Avaliação da radioiodoterapia com doses fixas de 10 e 15 mCi em pacientes com doença de graves

One institutions' experience with a true standard 15 mCi dose of I-131 for the treatment of Graves' disease

INTRODUCTION

Currently, there is a lack of consensus on the fixed dosage of RAI to be administered for this purpose between the main guideline frameworks set forth by the American Thyroid Association (ATA), Society of Nuclear Medicine and Molecular Imaging (SNMMI), European Association of Nuclear Medicine (EANM) and the European Thyroid Association (ETA). In this retrospective study, we will investigate the effectiveness of using a standard dose of 15 mCi ±10% of RAI in the treatment of Graves'.

METHODS

A retrospective chart review was conducted for the period between 1 May 2014 and 2 September 2020, to identify patients diagnosed with hyperthyroidism due to Graves' disease. The patients were grouped based on outcome and assessed for the efficacy of the dosage of 15 mCi ±10% of RAI in a successful treatment.

RESULTS

Sixty-seven patients were identified that met the inclusion criteria between 1 May 2014 and 2 September 2020. Of the 67 RAI ablations; 60 patients became hypothyroid [60/67, (89.55%)], 2 euthyroid [2/67, (2.99%)] and 5 remained hyperthyroid [5/67, (7.46%)].

CONCLUSIONS

For the treatment of Graves' disease, the use of a standard low dose of 15 mCi ±10% has a high success rate without additional measurements or calculations beyond a standard planar image and 24-h uptake %. The adoption of a standard low dose of 15 mCi of I-131 across institutional guidelines would streamline dosage questions and eliminate the need to determine the weight of the thyroid for calculations in all RAI treatments for hyperthyroidism caused by Graves' disease.

Suppurative Lymphadenitis after Radioactive Iodine Therapy for Graves' Disease: A Rare Complication?

BACKGROUND

Radioiodine (RAI) therapy for Graves' disease is a well-accepted and effective treatment with a good side effect profile. Short-term adverse effects can occasionally include radiation-induced thyroiditis. To my knowledge, cervical lymphadenitis associated with RAI therapy for Graves' disease has not been reported before.

CASE REPORT

A 38-year-old woman initially presented with uncontrolled thyrotoxicosis secondary to Graves' disease. She subsequently received RAI therapy for her condition. Within a week, she developed painful bilateral cervical lymphadenopathy that progressed to abscess formation requiring incision and drainage. No other causes (neoplastic or infective) were found. Symptomatic treatment was instituted, and within 2 months the lymphadenitis resolved completely.

DISCUSSION

RAI therapy for Graves' disease can sometimes cause radiation-induced thyroiditis but associated cervical lymphadenopathy or lymphadenitis has not been described. This may represent a continuum of the proinflammatory state induced by RAI manifesting as a rare but potentially morbid complication.

Evidence for higher success rates and successful treatment earlier in Graves' disease with higher radioactive iodine doses

BACKGROUND

Graves' disease is commonly treated with curative intent using radioactive iodine (RAI). While higher doses have been shown to increase success rates, more evidence is needed. Further, very few studies assess the time to treatment success without the need for antithyroid drugs after a single dose of RAI within the first year post-dose, despite earlier success being an important treatment objective. We aimed to evaluate the outcome of different RAI doses in terms of success rates and time to achieve this success (eu- or hypothyroidism). We hypothesized that higher doses would not only increase success rates, but bring about successful treatment earlier.

METHODS

We retrospectively analyzed the medical records of all patients diagnosed with Graves' disease between 1994 and 2009. Details of RAI treatment and outcomes thereof were documented. In our analysis, we divided the patients who received RAI treatment into three groups according to the dose received: I (≤15 mCi); II (16-20 mCi); III (≥21 mCi).

RESULTS

There were 498 patients diagnosed with Graves' disease. However, 105 were either lost to follow-up or still undergoing treatment. Of the remaining 393, there were 258 who received RAI treatment. The average initial dose was 21.42±6.5 mCi and overall success rate was 86%. Success rates were 74%, 85%, and 89% (p<0.05), while average time to successful treatment was 8.1, 4.6, and 2.9 months, respectively (p<0.001), for groups I, II, and III. When 20 mCi was given empirically, 85% obtained successful treatment; most of these within 3 months (mean 3.9; mode and median 3 months).

CONCLUSIONS

This study provides additional evidence that success post-treatment correlates with administered dose and shows clearly, for the first time, that successful treatment is achieved earlier with higher doses. This knowledge is relevant to all clinicians managing Graves' disease as it can be taken into consideration when discussing treatment plans with patients.

Extremely high doses of radioiodine required for treatment of Graves' hyperthyroidism: a case report

Introduction

Radioactive iodine (131I) is widely prescribed for treatment of Graves' disease. A dose of 370 to 555 MBq (10 to 15 mCi) is usually enough, but reports of improved remission rates with single doses up to 20-30 mCi, and 38.5 mCi at most, exist.

Case presentation

A 53-year-old male patient was evaluated in September 2005, with symptoms of thyrotoxicosis for 2 years. He presented with tachycardia (130 bpm) and a large goiter. Thyrotropin was <0.01 uIU/ml (0,41-4,5), free thyroxin >7.77 ng/dl (0.9-1.8), anti-thyreoperoxidase antibody: 374 IU/ml (<35) and anti-thyroglobulin antibody: 749 IU/ml (<115). Ultrasound: diffuse goiter, no nodules; right lobe: 7.9 × 3.8 × 3.8 cm; left: 7.7 × 3.5 × 3.8 cm; isthmus: 1.6 cm. Propylthiouracil 300 mg t.i.d. and propranolol were prescribed. Thyroid 99mTc-pertechnetate uptake: 52% (0.35-1.7%) and estimated thyroid volume: 149 mL. After 30 days, he received 555 MBq (15 mCi) of 131I-iodide. Six months after radioiodine therapy, under methimazole 40 mg, thyroid stimulating hormone was 1.5 uIU/ml; free thyroxine 0.54 ng/dl. Methimazole was suspended. In 21 days, thyroid stimulating hormone was 0.03 uIU/ml; free thyroxine 0.96 ng/dl. Methimazole was reintroduced. One year later, thyroid stimulating hormone was <0.01 uIU/ml and free thyroxine >7.77 ng/dl. Thyroid 99mTc-pertechnetate uptake was 45% and estimated thyroid volume 144 mL. A 1110 MBq (30 mCi) radioiodine therpy was administered. He used Methimazole for 8 months, when overt hypothyroidism appeared (TSH: 25.30 uIU/ml; free thyroxine: 0.64 ng/dl). Methimazole was interrupted. Hyperthyroidism returned 6 weeks later (thyroid stimulating hormone <0.01 uIU/ml; free thyroxine >7.77 ng/dl). Thyroid 99mTc-pertechnetate uptake was 25% and estimated thyroid volume 111 mL. Methimazole was prescribed again. In March 2008 he received a 2590 MBq (70 mCi) radioiodine therapy. By may/2008, under methimazole 20 mg, his TSH was 0.07 uIU/ml; free thyroxine 1.31 ng/dl. In October 2008 he presented overt hypothyroidism (TSH 91.6 uIU/ml; free thyroxine 0.34) and was given levothyroxine 75 mcg/day. He remains euthyroid under hormone replacement.

Conclusion

Our presented case of Graves' disease received a cumulative dose of 4255 MBq (115 mCi). The high uptake could indicate accelerated iodine turnover with 131I short time of action. Impaired hormone synthesis could also be present. We believe the extremely high dose required was due to the initial very high iodine uptake and large thyroid volume.

Extremely high doses of radioiodine required for treatment of Graves' hyperthyroidism: a case report

INTRODUCTION

Radioactive iodine ((131)I) is widely prescribed for treatment of Graves' disease. A dose of 370 to 555 MBq (10 to 15 mCi) is usually enough, but reports of improved remission rates with single doses up to 20-30 mCi, and 38.5 mCi at most, exist.

CASE PRESENTATION

A 53-year-old male patient was evaluated in September 2005, with symptoms of thyrotoxicosis for 2 years. He presented with tachycardia (130 bpm) and a large goiter. Thyrotropin was <0.01 uIU/ml (0,41-4,5), free thyroxin >7.77 ng/dl (0.9-1.8), anti-thyreoperoxidase antibody: 374 IU/ml (<35) and anti-thyroglobulin antibody: 749 IU/ml (<115). Ultrasound: diffuse goiter, no nodules; right lobe: 7.9 x 3.8 x 3.8 cm; left: 7.7 x 3.5 x 3.8 cm; isthmus: 1.6 cm. Propylthiouracil 300 mg t.i.d. and propranolol were prescribed. Thyroid (99m)Tc-pertechnetate uptake: 52% (0.35-1.7%) and estimated thyroid volume: 149 mL. After 30 days, he received 555 MBq (15 mCi) of (131)I-iodide. Six months after radioiodine therapy, under methimazole 40 mg, thyroid stimulating hormone was 1.5 uIU/ml; free thyroxine 0.54 ng/dl. Methimazole was suspended. In 21 days, thyroid stimulating hormone was 0.03 uIU/ml; free thyroxine 0.96 ng/dl. Methimazole was reintroduced. One year later, thyroid stimulating hormone was <0.01 uIU/ml and free thyroxine >7.77 ng/dl. Thyroid (99m)Tc-pertechnetate uptake was 45% and estimated thyroid volume 144 mL. A 1110 MBq (30 mCi) radioiodine therpy was administered. He used Methimazole for 8 months, when overt hypothyroidism appeared (TSH: 25.30 uIU/ml; free thyroxine: 0.64 ng/dl). Methimazole was interrupted. Hyperthyroidism returned 6 weeks later (thyroid stimulating hormone <0.01 uIU/ml; free thyroxine >7.77 ng/dl). Thyroid (99m)Tc-pertechnetate uptake was 25% and estimated thyroid volume 111 mL. Methimazole was prescribed again. In March 2008 he received a 2590 MBq (70 mCi) radioiodine therapy. By may/2008, under methimazole 20 mg, his TSH was 0.07 uIU/ml; free thyroxine 1.31 ng/dl. In October 2008 he presented overt hypothyroidism (TSH 91.6 uIU/ml; free thyroxine 0.34) and was given levothyroxine 75 mcg/day. He remains euthyroid under hormone replacement.

CONCLUSION

Our presented case of Graves' disease received a cumulative dose of 4255 MBq (115 mCi). The high uptake could indicate accelerated iodine turnover with (131)I short time of action. Impaired hormone synthesis could also be present. We believe the extremely high dose required was due to the initial very high iodine uptake and large thyroid volume.