Long‐term follow‐up of treatment of thyrotoxicosis by three different methods

Abstract

In view of continuing debate regarding the best definitive therapy for thyrotoxicosis, we examined the long-term outcome of radioiodine (131I) or surgical treatment of 1918 thyrotoxic patients divided into three groups: those given 131I at a dose calculated from thyroid size, 131I uptake and effective half-life to administer a fixed radioactivity dose to the thyroid; those treated with a dose of 131I (110, 185 or 370 MBq) chosen empirically; and those treated by partial thyroidectomy. A minimum 10-year follow-up was achieved for 1119 patients treated with a calculated 131I dose; a single dose resulted in control of disease in 90.5%. At 5 years, 18% were hypothyroid, the prevalence rising to 42% at 20 years. Of 504 patients treated with an empirical 131I dose and followed for at least 5 years, thyrotoxicosis was controlled by a single dose in 89.7%. The rate of hypothyroidism at 5 years (38.5%) was higher than that found in the calculated dose group. A minimum 10-year follow-up was achieved for 295 surgically treated patients; thyrotoxicosis was controlled in 89.2%. The prevalence of hypothyroidism (2% at 5 years, 27.5% at 20 years) was lower than that found after 131I, whether given by calculated or empirical dose. Each of the treatments employed resulted in an acceptable rate of cure of thyrotoxicosis. If maintenance of euthyroidism is the major objective, our findings suggest that surgery represents the treatment of choice. Furthermore, calculated dose 131I administration has advantages in terms of risk of hypothyroidism over empirical dose treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy of Low‐dose (2 millicurie) versus Standard‐dose (4 millicurie) Radioiodine Treatment for Cats with Mild‐to‐Moderate Hyperthyroidism

“…Permanent hypothyroidism develops by 1 year in at least 50% of patients given high doses42 and by 25 years in at least 50% of those given lower doses 41, 43. Furthermore, approximately 2–6% of humans with subclinical hypothyroidism will progress to overt hypothyroidism with each year after radioiodine treatment 34, 37, 41.…”

Análise retrospectiva do resultado do tratamento com iodo radioativo em 120 pacientes tirotóxicos por doença de Basedow-graves

“…A tabela 7, onde incluímos ao final os dados de nosso trabalho, apresenta os resultados da literatura com o uso do 131 I no tratamento da tirotoxicose da DBG (24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41). A análise desses trabalhos indica que o tratamento inicial com DATs antes do radioiodo é a prática comum; esta atitude, entretanto, tem sido reavaliada recentemente, pois vários autores têm evidenciado que as DATs tornam a tiróide mais resistente à ação do radioiodo, aumentando a taxa de persistência da tirotoxicose e diminuindo a evolução para hipotiroidismo (24,41).…”

“…Em nosso trabalho a atividade radioativa empregada foi de 80 mCi/g tecido tiroideano, mas a mediana final, após os cálculos e o valor total das doses empregadas, foi maior, chegando a 110 mCi/g tecido. Vários autores, utilizando doses médias de 10 mCi, obtiveram taxas de evolução para o hipotiroidismo em um ano de 50% e de cura até 80% (4,24,26,27). Para outros, ainda com a mesma dose empregada, a taxa de cura da tirotoxicose chegou a 87% em um ano (28) e 70% em dois anos (29).…”

“…Houve correlação inversa entre a taxa de cura obtida e o volume glandular, principalmente para os que empregaram doses fixas (28). Doses maiores, como 15 mCi, elevaram o número de pacientes com hipotiroidismo, mas reduziram a tirotoxicose; com o emprego de 15 mCi, houve taxas de hipotiroidismo de 41 a 64% (26,27,(30)(31)(32). As taxas de persistência de tirotoxicose variaram de 3 a 25% (30)(31)(32)(33)(34)(35).…”

Avaliação do peso corporal em pacientes com doença de Graves durante o tratamento com metimazol

“…Entretanto, a prevalência de hipotiroidismo durante o tratamento é de 42% a 67% (14), e esses pacientes também estão sujeitos a ganho de peso, do mesmo modo que pacientes com hipotiroidismo primário (15). Além disso, muitos pacientes não retornam ao peso pré-tratamento, mesmo após a reposição com levotiroxina (8,9,10,13).…”