Does Radioactive Iodine Treatment Damage the Lacrimal System?

PURPOSE: In this prospective study, we aimed to make a quantitative assessment of the lacrimal glands before and after radioactive iodine (RAI) treatment in patients with hyperthyroidism and thyroid cancer. METHODS: The study included 80 eyes of 40 patients. There were 25 patients in group 1 (hyperthyroid group) and 15 patients in group 2 (thyroid cancer group). Group 1 has received low dose ( 131 I) and group 2 high dose ( 131 I). Before, and at the first and sixth month after RAI treatment, all patients underwent ophthalmological examinations, Schirmer tests, TBUT tests, tear osmolarity (TO), and ocular surface examinations. RESULTS: The age and sex characteristics of both groups were similar. Although no significant change was observed in tear film tests before and after treatment in group 1, a significant decrease in Schirmer and TBUT values and a significant increase in TO were observed in group 2 in the first month after treatment. These values returned to normal in the sixth month. Although no Schirmer test was observed lower than 10 mm in any patient before RAI treatment, the Schirmer test was measured 5 to 10 mm in 4 (10%) patients in group 2 in the first month after treatment. Again, in these patients, TBUT was below 10 seconds and TO was greater than 308 mOsm/L. CONCLUSIONS: In this study, although no change was observed in tear function tests in patients receiving low doses of RAI, a decrease in tear secretion and an increase in TO were detected in patients receiving high doses in the early period.

Urine concentrating ability in cats with hyperthyroidism: Influence of radioiodine treatment, masked azotemia, and iatrogenic hypothyroidism.

BACKGROUND: Hyperthyroid cats often have urine specific gravity (USG) values <1.035. It remains unclear how USG changes after treatment, if USG can be used to predict azotemia after treatment, or how iatrogenic hypothyroidism influences USG values. OBJECTIVES: To determine the proportion of hyperthyroid cats with USG <1.035 vs ≥1.035; if USG changes after treatment; and whether USG <1.035 correlated with unmasking of azotemia or hypothyroidism. ANIMALS: Six hundred fifty-five hyperthyroid cats treated with radioiodine; 190 clinically normal cats. METHODS: Prospective, before-and-after study. Hyperthyroid cats had serum thyroxine, thyroid-stimulating hormone, and creatinine concentrations, and USG measured before and 6 months after successful treatment with radioiodine. RESULTS: Of untreated hyperthyroid cats, USG was ≥1.035 in 346 (52.8%) and <1.035 in 309 (47.2%). After treatment, 279/346 (80.6%) maintained USG ≥1.035, whereas 67/346 (19.4%) became <1.035; 272/309 (88%) maintained USG <1.035, whereas 37/309 (12%) became ≥1.035. Only 22/346 (6.4%) with USG ≥1.035 developed azotemia after treatment, compared with 136/309 (44%) with <1.035 (P < .001). Of cats remaining nonazotemic, 38% had USG <1.035, compared with 20% of normal cats (P < .001). The 137 cats with iatrogenic hypothyroidism had lower USG after treatment than did 508 euthyroid cats (1.024 vs 1.035), but USGs did not change after levothyroxine supplementation. USG <1.035 had high sensitivity (86.1%) but moderate specificity (65.2%) in predicting azotemia after treatment. CONCLUSIONS AND CLINICAL IMPORTANCE: Hyperthyroidism appears not to affect USG in cats. However, cats with evidence of sub-optimal concentrating ability before radioiodine treatment (USG < 1.035) are more likely to develop azotemia and unmask previously occult chronic kidney disease. Iatrogenic hypothyroidism itself did not appear to affect USG values.

Meta-Analysis of Randomized Controlled Trials Comparing the Efficacy of Radioactive Iodine Monotherapy versus Radioactive Iodine Therapy and Adjunctive Lithium for the Treatment of Hyperthyroidism.

Background: The objective of this article is to evaluate the outcomes in patients undergoing radioactive iodine (RAI) with adjunctive lithium (Li) therapy versus (vs.) RAI therapy alone for the treatment of hyperthyroidism.Methods: A systematic review of the literature was undertaken to analyze clinical trials comparing RAI with adjunctive Li therapy vs. RAI therapy alone for the treatment of hyperthyroidism.Results: Six randomized-controlled trials (RCT) involving 755 patients were analyzed. RAI with adjunctive Li was associated with a significantly higher cure rate for hyperthyroidism when compared to RAI alone. Furthermore, a significantly higher cure rate for hyperthyroidism at 12 months was achieved with RAI and adjunctive Li. Adjuvant Li with RAI for ≤ 7 days showed significantly higher cure rate compared to RAI alone, whereas > 7 days of adjuvant Li with RAI did not show any difference in cure rate compared to RAI alone. RAI with adjunctive Li was associated with a significantly higher cure rate for patients with Graves' disease compared to RAI alone. There was no significant difference between RAI with adjunctive Li and RAI alone for toxic nodular thyroid disorder (toxic nodule and toxic multinodular goiter) and thyroid volume >40 grams and ≤40 grams.Conclusions: RAI with adjunctive Li therapy demonstrated superiority over RAI therapy alone with regards to both curing hyperthyroidism and, reduced time till cure, with a limited side effect profile. A large multicenter RCT is required, and if this confirms the data from these smaller trials, then this could change current practice.

Is low radioiodine uptake a contraindication to radioiodine therapy in patients with benign thyroid disease?

BACKGROUND: Radioiodine therapy (131I) is a standard procedure in the treatment of hyperthyroidism in the course of Graves' disease or toxic nodules. However, the use of 131I in patients with low radioiodine uptake (RAIU) may be controversial. OBJECTIVES: To determine the influence of lithium carbonate (Li) on iodine kinetics. MATERIAL AND METHODS: Patients with hyperthyroidism and low RAIU (< 30%) were divided into 2 groups: a Li(-) group of 305 patients not receiving Li adjuvant therapy and a Li(+) group of 264 patients receiving adjuvant therapy. The serum concentrations of free triiodothyronine (fT3), free thyroxine (fT4) and thyroid stimulating hormone (TSH) were assessed at baseline, 24 h, 48 h, 72 h and 96 h, and 1, 6 and 12 months after 131I therapy. The RAIU was assessed after 5 h, 24 h, 48 h, 72 h, and 96 h. RESULTS: Levels of fT3 in the Li(+) group compared to the Li(-) group were significantly higher at baseline, lower after 48 h, 72 h, 96 h and 1 month, and did not differ significantly after 24 h, 6 months and 12 months. Levels of fT4 in the Li(+) group compared to the Li(-) group were significantly higher at baseline, lower after 24 h, 48 h, 72 h, 96 h and 1 month, and not differ significantly after 6 and 12 months. The RAIU in the hyperthyroidism Li(-) and Li(+) groups, respectively, was 11.9 ±5.6% compared to 23.9 ±10.1% (p < 0.001) after 5 h; 25.9 ±8.3% compared to 40.5 ±12.4% (p < 0.05) after 24 h; 7.8 ±8.1% compared to 40.9 ±13.7% (p < 0.05) after 48 h; 26.2 ±10.2% compared to 39.5 ±11.2% (p < 0.01) after 72 h; and 24.7 ±7.1% compared to 37.4 ±10.1% (p < 0.01) after 96 h. CONCLUSIONS: Adjuvant therapy with Li in patients with hyperthyroidism caused a significant increase in RAIU and positive changes in the fT3 and fT4 profiles. The use of lithium carbonate prior to the inclusion of 131I in hyperthyroid patients with low RAIU should be considered.

Predictors of euthyreosis in hyperthyroid patients treated with radioiodine 131I-: a retrospective study.

BACKGROUND: Radioiodine (RAI) treatment for hyperthyroidism is a very common modality, chosen by physicians worldwide. The outcome of the therapy, however, is not always predictable. While rendering a patient hypo- or euthyroid is meant as a therapeutic success, the latter does not require lifelong hormonal supplementation. The aim of our study is to determine predictors of euthyreosis in patients who underwent RAI treatment. METHODS: Medical records of 144 patients who had undergone RAI therapy were examined. Laboratory and clinical data were analyzed statistically. Ultrasonography findings, such as thyroid volume, nodules' size and characteristics had been collected at the beginning of treatment and 6 months after the administration of radioiodine 131I-. Moreover, scintigraphy results were taken into account. Multivariate logistic regression analysis model has been used to find predictors of euthyroidism after 12 months of follow-up. The predictors of normal thyroid function have also been analyzed separately for patients with GD (Graves' disease) and TMNG (toxic multinodular goiter). RESULTS: The analysis showed that age (OR 1,06; 95%CI 1.025-1.096, p = 0,001), thyroid gland volume (OR 1,04; 95%CI 1,02-1,06; p < 0.001) and iodine uptake level (OR 0,952; 95%CI 0,91-0,98; p = 0,004) were significant factors of achieving normal thyroid function after RAI therapy. According to multivariate logistic regression analysis, in GD patients only age has been shown to be a significant factor (OR 1,06; 95%CI 1,001-1,13; p = 0.047), while in TMNG patients' age (OR 1,04; 95%CI 1-1,09; p = 0.048), thyroid gland volume (OR 1.038; 95%CI 1.009-1.068; p = 0.009) and iodine uptake level (OR 0.95; 95%CI 0.9-0.99; p = 0.02) all have been proven to be significant predictors of achieving euthyroidism. CONCLUSIONS: The more advanced age, larger volume of thyroid gland and lower iodine uptake level are predictors of euthyreosis after RAI treatment.

Organ Dose Estimates for Hyperthyroid Patients Treated with (131)I: An Update of the Thyrotoxicosis Follow-Up Study.

The Thyrotoxicosis Therapy Follow-up Study (TTFUS) is comprised of 35,593 hyperthyroid patients treated from the mid-1940s through the mid-1960s. One objective of the TTFUS was to evaluate the long-term effects of high-dose iodine-131 ((131)I) treatment (1-4). In the TTFUS cohort, 23,020 patients were treated with (131)I, including 21,536 patients with Graves disease (GD), 1,203 patients with toxic nodular goiter (TNG) and 281 patients with unknown disease. The study population constituted the largest group of hyperthyroid patients ever examined in a single health risk study. The average number (± 1 standard deviation) of (131)I treatments per patient was 1.7 ± 1.4 for the GD patients and 2.1 ± 2.1 for the TNG patients. The average total (131)I administered activity was 380 ± 360 MBq for GD patients and 640 ± 550 MBq for TNG patients. In this work, a biokinetic model for iodine was developed to derive organ residence times and to reconstruct the radiation-absorbed doses to the thyroid gland and to other organs resulting from administration of (131)I to hyperthyroid patients. Based on (131)I data for a small, kinetically well-characterized sub-cohort of patients, multivariate regression equations were developed to relate the numbers of disintegrations of (131)I in more than 50 organs and tissues to anatomical (thyroid mass) and clinical (percentage thyroid uptake and pulse rate) parameters. These equations were then applied to estimate the numbers of (131)I disintegrations in the organs and tissues of all other hyperthyroid patients in the TTFUS who were treated with (131)I. The reference voxel phantoms adopted by the International Commission on Radiological Protection (ICRP) were then used to calculate the absorbed doses in more than 20 organs and tissues of the body. As expected, the absorbed doses were found to be highest in the thyroid (arithmetic means of 120 and 140 Gy for GD and TNG patients, respectively). Absorbed doses in organs other than the thyroid were much smaller, with arithmetic means of 1.6 Gy, 1.5 Gy and 0.65 Gy for esophagus, thymus and salivary glands, respectively. The arithmetic mean doses to all other organs and tissues were more than 100 times less than those to the thyroid gland. To our knowledge, this work represents the most comprehensive study to date of the doses received by persons treated with (131)I for hyperthyroidism.

Post-radioiodine De Novo Onset Graves' Ophthalmopathy: Case Reports and a Review of the Literature.

New-onset Graves' ophthalmopathy (GO) following radioiodine treatment (RAI) and worsening of existing GO are well-described in the endocrinology literature. These phenomena are recognized by ophthalmologists, yet poorly documented in the ophthalmology literature. Two male patients, aged 43 and 62 years, respectively, with Graves' disease without GO, received RAI. Four months later, one patient developed acute GO with unilateral reduction in visual acuity, conjunctival chemosis, lagophthalmos, bilateral severely restricted ocular motility, and lid retraction. High-dose intravenous steroids, followed by oral steroids, led to a dramatic clinical improvement. The second patient received a second dose of RAI for persistent hyperthyroidism and subsequently developed acute GO-comprising restricted ocular motility, peri-orbital swelling, and conjunctival chemosis. Symptoms gradually resolved on continued carbimazole treatment. Neither patient received pre-RAI prophylactic glucocorticoids, as currently they are only recommended for patients with pre-existing GO or multiple risk factors. We discuss the limitations of using this risk-based approach in preventing new-onset GO following RAI therapy.

Lithium as an adjunct to radioactive iodine for the treatment of hyperthyroidism: a systematic review and meta-analysis.

BACKGROUND: Radioactive iodine (RAI) is commonly used in the treatment of hyperthyroidism but is not uniformly successful. Lithium increases thyroidal iodine retention without reducing iodide uptake, increasing the radiation dose to the thyroid when administered with RAI. Although these actions suggest that adjuvant lithium may increase the efficacy of RAI, its role as an adjunct to RAI remains contentious. OBJECTIVE: To evaluate the safety and efficacy of adding lithium to RAI to treat hyperthyroidism. METHODS: Relevant studies were identified by a search of Medline and the Cochrane Central Register of Controlled Trials. To be included, a study had to be a controlled trial comparing the effect of RAI alone to RAI with lithium in the treatment of hyperthyroidism. Relevant data were extracted and meta-analyses were performed. RESULTS: Of the 75 identified studies, 6 met the inclusion criteria; 4 of these studies were interventional and 2 were observational trials. Meta-analysis of the observational trials (N = 851), both of which were retrospective cohort studies, showed significant improvement in the primary outcome (i.e., cure rate) with adjunctive lithium (odds ratio [OR], 1.92; 95% confidence interval [CI], 1.24 to 2.96). The combined interventional trials (N = 485) also showed an improvement in cure rate, but the difference did not reach statistical significance (OR, 1.28; 95% CI, 0.85 to 1.91). Adjunctive lithium reduced time to cure and blunted thyroid hormone excursions after RAI. Lithium-related side effects were infrequent and usually mild. CONCLUSION: The observational trials demonstrated significant improvement in the cure rate of hyperthyroidism when lithium is added to RAI. The improvements shown in the interventional trials did not reach statistical significance due to the effect of a single, large negative trial.

Radioprotective effect of the Barbados Cherry (Malpighia glabra L.) against radiopharmaceutical iodine-131 in Wistar rats in vivo.

BACKGROUND: The increasing consumption of fruits and vegetables has contributed to the improvement of populational health, due in part, to the abundance of antioxidants in these foods. Antioxidants reduce the level of oxidative damage to DNA caused by free radicals and ionizing radiation, including the radioisotope iodine-131 (131I). This isotope is used for the diagnosis and treatment of thyroid injuries, such as hyperthyroidism and cancer. METHODS: This study aimed to evaluate the radioprotective and cytotoxic activity of acute and subchronic treatments with Barbados Cherry (BC) (Malpighia glabra L.) fruit juice (5 mg), which is rich in potent antioxidants such as vitamin C, phenols, carotenoids, anthocyanins and yellow flavonoids and its activity against the mutagenic activity of the therapeutic dose of 25 µCi of radioiodine for hyperthyroidism. The test system used was the bone marrow cells of Wistar rats (Rattus norvegicus) that were treated in vivo by gavage. RESULTS: BC showed radioprotective activity in acute treatments, which is most likely due to the joint action of its antioxidant components. In subchronic treatments, the continuous treatment presented an effective radioprotective activity, which was significantly different from treatment with the radiopharmaceutical only. Treatment with BC prior to (PRE) and simultaneous with (SIM) ionizing radiation decreased the number of induced chromosomal alterations, while post-treatment produced no protective effect. In addition, BC exhibited no cytotoxic activity. CONCLUSIONS: These data serve as evidence that BC can be used as a preventive health measure to improve public health quality by countering the action of inevitable exposure to mutagens, such as 131I.

Radioactive iodine therapy.

PURPOSE OF REVIEW: Review of the management decisions that must be made by the endocrinologist during the use of radioactive iodine (RAI) therapy of hyperthyroidism and differentiated thyroid cancer. RECENT FINDINGS: Since the 1940s radioactive (131)I (RAI) therapy has been a major component of the treatment of hyperthyroidism and differentiated thyroid cancer. RAI is the most common definitive treatment of hyperthyroidism. Pretherapy decisions including use of antithyroid medication and low-iodine diet will be discussed with the relevant supportive literature. The method of semi-quantitative calculation used for RAI treatment of hyperthyroidism will be described. Evidence-based guideline for the management of differentiated thyroid cancer by the American Thyroid Association, new drug development and recent randomized controlled trials have changed current practice of how RAI is used for remnant ablation and adjuvant therapy of differentiated thyroid cancer. SUMMARY: RAI is a common tool for the endocrinologist in the management of hyperthyroidism and differentiated thyroid cancer. Review of the management decisions and practice of RAI therapy will educate the endocrinologist of the literature supporting current RAI use in hyperthyroidism and new developments in limiting the radiation exposure to the patients with differentiated thyroid cancer.

Adjuvant lithium improves the efficacy of radioactive iodine treatment in Graves' and toxic nodular disease.

CONTEXT: Lithium increases iodine retention in the thyroid gland and inhibits thyroid hormone release. Although lithium has been reported to improve the efficacy of radioactive iodine (RAI) treatment in Graves' disease, its role as an adjunct to RAI treatment of hyperthyroidism, particularly in toxic nodular disease, remains contentious. OBJECTIVE: To assess whether adjuvant lithium increases the efficacy of a fixed dose RAI regimen in Graves' and toxic nodular hyperthyroid patients. DESIGN AND SETTING: Retrospective cohort study in a tertiary referral centre. Two hundred and four hyperthyroid patients (163 Graves' disease, 26 toxic multinodular goitre and 15 solitary toxic thyroid adenoma). INTERVENTION: One hundred and three patients received RAI alone (median dose 558 MBq). One hundred and one patients received RAI (median dose 571 MBq) with adjuvant lithium (800 mg/day for 10 days). MAIN OUTCOME MEASURE: Proportion of patients cured at any time over a 1-year period following RAI treatment. Cure was defined as sustained (two or more sequential time points) biochemical euthyroidism or hypothyroidism during the follow-up period. RESULTS: The likelihood of cure at any time was 60% greater in all hyperthyroid patients (Graves' plus toxic nodular disease) receiving adjuvant lithium (n = 204, P = 0·003). In patients with Graves' disease receiving RAI + lithium, there was a similar occurrence in cure (n = 163, P = 0·006). Cure was twice as likely in patients with toxic nodular (non-Graves') disease receiving RAI + lithium compared with RAI alone (n = 41, P = 0·01). CONCLUSIONS: This study supports the use of adjuvant lithium to improve the efficacy of RAI in the treatment of Grave's disease and suggests a novel role in the management of toxic nodular (non-Graves') disease.

ACR-ASTRO practice guideline for the performance of therapy with unsealed radiopharmaceutical sources.

This guideline is intended to guide appropriately trained and licensed physicians performing therapy with unsealed radiopharmaceutical sources. Adherence to this guideline should help to maximize the efficacious use of these procedures, maintain safe conditions, and ensure compliance with applicable regulations. The topics dealt with in this guideline include indications for the use of iodine-131, both for the treatment of hyperthyroidism and thyroid carcinoma. In addition, indications for other less common procedures include those for the use of phosphorous-32 in its liquid and colloidal forms, strontium-89, samarium-153, and the use of Y-90 antibodies.

A prospective randomized study of the efficacy and cost-effectiveness of high and low dose regimens of I-131 treatment in hyperthyroidism.

OBJECTIVE: To compare the efficacy and cost-effectiveness of high and low dose regimens of I-131 treatment in patients with hyperthyroidism. MATERIAL AND METHOD: One hundred fifty patients with proven hyperthyroidism were randomly allocated into the high (74 patients) and low (76 patients) dose regimen of I-131 treatment. Four patients of the high dose group and one patient of the low dose group were excluded because of lost follow-up. A gland-specific dosage was calculated on the estimated weight of thyroid gland and 24-hour I-131 uptake. The high and low I-131 dose regimens were 150 microCi/gm and 100 microCi/gm, respectively. The first mean radioiodine activity administered to the high and low dose group was 10.2 and 8 mCi, respectively. Repeated treatment was given to 25 patients of the high dose group and 40 patients of the low dose group. Clinical outcome and calculated costs for outpatient attendances, and laboratory tests together with initial and subsequent treatments were evaluated for one year after I-131 treatment. Elimination of hyperthyroidism that resulted in either euthyroidism or hypothyroidism was classified as therapeutic success. The cost effectiveness was also compared. RESULTS: At 6 months after treatment, 45 (64.3%) patients receiving high dose and 59 (78.7%) patients receiving low dose were hyperthyroidism. Clinical outcome at one year showed persistence of hyperthyroidism in 21 (30%) patients of the high dose regimen and 36 (48%) patients of the low dose regimen. At one year post treatment, it was demonstrated that the high dose regimen could eliminate hyperthyroidism in a significantly shorter time than the low dose regimen, i.e., 259.6 days and 305.5 days, respectively, p = 0.008). For the persistent hyperthyroid patients, the average total cost of treatment in the low dose group was significantly higher than that of the high dose group, i.e., 13,422.78 baht and 10,942.79 baht, respectively; p = 0.050). CONCLUSION: A high dose regimen of radioactive iodine treatment is more effective than the low dose regimen. The successful outcome of a high dose regimen occurred significantly earlier than that of the low dose regimen. For the persistent hyperthyroid patients, the average total cost in the low dose group was significantly higher than that of the high dose group.

Transient cytotoxicity of ¹³¹I beta radiation in hyperthyroid patients treated with radioactive iodine.

BACKGROUND & OBJECTIVES: Radioiodine ( 131 I) or radioactive iodine in low doses is used worldwide as the first line of management in the treatment of hyperthyroidism. Information is available on the extent and severity of cell damage after a high dose radioiodine ( 131 I) therapy for thyroid cancer, but information is scanty on its cellular effects, its extent and severity of cell damage after a low dose 131 I therapy. The present investigation was aimed to study the cytotoxic effects of a low dose 131 I therapy in varying doses as is normally being used in routine clinical practice in the treatment of various forms of hyperthyroidism. METHODS: Peripheral blood lymphocytes were analyzed in 32 hyperthyroid patients. All of them received 131 I in the form of sodium iodide solution orally. Blood lymphocytes were studied for the presence of chromosomal aberrations (CA) and micro nucleus (MN) using micronucleus assay. Blood samples of these patients were drawn prior to the treatment, on 7 th and 30 th days after the treatment. RESULTS: The results indicated a positive relationship between 131 I dose, CA and MN frequency. A statistically significant increase in CA and MN frequency in day 7 post- therapy and a decrease in mean levels of CA and MN on day 30 post-therapy were observed when compared to pre-therapy. INTERPRETATION & CONCLUSIONS: This study showed that the cytogenetic damage induced by 131 I in low doses i.e., less than 555MBq was minimal and reversible. Patients can be motivated to undertake this safe and easy procedure as a first line of therapy in the treatment of hyperthyroidism.

Radiation safety in the treatment of patients with thyroid diseases by radioiodine 131I : practice recommendations of the American Thyroid Association.

BACKGROUND: Radiation safety is an essential component in the treatment of patients with thyroid diseases by ¹³¹I. The American Thyroid Association created a task force to develop recommendations that would inform medical professionals about attainment of radiation safety for patients, family members, and the public. The task force was constituted so as to obtain advice, experience, and methods from relevant medical specialties and disciplines. METHODS: Reviews of Nuclear Regulatory Commission regulations and International Commission on Radiological Protection [corrected] recommendations formed the basic structure of the recommendations. Members of the task force contributed both ideas and methods that are used at their respective institutions to aid groups responsible for treatments and that instruct patients and caregivers in the attainment of radiation safety. There are insufficient data on long-term outcomes to create evidence-based guidelines. RESULTS: The information was used to compile delineations of radiation safety. Factors and situations that govern implementation of safety practices are cited and discussed. Examples of the development of tables to ascertain the number of hours or days (24-hour cycles) of radiation precaution appropriate for individual patients treated with ¹³¹I for hyperthyroidism and thyroid cancer have been provided. Reminders in the form of a checklist are presented to assist in assessing patients while taking into account individual circumstances that would bear on radiation safety. Information is presented to supplement the treating physician's advice to patients and caregivers on precautions to be adopted within and outside the home. CONCLUSION: Recommendations, complying with Nuclear Regulatory Commission regulations and consistent with guidelines promulgated by the National Council on Radiation Protection and Measurement (NCRP-155), can help physicians and patients maintain radiation safety after treatment with ¹³¹I of patients with thyroid diseases. Both treating physicians and patients must be informed if radiation safety, an integral part of therapy with ¹³¹I, is to be attained. Based on current regulations and understanding of radiation exposures, recommendations have been made to guide physicians and patients in safe practices after treatment with radioactive iodine.

Radioiodine treatment in autoimmune hyperthyroidism: analysis of outcomes in relation to dosage.

BACKGROUND: Controversy exists regarding the optimal dose of radioiodine ((131)I) therapy in autoimmune hyperthyroidism (i.e., Graves' Disease). METHODS: In order to evaluate the efficacy and safety of high dose (131)I therapy in autoimmune hyperthyroidism, a retrospective review of patients who received (131)I therapy for Graves' disease from 1980 to 2000 in the Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City was carried out. RESULTS: The study population consisted of 596 autoimmune hyperthyroid patients with a mean age of 35 years. The mean follow-up period was 10.31 +/- 2.37 years. Remission of hyperthyroidism occurred in 81.9%, persistent hyperthyroidism was recorded in 14.4% and recurrence in 3.7%. (131)I doses of 5-9 mCi (185-333 MBq) and > or =20 mCi (> or =740 MBq) were associated with remission rates of 65.5% and 87.7% respectively. Remission occurred earlier and more often with high doses of (131)I. The high-dose group (20-30 mCi [740-1110 MBq]) had the lowest rate of persistence (9.7, 27.5 and 34.3%, for 20-30 [740-1110 MBq], 10-14 [370-518 MBq] and 5-9 [185-333 MBq] mCi, respectively p <0.05) and hypothyroidism occurred earlier in this group (p = 0.05). CONCLUSIONS: Remission of autoimmune hyperthyroidism is more likely with doses of 20-30 mCi (740-1110 MBq).

Effect of iopanoic acid on radioiodine therapy of hyperthyroidism: long-term outcome of a randomized controlled trial.

CONTEXT: Telepaque [iopanoic acid (IA)] is believed to rapidly ameliorate hyperthyroidism; however, it may preclude subsequent 131I therapy, possibly delaying it for several months. OBJECTIVE: Our objective was to see how early patients, made euthyroid with Telepaque, can be treated with 131I and to compare their short- and long-term outcome with patients treated with 131I, after making them euthyroid with carbimazole and beta-blockers. DESIGN: We conducted a randomized controlled trial. SETTING AND PATIENTS: We studied 200 hyperthyroid patients at a tertiary care teaching institute. INTERVENTIONS: The IA group received Telepaque, 500 mg/d orally, for 7 d and then no medication for 1 wk followed by 131I therapy if radioiodine neck uptake had recovered. The control group received 30-40 mg oral carbimazole daily until patients became euthyroid followed by 131I. MAIN OUTCOME: After 1 wk of Telepaque therapy and 6 wk of carbimazole, almost all patients became clinically and biochemically euthyroid, and 86 and 94% of patients were ready for 131I therapy after 1 and 2 wk off Telepaque, respectively. The cure rate, defined as euthyroid plus hypothyroid, after the first dose of 131I in controls and the IA group was 80 and 76.2%, respectively (P = 0.54). Thirty-two percent among controls and 25% in the IA group became hypothyroid within 1 yr (P = 0.33); thereafter, the annual rate of hypothyroidism was about 2% in both groups. After a mean follow-up duration of 11 yr, 58% of patients in the control group and 51% in the IA group were hypothyroid. CONCLUSIONS: Telepaque rapidly ameliorates hyperthyroidism without jeopardizing the subsequent radioiodine therapy, and the outcome of radioiodine therapy in this subset of patients is in no way different compared with those prepared by carbimazole.

Enhancement of radioiodine uptake in hyperthyroidism with hydrochlorothiazide: a prospective randomised control study.

The aim of this study was to determine whether hydrochlorothiazide (HCTZ) could improve radioiodine uptake in low-uptake hyperthyroid patients. Eighteen hyperthyroid patients with low 3-h and 24-h iodine-131 uptake were recruited to the study. Eleven patients were assigned to the HCTZ group, and seven to the control group. Two weeks after the first, baseline uptake study, a second uptake study was performed. Patients in both groups had a low-iodine diet after the first uptake study. In the HCTZ group, 50 mg of HCTZ was administered twice a day for 5 days prior to the second uptake study. Improvement in uptake at 3 and 24 h in the second uptake study, as compared with the baseline study, was assessed within and between groups. In the control group, compared with the baseline study there was a significant improvement in uptake at 3 h ( P=0.03) but a non-significant improvement at 24 h ( P=0.07). In the HCTZ group, significant improvements were observed at both 3 h ( P=0.0005) and 24 h ( P=2.28 x 10(-5)). Patients in the HCTZ group had statistically greater improvement in uptake at both 3 h and 24 h compared with the control group ( P=0.003 and 0.0008, respectively). There was a 7.18-fold average improvement in uptake in the HCTZ group at 24 h, compared with only a 1.33-fold improvement in the control group. Administration of HCTZ significantly improves 24-h radioiodine uptake in high-iodide pool, low-uptake hyperthyroid patients compared with patients who have received a low-iodine diet alone.

A randomized controlled trial to evaluate the adjuvant effect of lithium on radioiodine treatment of hyperthyroidism.

OBJECTIVE: To evaluate the role of lithium (Li) as an adjuvant in radioiodine therapy of hyperthyroidism. METHODS: A randomized controlled trial was carried out on 350 hyperthyroid patients with a mean follow-up period of 32.3 +/- 9.8 months (range, 12-60 months). The patients were randomized into two groups with 175 patients in each group: (1) radioiodine group (controls)-no lithium was given to these patients at any stage of their treatment and (2) radioiodine and lithium group (Li group)-lithium carbonate, 300 mg three times a day, for 3 weeks starting on the day of radioiodine administration. All patients were made euthyroid with antithyroid drugs prior to radioiodine therapy. RESULTS: Mean age was 41.8 +/- 11.5 years (range, 18-71) in the control group and 41.8 +/- 12.2 years (range, 19-73) in the Li group. Mean first dose and cumulative dose of (131)I were 229 +/- 85 MBq and 326 +/- 204 MBq in controls and 233 +/- 110 MBq and 344 +/- 281 MBq in the Li group. Average number of radioiodine therapy administered was the same (1.4) in both groups. The cure rate (euthyroid plus hypothyroid) after the first dose of radioiodine in the control and the lithium groups was 68.4% and 68.9%, respectively (p = ns). The overall cure rate at the end of the study was also the same in both groups (96.7% and 96.3%, respectively). Even in patients with a rapidly discharging gland or in patients with a large goiter, no significant statistical difference was observed in radioiodine therapy outcome between the two groups. Ten percent of the patients complained of mild to moderate side effects of lithium. CONCLUSION: The role of lithium as an adjuvant in radioiodine therapy of hyperthyroidism is insignificant.