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PubMed1978

Changing normal values for thyroid uptake of radioactive iodine.

The 24-hour radioactive iodine uptake remains a very useful clinical tool for evaluating the thyroid gland; however, the normal values have changed over the years. The traditional values of 15% to 45% are clearly not applicable today and the revised values of 9% to 32% are suspect in some areas where iodine content is rapidly changing in the general diet. The values in a relatively stable population in Ft. Smith, Arkansas, without significant access to a continuous-batch bread with a high iodine content do confirm the national trend of the early 1970's suggesting an overall normal range from 11% to 30%. Values in men were found to be lower with a range from 11% to 23%, whereas in women the values ranged from 13% to 32%. Each nuclear medicine department should be responsible for establishing its own normal range and reevaluating it on a fairly routine basis-certainly whenever known dietary iodine factors change.

Adolescent↗
PubMed2006

Risk of parathyroid adenomas in patients with thyrotoxicosis exposed to radioactive iodine.

External ionizing radiation is a risk factor for primary hyperparathyroidism. Whether exposure to radioactive iodine contributes to the risk of primary hyperparathyroidism is unknown. Patients with thyrotoxicosis are often treated with radioactive iodine and its accumulation in the thyroid gland exposes the adjacent parathyroid glands to radioactivity. Six thousand and eighty two patients with thyrotoxicosis (ICD-9 = 242) were identified from medical records. In a randomly selected subcohort we assessed the frequency of treatment with radioactive iodine to be 86%. The number of patient-years at risk was 77,118. Patients with parathyroid adenomas (ICD-9 = 195.1) were recruited from the Swedish Cancer Registry. Eleven patients with parathyroid adenomas following the diagnosis of thyrotoxicosis were identified. The standard incidence ratio (SIR) compared to the reference population of approximately 900,000 was 1.14 (95% CI 0.57-2.03). The median age at exposure was 59 years and the latency period between diagnosis of thyrotoxicosis and parathyroid adenoma was 7.4 years (range <1-19 years). This study does not indicate that patients with thyrotoxicosis treated with radioactive iodine in adult age have increased risk of developing parathyroid adenoma.

Adenoma↗
PubMed2004

Clinical review 170: A systematic review and metaanalysis of the effectiveness of radioactive iodine remnant ablation for well-differentiated thyroid cancer.

Radioactive iodine remnant ablation destroys residual thyroid tissue after surgical resection of papillary or follicular thyroid cancer. We systematically reviewed 1543 English references to determine whether remnant ablation decreases the risk of thyroid cancer-related death or recurrence after bilateral thyroidectomy for papillary or follicular thyroid cancer. In 13 cohort studies in which the analysis of thyroid cancer-related outcomes was statistically adjusted to a variable degree for prognostic factors or cointerventions, rates of recurrences of thyroid cancer-related outcomes were significantly decreased in the following: one of seven studies examining thyroid cancer-related mortality, three of six studies examining any tumor recurrence, three of three studies examining locoregional recurrence, and two of three studies examining distant metastases. Thyroid hormone suppressive therapy was not adjusted for in the majority of these analyses. In 18 cohort studies not adjusted for prognostic factors or interventions, the benefit of radioactive iodine ablation in decreasing the thyroid cancer-related mortality and any recurrence at 10 yr was inconsistent among centers. However, pooled analyses were suggestive of a statistically significant treatment effect of ablation for the following 10-yr outcomes: locoregional recurrence (relative risk of 0.31, 95% confidence interval, 0.2, 0.49) and distant metastases (absolute decrease in risk 3%, 95% confidence interval, risk decreases 1-4%). In conclusion, radioactive iodine ablation may be beneficial in decreasing recurrence of well-differentiated thyroid cancer; however, results are inconsistent among centers for some outcomes, and the incremental benefit of remnant ablation in low-risk patients treated with bilateral thyroidectomy and thyroid hormone suppressive therapy is unclear.

Humans↗
PubMed1986

The late effect of subtotal thyroidectomy and radioactive iodine therapy on calcitonin secretion and bone mineral density in women treated for Graves' disease.

This study was designed to evaluate the effect of subtotal thyroidectomy and/or radioactive iodine therapy on plasma immunocalcitonin (iCT) levels and bone densities in patients treated for Graves' disease. Forty-eight women whose ages ranged from 29 to 79 years (mean, 55 years) were evaluated. All were at least 10 years beyond treatment. Fourteen patients had undergone subtotal thyroidectomy, 22 had received radioactive iodine therapy, and 12 had received both. Serum calcitonin levels were measured with the patient fasting and at 30 minutes and 2 hours after the ingestion of 15 mg of calcium in orange juice. Single photon absorptiometry was used to measure bone mineral density of the middle and distal radius. The mean fasting plasma levels of iCT for patients undergoing subtotal thyroidectomy was 27 +/- 2 mumol/L; women treated with radioactive iodine, 26 +/- 2; women undergoing subtotal thyroidectomy followed by radioactive iodine, 24 +/- 2, and for normal control women, 48.5 +/- 4.7. The mean stimulated iCT level of each of the patient groups was significantly lower than that of the normal controls (p = 0.01). There were no significant differences among the groups. Although there was an increased loss of bone mineral density in postmenopausal patients, with age and race as covariates, the bone densities of the distal radius in women undergoing subtotal thyroidectomy and/or receiving radioactive iodine were not significantly lower than those of normal control subjects (p greater than 0.05). These findings are consistent with other observations that patients treated by thyroidectomy and/or radioactive iodine for Graves' disease have lower basal levels of calcitonin and decreased calcitonin response to a provocative stimulus. Whether this loss of calcitonin reserve is a significant factor in development of postmenopausal osteoporosis remains unanswered.

Adult↗
PubMed1982

Hyperparathyroidism after radioactive iodine therapy for Graves disease.

The association of external ionizing radiation to the head and neck and the subsequent development of hyperfunctioning parathyroid glands has been documented in recent years. This also has been demonstrated experimentally in animals. Despite the numbers of patients with Graves disease who have been treated with radioactive iodine, there are no reports in the literature of parathyroid surgery for hyperparathyroidism secondary to earlier treatment with radioactive iodine for Graves disease. This report describes the operative and pathologic findings in four patients with hyperparathyroidism. These patients had previously been treated with radioactive iodine for Graves disease. The pathologic findings at surgery included in three cases a single enlarged hyperplastic gland consistent with a parathyroid adenoma. One patient had hyperplasia of all four glands. The two largest glands and halves of the two remaining glands were removed. In a long-term follow-up of children and adolescents treated with radioactive iodine for Graves disease, Levy and Schumacher found calcium elevations in 10 of 159 patients. The increased incidence of hyperparathyroidism following radioactive iodine treatment for Graves disease in children and adolescents would seem several times higher than normal. Whether adults who have radioactive iodine treatment for Graves disease have a similar increase incidence is not known. Meanwhile it would seem reasonable to suggest that patients whose hyperthyroidism is treated with radioactive iodine should have their serum calcium levels determined at 5-year intervals.

Adenoma↗
PubMed1997

Effects of hyperthyroidism and radioactive iodine given to ablate the thyroid on the composition of whole stimulated saliva.

OBJECTIVE: For many years there has been speculation about possible damage to the salivary glands following administration of ablative doses of radioactive iodine for treatment of hyperthyroidism. We have investigated the changes that occur in the composition of saliva in hyperthyroidism and after the administration of an ablative dose of radioactive iodine to hyperthyroid subjects. DESIGN: The study consisted of two parts: first, a comparison of a group of hyperthyroid patients with a group of normal subjects with regard to the concentration or activity of 10 constituents of saliva; second, measurement of those constituents 3-42 weeks after administration of 370 MBq of radioactive iodine to a group of hyperthyroid subjects. PATIENTS: Saliva specimens from 38 untreated out-patients with hyperthyroidism due to Graves' disease or toxic nodular goitre were studied to evaluate the effects of hyperthyroidism and the results were compared with a group of 93 normal subjects. Seventy-one samples of saliva from 26 patients with persistent hyperthyroidism were collected and analysed 3-42 weeks after radioactive iodine administration. MEASUREMENTS: The flow rate; the concentrations of total protein, iodine, calcium, urate, phosphate, potassium and immunoglobulin A; and the activities of N-acetylglucosaminidase, lysozyme and lactate dehydrogenase were measured. RESULTS: In hyperthyroidism the salivary flow rate and the concentrations of urate and potassium were significantly (P < 0.05) increased and the concentrations of total protein, calcium and lactate dehydrogenase activity significantly decreased compared to the control group. After radioactive iodine was administered, significant positive trends were observed in the concentrations of total protein, N-acetylglucosaminidase and immunoglobulin A. These trends were independent of the free T3 levels obtained from the same specimens. CONCLUSIONS: Hyperthyroidism leads to a number of changes in salivary composition. For most of the salivary components measured no significant changes were observed 3-42 weeks after administration of 370 MBq of radioactive iodine to patients with persistent hyperthyroidism. The relatively small positive trends in the concentrations of total protein, N-acetylglucosamidase activity and immunoglobulin A may have been due either to changes in thyroid status or to the effects of radiation on the salivary glands, or both.

Acetylglucosaminidase↗
PubMed1984

Radioactive iodine therapy in cats with hyperthyroidism.

Eleven cats with hyperthyroidism were treated with radioactive iodine (131I). Previous unsuccessful treatments for hyperthyroidism included hemithyroidectomy (2 cats) and an antithyroid drug (7 cats). Two cats had no prior treatment. Thyroid scans, using technetium 99m, showed enlargement and increased radionuclide accumulation in 1 thyroid lobe in 5 cats and in both lobes in 6 cats. Serum thyroxine concentrations were high and ranged from 4.7 to 18 micrograms/dl. Radioactive iodine tracer studies were used to determine peak radioactive iodine uptake (RAIU) and effective and biological half-lives. Activity of 131I administered was calculated from peak RAIU, effective half-life, and estimated thyroid gland weight. Activity of 131I administered ranged from 1.0 to 5.9 mCi. The treatment goal was to deliver 20,000 rad to hyperactive thyroid tissue. However, retrospective calculations based on peak RAIU and effective half-life obtained during the treatment period showed that radiation doses actually ranged from 7,100 to 64,900 rad. Complete ablation of the hyperfunctioning thyroid tissue and a return to euthyroidism were seen in 7 cats. Partial responses were seen in 2 cats, and 2 cats became hypothyroid. It was concluded that 131I ablation of thyroid tumors was a reasonable alternative in the treatment of hyperthyroidism in cats. The optimal method of dosimetry remains to be determined.

Animals↗
PubMed1986

Place of radioactive iodine in treatment of thyrotoxicosis.

The effect of treatment of thyrotoxicosis with drugs, radioactive iodine, or surgery in different age groups is reviewed. In Graves' disease and toxic multinodular goitre the remission rate is about 40-50% after antithyroid drugs, but these drugs have little effect in toxic adenoma. Hypothyroidism developed in 35-49% of patients who had had thyroidectomy, and the risks of operation are high. The risk of malignant disease and genetic abnormalities was not significantly greater after treatment with radioactive iodine in any age group. In general, treatment with radioactive iodine should have priority over thyroidectomy at all ages.

Abnormalities, Drug-Induced↗
PubMed1985

Relapse of Graves' disease 23 years after treatment with radioactive iodine (131I).

The use of radioactive iodine (131I) in the treatment of Graves' disease results frequently in hypothyroidism requiring thyroid hormone supplementation. Relapse of Graves' disease months after inadequate treatment with 131I is well-recognized. However, late relapse of Graves' disease in a patient rendered hypothyroid by 131I years after therapy has not been reported. The authors discuss a patient who had a relapse of his Graves' disease 23 yr after treatment with 131I. Over the interval the patient had been on 1-thyroxine replacement for hypothyroidism and had persistently high levels of long acting thyroid stimulator or thyroid stimulating antibody. The authors speculate that the immune nature of Graves' disease may play a role in the observed clinical response to 131I.

Adult↗
PubMed1975

Chronic lymphocytic thyroiditis, thyrotoxicosis, and low radioactive iodine uptake. Report of four cases.

To characterize four patients with thyrotoxicosis and a low radioactive iodine uptake, thyroid biopsies were performed, and iodine metabolism was studied. Histologic examination showed the presence of chronic lymphocytic thyroiditis, with no features of Graves's disease, in all. Detailed studies in one patient revealed insufficient metabolism of iodine to account for the clinical and chemical features of thyrotoxicosis, which implies that release of stored hormone by the inflammatory process causes the thyrotoxic state. The thyrotoxicosis in this entity subsides spontaneously. Thus, this form of thyrotoxicosis differs from the usual form found in Graves's disease in that histologie features of Graves's disease are absent, the radioactive iodine uptake is low, and specific antithyroid therapy is contraindicated. The observations further demonstrate that the radioactive iodine uptake remains a valuable tool in the diagnosis of thyrotoxicosis and the differentiation of its various forms.

Adult↗
PubMed2002

Increasing the effectiveness of radioactive iodine therapy in the treatment of thyroid cancer using Trichostatin A, a histone deacetylase inhibitor.

BACKGROUND: Radioactive iodine is used to identify and treat recurrent and metastatic thyroid cancer of follicular cell origin. Between 30% and 40% of thyroid cancers are either resistant or become resistant to radioactive iodine. Increased sodium-iodide symporter (NIS) and decreased Pendrin (PDS) activity may be associated with increased radioactive iodine effectiveness. In this investigation the effects of Trichostatin A (TSA), a histone deacetylating inhibitor, on human thyroid NIS and PDS gene expression was investigated. METHOD: Cell lines from papillary, Hürthle, and follicular cell carcinomas were treated with TSA for 72 hours at concentrations up to 100 ng/mL. NIS and PDS gene expression was determined using quantitative RT-polymerase chain reaction. RESULTS: . NIS messenger RNA expression in cell carcinomas was increased 107- (1.8-307) and 217- (5.7-408) fold in papillary, 39- (20-63) and 58- (37-80) fold in Hürthle, and 459- (178-810) and 781- (412-1229) fold in follicular after treatment with 50 and 100 ng/mL of TSA, respectively. PDS messenger RNA expression in cell carcinomas was decreased 0.22- (0.05-0.45) and 0.27- (0.09-0.47) fold in papillary, 0.53- (0.46-0.60) and 0.54- (0.44-0.64) fold in Hürthle, and 0.32- (0.26-0.39) and 0.56- (0.47-0.64) fold in follicular, after the same treatment. CONCLUSIONS: In thyroid cancer cell lines, TSA dramatically increased NIS gene expression and reduced PDS expression. The increased NIS expression and reduced PDS expression may make radioiodine therapy more effective in patients with thyroid cancer, especially when the tumors have no or low uptake of radioiodine.

Carcinoma, Papillary↗
PubMedDate not supplied

Radioactive iodine therapy: effect on functioning metastases of adenocarcinoma of the thyroid.

A case of metastatic adenocarcinoma of the thyroid is reported in which treatment by means of radioactive iodine has been successful. The patient was completely thyroidectomized for "malignant adenoma" in 1923, with neither thyrotoxicosis then nor hypothyroidism postoperatively; 15 years later there developed classic symptoms of hyperthyroidism and severe pain in the lower back. In October 1939 a pulsating tumor removed from the level of the 12th thoracic vertebra proved to be metastatic thyroid adenocarcinoma (histologically well differentiated, with small follicles and colloid). In the next two years hyperthyroidism increased and roentgenograms revealed new metastases in the lungs, upper part of the right femur, second rib on the left side, left ilium, and skull. Roentgenologic irradiation of the metastases proved ineffectual. In March 1943 a tracer dose of radioactive iodine revealed iodine retention by all the known lesions and no evidence of residual thyroid tissue in the neck. Therapeutic amounts of radioactive iodine were administered orally between May and October 1943. Definite and lasting clinical improvement followed. In April 1944 and March 1945 additional I* was administered with a resultant disappearance of pain, increase in weight, and progressive change in all clinical criteria in the direction of hypothyroidism. Roentgenographic evidence pointed to an arrest if not a regression of the disease. No untoward effects followed this therapy. Radioactive iodine seems to be an effective therapeutic agent in the control of this type of tumor.

Adenocarcinoma↗
PubMedDate not supplied

Is it still worthwhile to treat bone metastases from differentiated thyroid carcinoma with radioactive iodine?

From 1964 to 1989, bone metastases were found in 28 of 600 patients operated on for differentiated thyroid carcinoma. Bone metastasis was the presenting symptom in 15 (54%) patients, was detected from the initial symptom in 4 (14.5%) patients, and occurred subsequently in 9 (32%) patients, with an average lag time of 4.5 years after surgical treatment. Pathological pattern of the thyroid cancer was follicular in 26 (93%) patients and papillary in 2 (7%) patients. Bone metastatic involvement was multiple in 21 (75%) patients and associated with other synchronous or metachronous distant metastases in 13 (46%) patients, especially in the lung (10 patients) or the brain (3 patients). The primary treatment of thyroid carcinoma was total thyroidectomy in all 28 patients, with additional modified neck dissection in 8 patients. All 15 patients presenting with symptoms had bone metastases demonstrated by x-ray studies. Six of the bone metastases only took up radioactive iodine 6 weeks after total thyroidectomy, as did 2 of 4 bone metastases detected at initial observation and 4 of 9 metachronous bone metastases. All 12 patients with functioning bone metastases were given radioactive iodine therapy; 4 of the metastases were surgically resected. Only 2 patients with bone metastases showed a complete response after an ablative dose of I-131; none of the metastases had been demonstrated by x-ray studies. Radioactive iodine therapy cures no more than 17% of patients with bone metastases taking up radioactive iodine and 7% of all patients with bone metastases. All patients cured of bone metastases were given radioactive iodine, either alone, or combined with other treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1996

The reactions of euthyroid and hyperthyroid glands to radioactive iodine.

BACKGROUND: Researchers generally assume that the thyroid gland reacts more or less comparably to external irradiation and radioactive iodine. DESIGN: The thyroid glands from 20 euthyroid patients and 20 hyperthyroid patients, all of which had been treated with radioactive iodine, were studied. RESULTS: The two groups manifested different reactions. Almost all the euthyroid glands displayed a fibrotic atrophic pattern, whereas the glands from the Graves' disease patients showed more adenomatous and Hashimoto lesions than atrophy. CONCLUSION: Differences in the reactivity of normal and hyperplastic follicles may cause different reactions to treatment with radioactive iodine.

Adenoma↗
PubMed1954

Therapeutic studies in hyperthyroidism; use of radioactive iodine.

Of 112 patients with hyperthyroidism who were treated with radioactive iodine, 110 were relieved of the disease. Nine had transient hypothyroidism. Twelve had permanent hypothyroidism. No other adverse effects that could be attributed to radioactive iodine were noted.

Drug-Related Side Effects and Adverse Reactions↗
PubMed2002

Radioactive iodine in the treatment of Graves' disease.

OBJECTIVES: This study was performed to evaluate the efficacy of radioactive iodine 131I therapy of Graves' hyperthyroidism at Sultan Qaboos University Hospital, Oman and to determine the optimal dose of 131I needed to achieve the euthyroid or hypothyroid status. METHODS: The medical records of 366 patients with Graves hyperthyroidism who received a single dose of 131I at Sultan Qaboos University Hospital, Oman between 1991 and 1999 were reviewed. The diagnosis was based on clinical, biochemical grounds and 99mTc thyroid scintigraphy. The patients were followed up for a minimum period of 12 months. For the analysis, the patients were divided into 6 groups according to the 131I dose administered: Dose one (350-399), dose 2 (400-449), dose 3 (450-499), dose 4 (500-549), dose 5 (550-599) and dose 6 (> or = 600) MBq. RESULTS: Fifty-eight percent of all the patients were hypothyroid after 3 months. Three hundred and twenty two patients (88%) were treated by a single dose of 131I in 12 months (85.5% hypothyroid and 2.5% euthyroid). Forty-one patients (11.2%) required a 2nd 131I dose and only 3 patients required 3 doses of 131I. The best cure rate (93%) was observed in group dose 5 (574.0 +/- 16.4 MBq) which however, was not significantly different from other dosage levels. The female to male ratio was 2:1 and the cure rates were not gender or age related. CONCLUSION: Treatment of Graves' hyperthyroidism from a single 131I dose is our aim, rather than avoidance of hypothyroidism. Our results indicate that cure rates are higher with larger doses of 131I except in group dose 6 (special category of patients). In the future, fixed doses would be adopted in our radioactive iodine treatment practice guidelines. As the majority of our patients were hypothyroid at 3 months regular monthly follow-up is essential. Whenever appropriate, physicians are encouraged to consider early referral of Graves' hyperthyroidism patients for radioactive iodine treatment as it is cheap, effective, easy to administer and free from serious side effects.

Adult↗
PubMed1983

[Hyperparathyroidism after radioactive iodine therapy for Graves' disease: a case report].

Herein we report a 36-year-old man with hyperparathyroidism and a past history of internal irradiation to the thyroid. Twelve years previously at age 24 years he had received 8 mCi of radioactive iodine for Graves' disease. An additional dose of 4 mCi was required 3 years later. A right lower parathyroid adenoma (28 X 23 X 20 mm, 5.7 g) was found at neck exploration. Although the association of external ionizing radiation to the head and neck and the subsequent development of hyperfunctioning parathyroid glands has been described in recent years, there are only 4 cases in the literature of parathyroid surgery for hyperparathyroidism secondary to earlier treatment with radioactive iodine for Graves' disease. In a long-term follow-up of 180 patients treated with radioactive iodine for Graves' disease, neither hypercalcemia nor hypophosphatemia was found. Whether internal radiation therapy can be a causative factor in the development of hyperparathyroidism should be elucidated in future. However, it seems reasonable to suggest that patients whose hyperthyroidism has been treated with radioactive iodine should have their serum calcium levels examined at 5-year intervals.

Adult↗