Ensuring Effective Prevention of Iodine Deficiency Disorders

BACKGROUND

Programs initiated to prevent iodine deficiency disorders (IDD) may not remain effective due to changes in government policies, commercial factors, and human behavior that may affect the efficacy of IDD prevention programs in unpredictable directions. Monitoring and outcome studies are needed to optimize the effectiveness of IDD prevention.

SUMMARY

Although the need for monitoring is compelling, the current reality in Europe is less than optimal. Regular and systematic monitoring surveys have only been established in a few countries, and comparability across the studies is hampered by the lack of centralized standardization procedures. In addition, data on outcomes and the cost of achieving them are needed in order to provide evidence of the beneficial effects of IDD prevention in countries with mild iodine deficiency.

CONCLUSION

Monitoring studies can be optimized by including centralized standardization procedures that improve the comparison between studies. No study of iodine consumption can replace the direct measurement of health outcomes and the evaluation of the costs and benefits of the program. It is particularly important that health economic evaluation should be conducted in mildly iodine-deficient areas and that it should include populations from regions with different environmental, ethnic, and cultural backgrounds.

Iodine status of UK schoolgirls: a cross-sectional survey

BACKGROUND

Iodine deficiency is the most common cause of preventable mental impairment worldwide. It is defined by WHO as mild if the population median urinary iodine excretion is 50-99 μg/L, moderate if 20-49 μg/L, and severe if less than 20 μg/L. No contemporary data are available for the UK, which has no programme of food or salt iodination. We aimed to assess the current iodine status of the UK population.

METHODS

In this cross-sectional survey, we systematically assessed iodine status in schoolgirls aged 14-15 years attending secondary school in nine UK centres. Urinary iodine concentrations and tap water iodine concentrations were measured in June-July, 2009, and November-December, 2009. Ethnic origin, postcode, and a validated diet questionnaire assessing sources of iodine were recorded.

FINDINGS

810 participants provided 737 urine samples. Data for dietary habits and iodine status were available for 664 participants. Median urinary iodine excretion was 80·1 μg/L (IQR 56·9-109·0). Urinary iodine measurements indicative of mild iodine deficiency were present in 51% (n=379) of participants, moderate deficiency in 16% (n=120), and severe deficiency in 1% (n=8). Prevalence of iodine deficiency was highest in Belfast (85%, n=135). Tap water iodine concentrations were low or undetectable and were not positively associated with urinary iodine concentrations. Multivariable general linear model analysis confirmed independent associations between low urinary iodine excretion and sampling in summer (p<0·0001), UK geographical location (p<0·0001), low intake of milk (p=0·03), and high intake of eggs (p=0·02).

INTERPRETATION

Our findings suggest that the UK is iodine deficient. Since developing fetuses are the most susceptible to adverse effects of iodine deficiency and even mild perturbations of maternal and fetal thyroid function have an effect on neurodevelopment, these findings are of potential major public health importance. This study has drawn attention to an urgent need for a comprehensive investigation of UK iodine status and implementation of evidence-based recommendations for iodine supplementation.

FUNDING

Clinical Endocrinology Trust.

Iodine uptake and loss-can frequent strenuous exercise induce iodine deficiency?

Most of the daily dietary iodine intake (approximately 90 %) will be excreted in the urine; measurement of urinary iodine excretion is thus routinely used as an index of dietary iodine intake. However, urinary excretion is not the only means of iodine loss. Subjects such as athletes or those participating in vigorous exercise can lose a considerable amount of iodine in sweat, depending on environmental factors such as temperature and humidity. In areas of lower to moderate dietary iodine intake, loss in sweat can equal that in urine. Although electrolyte loss in sweat is well-recognized and replacement strategies are adopted, there is less recognition of potential iodine loss. Crude calculations reveal that if sweat iodide losses are not replaced, dietary stores could be depleted in an athlete undergoing a regular training regime. The significance of these losses could be increased in areas where dietary iodine intake is lower in the summer months. Although there is little doubt that excessive sweating can induce a relative iodine deficiency state, there is no case as yet for iodine supplementation in those that take vigorous exercise. However, sustained iodine loss may have implications for thyroid status and possibly consequences for athletic performance.

Hypothyroidism and aging: the Rosses' survey

An earlier impression of a high prevalence of hypothyroidism in a general practice (4,190 patients including 1,544 adult females aged 18 years or more with 544 aged 50 years or more) in the Rosses, a coastal area in the northwest of Ireland was confirmed by this study. The accumulated prevalence of overt spontaneous primary hypothyroidism was 8.6% in 544 females aged 50 years or more but only 0.9% in the 1,000 females between 18 and 50 years of age. This prevalence was approximately twice that of an Irish National general practice population sample of 4,314 females aged 50 years or more (8.6% vs. 4.6%) p < 0.001. The reasons for this difference are unclear but may reflect the high level of opportunistic screening carried out in West Donegal. Thyroid peroxidase antibodies measured by radioimmunoassay were found in 75.6% of hypothyroid patients compared to 18.6% of practice controls (p < 0.01). Neither HLA-DRB1, DQA1, and DQB1 phenotype frequencies nor dietary iodine intake (median urinary iodine excretion 104 microg/L) appeared to be contributory factors. The finding of an 8.6% accumulated prevalence of hypothyroidism in females greater than 50 years of age when a population is aggressively investigated demonstrates the relative importance of its contribution to total morbidity and suggests that the disorder may be underdiagnosed, thus supporting the concept of targeted screening in this age group.

Increased prevalence of thyroglobulin antibodies in Sri Lankan schoolgirls--is iodine the cause?

OBJECTIVE

Iodine deficiency was the likely cause of a high prevalence of goitre previously in Sri Lankan schoolchildren. Salt iodination was made compulsory in 1993 but there has been no recent study, using modern techniques, of its benefits or harmful effects.

METHODS

Three hundred and sixty-seven schoolgirls between the ages of 11 and 16 years had ultrasound thyroid volume, free thyroxine (T4), free tri-iodothyronine (T3), thyrotrophin (TSH), anti-thyroglobulin (TgAb) and thyroid peroxidase (TPOAb) antibodies, and urine iodine concentrations measured.

RESULTS

Median ultrasound thyroid volume ranged from 4.8 ml (11-year-old girls) to 8.6 ml (16-year-old girls) with an age-related increase. Median urine iodine concentrations ranged from 105 to 152 microg/l. Free T4 and free T3 were normal in all, but TSH was elevated in four subjects (5. 53-41.29 mU/l). However, the prevalence of TgAb was markedly raised, ranging between 14.3% (11-year-old girls) and 69.7% (16-year-old girls) (P<0.03). In contrast, the prevalence of TPOAb was 10% or less in all age groups.

CONCLUSIONS

Normal median thyroid volumes, iodine concentrations and thyroid function would indicate that iodine deficiency is not a major problem in this group. The high prevalence of TgAb, hitherto unreported, most likely reflects excessive iodination of Tg resulting in increased immunogenicity. There is an urgent need to continuously monitor the adequacy and risks of iodination in this population.

Tissue iodine content and serum-mediated 125I uptake-blocking activity in breast cancer

In the thyroid, active transport of iodide is under control of the TSH-dependent Na+/I- symporter (NIS), whereas in the breast such control is less well understood. In this study, NIS expression was demonstrated by RT-PCR in 2 of 2 fibroadenomata and 6 of 7 breast carcinoma messenger ribonucleic acid isolates. In addition, mean total tissue iodine levels of 80.9 +/- 9.5 ng I/mg protein in 23 benign tumors (fibroadenomata) were significantly higher than those in 19 breast cancers taken from either the tumor (18.2 +/- 4.6 ng I/mg) or morphologically normal tissue taken from within the tumor-bearing breast (31.8 +/- 4.9 ng I/mg; P < 0.05 in each case). Inhibition of 125I uptake into NIS-transfected CHO cells was observed in serum from 20 of 105 (19.0%) breast carcinoma, 8 of 49 (16.3%) benign breast disease, and 27 of 86 (31.4%) Graves' patients, but in only 1 of 33 (3.0%) age-matched female controls. IgG purified from serum of patients showing positive 125I uptake inhibition also inhibited iodide uptake, suggesting that such inhibition was antibody mediated. 125I uptake inhibition was significantly associated with thyroid peroxidase antibody positivity (P < 0.05) in sera from breast cancer patients, but not in those with benign breast disease, once again suggesting an association between thyroid autoimmunity and breast carcinoma.

Assessment of goiter in an area of endemic iodine deficiency

Urinary iodone (UI) excretion and sonographically measured thyroid volume were investigated in 195 subjects living in 6 separate villages in the Casamance region of southeastern Senegal, West Africa. A comparison of goiter prevalence using thyroid palpation and volume measurement and of iodine excretion expressed as micrograms per gram (microg/g) creatinine or micrograms per deciliter (microg/dl) urine was undertaken, and possible pathogenetic factors were investigated. Ultrasound measured thyroid volumes were above the recommended upper limit of the reference range for an area replete in iodine in 83.1% or females, 52.3% of males, and 80.0% of children aged 13 years or younger. Overall sensitivity and specificity for palpation compared to sonographically demonstrated thyroid enlargement was 51.7% and 91.5%, respectively. Thyroid enlargement was not associated with ethnic origin, thiocyanate ingestion, HLA DR/DQ phenotype frequency, or thyroid growth-stimulating immunoglobulin (TGI) positivity. Median UI was 32 microg/g creatinine with 65.0% having values consistent with iodine deficiency (< 50 microg/g). When results were expressed as micrograms per deciliter, the percentage having values consistent with iodine deficiency (< 5.0 microg/dl) increased to 95.7%. The findings suggest a primary role for iodine deficiency in goitrogenesis in the study population. They demonstrate that classification of the severity of the endemia in this or other study populations in areas of iodine deficiency is dependent on the methods used to determine goiter prevalence (palpation or ultrasound measured thyroid enlargement), or dietary iodine status (iodine excretion expressed as micrograms per gram creatinine or micrograms per deciliter urine).

Variation in iodine handling during normal pregnancy

Reports in the literature are divided on changes in thyroid volume and urinary iodine excretion (UI) during normal pregnancy. Reports from Ireland, an area of modest dietary iodine intake (median UI 70 microg/L) showed an increase in UI that rose to a median value of 135 microg/L in the first trimester (T1) and continued at 124 microg/L in the second (T2) and 122 microg/L in the third trimester (T3). In parallel with the increase in UI, mean ultrasound measured thyroid volume increased by a maximum of 47% over nonpregnant values in the third trimester (T3). Although these findings were consistent with studies in Cardiff, UK (median UI 73 microg/L), which also showed a pregnancy-associated rise in UI excretion (maximum 176 microg/L) accompanied by a 30% increase in median thyroid volume, they differed from findings in Sri Lanka (median UI 146 microg/L), a country in which a successful program of salt iodination has recently been implemented, which showed no significant changes in UI excretion (T3 maximum 154 microg/L) but did show a modest (20%) maximum increase in median thyroid volume at T3. Prospective studies on Irish subjects showed that median UI fell precipitously to nonpregnant control values (76 microg/L) at delivery. In addition, UI in neonates sampled at 3-days postdelivery showed that excretion was greater in breast-fed than in bottle fed infants. Differences in reported UI excretion patterns during pregnancy may may reflect the existence of a threshold above which increased renal clearance results in increased iodine loss but that is masked at higher iodine intakes. Assuming constant dietary iodine intake during pregnancy, any increased urine loss will inevitably lead to negative iodine balance and thyroid depletion. In these circumstances, increased thyroid volume may in part be a compensatory mechanism to allow for greater iodine storage.

Vertebral shape: automatic measurement with active shape models

The shape and appearance of the spine on lateral dual x-ray absorptiometry scans were statistically modeled. To measure vertebral shape accurately, rapidly, and automatically with a computer, this trained model was matched to findings on previously unseen scans. The technique obtained entire shape information, was faster than manual analysis, and was as accurate as human observers in the measurement of vertebral shape.

Serum thyroid peroxidase autoantibodies, thyroid volume, and outcome in breast carcinoma

The prevalence of thyroid peroxidase autoantibodies (TPO.Ab) was assessed in patients with either breast carcinoma or benign breast disease, and its association with disease outcome in breast carcinoma was studied. TPO.Ab were detected by direct RIA in serum from 121/356 (34.0%) of patients with breast carcinoma, compared with 36/194 (18.5%) of controls (P < 0.001); and in 31/108 (28.7%) with benign breast disease, compared with 12/88 (13.6%) of controls (P < 0.05). Survival analysis in a group of 142 women with breast carcinoma demonstrated that TPO.Ab titres > or = 0.3 U/mL were associated with a significantly better disease-free [relative risk (RR) = 1.84, P < 0.05] and overall survival (RR = 3.46, P < 0.02), compared with those who were TPO.Ab-negative. Better outcome associated with higher TPO.Ab titres was confined to those who had thyroid volumes within the intermediate range (10.1-18.8 mL) and did not further enhance the good outcome recorded when volumes were < or = 10.0 mL or > 18.8 mL. Multivariate survival analysis showed that both TPO.Ab and thyroid volume were independently associated with prognosis in breast carcinoma and that RRs for disease-free survival were of a similar order of magnitude to well-established prognostic indices such as axillary nodal status or tumor size. These findings supply evidence that manifestations of thyroid autoimmunity are associated with a beneficial effect on disease outcome in breast carcinoma and provide the strongest evidence to date of a biological link between breast carcinoma and thyroid disease.

Maternal iodine status and thyroid volume during pregnancy: correlation with neonatal iodine intake

Differences in pregnancy-associated alterations in thyroid volume and urinary iodine (UI) excretion have been attributed to geographical variations in dietary iodine intake. In this study, ultrasound-measured thyroid volume and UI excretion were assessed during the 3 trimesters of pregnancy, at delivery, and at 6 weeks postpartum. Urine specimens also were obtained from mothers and both breast- and formula-feeding infants at 3 days after delivery. Thyroid volume showed a significant increase (maximum 47.0%), compared with nonpregnant control values over the 3 trimesters of pregnancy, which occurred as early as the first trimester and was paralleled by increased UI excretion, followed in turn by a precipitous fall at delivery. UI excretion in breast-feeding neonates (100 +/- 6.8 micrograms/L) was significantly higher than in their mothers (76 +/- 5.6 micrograms/L; p < 0.01) but was significantly lower (43 +/- 3.5 micrograms/L) in formula-fed infants. The results suggest that in an area of moderate dietary iodine intake, UI loss during pregnancy may result in maternal thyroid enlargement. The ability of the breast to transport iodine compensates for this loss in breast-fed infants, but this protection may be lost in formula feeding.

The thyroid and breast cancer: a significant association?

The coincidence of thyroid disorders and breast cancer has long been a subject of debate. Associations with hyperthyroidism, hypothyroidism, thyroiditis and nontoxic goitre have been reported. Although no convincing evidence exists of a causal role for overt thyroid disease in breast cancer, the preponderance of published work favours an association with hypothyroidism. Geographical variations in the incidence of breast cancer have been attributed to differences in dietary iodine intake and an effect of iodide on the breast has been postulated. Recent reports have shown a direct association between thyroid enlargement, as assessed by ultrasound, and breast cancer. Although the exact mechanism for the demonstrated association between diseases of the thyroid and breast cancer remains to be elucidated, there is at least the possibility that the presence of thyroid abnormalities may influence breast cancer progression and this alone should stimulate awareness into the coincidence of the two disorders.

Application of computer texture analysis to the Singh Index

The Singh Index, which describes trabecular patterns in the proximal femur, has been used as a predictor for hip fractures and as an indicator of osteopenia. Evidence suggests that its contribution to the assessment of hip fracture risk is in its description of the structural properties of the femur. However, subjectivity in its determination may limit its practical value. In this study, we have used computer texture analysis to characterize the textural changes in trabecular bone which occur in osteoporosis. Texture analysis of the proximal femur was used to rank radiographs of 25 cadaver femora by Singh grading. These rankings were compared with those performed by two experienced radiologists. The computer method performed better than the least consistent individual radiologist, but not as well as the two radiologists in combination. The method required no radiologist's time after the system had been 'trained' from a set of example radiographs. The method has potential for use in large studies in which speed and consistency of measurement are important.

Thyroid disorders and breast cancer

We have investigated the controversial association between diseases of the thyroid gland and breast carcinoma using methodology which allows positive exclusion of cases of breast disease from control groups and the detection of subclinical alterations in thyroid volume using high resolution ultrasonography, thus addressing the deficiencies of earlier studies. Whereas the prevalence of hyperthyroidism and hypothyroidism in patients with breast carcinoma and in healthy controls without clinical evidence of breast disease was similar, non-toxic goitre was more than twice as common in the breast carcinoma patients. Thyroid volumes were also significantly higher in breast carcinoma patients than in controls; using World Health Organisation criteria, 45.5% of breast carcinoma patients had thyroid enlargement compared with only 10.5% of controls. Finally, antithyroid peroxidase autoantibodies were twice as common in breast cancer patients than in controls. These findings provide clear evidence of a relationship between thyroid disease and breast carcinoma, although the mechanisms underlying this relationship require further study, future studies of breast cancer risk factors should therefore include assessment of thyroid function, antibody status and volume.

A direct relationship between thyroid enlargement and breast cancer

Despite extensive study, evidence to support a direct relationship between diseases of the thyroid and breast has not been established. In this study thyroid volume was assessed by ultrasound in 200 patients with breast cancer and 354 with benign breast disease. Results were compared to appropriate female control groups. Both mean thyroid volume (21.1 +/- 1.4 mL) and the percentage of individual patients with enlarged (> 18.0 mL) thyroid glands (41.5%) were significantly greater in the breast cancer group than equivalent values (13.2 +/- 0.5 mL and 10.5%, respectively) in age-matched controls (P < 0.01 in both cases). The mean thyroid volume of 14.5 +/- 0.34 mL in patients with benign breast disease was also significantly greater than that of 12.5 +/- 0.38 mL in younger controls (P < 0.01). The results support a direct association between breast cancer and increased thyroid volume as mean thyroid volumes and the percentage of individual patients with enlarged thyroid glands were similar in those studied both before (20.8 +/- 1.3 mL and 43.0%) and after (21.4 +/- 1.6 mL and 40.0%) therapies for breast cancer. Although there is no evidence that thyroid enlargement represents a risk factor for breast cancer, the results emphasize the importance of raising the consciousness of the coincidence of both disorders.

Thyroid disease and breast cancer

A review of the literature on the relationship between thyroid disorders and breast cancer does not provide conclusive evidence for the establishment of a causal relationship as breast cancer has been associated with hypothyroidism, hyperthyroidism and nontoxic goiter. Most reports on the association of thyroid enlargement and breast cancer have emanated from areas of endemic iodine deficiency and these reports have relied on neck palpation. The contribution of the present study is in the application of the highly sensitive technique of diagnostic ultrasound to the investigation of subtle changes in thyroid volume and anatomy in patients with breast cancer. The mean thyroid volume of 20.4 +/- 1.0 ml in 184 breast cancer patients was significantly greater than that of 12.9 +/- 1.2 ml in age-matched controls (p < 0.01). Also the number of individual patients with breast cancer having enlarged thyroid glands (73/184; 39.7%) was significantly greater than the corresponding number (13/150; 8.6%) in the control group (p < 0.001). There was a direct correlation between thyroid enlargement and breast tumour staging. Both mean thyroid volume and % of enlarged thyroids were identical in groups of patients scanned after (Retrospective Group) and before (Prospective Group) various therapies for breast cancer, thus excluding therapeutic intervention as a cause for thyroid enlargement. The results indicate a direct relationship between the two disorders perhaps involving a common growth stimulus and emphasise the importance of raising the consciousness of the coincidence of both disorders.

Quantitative cytochemistry of glucose-6-phosphate dehydrogenase in benign and malignant breast tumours

Glucose-6-phosphate dehydrogenase (G6PD) activity was quantified cytochemically in mammary epithelial cells within frozen tissue sections from 38 patients with breast cancer and 44 with benign breast disease. G6PD activities were measured under atmospheres of both N2 and O2. The mean (S.E.) G6PD value 2.5 (0.23) IE U/min measured in N2 in mammary epithelial cells from the group of malignancies was significantly greater than that of 1.6 (0.37) IE U/min in the benign group (P less than 0.001), but there was considerable overlap between individual values. G6PD measured in O2 was detectable in 84% of malignancies compared to only 14% of benign biopsies and the group mean of 1.3 (0.18) IE U/min in the former was significantly greater than that of 0.35 (0.20) IE U/min in the latter (P less than 0.001). Significant correlations between G6PD activities measured in N2 and O2 were observed in both groups. The techniques present a sensitive method of identifying increases in G6PD activity in mammary epithelial cells and provide an assay that in a majority of cases permits the separation of malignant from benign tissues.

Premorphological metabolic changes in human breast carcinogenesis

Malignant breast tissue is characterized by morphological and metabolic changes when compared with normal breast tissue. In this study, the cytochemical measurement of glucose-6-phosphate dehydrogenase (G6PD) activity was used to detect abnormal metabolism in breast tissue and to determine whether abnormal metabolic activity precedes morphological change during human breast carcinogenesis. Normal and benign breast tissue, morphologically normal tissue from cancer-containing breasts, and malignant breast tissue were studied. In malignant tissue, mean(s.e.m.) G6PD activity was significantly increased when compared with normal and benign tissue (9.69(2.3) versus 27.02(1.7) mean integrated extinction (MIE) x 100, P less than 0.01). G6PD activity was increased in morphologically normal tissue from cancer-containing breasts when compared with normal and benign breast tissue from breasts with no known cancer (27.02(1.7) versus 18.42(2.6) MIE x 100, P less than 0.05). These findings suggest that metabolic abnormalities precede morphological changes in breast carcinogenesis. Abnormal metabolism can be detected widely within a cancer-containing breast. The detection of such abnormality may prove helpful in identifying patients at high risk of developing breast cancer.

Sequential presentation of a case of hyperthyroidism with autonomously functioning nodules and Graves' disease in the presence of IgG thyroid stimulators

The rare occurrence of hyperthyroidism with an autonomously functioning nodule which following 131I therapy presented as toxic diffuse goitre (Graves' disease) is described in a 60 year old male. This progression was characterised by the presence of varying concentrations of IgG thyroid stimulators, thyroid stimulating immunoglobulins and thyroid growth stimulating immunoglobulins, as measured by cytochemical bioassay. It is postulated that the presence of the nodule and its associated hypersecretion of thyroid hormones may have protected the gland from the effects of IgG stimulators by bringing about inhibitory short-loop feedback on normal thyroid cells. It is further suggested that following therapeutic ablation of the nodule, normal thyroid cells became sensitive to the thyroid stimulators with the evolution of typical features of toxic diffuse goitre.

Cytochemical investigation of glucose-6-phosphate dehydrogenase activity in rat mammary tissue

Glucose-6-phosphate dehydrogenase (G6PD) activity in epithelial cells from six normal, eight lactating and 21 DMBA tumour bearing rat mammary tissues was investigated using techniques of quantitative cytochemistry. G6PD promoted H+ production was quantified under atmospheres of N2 and O2 in frozen sections from rat mammary tissue in the presence and absence of a H+ acceptor (Total H+ and Type I H+). There was a considerable overlap between the three tissue types in values for Total H+ measured under N2 or O2. However, maximum H+ production in lactating and DMBA tumour tissue took longer to achieve in O2 than in N2 (16-20 min vs 6-8 min). In normal tissue maximum production of Total H+ was not achieved until 45-50 min and the rate of reaction was similar in N2 and in O2. Type I H+ measured in N2 did not vary significantly between DMBA tumours and lactating tissue but under O2 was only present in DMBA tumour, being undetectable in both normal and lactating tissue. The results demonstrate that despite the overlap in G6PD activities between the tissues tested, the techniques of quantitative cytochemistry can provide a functional assay differentiating between non-malignant and malignant breast tissue in the rat.

The prevalence of immunological abnormalities in endemic simple goitre

Thyroid growth stimulating immunoglobulins microsomal antibodies and antibodies against thyroglobulin were determined in patients with simple goitre (n = 20) and controls (n = 6) living in an iodine deficient area. In addition, lymphocytic infiltration of thyroid tissue, the amount of the various lymphocyte subsets (Leu 4+, Leu 3a+, and Leu 2a+ T-cells as well as B1+ B cells) in the thyroid gland, as well as the expression of the histocompatibility antigen HLA-DR on thyrocytes and intrathyroidal T-lymphocytes were examined. Goitrous patients were subdivided into two groups according to their individual iodine supply estimated by iodine excretion values, and immunological parameters were compared between patients with low (group A, iodine excretion less than 70 micrograms/24 h) and with higher (group B, iodine excretion greater than 100 micrograms/24 h) iodine supply. Thyroid growth stimulating immunoglobulins and antithyroid antibodies were equally prevalent in the two patient groups, but were absent in controls. Lymphocytic infiltration of thyroid tissue was present to a comparable extent in patients of groups A and B, but to a distinctly lower degree in control persons. Intrathyroidal T-lymphocyte subsets did not differ between patients and controls. B-lymphocytes, germinal centres as well as DR+ thyrocytes were detected in goitrous patients of both groups, but never in control persons. Thus, immunological abnormalities frequently occur in patients with simple goitre and do not depend upon individual iodine supply.

Thyroid growth-stimulating immunoglobulins in goitrous disease: relationship to thyroid-stimulating immunoglobulins

Thyroid growth stimulating immunoglobulins (TGI) were assayed in IgG concentrates prepared from human plasma using a cytochemical bioassay (CBA) based on the measurement of changes in glucose-6-phosphate dehydrogenase (G6PD) activity in guinea pig thyroid follicular cells. TGI was present in all 8 patients studied who had goitrous Graves' disease, in 9 who had toxic diffuse goitres with asymmetric uptake on scintigram and/or symptomatic ophthalmopathy and in 4:8 who had toxic uninodular goitre with autonomously functioning nodules. TGI were also present in 34:54 (64%) of patients who had non-toxic goitres. In contrast, TGI were undetectable in 4 patients who had Graves' disease without palpable goitre and in all 18 euthyroid non-goitrous volunteers. Maximum increases in G6PD activity occurred at an IgG concentration of 50 micrograms/ml in all patients who had goitrous Graves' disease and in 5:7 who had diffuse non-toxic goitres. In contrast, IgG concentrates from 20:27 patients with nodular goitres caused maximum increases in G6PD activity at an IgG concentration of 500 micrograms/ml. A comparison of the prevalence of TGI with that of thyroid stimulating immunoglobulins (TSI), also measured by CBA, in 63 patients showed that although both stimulators were present in 8 patients who had goitrous Graves' disease they were only simultaneously present in 18:43 (42%) who had non-toxic goitres of various aetiologies. Thyrotrophin receptor antibodies (TRAb) were present in 11/44 (25%) of non-toxic goitrous patients but there was no significant correlation with IgG stimulators in such patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal abnormalities in polycystic ovary syndrome

This study was undertaken to examine the role of adrenal androgen excess in the pathogenesis of polycystic ovary syndrome (PCOS) and, if such was present, to assess its reversibility using dexamethasone given in physiological dosage at night. Mean plasma testosterone (T), T/sex-hormone binding globulin (T/SHBG) ratio, androstenedione, and 17-OH-progesterone levels were elevated in the 19 patients studied. Plasma estrone values were elevated, whereas estradiol levels were normal. Plasma FSH was decreased and LH responsiveness to LHRH was exaggerated. Metyrapone, an 11-hydroxylase inhibitor, was administered at 2400 h to induce hypocortisolemia and compensatory ACTH secretion so that adrenal androgen and glucocorticoid responsiveness to endogenous stimulation could be examined. Plasma T, androstenedione, and 11-deoxycortisol responses to metyrapone were excessive in PCOS patients, thus indicating a specific adrenal abnormality. After 3 months treatment with dexamethasone, 0.5 mg at night, mean plasma T/SHBG and androstenedione declined to normal, and mean plasma dehydroepiandrosterone and dehydroepiandrosterone sulfate declined to below normal. The mean estrone value was slightly lower during dexamethasone. Plasma LH responsiveness to LHRH was no longer significantly different from normal, but FSH was suppressed. During treatment androgen responsiveness to metyrapone stimulation was normal, whereas 11-deoxycortisol responsiveness was suppressed. Fifteen patients completed 3 months of treatment with dexamethasone. Of these, 10 resumed regular menstruation. The latter group had suppression of plasma T, T/SHBG, androstenedione, dehydroepiandrosterone, and dehydroepiandrosterone sulfate. Only plasma androstenedione fell significantly in the remainder. These observations support the hypothesis that, in at least some patients, PCOS develops in response to abnormal gonadotropin secretion induced by hyperestronemia occurring as a consequence of excessive adrenal androgen secretion.

Altered androstenedione and estrone dynamics associated with abnormal hormonal profiles in amenorrheic subjects with weight loss or obesity

The present study was designed for exploration of hormonal disturbances underlying common forms of amenorrhea. Polycystic ovary syndrome (PCO) patients and obese amenorrheic subjects had significantly elevated estrone (E1) levels, elevated luteinizing hormone/follicle-stimulating hormone ratios, and an exaggerated luteinizing hormone response to luteinizing hormone-releasing hormone. However, androstenedione (delta 4A), the precursor of E1, was elevated only in PCO. Thus, the E1/delta 4A ratio, which provides an indirect index of aromatase activity in extraglandular sites, was raised in obese subjects as a group but not in PCO subjects. These findings suggest that elevated E1 levels, which give rise to abnormal gonadotropin secretion, arise from increased available androgens in PCO but from an increased effect of aromatase (present in adipose tissue) in obese subjects. Measurement of androgens and the E1/delta 4A ratio provides insights into the relative contributions of hyperandrogenemia and enhanced aromatase activity to the genesis of amenorrhea in these groups. In patients with suppressed estradiol levels associated with hyperprolactinemia or weight loss, follicle-stimulating hormone levels were suppressed, while luteinizing hormone was not elevated. Prolactin excess explains these findings in hyperprolactinemia. Plasma E1 levels and the E1/delta 4A ratio were suppressed in patients with weight loss, possibly as a consequence of reduced adiposity. This finding suggests that hypothesis that a minimum level of E1, dependent upon adequate adiposity, is critical for the normal mature function of the hypothalamic-pituitary-ovarian axis. Abnormal E1/delta 4A ratios, high in obesity-associated amenorrhea and suppressed in weight loss-associated amenorrhea, may provide specific markers for these groups of patients.

Hyperthyroidism following primary hypothyroidism in association with polyendocrine autoimmunity

A 37 year old male with a strong family history of autoimmune disease presented with typical symptoms of hyperthyroidism. He had exophthalmos but no goitre. Hyperthyroidism was confirmed by failure of 131I neck uptake to suppress after 7 days treatment with triiodothyronine. Six years previously a diagnosis of primary hypothyroidism has been made. At diagnosis of hyperthyroidism, thyroglobulin antibodies, thyroidal microsomal antibodies and thyroid stimulating immunoglobulins were detected. The absence of thyroid growth stimulating immunoglobulins and presence of immunoglobulins blocking TSH-induced growth may account for the absence of goitre throughout. HLA -B8, -B, -DR3 and -DR4 genotypes, low C4 complement concentrations and islet cell autoantibodies were detected at the time of diagnosis and 1 year later diabetes mellitus developed.

Immunological features of nonimmunogenic hyperthyroidism

Blood lymphocyte subpopulations (Leu 4+ cells = pan-T cells, Leu 3a+ cells = helper/inducer cells, and Leu 2a+ cells = suppressor/cytotoxic cells), thyroid-stimulating immunoglobulins, microsomal antibodies and antibodies against thyroglobulin were determined in 10 patients with hyperthyroidism due to single autonomously functioning thyroid nodules (ATN), 11 patients with hyperthyroidism due to Graves' disease (GD) and in 20 normal subjects. Thyroidectomy was performed in 8 of the patients with ATN and in 6 of those with GD after 3 weeks of antithyroid drug treatment with methimazole. Lymphocytic infiltration of thyroid tissue, the amount of the various lymphocyte subsets (Leu 4+, Leu 3a+, and Leu 2a+ T cells as well as B+ B cells) in the thyroid gland, as well as the expression of the histocompatibility antigen HLA-DR on thyrocytes and intrathyroidal lymphocytes were examined. Blood Leu 4+ cells were reduced due to a lack of Leu 2a+ cells in patients with ATN and GD when compared to normal subjects. Thyroid-stimulating immunoglobulins were detected in all patients with ATN and GD, but in none of the normal subjects. Lymphocytic infiltration of thyroid tissue was present in patients with ATN and GD. The various lymphocyte subsets in the thyroid gland did not differ between the two patient groups. DR expression on thyrocytes was seen in 6 of the patients operated for ATN and in 5 of those who underwent surgery for GD. Infiltration with DR+-T lymphocytes was found in all thyroid glands investigated. Thus immunological findings usually classified as proof for the autoimmune origin of GD exist also in patients with ATN. An overlap in the pathogenetic background of both diseases seems possible.

Prolactin in hirsute women: possible roles for androgens in suppressing basal levels, and for oestrogens in enhancing TRH-induced responses

Hyperprolactinaemic patients occasionally demonstrate hirsutism and elevated levels of DHA-S, a weak androgen of adrenal origin. Abnormal adrenal function is frequently observed in hirsute patients. These observations prompted speculation that prolactin may modulate normal adrenal secretion and that derangements of adrenal androgen secretion may be due to abnormalities in prolactin. In this study we examined the possibility that elevated prolactin levels may be involved in the pathogenesis of hyperandrogenaemia in hirsute patients. However, basal prolactin levels in hirsute women, with or without menstrual disturbances, 201 +/- 24.3 mU/l (mean +/- SE) and 192 +/- 24.3 mU/l respectively, were significantly suppressed below levels in normal women, 289 +/- 12.2 mU/l. The prolactin responses to stimulation with TRH and to suppression with L-dopa were also studied in hirsute patients. The prolactin response to TRH (maximum increment or integrated response) was exaggerated significantly in hirsute women with menstrual disturbances when compared to normal women, to hirsute women with normal menses or to normal men. This abnormal response may have been due to elevated oestrone levels present in patients with oligomenorrhoea (318 +/- 49.5 pmol/l compared to 191 +/- 12.1 pmol/l in normal women and 161 +/- 15.5 pmol/l in hirsute women with normal menses, P less than 0.05). There were no abnormalities detected in the suppression of prolactin in response to L-dopa in any of these groups. These findings do not support a role for prolactin in the pathogenesis of hyperandrogenaemia in hirsute patients. However, elevated androgen levels in women may bring about suppression of basal prolactin levels to values seen in normal men. (ABSTRACT TRUNCATED AT 250 WORDS)

In vitro generation of NADPH as an index of thyroid stimulating immunoglobulins (TGI) in goitrous disease

A quantitative cytochemical assay for the measurement of total NADPH formation in guinea pig thyroid tissue following incubation with thyroid stimulators was validated and applied to the measurement of such stimulators in IgG concentrates prepared from human plasma. Pentose shunt enzyme activity was not uniformly distributed in thyroid tissue but this could be overcome and NADPH generation in such tissue used to assess accurately thyroid stimulators if a sufficient number of thyroid cells were measured. Specificity studies showed that antiserum to human IgG significantly diminished the NADPH generating capacity of IgG concentrates prepared in plasma from goitrous patients while antiserum to h-TSH had no such effect. The measurement of thyroid growth stimulating immunoglobulins (TGI) depended not only on the amount of NADPH generated but also on the IgG concentration at which maximum responses occurred. TGI present in goitrous Graves' disease were 10 times more potent than those present in euthyroid goitre, while such stimulators when present in toxic nodular goitre appeared to possess an intermediate potency. This finding, when taken together with the demonstration that TSH stimulation decreased intercellular differences in pentose shunt activity, provides experimental evidence for the hypothesis that an acute intense growth stimulus affecting all thyroid cells produces the diffuse hyperplasia characteristic of Graves' disease. In contrast, the weaker stimulus observed in nodular goitre may, over a period of time, result in the asymmetric hyperplasia commonly observed in this condition.

Association of thyroid-stimulating immunoglobulins and thyrotropin-releasing hormone responsiveness in women with euthyroid goiter

Thyroid-stimulating immunoglobulins (TSI) were measured, using a highly sensitive cytochemical bioassay, in plasma from 26 euthyroid women with idiopathic diffuse or multinodular goiter selected on the basis of their serum TSH responses to TRH stimulation. Thirteen were chosen because they were previously identified to have impairment in TRH responsiveness and were compared with 13 consecutive patients who had normal responses to TRH. TSI were present in a significantly greater number of those who had subnormal TRH responses (11:13) compared to those who had normal responses (3:13) P less than 0.005. Although serum T4, T3, and basal TSH values were all within the normal range, mean serum T4 and T3 values were significantly higher and basal TSH significantly lower in the 14 patients who had TSI than in the 12 in whom TSI was absent. The coexistence of impaired TRH responsiveness and TSI was associated with a family history of thyroid disease. The data suggest that TSI in patients with euthyroid goiter cause a modest increase in thyroid secretion sufficient to blunt the TSH response to TRH but not to cause clinical hyperthyroidism.

Lysosomal membrane recovery following labilization by thyroid stimulators

Lysosomal membrane permeability was assessed by measuring freely available naphthylamidase activity in intact preparations of guinea pig thyroid follicular cells following exposure of thyroid tissue to sequential stimulation by two thyroid stimulators, thyrotrophin (TSH) and thyroid stimulating immunoglobulins (TSI). These investigations showed that following labilization by TSH, the lysosomal membranes recovered and were capable of responding to a second thyroid stimulator (TSI). That such recovery represented restabilization of lysosomal membranes was confirmed by the finding that latent naphthylamidase activity was restored without a change in total activity of the enzyme.

Dose-response relationships in a cytochemical section bioassay for thyroid stimulators

The thyroid stimulators TSH and thyroid stimulating immunoglobulins (TSI) have previously been distinguished in a cytochemical section bioassay (CBA) by the different times at which they caused maximum increase of lysosomal membrane permeability within guinea-pig thyroid follicular cells. The present study demonstrates that the times at which maximum stimulation occurs in the assay depends not only on the type (TSH or TSI) but also on the concentration of the stimulator. At higher concentrations of stimulator earlier times of maximum stimulation were observed for both TSH and TSI. When both stimulators were simultaneously present in plasma at higher concentrations a single peak of stimulatory activity occurred. Neutralization studies using specific antisera revealed that the single peak represented a merging of TSH and TSI peaks. These findings explain the lack of parallelism to the standard curve seen at higher concentrations of TSH or TSI in the CBA. They emphasize the necessity of measuring plasma samples at a variety of dilutions in order to achieve parallelism and to avoid intra-assay interference between TSH and TSI. When these conditions are observed CBA can be used to detect TSH and TSI with extreme sensitivity even when both are simultaneously present in plasma.

The prevalence of thyroid-stimulating antibodies in goitrous disease assessed by cytochemical section bioassay

Thyroid-stimulating antibodies (TSAb) were detectable using a highly sensitive cytochemical section bioassay in plasma from all 56 hyperthyroid patients studied, including those who had either diffuse hyperplasia or nodular goiters. The maximum dilution at which TSAb was detectable ranged from 10(-2) - 10(-6). Six of these patients had scintigraphic evidence of single functioning nodules, and, surprisingly, TSAb was present in all. Of 27 patients who had nontoxic goiter, 14 (52%) had positive titers for TSAb ranging from 10(-2) - 10(-4). The mean serum T3 value in nontoxic goitrous patients who had TSAb was significantly higher than that in subjects in whom TSAb was absent; in contrast, mean serum T4 values were not significantly different in those two groups. It is concluded that idiopathic nontoxic goiter, toxic nodular goiter with functioning nodules (Plummer's disease), and toxic diffuse goiter (Graves' disease) share, in part, a common pathogenesis.

Validation of the cytochemical section bioassay for thyroid stimulating antibodies

A cytochemical bioassay for thyroid stimulators which utilised 12 micrometer sections of guinea pig thyroid as the target tissue was validated and applied to the measurement of thyroid stimulating antibodies (T.S.Ab.) in human plasma. T.S.H. and T.S.Ab. could be distinguished in the assay by the times at which they produced maximal responses; 90 seconds for T.S.H. and 180 seconds for T.S.Ab. Homogeneity of responses to stimulation was relatively uniform throughout thyroid tissue enabling simultaneous measurement of several plasma samples per guinea pig. Sensitivity of the assay was 1.5 x 10(-9) microU/l MRC L.A.T.S.-B. Antiserum to H-T.S.H. produced no significant change in T.S.Ab.-like activity when added to plasma from a thyrotoxic patient. Both anti-IgG and aliquots of a homogenate of thyroid tissue from a thyrotoxic patient diminished responses of thyrotoxic plasma in a concentration dependent manner. T.S.Ab. was present at titres of 1/100 to 1/100,00 in 13 hyperthyroid patients tested to date.

Effect of stilboesterol therapy on thyrotrophin-releasing hormone (TRH) responsiveness in males

TRH responsiveness was investigated in twenty-four males (aged 66-83 years) undergoing stilboesterol therapy for carcinoma of the prostrate. Twelve were taking 2-6 mg daily by mouth for periods of 5 days to 12 months (mean 5 months) (Group A) and the remainder were on daily i.v. doses of 250-500 mg for periods of 3-10 days (mean 8 days) (Group B). In the former group TRH responsiveness was enhanced compared to age matched controls. A contrary effect was observed in the latter group in that the group mean TRH response was significantly lower than that of Group A or of the control group. Basal serum TSH values were unchanged in Group A compared to controls, but a significant elevation in the basal mean value was observed in Group B. The mechanism of action of stilboesterol in the subjects studied remains to be elucidated. Our data are in keeping with either a hypothalamic or pituitary locus for such actions.