Prevalence of subclinical thyroid failure in insulin-dependent diabetes

Rapid Screening of Thyroid Dysfunction Using Raman Spectroscopy Combined with an Improved Support Vector Machine

This study aimed to screen for thyroid dysfunction using Raman spectroscopy combined with an improved support vector machine (SVM). In spectral analysis, in order to further improve the classification accuracy of the SVM algorithm model, a genetic particle swarm optimization algorithm based on partial least squares is proposed to optimize support vector machine (PLS-GAPSO-SVM). In order to evaluate the performance of the algorithm, five optimization algorithms are used: grid search-based SVM (Grid-SVM), particle swarm optimization algorithm-based SVM (PSO-SVM), genetic algorithm-based SVM (GA-SVM), artificial fish coupled uniform design algorithm-based SVM (AFUD-SVM), and simulated annealing particle swarm optimization algorithm-based SVM (SAPSO-SVM). In this experiment, serum samples from 95 patients with confirmed thyroid dysfunction and 90 serum samples from normal thyroid function were used for Raman spectroscopy. The experimental results show that the GAPSO-SVM algorithm has a high average diagnostic accuracy of 95.08% and has high sensitivity and specificity (91.67%, 97.96%). Compared with the traditional optimization algorithm, the algorithm has high diagnostic accuracy, short execution time, and good reliability. It can be seen that Raman spectroscopy combined with GAPSO-SVM diagnostic algorithm has enormous potential in noninvasive screening of thyroid dysfunction.

Prevalence of subclinical hypothyroidism in adults visiting primary health-care setting in Riyadh

Background and objectives: Subclinical hypothyroidism is an asymptomatic condition with normal thyroxin and raised thyroid stimulating hormone (TSH) level. The objective of the study was to determine the prevalence of subclinical hypothyroidism in primary health care (PHC) settings in Riyadh and explore the relationship of TSH level with age, gender, family history, body mass index, and co-morbid conditions.

Subjects and methods: A cross-sectional study of adult visitors to nine satellites PHC clinics in military housing in Riyadh was carried out. TSH concentration and free T4 levels were measured. Data were collected by nurses and physicians during routine clinical practice in primary care. Descriptive analysis was performed on all variables in study, and relationships were explored using chi-square, t-test, analysis of variance, and linear regression.

Results: A total of 340 out of 394 participants in the study gave blood samples. Subclinical hyperthyroidism was identified in 2.1% (p = .001) and subclinical hypothyroidism in 10.3% (p = .001) of the PHC visitors. TSH levels were found to be significantly higher (p = .047) in elderly population of ≥60 years and those with family history of thyroid disease. Non-significant upward trends were noted in TSH levels with hyperlipidemia and increasing blood pressure. No overt hyperthyroidism or hypothyroidism was found in our study sample.

Conclusion: Subclinical hypothyroidism has a prevalence of 10% of adults visiting PHC’s. TSH levels are higher in the elderly, which warrants screening of those aged 60 years and above.

Low-dose T₃ replacement restores depressed cardiac T₃ levels, preserves coronary microvasculature and attenuates cardiac dysfunction in experimental diabetes mellitus

Thyroid dysfunction is common in individuals with diabetes mellitus (DM) and may contribute to the associated cardiac dysfunction. However, little is known about the extent and pathophysiological consequences of low thyroid conditions on the heart in DM. DM was induced in adult female Sprague Dawley (SD) rats by injection of nicotinamide (N; 200 mg/kg) followed by streptozotocin (STZ; 65 mg/kg). One month after STZ/N, rats were randomized to the following groups (N = 10/group): STZ/N or STZ/N + 0.03 μg/mL T3; age-matched vehicle-treated rats served as nondiabetic controls (C). After 2 months of T3 treatment (3 months post-DM induction), left ventricular (LV) function was assessed by echocardiography and LV pressure measurements. Despite normal serum thyroid hormone (TH) levels, STZ/N treatment resulted in reductions in myocardial tissue content of THs (T3 and T4: 39% and 17% reduction versus C, respectively). Tissue hypothyroidism in the DM hearts was associated with increased DIO3 deiodinase (which converts THs to inactive metabolites) altered TH transporter expression, reexpression of the fetal gene phenotype, reduced arteriolar resistance vessel density, and diminished cardiac function. Low-dose T3 replacement largely restored cardiac tissue TH levels (T3 and T4: 43% and 10% increase versus STZ/N, respectively), improved cardiac function, reversed fetal gene expression and preserved the arteriolar resistance vessel network without causing overt symptoms of hyperthyroidism. We conclude that cardiac dysfunction in chronic DM may be associated with tissue hypothyroidism despite normal serum TH levels. Low-dose T3 replacement appears to be a safe and effective adjunct therapy to attenuate and/or reverse cardiac remodeling and dysfunction induced by experimental DM.

Decreased plasma nesfatin-1 level is related to the thyroid dysfunction in patients with type 2 diabetes mellitus

AIMS

Thyroid dysfunction is frequently observed in patients with type 2 diabetes mellitus (T2DM), but the underlying mechanism is still poorly understood. The present study aimed to investigate whether nesfatin-1 played a role in the thyroid dysfunction in patients with T2DM.

METHODS

55 euthyroid patients were enrolled in this study including 30 patients with T2DM and 25 patients with impaired glucose regulation (IGR). 30 age-matched healthy people were also included as the control. The plasma levels of nesfatin-1, thyrotropin (TSH), and glycosylated hemoglobin (HbA1c) as well as the body mass index (BMI) were comparatively analyzed among the three groups.

RESULTS

The nesfatin-1 was significantly lower in patients with T2DM than in patients with IGR and in the control. On the contrary, the TSH level was significantly higher in patients with T2DM than in patients with IGR and in the control. Simple regression analysis showed that the plasma nesfatin-1 was negatively correlated with the TSH and HbA1c levels and positively correlated with the BMI. With multiple stepwise regression analysis, the nesfatin-1 remained to be independently correlated with the TSH, BMI, and HbA1c.

CONCLUSIONS

The study was suggesting a role of nesfatin-1 in thyroid dysfunction in patients with T2DM.

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

BACKGROUND

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

AIMS

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

RESULTS

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

CONCLUSIONS

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

Iodine status, thyroid function, thyroid volume and thyroid autoimmunity in patients with type 1 diabetes mellitus in an iodine-replete area

OBJECTIVE

To analyze the prevalence and clinical significance of thyroid autoimmunity, thyroid volume and iodine status in patients with type 1 diabetes mellitus compared with age and sex matched healthy controls, in an iodine-deficiency improved area.

METHOD

Fifty-eight patients with type 1 DM, 30 female and 28 male, who attended the pediatric endocrinology clinic of Karadeniz Technical University Hospital were included into the study. They were compared with 58 healthy children matched for sex and age. Routine thyroid function parameters, thyroid autoantibodies (TPOAb, TGAb and TRAb) and urinary iodine excretion were measured and thyroid volume was determined by ultrasonography (US).

RESULTS

Twenty-six patients (44.8%) in diabetic patients and 20 subjects (34.5%) in the control group had thyroid autoantibody positivity. TPOAb and TGAb positivity were significantly high in diabetic patients (P=0.01 and P=0.032, respectively). Thyroid US revealed a thyroid volume of 6.6+/-3.5 ml (median 6.4 ml, range 1.117.2 ml) in the diabetic patients compared with 3.7+/-2 ml (median 3.1 ml, range 0.8-8.6 ml) in the control group (P=0.0001). Median urinary iodine levels of both groups were clearly above the threshold level for iodine deficiency, but 26 patients with type 1 DM (44.8%) and 16 controls (27.5%) had urinary iodine excretion below 100 microg/L, and 21 (36.2%) of diabetic patients and two subjects (3.4%) of the control group were consistent with severe iodine deficiency. No significant differences were noted in diabetic patients in terms of age, duration and metabolic control of the disease and thyroid volume when compared according to the autoantibody presence. Additionally, there were no significant differences between the iodine deficient and iodine sufficient diabetic patients in terms of age, sex, duration of disease, HbA1c, thyroid hormones and thyroid volumes. Thyroid autoimmunity was lower in patients with iodine deficiency (38.4% vs. 50%), but not statistically significant.

CONCLUSION

We found that type 1 DM patients had larger thyroid volume compared with healthy control groups, and a large portion of them had the markers of autoimmune thyroid disease and iodine deficiency. Surprisingly, we found that a large portion of the healthy children had TRAb positivity. We proposed that TRAb must be considered in community surveys or prevalence studies of autoimmune thyroid disorders in iodine-replete areas. Additionally, prospective longitudinal studies are needed to determine the clinical significance of TRAb positivity in diabetic patients.

Investigations of thyroid hormones and antibodies based on a community health survey: the Busselton thyroid study

OBJECTIVE

Overt or subclinical thyroid dysfunction is common within the community, yet the significance of subtle anomalies in thyroid function tests remains contentious. The aims of this study were to: (a) establish reference intervals for serum-free thyroxine (FT4), thyroid-stimulating hormone (TSH) and thyroid antibodies (antithyroperoxidase, TPOAb and antithyroglobulin, TgAb) in the Busselton community of south-western Western Australia; and (b) determine the prevalence of thyroid hormone anomalies in this community.

SUBJECTS AND DESIGN

In 1981, 2115 adults residing in Busselton participated in a cross-sectional health survey that involved blood collection and a questionnaire on lifestyle and general health history.

MEASUREMENTS

Serum samples were analysed for FT4, TSH, TPOAb and TgAb by immunochemiluminescent assays.

RESULTS

Based on standard statistical approaches and using guidelines recommended by the National Academy of Clinical Biochemistry (NACB), reference intervals were derived for each analyte: 9-23 pmol/l for FT4, 0.4-4.0 mIU/l (TSH), < 35 KIU/l (TPOAb) and < 55 KIU/l (TgAb). The prevalence of elevated thyroid antibodies was 12.4% among subjects without a history of thyroid disease and is more common in women than in men. Elevated thyroid antibody levels were observed at both extremes of TSH abnormality, but were more commonly increased when TSH levels were above 4.0 mIU/l (63% subjects) than for those with TSH levels 0.4-4.0 mIU/l (7.8% subjects).

CONCLUSIONS

This study establishes the prevalence of antibodies to thyroperoxidase and thyroglobulin in a community-based sample and reference intervals for free T4 and TSH. When the NACB decision limits are applied to older men or women, there is a markedly increased number with 'elevated' autoantibody levels compared to sex- and age-specific reference intervals.

Prevalência de doença tireoideana em pacientes com diabetes tipo 1

INTRODUÇÃO: O diabetes mellitus tipo 1 (DM1) freqüentemente se acompanha de outras doenças autoimunes, principalmente doença autoimune da tireóide (DAT). OBJETIVO: Determinar a prevalência de DAT em pacientes com DM1 e investigar possível relacionamento com outros fatores. MÉTODOS: Em 126 pessoas com DM1, foram mensurados TSH, T4 livre, anticorpo anti-peroxidase e hemoglobina A1c. RESULTADOS: DAT foi encontrada em 26 pacientes (20,6%), sendo 11 (8,7%) com hipotireoidismo clínico, 6 (4,8%) com hipotireoidismo subclínico e 9 (7,1%) com tireoidite sem disfunção tireoideana. Em um paciente (0,8%), a DAT (hipertireoidismo) precedeu o DM1. Houve relação entre DAT e idade atual e no diagnóstico do DM1. Não foram encontradas significâncias para sexo, grupo racial, duração do DM, paridade e local de moradia. CONCLUSÕES: A prevalência de DAT é bastante alta para justificar seu rastreamento e está relacionada com a idade atual e a idade do diagnóstico do DM1.

TSH induces insulin receptors that mediate insulin costimulation of growth in normal human thyroid cells

The mitogenic/goitrogenic effects of thyrotropin (TSH) on human thyrocytes in vitro and in vivo depend on permissive comitogenic effects of insulin-like growth factors (IGFs), which are mimicked in vitro by the low-affinity binding of high supraphysiological concentrations of insulin to IGF-I receptors. Contrary to general assumption, we show here that very low concentrations of insulin, acting through insulin receptors but not IGF-I receptors, can also support the stimulation of DNA synthesis by TSH in primary cultures of normal human thyrocytes. Moreover, TSH through cAMP increases the content of insulin receptors demonstrated by Western blotting and the cells' responsiveness to low insulin concentrations. These observations provide the first in vitro evidence in normal human thyroid cells of a functional interaction between TSH and insulin acting through its own receptor.

Cardiovascular and atherogenic aspects of subclinical hypothyroidism

Subclinical hypothyroidism (SH) is common, especially among elderly women. There is no clear evidence to date that SH causes clinical heart disease. However, mild thyroid gland failure, evidenced solely by elevation of the serum thyrotropin (TSH) concentration, may be associated with increased morbidity, particularly for cardiovascular disease, and subtly decreased myocardial contractility. In SH, both cardiac structures and function remain normal at rest, but impaired ventricular function as well as cardiovascular and respiratory adaptation to effort may become unmasked during exercise. These changes are reversible when euthyroidism is restored. Flow-mediated vasodilatation, a marker of endothelial function, is significantly impaired in SH, and decreased heart rate variability, a marker of autonomic activity, suggests hypofunctional abnormalities in the parasympathetic nervous system. SH does result in a small increase in low-density lipoprotein (LDL) cholesterol (C) and a decrease in high-density lipoprotein (HDL)-C, changes that enhance the risk for development of atherosclerosis and coronary artery disease (CAD). After coronary revascularization, a trend toward higher rates of chest pain, dissection, and reocclusion has been noted in SH subjects. Smoking may contribute to the high incidence of SH and may aggravate its metabolic effects. Subjects with SH with marked TSH elevation and high titers of thyroid autoantibodies are at higher risk of unnoticed progression to overt hypothyroidism. Especially women over 50 years with TSH levels greater than 10 mU/L and smoking habits have the highest risk for cardiovascular complications. The magnitude of the lipid changes and the subtle impairment of left ventricular function and cardiopulmonary exercise capacity in SH may justify use of hormone replacement. Early levothyroxine (LT4) treatment in SH may reduce the C level by an average of 8% and normalize all metabolic effects in smokers, nevertheless, in some patients, LT4 therapy may exacerbate angina pectoris or an underlying cardiac arrhythmia. Longitudinal follow-up to define the actual cardiovascular disease risk associated with SH is warranted.

Thyroid Function During Pregnancy and The Postpartum Period: Iodine Metabolism and Disease States

OBJECTIVE

To review various aspects of thyroid function during and early after pregnancy.

METHODS

We discuss biochemical and potential pathologic changes in the thyroid associated with the gestational and postpartum periods.

RESULTS

Urinary iodine excretion during the last trimester of gestation in healthy euthyroid women shows that, in areas with mild iodine intake, iodine supplementation is necessary during pregnancy and the postpartum period. This measure should be considered in iodine-sufficient areas as well. Thyroglobulin is the main biochemical marker of persistent thyroidal stimulation. Alterations in thyroid volume during pregnancy can persist after delivery, especially in breast-feeding mothers. In most patients, the goitrogenic stimulus of pregnancy can be suppressed with iodine supplementation. Autoimmune thyroid disease during pregnancy and the postpartum period is reflected by monitoring of thyroid peroxidase antibodies (TPO-Ab). Women with positive test results for TPO-Ab early in gestation showed a highly significant decrease in free thyroxine and increased thyroid-stimulating hormone levels late in gestation. The main marker of Graves' disease during pregnancy is thyroid-stimulating antibodies. Nonautoimmune gestational hyperthyroidism differs from Graves' disease in that thyroid-stimulating antibodies are not detectable.

CONCLUSION

Clinicians should be alert to the fact that pregnancy can induce thyroidal pathologic conditions.

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

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

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.

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.

Prevalence of abnormal thyroid function tests in connective tissue disease

The prevalence of thyroid function tests' abnormalities in 170 patients with various connective tissue diseases (CTD) was examined and compared to a group of 100 age- and sex-matched controls. The overall prevalence of diagnosed thyroid disease was 3.5%. Categorizing the patients into 5 "functional groups" by the concurrent thyroid function test/results showed normal thyroid function tests in 14%, isolated elevated TSH levels with normal T4 and T3 levels in 4% and findings consistent with the laboratory diagnosis of primary hypothyroidism in 3%. The "euthyroid sick syndrome" was evidenced in 54% and elevated T4 levels and/or increased or normal T3 values with normal TSH in 25%. Antimicrosomal antibodies were noted in 12 patients (7%), with the highest incidence in systemic lupus erythromatosus patients (10%). patients with mixed connective tissue disease had significantly (p < 0.0005) higher frequency of hypothyroidism, whereas patients with systemic vasculities had higher frequency of hyperthyroxinemia. In conclusion, CTD patients frequently have abnormal results of one or more of thyroid function tests. Hypothyroidism and hyperthyroidism should be considered when evaluating symptoms and signs in CTD and a significant subset of CTD patients appears to be predisposed to the development of hyperthyroidism.

Thyroid ultrasound in IDDM

Insulin dependent diabetes mellitus (IDMM) is often associated with autoimmune thyroiditis (AIT) and a high prevalence of thyroid antibodies (TA). Ultrasound imaging of the thyroid may contribute to the evaluation of patients with AIT. We therefore investigated ultrasound findings of the thyroid in 83 IDDM patients (44F, 39M) with an age range of 2.3-22.3 yrs (median 11.1). Thyroid volume (ml) determined by ultrasound ranged between 1.3 and 17.9 (median 5.7). Thyroid volumes of 75 healthy children (32F, 43M) with an age range of 2.0 to 11.8 yrs (median 7.6) ranged between 1.6 and 13.2 ml (median 4.8) and did not show a significant difference from the IDDM group from age 4 to 12. TA were positive in 18.8% of the IDDM group. Thyroid volume was higher in TA (+) diabetics (p = 0.05), a finding which may be attributed to a higher percentage of cases with elevated TSH in the TA (+) group. Two diabetic patients showed non-homogeneous hypoechogenicity in the ultrasound compatible with AIT which was later confirmed in one of these cases by aspiration biopsy. Ultrasound imaging of the thyroid may contribute to the evaluation of patients with AIT in IDDM.

Low titer, competitive insulin autoantibodies are spontaneously produced in autoimmune diseases of the thyroid

The occurrence of multiple endocrine autoimmunity with organ-specific autoantibodies is well known. In this study we evaluated the presence of competitive insulin autoantibodies (IAA) in immune and non-immune diseases of the thyroid, utilizing a sensitive and specific radiobinding assay. We studied 37 patients with Graves' disease, 44 patients with Hashimoto's thyroiditis, 11 patients with non-immune thyroid diseases and 30 normal controls. In 5/37 (13.5%), 7/44 (15.9%) patients with Graves' and Hashimoto's diseases, respectively, but in none of those with non-immune thyroid disease or of the controls, IAA levels exceeded our upper limit of normal range (50 nunits/ml) (P < 0.01). Positive IAA levels ranged between 50 and 123 nunits/ml with fluctuation of these levels over time. Islet cell antibodies were not detected in any of the patients and the controls in the study. No association was found between propylthiouracile treatment and level of IAA. In none of 10 IAA-positive patients was the early phase insulin secretion of the intravenous glucose tolerance test below 46 mu units/ml, and in 2 subjects repeated tests after 3 years showed conserved insulin secretion. In conclusion, our findings show that 15% of patients with autoimmune thyroid diseases, produce specific IAA which do not seem to reflect aggressive beta cell destruction.

Familial occurrence of growth hormone deficiency and primary hypothyroidism

We examined endocrine function in three male siblings with growth hormone (GH) deficiency and primary hypothyroidism. Low GH responses to various provocative tests were revealed in all three. Exaggerated thyrotropin (TSH) responses to thyrotropin-releasing hormone increased basal TSH levels, and low free thyroxine levels were also found in all three. Additionally, a low testosterone response to human chorionic gonadotropin and low gonadotropin responses to luteinizing hormone-releasing hormone were noted in the youngest sibling. Skull X-ray films, computerized tomography and magnetic resonance imaging revealed no abnormalities of the pituitary gland or sella turcica. The GH gene was intact in all of the children and their parents. We diagnosed all siblings as having GH deficiency and primary hypothyroidism. This is the first report of familial occurrence of GH deficiency and primary hypothyroidism.

In vitro effect of insulin on the uptake of glucose and alpha-aminoisobutyric acid in the thyroid gland of the turtle (Chrysemys dorbigni)

The presence of specific insulin binding sites in the thyroid gland of the turtle Chrysemys dorbigni has been previously reported. The purpose of the present work was to investigate the probable action of insulin on the uptake of [14C]deoxy-D-glucose ([14C]DG) and [14C]alpha-aminoisobutyric acid ([14C]AIB) in turtle (C. dorbigni) thyroid glands in vitro. Thyroid fragments (+/- 40 mg) were incubated at 25 degrees in Krebs-Ringer-bicarbonate buffer containing 0.2 microCi of [14C]DG or [14C]AIB without or with bovine insulin at different periods of time. The uptake of [14C]DG and [14C]AIB increased with incubation time. The presence of insulin (7 x 10(-6) M) in the incubation medium during 240 min did not modify the [14C]DG uptake. However if the thyroid fragments were previously incubated with insulin (60 min) and then incubated (240 min) with the same concentration of the hormone, the [14C]DG uptake was markedly increased. This stimulatory effect of insulin was dose-dependent. In similar experimental conditions, insulin also produced a significant increase in the uptake of [14C]AIB. Therefore, these findings strongly support the hypothesis that insulin might exert a direct action on the thyroid function.

Differentiation expression during proliferative activity induced through different pathways: in situ hybridization study of thyroglobulin gene expression in thyroid epithelial cells

In canine thyrocytes in primary culture, our previous studies have identified three mitogenic agents and pathways: thyrotropin (TSH) acting through cyclic AMP (cAMP), EGF and its receptor tyrosine protein kinase, and the phorbol esters that stimulate protein kinase C. TSH enhances, while EGF and phorbol esters inhibit, the expression of differentiation. Given that growth and differentiation expression are often considered as mutually exclusive activities of the cells, it was conceivable that the differentiating action of TSH was restricted to noncycling (Go) cells, while the inhibition of the differentiation expression by EGF and phorbol esters only concerned proliferating cells. Therefore, the capacity to express the thyroglobulin (Tg) gene, the most prominent marker of differentiation in thyrocytes, was studied in proliferative cells (with insulin) and in quiescent cells (without insulin). Using cRNA in situ hybridization, we observed that TSH (and, to a lesser extent, insulin and insulin-like growth factor I) restored or maintained the expression of the Tg gene. Without these hormones, the Tg mRNA content became undetectable in most of the cells. EGF and 12-0-tetradecanoyl phorbol-13-acetate (TPA) inhibited the Tg mRNA accumulation induced by TSH (and/or insulin). Most of the cells (up to 90%) responded to both TSH and EGF. Nevertheless, the range of individual response was quite variable. The effects of TSH and EGF on differentiation expression were not dependent on insulin and can therefore be dissociated from their mitogenic effects. Cell cycling did not affect the induction of Tg gene. Indeed, the same cell distribution of Tg mRNA content was observed in quiescent cells stimulated by TSH alone, or in cells approximately 50% of which had performed one mitotic cycle in response to TSH + insulin. Moreover, after proliferation in "dedifferentiating" conditions (EGF + serum + insulin), thyrocytes had acquired a fusiform fibroblast-like morphology, and responded to TSH by regaining a characteristic epithelial shape and high Tg mRNA content. 32 h after the replacement of EGF by TSH, cells in mitosis presented the same distribution of the Tg mRNA content as the rest of the cell population. This implies that cell cycling (at least 27 h, as previously shown) did not affect the induction of the Tg gene which is clearly detectable after a time lag of at least 24 h. The data unequivocally show that the reexpression of differentiation and proliferative activity are separate but fully compatible processes when induced by cAMP in thyrocytes.(ABSTRACT TRUNCATED AT 400 WORDS)

De novo clinical hypothyroidism in pregnancies complicated by type I diabetes, subclinical hypothyroidism, and proteinuria: a new syndrome

Fifty-one women with type I diabetes who had normal thyroxine values before becoming pregnant were evaluated. Abnormalities of thyroid tests other than thyroxine were encountered in 26 women, of whom 8 developed a low serum thyroxine level, an elevated thyroid-stimulating hormone level, and a low insulin requirement in the second trimester subsequent to an increase in 24-hour urinary protein excretion to greater than 4 gm/24 hr. Thyroid replacement led to an increase in insulin requirement to levels appropriate for gestational age. It is concluded that the woman with type I diabetes who develops proteinuria greater than 4 gm/24 hr during gestation is at risk for the development of de novo hypothyroidism during pregnancy, evidenced by a low serum thyroxine level, an elevated thyroid-stimulating hormone level, and a drop in insulin requirement.

Prevalence of thyroid disease and abnormal thyroid function test results in patients with systemic lupus erythematosus

Although thyroid disease has been associated with other autoimmune conditions, it is not well recognized in systemic lupus erythematosus (SLE) patients. We found that in 332 SLE patients hospitalized during a 5-year period, the overall prevalence of diagnosed thyroid disease (7.5%) was similar to that in other female populations, but the prevalence of diagnosed hypothyroidism (6.6%) was unexpectedly high. There was also a high frequency of abnormal thyroid function test results in 175 SLE patients without diagnosed thyroid disease who underwent laboratory screening. More than 45% of these patients had elevated levels of thyroid-stimulating hormone, 34% had low T3 determinations, and 18% had high antimicrosomal antibody titers. When patients were categorized into "functional groups," some showed evidence of the "euthyroid sick syndrome" (15%), but many more had laboratory test results suggestive of true (5%) or incipient (39%) primary hypothyroidism. We conclude that abnormal thyroid function test results are common in patients with SLE and that hypothyroidism, especially, should be considered when evaluating symptoms and signs in SLE patients.

Autoimmune thyroid disease: an expanding spectrum

Autoimmune thyroid disease classically has included Hashimoto's thyroiditis and Graves' disease. Hashimoto's thyroiditis probably also includes focal thyroiditis, fibrous thyroiditis, primary myxedema, and Hashitoxicosis as variants. Graves' disease is associated with ophthalmopathy and dermopathy, and recent evidence suggests that these manifestations are autoimmune phenomena as well. Other associated autoimmune disorders include idiopathic thrombocytopenic purpura and antigen-antibody complex nephritis. Nonthyroid endocrine autoimmune deficiency disorders also have been classified as part of the spectrum of thyroid autoimmune disease. With the recent recognition of the spectrum of autoimmune mechanisms and antibody types and methods to distinguish antibody functions or types, our understanding of postpartum and neonatal thyroid disorders has been advanced considerably. The spectrum of neonatal thyroid disorders in the infants of women with autoimmune disease relates to the levels and types of antithyroid antibodies acquired from the mother. Finally, there is suggestive evidence that nonspecific goiter, including simple adolescent goiter and multinodular goiter as well as some cases of sporadic cretinism, may be part of an even more expanded spectrum of autoimmune thyroid disease.

Effect of antithyroid autoantibodies on pancreatic islet-cell function

Insulin-dependent diabetes mellitus is frequently associated with organ-specific autoimmune diseases and/or high titers of organ-specific autoantibodies. The effects of thyroid autoantibodies on islet-cell function were examined in the present study. Islet cell surface antibody (ICSAb) was detected in sera from 6 of 40 patients with autoimmune thyroid disease (AITD) who were positive for thyroid microsomal autoantibodies (TMA). Furthermore, all of the ICSAb-positive patients had high TMA titers. In vitro study using isolated rat pancreatic islets revealed that TMA positive sera significantly suppressed glucose-induced insulin release. Only one of 19 (5%) AITD patients showed complement-dependent antibody-mediated cytotoxicity and only one of 6 AITD patients (17%) was positive for antibody-dependent cellular cytotoxicity. These results suggest that TMA has an effect on an antigen of the islet cell membrane in which insulin releasing mechanism might be involved.

Polyglandular autoimmune syndromes

Dysfunction of multiple endocrine glands may develop as the result of hypopituitarism, various infiltrative disorders, or an organ-specific autoimmune mechanism. When dysfunction of two or more endocrine glands occurs in association with circulating organ-specific antibodies directed against the involved glands, the term polyglandular autoimmune syndrome is applied. Characteristics of polyglandular autoimmunity include specific patterns of disease association and frequently a family history of similar involvement. The principal endocrine components of these syndromes are adrenal insufficiency, autoimmune thyroid disease, insulin-dependent diabetes mellitus, and premature gonadal failure. In addition, primary hypoparathyroidism is a key feature of one form of polyglandular autoimmunity that occurs in children. Several nonendocrine organ-specific autoimmune disorders are also associated with polyglandular autoimmunity, of which pernicious anemia is the most frequent. The underlying abnormality responsible for polyglandular autoimmunity is most likely a defect in T suppressor cell function, but there is evidence that aberrant expression of HLA DR antigens also plays an important role in the pathogenesis of these disorders.

Anti-tubulin antibodies in recent onset type 1 (insulin-dependent) diabetes mellitus: comparison with islet cell antibodies

Antibodies to tubulin, the fundamental protein of microtubules, were studied by radioimmunoassay in patients with Type 1 (insulin-dependent) diabetes of varying duration and in healthy control subjects. Elevated levels of anti-tubulin antibodies were found in 46% of 28 patients with Type 1 diabetes of recent onset (less than or equal to 6 months) and in only 6.2% of 64 patients with long-standing Type 1 diabetes (duration 6-43 years). None of 34 DR3-positive normal subjects and none of 20 Type 2 (non-insulin-dependent) diabetic patients were positive for anti-tubulin antibodies. Anti-tubulin antibody levels were elevated in two out of 26 first-degree relatives of Type 1 diabetic patients. The specificity of the detection of anti-tubulin antibodies was demonstrated by dilution of the sera, competitive binding experiments between labelled and unlabelled tubulin, immunoblotting. Antibodies to tubulin were elevated in 60% of patients with islet cell surface antibodies and there was a significant association between anti-tubulin antibodies and islet-cell surface antibodies. These antibodies, however, recognize different specificities, since adsorption of islet cell surface antibody by rat islets did not alter the anti-tubulin antibody activity. Elevated anti-actin antibody responses were found in two out of 17 and one out of 26 patients with recent onset and long-standing Type 1 diabetes, respectively. In conclusion, anti-tubulin antibodies are detected in a high proportion of patients with diabetes of recent onset, are associated with islet cell surface antibodies and like islet cell surface antibodies decrease or disappear during the course of the disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Natural history of thyroid function in diabetics with impaired thyroid reserve: a four year controlled study

An attempt was made to compare the natural history of thyroid function in 80 diabetics having raised serum TSH concentrations (median 8.9 mU/l, range 5.8-46.3 mU/l) but serum T4 concentrations within the normal range (Group 1), and in 59 diabetics having normal serum TSH (median 1.9 mU/l, range 0.8-4.7 mU/l) and T4 concentrations (Group 2). Thyroid microsomal antibodies were present initially in 65% of patients in Group 1 and 15% of patients in Group 2. By 1981, 59 patients (74%) in Group 1 and 47 patients (80%) in Group 2 had been followed for a mean +/- SD duration of 4.2 +/- 1.8 and 4.2 +/- 1.5 years, respectively. Hypothyroidism developed in 9 patients in Group 1, but none from Group 2. Of patients in Group 1, hypothyroidism developed at a rate of 5% per annum in those with thyroid microsomal antibodies, but only 1% per annum in those without antibodies. Therefore, the risk of development of hypothyroidism is greatest in diabetics having both elevated serum TSH concentrations and thyroid microsomal antibodies and such patients should have regular review of thyroid function. Either risk factor alone appears to be a poor predictor of development of hypothyroidism.