an increase in differentiated and decrease of anaplastic cancer. The ratio of papillary to follicular thyroid cancer ranges from 6.5:1 to 3.4:1 in areas with high iodine intake, decreases 3.7:1 to 1.6:1 in areas with moderate iodine intake, and ranges from 1.7:1 to 0.19:1 in IDA.

Cost effectiveness of screening for subclinical hypothyroidism in the elderly. A decision-analytical model

OBJECTIVE

The value of early detection of subclinical hypothyroidism is the object of a long lasting debate. In this study, we assessed the cost effectiveness of a policy based upon screening for this condition through thyroid-stimulating hormone (TSH), triiodothyronine (T3) and thyroxine (T4) serum level measurements in the elderly.

DESIGN

A Markov model was developed where hypothetical elderly patients (i.e. > or = 60 years of age), who attend general practitioner (GP) clinics for periodic health examinations in a primary-care setting in Italy, made transitions between health states at annual interval for 15 years, thus allowing an estimation of the average cost and of the expected average number of quality-adjusted life-years (QALY). In this model, patients were assumed to be seen at annual intervals by GPs for clinical examination and serum cholesterol level measurement, to which a TSH, T3 and T4 serum measurement was added. In the base-case analysis, TSH was measured every 5 years and, if abnormal, T3 and T4 serum levels were also determined. Costs were analysed from the perspective of the Italian National Health Service (NHS) and reflected 1996 values.

MAIN OUTCOME MEASURES AND RESULTS

In the base-case analysis, the additional benefit estimated from testing a female population for subclinical hypothyroidism every 5 years was 0.36 QALY, with a cost per QALY gained of 668,298 lire (L). The expected gain in QALY for men was 0.20 and the cost per QALY gained was L270,322. In general, the best cost-effectiveness profile was seen with testing every 3 years. Results were sensitive to variations in the prevalence of disease among the target population, both in men and women.

CONCLUSIONS

Our study indicates that a screening policy for subclinical hypothyroidism in the elderly population could be worthwhile. However, as the costs could be significant when applied at the population level, this policy deserves further assessment through well-designed primary research.

Psychoneuroendocrinology of mood disorders. The hypothalamic-pituitary-thyroid axis

Abnormal thyroid functioning can affect mood and influence the course of unipolar and bipolar disorder. Even mild thyroid dysfunction has been associated with changes in mood and cognitive functioning. Thyroid hormone supplementation may have role in the treatment of certain mood disorders, particularly rapid-cycling bipolar disorder. Women are more vulnerable to thyroid dysfunction than men and also respond better to thyroid augmentation. This article reviews the relationship between thyroid function and mood, and the use of thyroid hormones in the treatment of mood disorders. The impact of gender on these issues is also discussed.

Normal thyroxine and elevated thyrotropin concentrations: evolving hypothyroidism or persistent euthyroidism with reset thyrostat

BACKGROUND

The natural course in subjects manifesting normal serum thyroxine (T4), and triiodothyronine (T3), with an elevated thyrotropin (TSH) level demonstrated two distinct outcomes, one progressing to well defined hypothyroidism as expressed by onset of subnormal T4, T3 and a further rise in TSH and the other remaining in the same state. However, thyroid hormone concentrations at the time of diagnosis fail to distinguish between the two groups. Therefore, we examined the influence of alteration in circulating TSH levels on thyroid gland function at the time of diagnosis in subjects with this syndrome to assess the role of pituitary thyroid axis in these different outcomes.

METHODS

24 hour 131I thyroidal uptake was determined in 14 men and 3 women manifesting normal T4, T3 and elevated TSH prior to and again after 1) subcutaneous administration of bovine TSH, 10 units daily for 3 days and 2) daily oral administration of L-triiodothyronine 75 micrograms for 7 days in a randomized sequence at interval of 4 weeks. Subjects were then followed for up to 16 years to assess the natural course.

RESULTS

Basal 24 hour 131I uptake values were within the normal range (10-35%) in all subjects and increased on TSH administration and declined following LT3 administration. However, in eight subjects, these responses were markedly lower (< 20%) when compared with the minimum change (50%) noted in normal volunteers. These subjects progressed to manifest hypothyroidism requiring LT4 therapy within two years as reflected by a progressive decrease to subnormal T4 levels with a further rise in serum TSH. The remaining nine subjects, demonstrated normal responses (> 50%) and only one of these became hypothyroid during the follow-up period of 16 years.

CONCLUSION

All subjects with normal T4 and T3 with elevated TSH do not manifest "subclinical or evolving hypothyroidism". Two distinct populations seem to exist, one with inhibited pituitary thyroid axis progressing to hypothyroidism or true "subclinical hypothyroidism" at the time of diagnosis and the other with normal pituitary thyroid axis, a state of euthyroidism with "reset thyrostat" at a higher TSH concentration, a state probably persisting for their remaining life span.

Decision analysis in endocrinology and metabolism

Decision analysis is a powerful tool for synthesizing and analyzing clinical decisions in the practice of endocrinology and metabolism. The technique involves defining strategies for comparison, choosing a time horizon, constructing a decision tree and model, selecting outcomes and assigning probabilities, taking into account the value of time, calculating the net clinical and cost outcomes, and performing sensitivity analysis. This technique and its utility for different populations and changing health care settings are illustrated for the decision of screening for mild thyroid failure with a thyroid-stimulating hormone assay at the periodic health examination. The strengths and limitations of decision analysis and future applications in endocrinology and metabolism are explored.

Association between dementia and elevated TSH: a community-based study

We report on 194 individuals (96 men and 98 women), aged 65 and over, who had dementia assessments and basal TSH measurements as part of an ongoing epidemiological study of dementing disorders in a larger population. Dementia was diagnosed according to DSM-III-R and measured by the Clinical Dementia Rating scale; CDR scores of 0, 0.5, and > or = 1, represent individuals with no dementia (n = 122), possible dementia (n = 29), and definite dementia (n = 43), respectively. The odds ratio for the association of elevated TSH with definite dementia (CDR > or = 1) was 3.8 (95% confidence interval = 1.6, 9.1) and with possible and/or definite dementia (CDR > or = 0.5) was 3.8 (95% confidence interval = 1.6, 9.2), after adjusting for the effects of age, gender, and level of education. This is the first community-based study to report an association between TSH elevation and dementia. Our findings are consistent with recent evidence that subclinical hypothyroidism is associated with cognitive impairment, and that thyroidal state may influence cerebral metabolism.

Pituitary responses to thyrotropin releasing hormone stimulation in depressed women with thyroid gland disorders

From an endocrine outpatient clinic and psychiatric outpatient clinic in Kaunas, Lithuania, 41 women with major depression were selected for study. Three groups of depressed women were established: 15 with autoimmune thyroiditis (AIT); 13 with diffuse non-toxic goiter (DNG); 13 with no thyroid disease (NTD). Standard biochemical tests were used to exclude patients with overt hypothyroidism or overt hyperthyroidism. At baseline the three groups were similar in age and almost identical in severity of depression. In part because of exclusion criteria, all baseline biochemical measures were similar. However, a slight elevation of thyroid-stimulating hormone (TSH) in the AIT group was noted and considered to indicate a tendency toward subclinical hypothyroidism. After thyrotropin-releasing hormone (TRH) administration, six AIT women and six DNG women, but no NTD women, showed blunted TSH responses. As a group DNG women showed smaller TRH responses than other women. Four AIT women showed exaggerated TSH responses. In all three groups basal TSH correlated positively with TSH response to TRH. Basal prolactin (PRL) responses to TRH infusion were similar in all three groups. However, the four AIT women with enhanced TSH responses also showed enhanced PRL responses. Indeed, in the AIT group, but only in this group, PRL responses were correlated with both TSH and basal TSH. In all groups of women the PRL response was unrelated to basal PRL.

Six-year follow-up of thyroid function during lithium treatment

A cohort of patients at various stages of lithium treatment was followed up for 6 years in order to evaluate the course of thyroid abnormalities. Ultrasonography confirmed that lithium can increase thyroid size, especially in cigarette smokers, and that it can affect the texture of the gland. However, the incidence of clinical hypothyroidism or specific thyroid autoimmunity does not exceed that found in the general population. Repeated determinations of thyrotrophin (TSH) concentrations can prevent clinically relevant consequences. Addition of carbamazepine to lithium can counteract lithium-induced subclinical hypothyroidism, possibly improving prophylactic efficacy in recurrent affective disorders.

Subclinical thyroid disease

Thyroid disease can roughly be divided into functional and anatomical disorders. Subclinical disease is by definition not accompanied by symptoms or signs and usually goes unrecognized for the bearer (and the observer). In this communication an overview will be given of existing literature and some own results concerning subclinical hypothyroidism, subclinical thyrotoxicosis and thyroid incidentalomas. Apart from definitions, data on prevalence, clinical effects, prognostic significance and the need for and response to therapy will be discussed.

Clinical use of sensitive assays for thyroid-stimulating hormone

OBJECTIVE

To review the optimal use of sensitive assays for thyroid-stimulating hormone (TSH) by clinicians.

METHODS

The available literature pertinent to the clinical application of sensitive TSH testing was identified through a systematic MEDLINE search and reviewed. Selection of materials for inclusion was based on clinical validity of the data and relevance to the study question.

SYNOPSIS

Sensitive TSH assays have contributed greatly to our basic knowledge of thyroid physiology and are a powerful clinical tool in the diagnosis and treatment of thyroid disease. The clinical applicability of these assays, as is our understanding of their appropriate use, is rapidly expanding. Based upon the best evidence and current understanding of thyroid physiology, strategies are presented for appropriate use of sensitive TSH assays in healthy outpatients, in patients who are likely to have a disturbed hypothalmic-pituitary-thyroid axis, and in patients on levothyroxane therapy.

CONCLUSIONS

Although many clinical questions regarding the use of sensitive TSH assays remain to be studied, it has emerged as a powerful tool for the diagnosis and management of thyroid disease. Optimal use of sensitive TSH assays requires an understanding of TSH physiology and measurement, coupled with appropriate application and interpretation in specific clinical settings.

Enhanced cellular proliferative activity and cell death in chronic thyroiditis and thyroid papillary carcinoma

For the analysis of cellular proliferative activity and cell death in thyroid diseases, the Ki-67 labeling index, bcl-2 protein expression and cell death of follicular epithelia by immunohistochemistry and in situ DNA nick-end labeling methods were evaluated in normal thyroid tissues as well as in surgical specimens from cases of Hashimoto's disease (16 cases), focal lymphocytic thyroiditis (13 cases), Graves' disease (15 cases), follicular adenoma (20 cases) and papillary carcinoma (43 cases). Cellular proliferative activity and cell death were both enhanced in cases of thyroiditis, including Hashimoto's disease and focal lymphocytic thyroiditis. Thyroids from patients with follicular adenoma and papillary carcinoma also showed increased cellular proliferative activity and cell death. In addition, predominant high cellularity and partial loss of bcl-2 protein expression in papillary carcinoma suggested that the overgrowth and dedifferentiation were associated with malignancy.

Association of chronic lymphocytic thyroiditis and thyroid papillary carcinoma. A study of surgical cases among Japanese, and white and African Americans

BACKGROUND

An association between lymphocytic thyroiditis and thyroid papillary carcinoma is still controversial. To determine a definite statistical relation, a histopathologic study was performed on tissues from in three races, because there is a racial and age-related difference in the susceptibility to thyroiditis.

METHODS

The prevalence and severity of thyroiditis combined with adenomatous goiter, follicular adenoma, or papillary carcinoma was defined by examination of surgically resected materials from Japanese (626 patients), and white and African Americans (330 and 90 patients, respectively).

RESULTS

The prevalence of lymphocytic infiltrates, which are indicative of autoimmune thyroiditis, was significantly higher in patients with papillary carcinoma than in patients with adenomatous goiter or follicular adenoma among Japanese females (63.0%) and males (50.0%), white females (76.0%), and African American females (46.2%). Lymphocyte infiltration into the follicular adenoma or papillary carcinoma correlated with the severity of combined thyroiditis.

CONCLUSION

An association between chronic lymphocytic thyroiditis and papillary carcinoma was confirmed in the Japanese, and white and African American populations. The possibility of autoimmune thyroiditis as a predisposing factor for papillary thyroid carcinoma, is suggested.

Elevated serum lipoprotein(a) in subclinical hypothyroidism

OBJECTIVES

Asymptomatic lymphocytic thyroiditis and subclinical hypothyroidism are associated with increased risk for coronary artery disease. The present study aimed at evaluating serum lipoprotein(a)(Lp(a)), measured as apo(a), and other lipid parameters in 32 subjects with asymptomatic subclinical hypothyroidism.

SUBJECTS

Thirty-two Chinese subjects with asymptomatic subclinical hypothyroidism were compared to 96 age and sex-matched healthy controls.

RESULTS

Subclinical hypothyroid patients had higher (P < 0.005) apo(a), total triglyceride (TG), total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C) but lower (P < 0.05) high density lipoprotein cholesterol (HDL-C) levels compared with sex and age-matched controls (apo(a) 296 (48-1650) vs 182 (19-1952 U/l), geometric mean (range); TG 1.86 +/- 0.94 vs 1.33 +/- 0.74 mmol/l (mean +/- SD); TC 6.10 +/- 1.17 vs 5.42 +/- 1.13 mmol/l; LDL-C 4.10 +/- 1.00 vs 3.49 +/- 0.96 mmol/l; HDL-C 1.15 +/- 0.40 vs 1.34 +/- 0.40 mmol/l, respectively). APo A-I and apo B were also higher than controls (1.96 +/- 0.48 vs 1.48 +/ 0.29 g/l and 1.44 +/- 0.42 vs 1.05 +/- 0.29 g/l, respectively). Total cholesterol/HDL ratio and LDL/HDL ratio were also elevated in these subjects (5.77 +/- 1.96 vs 4.28 +/- 1.19 and 3.89 +/- 1.41 vs 2.79 +/- 0.97, respectively, both P < 0.0005). Individual analysis revealed that 16 (50%) subjects had hyperlipoproteinaemia (TC > 5.2 mmol/l in 10; TC > 5.2 mmol/l and TG > 2.3 mmol in six) as compared to 21(20.8%) in the control group (P < 0.005). Subjects with TSH > or = 11.0 mIU/l had significantly higher TC/HDL and LDL/HDL ratios. A significant correlation was observed between TSH levels and TC/HDL ratios (r = 0.455, P < 0.01).

CONCLUSIONS

Subclinical hypothyroidism is associated not only with elevated LDL-cholesterol levels and low HDL-cholesterol levels but also with elevated lipoprotein (a). This may further increase the risk development of atherosclerosis.

Chronic lymphocytic (Hashimoto's) thyroiditis in Kuwait diagnosed by fine needle aspirates

A retrospective analysis of 4185 consecutive fine needle aspirates (FNA) of the thyroid over an eight year period at a teaching hospital in Kuwait revealed that 14.3% of all the aspirates had features of chronic lymphocytic (Hashimoto's) thyroiditis (HT). The proportion of patients with HT showed a slight increase in the last two years but the pattern of clinical presentation has remained unchanged. Hashimoto's thyroiditis was most prevalent in the age group from 16 to 35 and the majority of young patients with Hashimoto's thyroiditis presented with diffuse goiter (DG) whereas multinodular goiter (MNG) and solitary thyroid nodule (STN) were more common in the older age group. Of patients who presented with STN, the most common abnormality on thyroid scan was a "cold nodule". Functional disturbances (hypo and hyperthyroidism) occurred less frequently in patients presenting as STN than in patients presenting with DG or MNG. We conclude that FNA is indicated in all young patients with diffuse goiter in this region in order to facilitate early detection and initiation of suppressive thyroxine therapy. Further, when young patients present with "cold" solitary nodules of the thyroid, HT is a more common cause than a thyroid carcinoma in Kuwait.

Frequency of thyroid dysfunction in diabetic patients: value of annual screening

A randomly selected group of 1310 adult diabetic patients attending a diabetic outpatient clinic received annual screening for thyroid disease, by estimating serum free thyroxine and TSH concentrations. The overall prevalence of thyroid disease was found to be 13.4%, and was highest (31.4%) in Type 1 diabetic females, and lowest in Type 2 diabetic males (6.9%). As a direct result of screening, new thyroid disease was diagnosed in 6.8% (89 patients) of the population screened; the commonest diagnosis was subclinical hypothyroidism (4.8%), followed by hypothyroidism (0.9%), hyperthyroidism 0.5%), and subclinical hyperthyroidism (0.5%). Female patients with Type 1 diabetes had the highest annual risk of developing thyroid disease (12.3%), but all patient groups had a higher incidence of thyroid dysfunction, compared to that reported in the general population. This study suggests that thyroid function should be screened annually in diabetic patients to detect asymptomatic thyroid dysfunction which is increased in frequency in a diabetic population.

The incidence of thyroid disorders in the community: a twenty-year follow-up of the Whickham Survey

BACKGROUND AND OBJECTIVE

The original Whickham Survey documented the prevalence of thyroid disorders in a randomly selected sample of 2779 adults which matched the population of Great Britain in age, sex and social class. The aim of the twenty-year follow-up survey was to determine the incidence and natural history of thyroid disease in this cohort.

DESIGN, PATIENTS AND MEASUREMENTS

Subjects were traced at follow-up via the Electoral Register, General Practice registers, Gateshead Family Health Services Authority register and Office of Population Censuses and Surveys. Eight hundred and twenty-five subjects (30% of the sample) had died and, in addition to death certificates, two-thirds had information from either hospital/General Practitioner notes or post-mortem reports to document morbidity prior to death. Of the 1877 known survivors, 96% participated in the follow-up study and 91% were tested for clinical, biochemical and immunological evidence of thyroid dysfunction.

RESULTS

Outcomes in terms of morbidity and mortality were determined for over 97% of the original sample. The mean incidence (with 95% confidence intervals) of spontaneous hypothyroidism in women was 3.5/1000 survivors/year (2.8-4.5) rising to 4.1/1000 survivors/year (3.3-5.0) for all causes of hypothyroidism and in men was 0.6/1000 survivors/year (0.3-1.2). The mean incidence of hyperthyroidism in women was 0.8/1000 survivors/year (0.5-1.4) and was negligible in men. Similar incidence rates were calculated for the deceased subjects. An estimate of the probability of the development of hypothyroidism and hyperthyroidism at a particular time, i.e. the hazard rate, showed an increase with age in hypothyroidism but no age relation in hyperthyroidism. The frequency of goitre decreased with age with 10% of women and 2% of men having a goitre at follow-up, as compared to 23% and 5% in the same subjects respectively at the first survey. The presence of a goitre at either survey was not associated with any clinical or biochemical evidence of thyroid dysfunction. In women, an association was found between the development of a goitre and thyroid-antibody status at follow-up, but not initially. The risk of having developed hypothyroidism at follow-up was examined with respect to risk factors identified at first survey. The odds ratios (with 95% confidence intervals) of developing hypothyroidism with (a) raised serum TSH alone were 8 (3-20) for women and 44 (19-104) for men; (b) positive anti-thyroid antibodies alone were 8 (5-15) for women and 25 (10-63) for men; (c) both raised serum TSH and positive anti-thyroid antibodies were 38 (22-65) for women and 173 (81-370) for men. A logit model indicated that increasing values of serum TSH above 2mU/l at first survey increased the probability of developing hypothyroidism which was further increased in the presence of anti-thyroid antibodies. Neither a positive family history of any form of thyroid disease nor parity of women at first survey was associated with increased risk of developing hypothyroidism. Fasting cholesterol and triglyceride levels at first survey when corrected for age showed no association with the development of hypothyroidism in women.

CONCLUSIONS

This historical cohort study has provided incidence data for thyroid disease over a twenty-year period for a representative cross-sectional sample of the population, and has allowed the determination of the importance of prognostic risk factors for thyroid disease identified twenty years earlier.

Commonly asked questions about thyroid function

Thyroid function abnormalities in asymptomatic outpatients are common. When a patient is found to have an abnormality in thyrotropin (thyroid-stimulating hormone) or free or total thyroxine (T4), a review of the patient's medications and a careful neck examination will usually provide the explanation. Further diagnostic laboratory studies should include additional tests of T4 or thyrotropin. Determining the presence of antimicrosomal antibodies is useful for further assessment of "subclinical" hypothyroidism, and measures of protein binding (T4-binding capacity or T4-binding protein electrophoresis) help confirm a suspected congenital or acquired abnormality of T4 binding. Recognition of euthyroid hypothyroxinemia and hyperthyroxinemia is important in order to avoid intervention with inappropriate treatment. Management of subclinical hypothyroidism and hyperthyroidism necessitates clinical judgment about the patient's symptom profile and risks for long-standing or progressive thyroid dysfunction.

Thyroid antoantibodies and the response to thyrotropin releasing hormone in patients with subclinical hypothyroidism

AIM

To evaluate the clinical usefulness of the thyrotropin releasing hormone (TRH) test and estimation of thyroid autoantibody concentrations in patients with borderline raised thyroid stimulating hormone (TSH).

METHODS

The records of 34 consecutive patients with persistent borderline increased TSH (4.4-9.9 mU/l) referred to the Medical Investigation Unit were reviewed. The response of patients with thyroid autoantibodies to the TRH test was compared with that of patients with a negative antibody screen.

RESULTS

Eleven (44%) of 25 patients with positive anti-thyroid microsomal and/or thyroglobulin antibody tests and three (33%) of nine patients with a negative antibody screen had hypothyroid responses to TRH. Neither age nor sex affected the response to TRH. Basal TSH alone was poorly correlated with these indices. Twelve (35%) patients who had elevated basal TSH had a normal response to the TRH test.

CONCLUSION

Patients with positive or negative thyroid autoantibodies and an exaggerated response to the TRH test should be regarded as hypothyroid and treated with thyroxine. Patients with positive thyroid autoantibodies and normal TSH response may subsequently develop hypothyroidism and should be given long term follow up.

Prevalence of thyroid antibodies among healthy middle-aged women. Findings from the thyroid study in healthy women

Autoimmune thyroiditis is the most common cause of subclinical hypothyroidism in North America, is more common in women than men, and is a risk factor for the development of coronary heart disease (CHD). We measured thyroid-stimulating hormone (TSH) and two thyroid antibodies, thyroid peroxidase and thyroglobulin, in stored sera of the participants (aged 44 to 54 years) of the Healthy Women Study. We selected 254 samples from the premenopausal baseline examination in 1983 to 1985 and from a follow-up examination that occurred an average of 5.7 years later (range, 3 to 7.7 years). At follow-up, 95 women remained premenopausal, 98 had ceased menstruating for at least 12 months, and 61 were taking postmenopausal hormone therapy. Overall, the prevalence of the thyroid antibodies in this healthy population was high at both time points (21 to 26%). Women with antibodies had higher TSH concentrations than did those with no antibodies (2.68 +/- 1.3 versus 1.51 +/- .73 mU/L, P < 0.001); this relationship was statistically significant even after excluding those with subclinical hypothyroidism (TSH > 6.0 mU/L). TSH and antibody levels did not differ by menopausal status or hormone therapy use at follow-up. Given the high prevalence of thyroid antibodies among healthy middle-aged women, long-term follow-up is warranted to ascertain whether the presence of antibodies is associated with subsequent excess risk of disease, in particular, CHD.

Clinical presentation of spontaneous primary hypothyroidism in adults

In a retrospective study of 309 cases of hypothyroidism seen at King Fahd Hospital of the University (KFHU), Al-Khobar, 124 (90 Saudis and 34 non-Saudis) adult patients with spontaneous primary hypothyroidism satisfied the inclusion criteria for detailed analysis. Their male:female ratios for Saudis and non-Saudis were 1:4.6 and 1:3.9 respectively. The majority were diagnosed in their third and fourth decades. The prevalence of previously undiagnosed spontaneous and biochemically overt primary hypothyroidism in Saudis was 5.2/1000 females and 0.94/1000 males. FT4I was normal in 43 (35%) and low in 81 (65%). FT4I correlated with cold intolerance, constipation, dry skin, hoarseness, delayed reflex relaxation, and coarse and cold skin. In rank order, presenting symptoms in those with low FT4I were tiredness (56%), cold intolerance (38%), constipation, weight gain, menstrual disturbance - especially amenorrhea - (36% each), dry skin (35%), hoarseness (31%); signs were coarse skin (53%), delayed reflex relaxation (32%), cold skin and goiter (24% each). The above clinical findings may help physicians in the early detection of primary hypothyroidism. Population-based studies are necessary to provide more data on this disease in this country.

Borderline hypothyroidism and depression

This review defines subclinical hypothyroidism and examines its influence on the occurrence and course of major depression. Recommendations are presented for the identification and treatment of patients with coexisting mood disorders and borderline thyroid failure.

A prospective evaluation of antithyroid antibody prevalence in 100 patients with rheumatoid arthritis

The prevalence of thyroid antibodies in 100 patients with rheumatoid arthritis in Northern Norway was studied. The serological data were compared with those from a major population survey in the same area. Compared to the prevalence in the normal population, the present study demonstrates that patients with rheumatoid arthritis have a higher prevalence of antibodies to both thyroid microsomal antigen and thyroglobulin.

Thyrotropin response to TRH stimulation in depressed patients with autoimmune thyroiditis

Two thyroid axis findings are often reported in depressed patients: autoimmune thyroiditis and abnormal thyrotropin (thyroid stimulating hormone, TSH) responses to thyrotropin-releasing hormone (TRH). The TSH response to TRH can be exaggerated, suggesting subclinical hypothyroidism; it can alternatively be blunted, for reasons poorly understood. We selected 28 women who had been found to have major depression for TRH testing. Fifteen patients had autoimmune thyroiditis and 13 had diffuse nontoxic goiter. The endocrinological diagnoses were verified by fine-needle aspiration biopsy and cytological assessment. Patients with overt hypothyroidism and hyperthyroidism were excluded from the study. There were no differences between the two groups in total triiodthyronine and thyroxine plasma levels or severity of depression. In the autoimmune group, basal TSH and Dmax TSH tended to be higher (p < 0.1); peak TSH was significantly higher (p < 0.05), suggesting that the prevalence of subclinical hypothyroidism was also higher. Blunted TSH responses were found about as often in one group as the other.

Association of sperm antibodies with other autoantibodies in infertile men

PROBLEM

In many autoimmune diseases there is an increased incidence of other autoantibodies. However, the incidence of other autoantibodies in patients with seminal sperm antibodies is unknown. The most widely used tests to detect seminal and serum sperm antibodies are the mixed antiglobulin reaction (MAR) and the Tray agglutination test (TAT).

METHOD

We therefore determined the incidence of antinuclear, antimitochondrial, thyroid peroxidase, and thyroglobulin antibodies, and rheumatoid factor in 147 patients investigated with MAR and 157 patients investigated with TAT.

RESULTS

TAT positive patients had a significantly elevated incidence of antinuclear antibodies (chi 2 test, P < 0.005) and thyroglobulin antibodies (chi 2 test, P < 0.001). Thyroglobulin antibodies were increased in patients with MAR IgG > 40% and also significantly (chi 2 test, P < 0.05) increased in MAR IgA positive patients. Furthermore, thyroid peroxidase antibodies were only found in TAT positive patients.

CONCLUSIONS

The consistently increased incidence of thyroid autoantibodies in infertile patients with sperm antibodies may indicate an increased risk for the development of autoimmune thyroid disease. This finding therefore suggests screening of patients with immunologic infertility for autoimmune thyroid disease and a further evaluation of the prognostic and pathophysiologic significance of thyroid autoantibodies in immunologic infertility.

Thyroxine therapy

The availability of sensitive thyrotropin assays allows effective biochemical monitoring of both replacement and suppressive therapy with thyroxine. Whatever target organ is examined, there is tissue thyrotoxicosis if the serum thyrotropin concentration is low, even if the serum triiodothyronine and thyroxine concentrations are normal. Although suppression of thyrotropin secretion is recommended in the treatment of patients with thyroid carcinoma, the aim of thyroxine-replacement therapy in patients with primary hypothyroidism should be to maintain the serum thyrotropin concentration in the normal range. The most convincing argument for the treatment of subclinical hypothyroidism is progression to overt hypothyroidism at a rate of 5 to 20 percent per year.

Frequency of biochemical hypothyroidism in sera referred for autoantibody testing

We examined sera submitted for autoantibody testing for thyroid microsome antibodies (TMA), elevated thyroid-stimulating hormone (TSH), and free thyroxine concentrations. The frequency of TMA in antinuclear antibody-positive sera was higher (19%) than that in antinuclear antibody-negative sera (12%). Elevated TSH concentrations in serum and subnormal thyroxine concentrations in serum were associated with the presence of TMA; TMA titer and the frequency of elevated TSH concentrations were also associated with the presence of TMA.

The importance of thyroid microsomal antibodies in the development of elevated serum TSH in middle-aged women: associations with serum lipids

OBJECTIVE

We assessed the relative risk of both serum TSH and antithyroid antibody concentrations with regard to progression of thyroid failure and studied the lipid profiles of individuals with elevated TSH levels.

DESIGN, PATIENTS AND MEASUREMENTS

In a randomly selected group of 427 women aged 40-60 (mean 55) years volunteering in an epidemiological survey in Zoetermeer, TSH and thyroid microsomal antibodies (TMA) were determined. Ten years after the initial survey only TSH was measured and the lipid profiles of the individuals with elevated serum TSH levels were studied and compared with a reference group.

RESULTS

During follow-up, four of 427 women were treated with thyroxine. Seventeen of 423 women initially had elevated serum concentrations of TSH (> 4.2 mU/l), 11 of whom were TMA positive. In the group of 406 women with initially a normal TSH, nine out of 37 (24%) TMA-positive women developed elevated serum levels of TSH over 10 years. In contrast only 10 of 369 (3%) TMA-negative women had elevated serum TSH levels 10 years after the initial survey (P < 0.001). Altogether, at the end of the observation period, 40% of TMA-positive subjects had elevated serum TSH concentrations, compared to 3% in the TMA-negative group (P < 0.01). TSH levels in the upper part of the normal range also appeared to have a predictive value: if those both with TSH levels between 2.0 and 4.2 and with a positive TMA status were contrasted with those without antibodies and low TSH, the crude relative risk was 71.5 (31.0-164.3), whereas the crude relative risk of presence versus absence of TMA was only 36.3 (18.8-70.3). Women with elevated TSH levels did not show changes in serum concentrations of total cholesterol (7.4 +/- 1.1 mmol/l), apo-A, (4.7 +/- 1.0 mmol/l) and apo-B (3.1 +/- 0.7 mmol/l) lipoproteins, compared with control individuals (7.2 +/- 1.3, 4.7 +/- 0.8 and 3.0 +/- 0.7 mmol/l, respectively).

CONCLUSIONS

The determination of serum TMA in middle-aged women can identify an important group of women at risk of developing an elevated serum TSH. TMA measurement is of potential use in the prevention of cardiovascular disease. An elevated serum TSH, however, in our study-group does not seem to be accompanied by an abnormal lipid profile, as reported by others.

The course of thyroid abnormalities during lithium treatment: a two-year follow-up study

A total of 116 patients on lithium treatment were followed up for 2 years to determine the course and the clinical relevance of thyroid abnormalities. Elevated thyroid-stimulating hormone (TSH) concentrations were transitory in most patients, except those with serum antithyroid antibodies. The patients who initially had microsomal antibodies remained positive, with an increase in titre in two-thirds of cases. Three young patients of both sexes developed thyroid autoimmunity early in the treatment. The risk of developing hypothyroidism was higher in women, especially in the presence of antibodies. TSH concentrations were significantly lower when carbamazepine was combined with lithium.

Risks Associated with Treating Hypothyroidism: Potential hazards of L-thyroxine therapy

Most patients with hypothyroidism can be treated simply and safely with physiologic replacement dosages of L-thyroxine. Recently, concerns have been raised about potential hazards of L-thyroxine therapy, including a possible increased risk of osteoporosis and ischemic heart disease. The author reviews these concerns and describes a modern approach to initiation and maintenance of thyroid hormone replacement therapy.

Assessment of a screening process to detect patients aged 60 years and over at high risk of hypothyroidism

General practitioners are increasingly expected to screen elderly patients for common disorders, such as hypothyroidism, and the identification of at-risk patients by simple means would reduce the financial and other costs of such screening. A general practice based study of 1193 patients aged 60 years and over has been carried out to investigate the usefulness of the following factors in identifying those in whom biochemical testing for hypothyroidism would be indicated: personal history or family history of thyroid disease, symptoms of thyroid disease and body mass index. Of the 190 patients with either a personal or family history of thyroid disease, 28 (14.7%) had an elevated concentration of thyroid-stimulating hormone. Thus, 66 of the 94 patients (70.2%) with elevated concentrations of thyroid-stimulating hormone had no such thyroid history. Similarly, only nine (4.7%) of the patients with a personal or family history of thyroid disease required thyroxine replacement therapy. Thus, 22 of the 31 patients (71.0%) requiring such treatment had no such history. Discriminant analysis of the responses of women patients to questions concerning personal or family history of thyroid disease, the presence of symptoms of hypothyroidism, their age and body mass index identified only 51.3% of those with an elevated thyroid-stimulating hormone concentration and 77.2% of those with normal thyroid-stimulating hormone. Analysis of the responses of the men patients was even less discriminating.(ABSTRACT TRUNCATED AT 250 WORDS)

Follow-up of mild hypothyroidism in a nursing home

The course of untreated mild hypothyroidism was followed in 67 nursing home residents (mean age 78 years). The diagnosis was based on a normal free thyroxine index (FTI) and elevated thyrotropin concentration (TSH 4.6 to 15.0 microIU/mL, nl less than or equal to 4.5 microIU/mL. FTI and FSH were measured in follow-up 42-378 (mean 161) days after the diagnosis of mild hypothyroidism had been made. In 45 patients initial TSH was less than 6.8 microIU/mL; in 23 of these subjects TSH returned to normal during the observation period, whereas in 22 TSH remained elevated. In all 22 residents whose initial TSH was greater than 6.8 microIU/mL, TSH remained elevated at follow-up. In 4 subjects whose initial TSH concentrations ranged from 5.0 to 9.6 microIU/mL, FTI fell below normal 91-141 days after the diagnosis of mild hypothyroidism was made. Clinical progression of the signs or symptoms of hypothyroidism was not detected in the 4 patients who developed hypothyroxinemia. Three demonstrated positive thyroid antibody titers, and 1 had myasthenia gravis. These observations suggest a need for replacement therapy in debilitated patients with mild hypothyroidism and evidence of thyroid autoimmunity.

Thyroiditis. Acute, subacute, and chronic

Inflammatory diseases of the thyroid are collectively the commonest thyroid disorder. Individually, they range from the rare case of acute bacterial thyroiditis to the other end of the spectrum, the even rarer Riedel's thyroiditis. Relatively common thyroid inflammatory diseases include the subacute thyroiditis syndromes. Of particular interest to endocrinologists is that both subacute granulomatous (painful) thyroiditis and subacute lymphocytic (painless) thyroiditis are very similar in terms of clinical course, although most likely have different etiologies. Nevertheless, their similarities suggest the possibility that there may be etiologic heterogeneity for the syndromes. From a clinical standpoint, it is essential to differentiate subacute painless thyroiditis from Graves' disease, because these two disorders also may mimic each other, yet only Graves' disease requires specific therapy. Chronic lymphocytic (Hashimoto's) thyroiditis, the commonest of the thyroiditides, presents with goiter and either hyperthyroidism (uncommon), hypothyroidism (common), or euthyroidism (most common). When L-T4 therapy is used in the treatment of Hashimoto's thyroiditis, the physician must be alert to the possibility of excess thyroid hormone administration. Sensitive TSH measurements help to avoid this therapeutic pitfall.

Prevalence and follow-up of abnormal thyrotrophin (TSH) concentrations in the elderly in the United Kingdom

Increasing use of assays for TSH with improved sensitivity as a first-line test of thyroid function has raised questions regarding prevalence and clinical significance of abnormal results, especially values below normal. We have assessed the thyroid status of 1210 patients aged over 60 registered with a single general practice by measurement of serum TSH using a sensitive assay. High TSH values were more common in females (11.6%) than males (2.9%). TSH values below normal were present in 6.3% of females and 5.5% of males, with values below the limit of detection of the assay present in 1.5% of females and 1.4% of males. Anti-thyroid antibodies were found in 60% of those with high TSH but only 5.6% of those with subnormal TSH. Eighteen patients were hypothyroid (high TSH, low free thyroxine) and one thyrotoxic (low TSH, raised free thyroxine) at initial testing. Seventy-three patients with elevated TSH but normal free T4 were followed for 12 months; 13 (17.8%) developed low free T4 levels and commenced thyroxine, TSH returned to normal in four (5.5%) and 56 (76.7%) continued to have high TSH values. Sixty-six patients with TSH results below normal were followed. Of the 50 subjects with low but detectable TSH at initial testing, 38 (76%) returned to normal at 12 months; of those 16 with undetectable TSH followed, 14 (87.5%) remained low at 12 months. Only one subject (who had an undetectable TSH) developed thyrotoxicosis. In view of the marked prevalence of thyroid dysfunction in the elderly, we suggest that screening of all patients over 60 should be considered.(ABSTRACT TRUNCATED AT 250 WORDS)

Performance of two agglutination techniques in the detection of thyroid antibodies and assessment of their clinical significance

Two clinically most widely used agglutination tests, Thymune and Serodia distributed by Wellcome and Fjirebio/Ames, respectively, to determine thyroid autoantibodies were compared. The Serodia tests seemed to be considerably more sensitive than the corresponding Thymune tests; first, Serodia tests resulted in several new positive samples and second, 16% and 30% of positive thyroglobulin and thyroid microsomal antibodies by Serodia resulted in at least 16 times higher titres, respectively. Over 300 healthy blood donor sera were used to determine the occurrence of thyroid autoantibodies in normal population. Titre limits of 400 and 6400 in anti-thyroglobulin and anti-microsomal antibodies were adapted for clinical use, respectively, even though the results suggested that the lower titre limits could be applied for males and subjects younger than 40 years. These defined titre limits were applied to examine randomly selected clinical patient material gathered during 1 year. The main patient groups identified included patients with chronic thyroiditis, thyroid malignancy, diabetes. Graves' disease and rheumatoid diseases as well as patients with vaguely defined clinical conditions. Without the aid of antithyroglobulin antibodies only one patient with chronic thyroiditis would have been missed if thyroid microsomal antibodies were used alone. Thus, in general clinical practise thyroid microsomal antibodies can be used as a sole diagnostic test for autoimmune thyroid diseases.