Search

Aim: This study was performed to determine the results of ablative radioiodine therapy (RIT) when the achieved dose in the thyroid was above 200 Gy and to characterize predictive factors for treatment outcome., Patients, Methods: A total of 571 consecutive patients were observed for 12 months between July 2001 and June 2004. Inclusion criteria were a confirmed diagnosis Graves' disease, compensation of hyperthyroidism and withdrawal of antithyroid drugs two days before preliminary radioiodine-testing and RIT. The intended dose was 250 Gy and the therapeutically achieved dose was calculated from serial uptake measurements. The end-point measure was thyroid function 12 months after RIT; success was defined as elimination of hyperthyroidism. The relation between success rate and the achieved dose, thyroid volume, age and sex of patients, TSH- and TRAb-values and presence of ophthalmopathy was analysed., Results: Relief from hyperthyroidism was achieved in 96% of patients who received more than 200 Gy, even for thyroid volumes >40 ml. The success of ablative RIT was not influenced by age or sex of patients, or by TSH- or TRAb values or concomitant ophthalmopathy. The mean achieved dose in the thyroid was 298 Gy with a standard deviation of 74.6 Gy., Conclusion: To achieve a dose of over 200 Gy with the above standard deviation, we recommend calculating an intended dose of 250 Gy and using a dosimetric approach with early and late uptake values in the radioiodine test, to allow early therapeutic intervention should the posttherapeutic thyroid dose fall unexpectedly below 200 Gy.

Aim: This study was performed to analyse the impact of the choice of antithyroid drugs (ATD) on the outcome of ablative radioiodine therapy (RIT) in patients with Graves' disease., Patients, Material, Methods: A total of 571 consecutive patients were observed for 12 months after RIT between July 2001 and June 2004. Inclusion criteria were the confirmed diagnosis of Graves' disease, compensation of hyperthyroidism and withdrawal of ATD two days before preliminary radioiodine-testing and RIT. The intended dose of 250 Gy was calculated from the results of the radioiodine test and the therapeutically achieved dose was measured by serial uptake measurements. The end-point measure was thyroid function 12 months after RIT; success was defined as elimination of hyperthyroidism. The pretreatment ATD was retrospectively correlated with the results achieved., Results: Relief from hyperthyroidism was achieved in 96% of patients. 472 patients were treated with carbimazole or methimazole (CMI) and 61 with propylthiouracil (PTU). 38 patients had no thyrostatic drugs (ND) prior to RIT. The success rate was equal in all groups (CMI 451/472; PTU 61/61; ND 37/38; p = 0.22)., Conclusion: Thyrostatic treatment with PTU achieves excellent results in ablative RIT, using an accurate dosimetric approach with an achieved post-therapeutic dose of more than 200 Gy.

Aim: Graves' hyperthyroidism and antithyroid drugs empty the intrathyroid stores of hormones and iodine. The consequence is rapid 131I turnover and impending failure of radioiodine therapy. Can administration of additional inactive iodide improve 131I kinetics?, Patients, Methods: Fifteen consecutive patients, in whom the 48 h post-therapeutically calculated thyroid dose was between 150 and 249 Gy due to an unexpectedly short half-life, received 3 x 200 microg inactive potassium-iodide (127I) daily for 3 days (Group A), while 17 consecutive patients with a thyroid dose of > or = 250 Gy (Group B) served as the non-iodide group. 48 hours after 131I administration (M1) and 4 or 5 days later (M2) the following parameters were compared: effective 131I half-life, thyroid dose, total T3, total T4, 131I-activity in the T3- and T4-RIAs., Results: In Group A, the effective 131I half-life M1 before iodine (3.81 +/- 0.93 days) was significantly (p < 0.01) shorter than the effective 131I half-life M2 (4.65 +/- 0.79 days). Effective 131I half-life M1 correlated with the benefit from inactive 127I (r = -0.79): Administration of 127I was beneficial in patients with an effective 131I half-life M1 of <3 or 4 days. Patients from Group A with high initial specific 131I activity of T3 and T4 showed lower specific 131I activity after addition of inactive iodine compared with patients from the same group with a lower initial specific 131I activity of T3 and T4 and compared with the patient group B who was given no additional inactive iodide. This correlation was mathematically described and reflected in the flatter gradient in Group A (y = 0.5195x + 0.8727 for 131I T3 and y = 1.0827x - 0.4444 for 131I T4) and steeper gradient for Group B (y = 0.6998x + 0.5417 for 131I T3 and y = 1.3191x - 0.2901 for 131I T4). Radioiodine therapy was successful in all 15 patients from Group A., Conclusion: The administration of 600 microg inactive iodide for three days during radioiodine therapy in patients with Graves' hyperthyroidism and an unexpectedly short half-life of <3 or 4 days was a safe and effective alternative to the administration of a second radioiodine capsule.

Background: Radioiodine therapy (RIT) combined with glucocorticoids is an effective therapy for Graves' disease, but it is debatable whether glucocorticoids should be applied in patients without Graves' ophthalmopathy (GO)., Methods: The effect of 0.4 - 0.5 mg prednisone every second day over a period of 5 weeks after RIT was monitored over a follow-up period of at least 12 months after RIT. A questionnaire was sent to 186 consecutive patients without GO concerning eye symptoms after RIT. 148 patients (80 %) answered. If eye symptoms had occurred after RIT, additional clinical examination was carried out at our outpatient clinic. The primary endpoint was the absence or onset of GO within the first year after RIT., Results: Within 12 months after RIT the examination confirmed GO in 5 out of 148 patients (3.4 %). In all cases the symptoms were transient. No adverse reaction to the use of prednisone after RIT was noted., Conclusions: The risk of new GO in the first year after RIT was low and the clinical course of GO was mild when RIT was combined with a low-dose glucocorticoid regimen. Preventive administration of glucocorticoids can therefore be recommended in patients with Graves' disease even without evident GO.

Background: The aim of the study was to analyze retrospectively the incidence of postradioiodine immunogenic hyperthyroidism/Graves' disease in relation to a temporary increase in TSH-receptor antibodies without overt hyperthyroidism after radioiodine therapy for autonomous thyroid disease., Patients and Methods: Between May 2000 and May 2003 all patients (n = 1,357) who had undergone radioiodine therapy for autonomous thyroid disease were retrospectively analyzed for development of postradioiodine immunogenic hyperthyroidism. On pretreatment evaluation 565 of 1,357 patients (41.6%) had unifocal autonomous thyroid disease (UFA), 693 of 1,357 patients (51.1%) had multifocal autonomous thyroid disease (MFA), and 99 of 1,357 patients (7.3%) had diffuse thyroid disease (DISS). Free triiodothyronine (FT(3)), free thyroxine (FT(4)), thyrotropin (TSH), and thyroid antibodies were measured. Ultrasound examinations and thyroid scintigraphy were performed before and after radioiodine therapy. A sensitive assay with the human TSH receptor as antigen was chosen for measurement of the TSH receptor antibody and the study was limited to analysis of data obtained since introduction of this assay., Results: Fifteen of 1,357 patients (1.1%) (UFA, 8/565 = 1.4%; MFA, 6/693 = 0.9%; DISS 1/99 = 1.0%) developed postradioiodine hyperthyroidism between 1 and 13 months after radioiodine therapy with clinically overt hyperthyroidism and an elevation of TSH receptor antibodies. Patients with elevated thyroid peroxidase (TPO) antibodies before radioiodine therapy had an almost 10-fold (6/57 patients =10.5%) higher risk of developing postradioiodine immunogenic hyperthyroidism. Thirteen of 999 patients (1.3%) with antibody measurements after radioiodine therapy (UFA, 2/421 = 0.5%; MFA, 9/494 = 1.8%, DISS, 2/84 = 2.4%) had increased levels of TSH receptor antibodies and, to some extent, TPO antibodies without development of clinically overt hyperthyroidism., Conclusions: There is an estimated 1.1% risk of developing postradioiodine immunogenic hyperthyroidism/Graves' disease in patients undergoing radioiodine therapy for autonomous thyroid disease and this increases approximately 10-fold when TPO antibody levels are elevated before radioiodine therapy. Furthermore, there is an estimated 1.3% risk of a temporary increase of TSH receptor antibodies after radioiodine therapy for autonomous thyroid disease without development of clinically overt hyperthyroidism.

The version 2 of the procedure guideline for radioiodine test is an update of the guideline published in 1999. The following statements were added or modified: The procedure guideline discusses the pros and cons of a single measurement or of repeated measurements of the iodine-131 uptake and their optimal timing. Different formulas are described when one, two or three values of the radioiodine kinetic are available. The probe with a sodium iodide crystal, alternative or additionally the gamma-camera using the ROI-technique are instrumentations for the measurement of iodine-131 uptake. A possible source of error is an inappropriate measurement (sonography) of the target volume. The patients' preparation includes the withdrawal of antithyroid drugs 2-3 days before radioiodine administration. The patient has to avoid iodine-containing medication and the possibility of additives of iodide in vitamin- or electrolyte-supplementation has to be considered.

Treatment options for benign diseases of the thyroid include medication, radioiodine therapy and surgery. Patients with hyperthyroidism initially receive antithyroid drugs, with further treatment determined by the relapse risk. In the case of Graves' disease this is determined by a number of risk factors, including the volume of the thyroid gland or the presence of endocrinal ophthalmopathy. In such cases with a high relapse risk, radioiodine therapy is the recommended first-line treatment. Further indications--if surgery is not necessary--are autonomous goiter, recurrent (autonomous) goiter and latent hyperthyroidism. A single radioiodine treatment suffices to control the situation in more than 90% of the cases, and the goiter clearly diminishes in size. Radiation-induced malignancies or malformations have not been seen, but iodine treatment is contraindicated in pregnancy. In view of the short hospital stay of only four to five days, and the ready availability of treatment units, the authors consider radioiodine therapy a suitable first-line option in patients with Graves' hyperthyroidism.

Centrocytes in germinal centers on selection differentiate into plasma cells and/or memory B cells. Cells that have acquired autoreactivity by somatic mutation generally fail to undergo positive selection and die by apoptosis. Presence of isotype-switched high-affinity autoantibodies in serum of autoimmune patients suggests that autoreactive plasma cells eventually emerge from a germinal center reaction. Currently, it is still unclear to which extent the same is true for autoreactive memory B cells. To address this question, we have analyzed whether IgG-bearing memory B cells with specificity for thyroid peroxidase (TPO) can be found in blood of patients with autoimmune thyroid disease and in normal blood donors. Autoreactive TPO-specific IgG+ memory B cells were identified using a previously described assay combining two-step immunomagnetic enrichment with flow cytometric detection. Autoreactive IgG+ memory B cells were found in 65% of the patients with autoimmune thyroid disease and in 17% of normal blood donors; 40% of the latter had no detectable TPO-specific IgG in the serum. The specificity of enriched TPO-specific IgG+ memory B cells was confirmed by in vitro proliferation and differentiation into antibody-secreting cells at limiting dilution and analysis of the supernatants for the presence of TPO-specific IgG. Detection of TPO-specific IgG+ memory B cells in most patients with clinically manifested autoimmune thyroid disease and few normal blood donors may argue for a role of circulating memory B cells in onset of disease.

At the 15th conference on the human thyroid in Heidelberg in 2001 the following aspects of the radioiodine therapy of benign thyroid disorders were presented: General strategies for therapy of benign thyroid diseases, criterions for conservative or definitive treatment of hyperthyroidism as first line therapy and finally preparation, procedural details, results, side effects, costs and follow-up care of radioiodine therapy as well as legal guidelines for hospitalization in Germany. The diagnosis Graves' hyperthyroidism needs the decision, if rather a conservative treatment or if primary radioiodine therapy is the best therapeutic approach. In the USA 70-90% of these patients are treated with radioiodine as first line therapy, whereas in Germany the conservative therapy for 1-1.5 years is recommended for 90%. This review describes subgroups of patients with Graves' disease showing a higher probability to relapse after conservative treatment. Comparing benefits, adverse effects, costs, and conveniences of both treatment strategies the authors conclude that radioiodine therapy should be preferred as first line therapy in 60-70% of the patients with Graves' hyperthyroidism.

Aim: Premedication with antithyroid drugs (ATD) compared to patients not pretreated with ATD causes a higher failure rate of radioiodine therapy (RITh) or demands higher therapeutical dosage of radioiodine (RI). For clinical reasons and because of accelerated iodine metabolism in hyperthyreosis a compensated thyroid metabolism is desirable. Aim of this study was to investigate the influence of ATD on the biokinetics of RI in case of Graves' disease in order to improve RITh of patients pre-treated with ATD., Methods: 385 consecutive patients who underwent RITh because of Graves' disease for the first time were included: Group A (n = 74): RITh under continuous medication with ATD; Group B (n = 111): Application of RI under continuous medication with ATD, in case of insufficient RI-uptake or shortened effective RI-half-life ATD were stopped 1-5 days after RITh; Group C (n = 200): ATD were stopped 2 days prior to RITh in all patients. We examined the influence of ATD on RI-uptake and effective RI-half-life as well as the absorbed dose achieved on the thyroid in dependence of thyroid volume and applied RI-dosage [TEQ--therapy efficiency quotient, (2)]., Results: In the RI-pretest (all patients under ATD) the RI-uptake was comparable in all three groups. During RITh RI-uptake, effective RI-half-life and therefore the TEQ were significantly higher in Group C as compared to Groups A and B (p < 0.001, respectively). In Group B the medication with ATD was stopped in 61 of 111 cases 1-5 days after RITh. In this subgroup the effective RI-half-life increased from 4.4 +/- 1.7 d to 5.1 +/- 1.6 d after stopping of ATD (p = 0.001)., Conclusion: Stopping of ATD 2 days prior to RITh leads to an increased efficiency of about 50% compared to RITh carried out under ATD and therefore to a clear reduction of radiation exposure to the rest of the body with equal absorbed doses of the thyroid. Stopping of ATD shortly after RITh increases efficiency in case of short effective RI-half-life, but it is inferior to stopping ATD 2 days prior to RITh.

Aim: The change of both amount and chemical forms of radioiodine exhaled in the air of rooms with patients on the therapy ward should be investigated depending on radioactivity applied, time after application, and kind of thyroid disease., Methods: The air of ward-rooms of 62 patients with thyroid carcinoma, Graves' Disease, and autonomy which received different therapy doses, was investigated with an portable constant air flow sampler. Different chemical iodine species (organic, elemental, aerosol bound) were collected during 8 hr in various filters until 3 days after application of the radioiodine capsule, according to their chemical form. The radioactivity in the filters was measured with a well counter on defined time points after application., Results: The radioactivity exhaled was between 0.008 and 0.03% related to activity of radioiodine applied. The percentage of radioiodine exhaled related to the activity applied, differed significantly depending on disease and changed as follows: Grave's Disease > autonomy > carcinoma. The exhalation of radioiodine became stronger with increasing applied activities and showed an exponential decrease with time. The most part of radioiodine was present in organic bound form. This organic portion decreased with time in favour of the other iodine species., Conclusion: The degree of accumulation of radioiodine orally applied within thyroid seems to be in direct proportion to the extend of its exhalation. Further measurements directly in the breathing air of RIT-patients are necessary, in order to clarify the relationship between degree of thyroid uptake and quantity as well as chemical form of radioiodine exhaled.

Aim: We investigated whether additional application of "cold" iodine after therapy with radioiodine could result in a prolongation of the effective half life of iodine-131 and would thus lead to an increase of the effective thyroid radiation dose., Methods: Time-activity-curves after therapy with radioiodine were analysed in 25 patients (16 women, 9 men). Nine patients suffered from autonomously functioning thyroid nodules, 5 from autonomous multinodular goiter and 11 from Graves' disease. These patients had an effective half life shorter than 4 days resulting in an undertreatment of > 20% with respect to the desired effective thyroid radiation dose. 2-4 days after therapy with radioiodine all patients received "cold" iodine for three days in a dose of 3 x 200 micrograms per day., Results: In 14 of the 25 patients an increase of the effective half life was observed. Patients with an autonomously functioning thyroid nodule showed a mean increase of the effective thyroid radiation dose of 40 +/- 44 Gy, patients with toxic multinodular goiter of 29 +/- 30 Gy and patients with Graves' disease of 37 +/- 37 Gy., Conclusion: Additional application of "cold" iodine after therapy with radioiodine can prolong the effective half life in selected patients. We suspect a correlation with the thyroid iodine pool. This will be the basis for further investigations hopefully resulting in a better patient preselection to determine who might respond to this therapy.

Aim: As first-line therapy of hyperthyroidism caused by Graves' disease antithyroid drugs are favoured in Europe, while radioiodine therapy is favoured in the USA. Radioiodine therapy has become more economic in Germany since the new recommendations by the Federal German Radiation Protection Committee (SSK) for patient discharge guidelines., Method: Sensitivity analyses took into account the long-term relapse rate of conservative or radioiodine therapy, use of diagnostic tests, level of health insurance, drops in productivity and a discount factor. Costing models included the costs of follow-up care over 30 years. The costs of the hospitalisation for radioiodine therapy were calculated for 300 patients, discharged with 250 MBq 1-131 residual activity., Result: Antithyroid drugs were considered cost-effective when they achieved relapse rate of 50% or less, a cut in the number of tests needed and reduced working hours. Failure to meet any one of these conditions makes primary radioiodine therapy more cost-effective in 1593 of 1944 calculated costing models. Repeated conservative therapies will increase clearly the overall costs., Conclusion: Radioiodine is a cost-effective, first-line therapy in patients with a special risk of relapse after primary conservative therapy (goitre, younger patient, persistent elevated TSH-receptor-antibodies or Tc-uptake).

Whether or not thyroid-associated orbitopathy is exacerbated by radioiodine therapy is a matter of controversy. Several risk factors can be listed: pre-existing active ophthalmopathy, hypothyroidism following radioiodine therapy, elevated T3 levels during radioiodine therapy, recurrent or persisting hyperthyroidism after low-dose radioiodine therapy and smoking. Recent studies and own data demonstrate that worsening of pre-existing thyroid-associated orbitopathy after radioiodine therapy can be prevented by the administration of glucocorticoids. Even in patients without evident ophthalmopathy the prophylactic use of glucocorticoids is in our opinion justified to minimize a small but known risk of the development of ocular symptoms. Larger prospective randomized studies are needed to establish the optimal dose and duration of the required anti-inflammatory therapy.

Aim: A two-step radioiodine therapy (RITh) is occasionally necessary in patients with benign thyroid disorders, when strong differences to the pretherapeutic radioiodine test occur. In this study, the parameters (uptake and effective half-life of I-131) of the radioiodine test are compared with those of the first and second RITh., Methods: 100 patients were evaluated, who received a two-step RITh in our department between June 1992 and March 1994. Uptake and effective half-life of I-131 and the absorbed dose in the first and second therapy were compared with each other based on the daily measured activity of the thyroid., Results: A two-step RITh was necessary in 10% of the patients. The uptake of I-131 in the first RITh was significantly lower as compared to the test and significantly higher as compared to the second RITh. There were no significant changes between the effective half-life of I-131 in test, first and second RITh., Conclusion: The importance of radioiodine test for the calculation of therapeutic doses is emphasized. The data gathered in our study concerning the diminution of uptake of I-131 in the second RITh can be useful for dose calculation.

The radiolabeled glucose surrogate F-18-fluoro-deoxyglucose (F-18-FDG) and positron emission tomography (PET) were used to measure glucose metabolism of the thyroid in vivo. We evaluated patients with Graves' disease before therapy with radioiodine in comparison to patients with normal thyroids. Thirty-six patients with Graves' disease underwent scanning the day before radioiodine therapy. Twenty patients with head tumors and normal thyroids were the controls. Overall F-18-FDG uptake was determined for all thyroids and modeling of glucose metabolism was performed in order to differentiate between glucose concentration in the fractional blood volume, glucose transport, and glucose utilization. F-18-FDG uptake was significantly higher in Graves' disease patients compared with controls. In these patients F-18-FDG uptake increased with increasing antithyroid antibodies and shorter radioiodine half-life. Modeling of glucose metabolism revealed substantial differences in thyroid F-18-FDG utilization constants (k3 values) corresponding to enhanced local metabolic rates in Graves' disease. No significant differences in the remaining rate constants and the fractional blood volume were detected. These results indicate that glucose metabolism is enhanced in the thyroid of Graves' disease patients not only due to enhanced fractional blood volume but to enhanced utilization. Whether a lymphocytic infiltration or thyroid epithelial cells utilize this surplus of glucose cannot be determined using in vivo PET measurements in humans. Still, the correlation of radioiodine half-life and glucose hypermetabolism suggests direct or nondirect connections of glucose metabolism and hormone synthesis in thyroid cells.

Aim: This study evaluates F-18-FDG PET of the thyroid in Graves' disease., Methods: Thirty patients were investigated the day before radioiodine therapy, 15 patients 3-10 days after radioiodine therapy. Twenty patients with cancer of the head or neck and normal thyroid function served as controls., Results: F-18-FDG uptake was higher in Graves' disease patients than in controls. Negative correlations of F-18-FDG uptake with half-life of radioiodine and absorbed radiation dose due to radioiodine therapy were found along with a positive correlation to autoantibody levels., Conclusion: Thus F-18-FDG PET is likely to give information on the biological activity of Graves' disease as well as on early radiation effects.

Aim: Our goal was to show the development of EO in RITH and compare it with the outcome of surgery or thyreostatic therapy., Methods: In this study 103 cases of an RITH at 82 patients were performed. The EO findings were measured before RITH and several times afterwards by the same experienced researcher according to the following criteria: 1. subjective complaints, 2. NOSPECS-classification, 3. exophthalmometry, 4. by photo. The observation period was at least 12 months. The measured dosage to the thyroid gland was on average 210 +/- 80 Gy. In 57 cases no EO and in 46 cases an EO of grades I to IV before therapy occurred., Results: In 11 cases there was an improvement and in 8 cases a worsening of the EO. In 84 cases the EO findings remained unchanged. Our data pointed towards the fact that with an achieved dosage to the thyroid of less than 200 Gy, a pretherapeutic thyroid gland volume greater than 55 ml, or implementation of RITH with preexisting EO without accompaning cortison therapy can worsen the EO findings., Conclusion: In comparison to surgical or thyreostatic therapy there was no increased risk of EO during or subsequent to RITH under cortison.

Estimations regarding the simultaneous occurrence of Graves' ophthalmopathy and autonomously functioning thyroid nodules expect frequencies of 0.05-0.2%. Contrary to these estimated numbers, only 3 patients with these simultaneous manifestations were identified in an out patient thyroid clinic within a period of 10 years. The possible protection by the autonomous thyroid nodules against the manifestations of Graves' disease is discussed.

Aim: It is well known that radioiodine therapy (RITh) leads to a significant thyroid volume reduction (TVR). But until now only little data has been presented due to the course of time and the extent of TVR., Method: Therefore the data of 33 patients with Graves' disease (GD), 36 patients with multifocal (MAG) and 31 with solitary (SAG) autonomous goitre were analyzed retrospectively., Results: All the patients showed a highly significant (p < 0.001) TVR, which continued up to 1 year after RITh. Receiving equal effective radiation doses, the extent of TVR was significantly greater for GD than for MAG. This difference developed within six weeks up to 3 months after RITh., Conclusion: This observation suggests that the underlying thyroid disease affects the therapeutic effect of RITh and may be partially explained by the total suppression of non-autonomous thyroid tissue in AG at the time of RITh. In patients with SAG with a 1.7 times higher effective radiation dose than in MAG relative TVR was about 1.6 times stronger in SAG than in MAG. This demonstrates a direct relation between the effective radiation dose and the extent of the TVR after RITh.

The aim of this study was to determine the significance of the radioiodine uptake test for predicting the kinetics of therapeutic 131I doses in the treatment of benign thyroid disorders. We studied retrospectively the histories of 518 consecutive patients treated with 131I for hyperthyroidism or autonomous thyroid goiter, with respect to uptake and effective half-life of tracer and therapeutic doses. The mean half-life and uptake of the therapeutic doses were significantly smaller than that of the tracer dose. A comparison of different methods of calculation showed that the radioiodine uptake test is indispensible for dose calculation in radioiodine treatment but a single measurement after 24 or 48 h is sufficiently accurate because, on average, the therapeutic dose was achieved as planned and with the smallest scatter. Average half-lives specific to the disease to be treated may be used in the calculations.

A reversibly decreased iodine absorption was observed in a patient with Graves' disease. This was associated with a reversible interference of iodination and was probably caused by thyrostatic medication.

In 200 patients follow-up examinations were performed up to one year after radioiodine therapy (RITh) with individual dose calculation. The mean applied dose was significantly lower in patients with immunogenic hyperthyroidism (Graves' disease) as compared to patients with non-immunogenic hyperthyroidism (disseminated/multifocal autonomy, HYDA). In Graves' disease the rate of recurrent hyperthyroidism was significantly higher and that of posttreatment hypothyroidism lower. Considering the high recurrence rate in Graves' disease a higher dose, e.g. 150 Gy, seems to be appropriate. In patients with HYDA who received antithyroid drugs during RITh, recurrence of hyperthyroidism appeared slightly more, and posttreatment hypothyroidism slightly less, frequent. The efficiency of RITh was not significantly reduced by additional treatment with antithyroid drugs. Posttreatment hypothyroidism in patients with euthyroid goiter and disseminated/multifocal autonomy (EUDA) occurred significantly more frequent if the basal TSH level was greater than or equal to 0.5 muIE/ml before therapy. The goiter size was reduced independent of the basal TSH level. In this group protection by thyroxine could avoid posttreatment hypothyroidism without impairing the reduction of goiter. In HYDA patients after thyroid surgery recurrence appeared less, and in those with EUDA posttreatment hypothyroidism significantly more, frequent. A lower dose seems to be suitable in patients who underwent thyroid surgery before. In patients with focal autonomy after RITh no recurrence of hyperthyroidism was observed. In 9% a suppressed basal TSHh level indicating persistent autonomy was seen. Posttreatment hypothyroidism in focal autonomy appeared only in patients without manifest hyperthyroidism before RITh and was significantly more frequent in this group as compared to the other groups of patients.(ABSTRACT TRUNCATED AT 250 WORDS)

An attempt was made to classify 326 patients with hyperthyroidism due to Graves' disease and due to autonomous goiter in an area of endemic iodine deficient goiter using the following two sets of criteria: Primary criteria: the presence of endocrine ophthalmopathy (Graves' disease) and the absence of endocrine ophthalmopathy and the absence of microsomal antibodies greater than or equal to 1:1600 (autonomous goiter). Sixty-nine percent of the patients could be divided in the two groups with the aid of these criteria. Secondary criteria: age greater than 50 years, presence of a goiter, presence of thyroid nodules, activity distribution in the scan, iodine intake determined by iodine excretion in the urine. These criteria had to be applied in the 31% of the patients who could not be divided into one of the two groups using the primary criteria. The secondary criteria were accumulative. Using these criteria 55% of the 326 patients were classified as having Graves' disease and 45% as having autonomous goiter. The probability of correct grouping when both primary and secondary criteria were applied was estimated to be 90% compared to 54% when we used only the classical terms, i.e. endocrine ophthalmopathy and diffuse goiter on the one hand and multinodular goiter without endocrine ophthalmopathy on the other hand. In a second group of 120 hyperthyroid patients classified in this way, thyrotropin displacing activity was determined independently. Its prevalence was 79% in patients classified as having Graves' disease but only 3% in those classified as having autonomous goiter. The prevalence of TDA observed in patients who presumably had autonomous goiter was in the same range as in the following groups: 45 normal individuals; 126 patients with euthyroid goiter; and in 112 patients with euthyroid and hyperthyroid autonomous adenoma.(ABSTRACT TRUNCATED AT 250 WORDS)