[Follow-up of high-risk patients with differentiated thyroid cancer without persistent disease after initial therapy]. / Seguimento de pacientes de alto risco com carcinoma diferenciado de tireóide sem doença persistente após a terapia inicial.

This study evaluated the follow-up of high-risk patients with thyroid cancer after initial therapy. A total of 125 high-risk patients (tumor >4 cm and/or extrathyroid invasion and/or lymph node metastases, and age >45 years), with complete resection of the tumor, were selected. All patients underwent total thyroidectomy and ablation with (131)I[3.7-5.5 GBq (100-150 mCi)]. Eighteen patients (14.8%) presenting metastases on post-dose whole-body scan (RxWBS) were excluded. The negative predictive value of stimulated Tg < or =1 ng/ml in combination with neck US during first assessment (612 mo. after ablative therapy) was 96.2% for the absence of recurrence up to 5 years. This value increased to 98.7% when adding WBS performed with 185 MBq (5 mCi) (131)I (DxWBS). The positive predictive value (PPV) of stimulated Tg >1 ng/ml was 52% for the detection of the presence of metastases up to 5 years; however, considering only patients with initially negative DxWBS and US, the PPV was 19% (9% if Tg of 110 ng/ml vs. 40% if Tg >10 ng/ml). Tg levels decreased spontaneously in patients with stimulated Tg >1 ng/ml during first assessment, negative US and DxWBS, and no recurrence during follow-up, with Tg being undetectable in half these patients at the end of 5 years. Twenty patients presented uptake in the thyroid bed upon DxWBS during the first year after ablative therapy, with stimulated Tg and US being negative, and were not treated with 131I; these patients did not relapse and no uptake on DxWBS was observed in 60% after 5 years. Recurrence after 5 years was only 1.3% in patients without apparent disease (negative US and DxWBS) and stimulated Tg <1 ng/ml. An algorithm for the follow-up of high-risk patients after initial therapy is presented in this study.

Malformations in the offspring of women with thyroid cancer treated with radioiodine for the ablation of thyroid remnants.

RATIONALE: Since ovarian function is only temporarily compromised by radioiodine therapy, many women with thyroid cancer treated with radioiodine can become pregnant. The present study evaluated the evolution of these pregnancies and the consequences for the offspring. PATIENTS AND METHODS: We retrospectively analyzed 78 pregnancies of 66 women submitted to total thyroidectomy, followed by radioiodine therapy 3.75-5.5 GBq (131)I, mean 4.64 GBq). In all patients, conception occurred one year after ablative therapy (mean of 30 months). Age ranged form 19 to 36 years (mean of 30.6 years) at the time of radioiodine treatment and from 23 to 39 years (mean of 32.8 years) at the time of conception. RESULTS: Four (5.1%) of the 78 pregnancies resulted in spontaneous abortions. Three (4%) of the 74 deliveries were preterm and there was no case of stillbirth. The birthweight was > 2500 g in 94.6% of the children (+/- SD: 3350 +/- 450 g) and only one infant (1.3%) presented an apparent malformation at birth (intraventricular communication). No difference in the age at the time of radioiodine therapy or conception or in radioiodine dose was observed between pregnancies with an unfavorable outcome and those with a favorable outcome. CONCLUSION: We conclude that pregnancies that occur 12 months after ablative therapy are safe.

Thyroglobulin before ablation and correlation with posttreatment scanning.

OBJECTIVES/HYPOTHESIS: To determine the usefulness of thyroglobulin (Tg) before ablation and the correlation with posttreatment scanning in patients with thyroid carcinoma. STUDY DESIGN: Prospective. METHODS: Tg during hypothyroidism was determined in 212 patients after thyroidectomy and before ablation. The disease stage was based on clinical examination, Tg, posttherapy scanning, other imaging methods, and histologic confirmation in selected cases. RESULTS: One hundred sixty-four patients presented thyroid remnants only, 31 had lymph node metastases, and 17 had distant metastases. Posttreatment scanning showed a sensitivity of 71% for lymph node and of 94.1% for distant metastases. Ectopic uptake was observed in 5.6% of patients with Tg less than 1 ng/mL, in 9% with levels from 1 to 5 ng/mL, in 10.7% with Tg from 5 to 10 ng/mL, and in 51% with Tg greater than 10 ng/mL. The sensitivity of Tg for metastases was 73 and 66.5% and specificity was 73 and 88.4% at a cut-off value of 5 and 10 ng/mL, respectively. CONCLUSIONS: Postoperative Tg less than 10 ng/mL rarely show distant metastases and because these metastases were observed in 31% of patients with values greater than 10 ng/mL, this criterion can be selected for the indication of imaging methods, in addition to neck ultrasound (US). For cases with Tg less than 10 ng/mL, US is necessary because even patients with undetectable Tg had lymph node metastases. The same cut-off can be used for the indication of radioiodine therapy even in the absence of any evidence of disease because 51% of the patients with Tg greater than 10 ng/mL showed ectopic uptake on posttreatment scanning.

[Recombinant TSH in ablative therapy and follow-up of patients with differentiated thyroid carcinoma]. / TSH recombinante no tratamento e seguimento de pacientes com carcinoma diferenciado de tireóide: uso na prática clínica.

The studies evaluating the efficacy and safety of recombinant TSH in the ablative therapy and follow-up of patients with differentiated thyroid carcinoma by serum thyroglobulin (Tg) measurement and iodine scanning were reviewed in this article. Recombinant TSH is comparable to hypothyroidism in the generation of Tg and in the execution of iodine-131 whole-body scanning, with the advantage of sparing patients from the symptoms of hypothyroidism and from impaired quality of life induced by levothyroxine withdrawal, in addition to a reduced exposure to elevated TSH and shorter absence from work, with recombinant TSH being the preparation indicated for the diagnosis of metastases in both low risk (Tg after recombinant TSH) and moderate or high risk patients (Tg and iodine-131 scanning after recombinant TSH). In the case of ablative therapy, the results are promising when using a dose of 100 mCi for remnant ablation, but hypothyroidism is still preferred, except for patients in whom the desired TSH elevation after levothyroxine withdrawal is not achieved, patients with base diseases that are aggravated by acute and severe hypothyroidism (severe heart and lung disease, coronary disease, compromised renal function, history of psychosis due to myxedema), patients debilitated by advanced disease, and elderly individuals. The studies also show that the administration of recombinant TSH is safe, with few mild or moderate adverse effects.

[Safety of radioiodine therapy in patients with thyroid carcinoma younger than 21 years]. / Segurança da radioiodoterapia em pacientes com carcinoma de tireóide com menos de 21 anos.

We studied 20 patients with differentiated thyroid carcinoma undergoing radioiodine therapy (> or = 100 mCi dose) before the age of 21: 10 patients without distant metastases received a mean dose of 145 mCi and 10 with lung involvement received 270 mCi. One or more years after ablative therapy, xerostomia was present in two patients but was not accompanied by more severe complications such as oral ulcers or fissures, and 99mTcO4- scintigraphy confirmed salivary dysfunction. One patient showed keratoconjunctivitis sicca. Blood counts did not reveal abnormalities caused by radioiodine therapy. FSH was normal in 18 patients. Patients with elevated levels had received radioiodine just over a year ago and repetition of the exam after 6 months showed that FSH had returned to normal. The 6 male patients had normal LH and testosterone levels. Analysis did not reveal signs of pulmonary fibrosis secondary to treatment in the 10 cases with iodine-accumulating metastases in this organ. Our data suggest that ablative therapy employing a dose of 100 to 300 mCi is safe in young individuals, but persistent complications such as salivary dysfunction and conjunctivitis may occur.

Post I-131 therapy scanning in patients with thyroid carcinoma metastases: an unnecessary cost or a relevant contribution?

RATIONALE: In patients with elevated serum thyroglobulin (Tg) and a negative whole-body scan (WBS), posttherapy scanning can reveal metastases in many cases and is therefore recommended. In contrast, the routine use of posttherapy scanning is questioned. MATERIALS AND METHODS: One hundred six patients with differentiated thyroid carcinoma had pre- and posttherapy scanning, with metastatic uptake on the diagnostic scan and were divided into 2 groups: 60 patients assessed on first ablation after thyroidectomy and 46 patients with tumor persistence or recurrence after initial ablative therapy. Data modifying the disease stage or treatment were considered to be clinically relevant. RESULTS: Posttherapy scanning on first ablation changed the disease stage in 8.3% of the patients and therapeutic approach in another 15%, and provided clinically relevant information for 26% of patients with 1 previous ablation. Even when excluding cases whose lesions were known by the time of the first postablative scan, the therapeutic approach was influenced by posttherapy scanning in 15.6% of the patients. Only 4 of 211 metastases detected on pretherapy WBS did not appear on postablative scans. CONCLUSIONS: Posttherapy scanning provides important information, even in patients whose pretherapy WBS is positive for metastases, with this approach being useful both during the first ablation and subsequent treatment.

[Revisiting serum thyroglobulin in the follow-up of patients with differentiated thyroid carcinoma]. / Revisitando a tireoglobulina sérica no seguimento de pacientes com carcinoma diferenciado de tireóide.

This study analyzed serum thyroglobulin (Tg) during hypothyroidism in 207 patients with differentiated thyroid carcinoma treated with total thyroidectomy and radioiodine ablation and undetectable anti-Tg antibodies. Disease staging was defined by clinical examination, stimulated Tg, pre- and post-ablative radioiodine scanning, and other imaging methods (X-Ray, US, CT and MIBI-scan). The average interval from initial therapy was 2.3 years. 153 patients (74%) had no evident disease, 34 (16.4%) presented neck/mediastinal disease, and 20 (9.6%) had distant metastases (Mt). The best cut-off for Tg was 1 ng/ml, showing 100% sensitivity for distant Mt and 88.2% for local recurrence or lymph node Mt, and 88.8% specificity for any Mt and 74.8% for distant Mt. In patients with Tg <1 ng/ml, 2.8% showed cervical lymph nodes Mt. Cervical or mediastinal disease were 26% of cases with Tg between 1 and 5 ng/ml. Tg from 5 to 10 ng/ml was associated to distant Mt in 14.2% of the cases and others showed lymph nodes Mt. In patients with Tg >10 ng/ml, 51.3% presented distant Mt. We suggest the need for neck US even in cases with Tg <1 ng/ml. In addition, patients with Tg levels <5 ng/ml should be investigated by neck US and mediastinal CT only, and empirical therapy should be limited to patients with a minimum Tg level >5 ng/ml.

[Clinical manifestations and diagnosis of distant metastases of differentiated thyroid carcinoma after initial therapy]. / Manifestações clínicas e diagnóstico de metástases distantes de carcinoma diferenciado de tireóide após a terapia inicial.

We studied 58 patients with distant metastases of differentiated thyroid carcinoma diagnosed after initial therapy. Lymph node metastases were observed in 65% of the patients on initial presentation. All lymph node metastases, ninety percent of the lung metastases and only 25% of the bone metastases were asymptomatic. Radiography revealed lytic metastases in cases of bone involvement, was normal in 39.6% of the patients, and showed micrometastases in 34.5% and macrometastases in 25.8% of the patients with lung disease. Thyroglobulin (Tg) under thyroxine use was detectable in all patients without antibodies at a cut-off > 1 ng/ml, in 90% at > 5 ng/ml and in 80% at > 10 ng/ml, and after thyroxine withdrawal in 100% at a cut-off > 5 ng/ml and in 94% at > 10 ng/ml. In the case of patients with antibodies (13.8%), Tg was undetectable in half of them. Diagnostic scanning was positive in 83 and 77.6% of the patients with bone and lung metastases, respectively. After ablative therapy, the sensitivity was 100 and 93%, respectively. Eighty-five percent of patients with a negative diagnostic scan had lung metastases visible on radiographs. The determination of serum Tg is the best method in the follow-up of patients with differentiated thyroid cancer. Elevated Tg levels suggest the presence of metastases, indicating the need for ablative therapy with posttreatment scanning, which might reveal non-apparent metastases.

Ultrasonographic differentiation between metastatic and benign lymph nodes in patients with papillary thyroid carcinoma.

OBJECTIVE: The purpose of this study was to evaluate the ultrasonographic characteristics of metastatic lymph nodes in patients with papillary thyroid carcinoma. METHODS: The ultrasonographic characteristics of lymph nodes were analyzed in 112 consecutive patients who underwent thyroidectomy and lymph node dissection, with the diagnosis being confirmed by anatomopathologic examination. RESULTS: A total of 198 lymph nodes were metastatic, and 152 were benign (normal or with nonspecific lymphadenitis). Minimum axial diameters of 7 mm for level II (upper internal jugular chain) and 6 mm for the rest of the neck were observed in 93% of metastatic lymph nodes, absence of an echogenic hilum in 88%, hyperechogenicity in relation to the adjacent muscles in 86%, a round shape in 80%, calcifications in 49.5%, and intranodal cystic necrosis in 20%. These ultrasonographic characteristics were observed in 17%, 10%, 4.5%, 29.5%, 0%, and 0% of benign lymph nodes, respectively. CONCLUSIONS: Even basic ultrasonographic characteristics (shape, echogenicity and echogenic hilum, calcifications, and intranodal cystic necrosis) help in the differentiation between metastatic and nonmetastatic lymph nodes in patients with papillary thyroid carcinoma.

Malformations in the offspring of women with thyroid cancer treated with radioiodine for the ablation of thyroid remnants / Malformações na prole de mulheres com câncer de tireóide tratadas com radioiodo para ablação de remanescentes tireoideanos

RATIONALE: Since ovarian function is only temporarily compromised by radioiodine therapy, many women with thyroid cancer treated with radioiodine can become pregnant. The present study evaluated the evolution of these pregnancies and the consequences for the offspring. PATIENTS AND METHODS: We retrospectively analyzed 78 pregnancies of 66 women submitted to total thyroidectomy, followed by radioiodine therapy (3.7­5.5 GBq 131I, mean 4.64 GBq). In all patients, conception occurred one year after ablative therapy (mean of 30 months). Age ranged form 19 to 36 years (mean of 30.6 years) at the time of radioiodine treatment and from 23 to 39 years (mean of 32.8 years) at the time of conception. RESULTS: Four (5.1 percent) of the 78 pregnancies resulted in spontaneous abortions. Three (4 percent) of the 74 deliveries were preterm and there was no case of stillbirth. The birthweight was > 2500 g in 94.6 percent of the children (mean ± SD: 3350 ± 450 g) and only one infant (1.3 percent) presented an apparent malformation at birth (intraventricular communication). No difference in the age at the time of radioiodine therapy or conception or in radioiodine dose was observed between pregnancies with an unfavorable outcome and those with a favorable outcome. CONCLUSION: We conclude that pregnancies that occur 12 months after ablative therapy are safe.

ARRAZOADO: Uma vez que a função ovariana está apenas temporariamente comprometida pela terapia com radioiodo, muitas mulheres com câncer de tireóide tratadas com radioiodo podem engravidar. O presente estudo avaliou a evolução dessas gravidezes e suas conseqüências para a prole. PACIENTES E MÉTODOS: Analisamos retrospectivamente 78 gravidezes de 66 mulheres submetidas a tiroidectomia total seguida de radioiodoterapia (3,7­5,5 GBq 131I, média 4,64 GBq). Em todas, a concepção ocorreu um ano após a terapia ablativa (média de 30 meses). A idade variou de 19 a 36 anos (media de 30,6) à época do tratamento com radioiodo e de 23 a 39 anos (média de 32,8) na época da concepção. RESULTADOS: Quatro (5,1 por cento) das 78 gravidezes resultaram em abortamento espontâneo. Três (4 por cento) dos 74 partos foram pré-termo, mas não houve nenhum natimorto. O peso ao nascer foi >2.500 g em 94,6 por cento das crianças (média ± DP: 3.350 ± 450 g) e somente uma delas (1,3 por cento) apresentou uma malformação aparente ao nascimento (comunicação intraventricular). Nenhuma diferença quanto à idade na época da radioiodoterapia ou na concepção ou na dose de radioiodo foi observada entre as gravidezes com ou sem um desfecho favorável. CONCLUSÃO: Gravidezes que ocorrem 12 meses após terapia ablativa com radioiodo são seguras.

Seguimento de pacientes de alto risco com carcinoma diferenciado de tireóide sem doença persistente após a terapia inicial / Follow-up of high-risk patients with differentiated thyroid cancer without persistent disease after initial therapy / Follow-up of high-risk patients with differentiated thyroid cancer without persistent disease after initial therapy

Este estudo avaliou o seguimento de pacientes com câncer de tireóide de alto risco, após a terapia inicial. Foram selecionados 125 pacientes de alto risco (tumor >4 cm e/ou invasão extra-tireoidiana e/ou metástases linfonodais e idade >45 anos), com ressecção tumoral completa. Todos foram tratados com tireoidectomia total e ablação com 131I [3,7­5,5 GBq (100­150 mCi)] e foram excluídos 18 casos (14,8 por cento) com metástases na PCI pós-dose (t-PCI). O valor preditivo negativo da Tg estimulada <1 ng/ml combinada ao US cervical na primeira avaliação (6­12 meses após a terapia ablativa) foi de 96,2 por cento para ausência de recidivas em até 5 anos. Este valor aumentou para 98,7 por cento quando acrescentamos a PCI com 185 MBq (5 mCi) 131I (d-PCI). O valor preditivo positivo (VPP) da Tg estimulada >1 ng/ml foi de 52 por cento para presença de metástases detectadas até 5 anos depois, mas considerando apenas pacientes que apresentaram d-PCI e US negativos inicialmente, o VPP foi 19 por cento (9 por cento se Tg 1­10 ng/ml vs. 40 por cento se Tg >10 ng/ml). Tg reduziu espontaneamente nos pacientes com Tg estimulada >1 ng/ml na primeira avaliação, US e d-PCI negativos e sem recidiva no seguimento, sendo indetectável em metade destes ao final de 5 anos. No primeiro ano após a terapia ablativa, 20 pacientes tiveram captação em leito tireoidiano na d-PCI com Tg estimulada e US negativos e não foram tratados com 131I; estes evoluíram sem recidiva e 60 por cento apresentavam uma d-PCI sem nenhuma captação após 5 anos. Em pacientes sem doença aparente (no US e d-PCI) e Tg estimulada <1 ng/ml, a recidiva em 5 anos foi de apenas 1,3 por cento. Um algoritmo para o seguimento de pacientes de alto risco após a terapia inicial é apresentado por este estudo.

This study evaluated the follow-up of high-risk patients with thyroid cancer after initial therapy. A total of 125 high-risk patients (tumor >4 cm and/or extrathyroid invasion and/or lymph node metastases, and age >45 years), with complete resection of the tumor, were selected. All patients underwent total thyroidectomy and ablation with 131I [3.7­5.5 GBq (100-150 mCi)]. Eighteen patients (14.8 percent) presenting metastases on post-dose whole-body scan (RxWBS) were excluded. The negative predictive value of stimulated Tg <1 ng/ml in combination with neck US during first assessment (6­12 mo. after ablative therapy) was 96.2 percent for the absence of recurrence up to 5 years. This value increased to 98.7 percent when adding WBS performed with 185 MBq (5 mCi) 131I (DxWBS). The positive predictive value (PPV) of stimulated Tg >1 ng/ml was 52 percent for the detection of the presence of metastases up to 5 years; however, considering only patients with initially negative DxWBS and US, the PPV was 19 percent (9 percent if Tg of 1­10 ng/ml vs. 40 percent if Tg >10 ng/ml). Tg levels decreased spontaneously in patients with stimulated Tg >1 ng/ml during first assessment, negative US and DxWBS, and no recurrence during follow-up, with Tg being undetectable in half these patients at the end of 5 years. Twenty patients presented uptake in the thyroid bed upon DxWBS during the first year after ablative therapy, with stimulated Tg and US being negative, and were not treated with 131I; these patients did not relapse and no uptake on DxWBS was observed in 60 percent after 5 years. Recurrence after 5 years was only 1.3 percent in patients without apparent disease (negative US and DxWBS) and stimulated Tg <1 ng/ml. An algorithm for the follow-up of high-risk patients after initial therapy is presented in this study.

Seguranca da radioiodoterapia em pacientes com carcinoma de tireóide com menos de 21 anos / Safety of radioiodine therapy in patients with thyroid carcinoma younger than 21 years

Avaliamos 20 pacientes com carcinoma diferenciado de tireóide que receberam radioiodoterapia (dose > 100mCi) antes dos 21 anos: 10 sem metástases distantes receberam uma dose média de 145mCi e 10 com acometimento pulmonar difuso, 270mCi. Após um ano ou mais da terapia ablativa, xerostomia estava presente em dois pacientes sem complicacões mais sérias, como úlceras orais ou fissuras, e a cintilografia com 99mTcO4- confirmou a disfuncão salivar. Um deles apresentava ceratoconjutivite seca. O hemograma não revelou anormalidades atribuíveis à radioiodoterapia. FSH foi normal em 18 deles, e os pacientes com valores elevados haviam recebido radioiodo há pouco mais de um ano e, na repeticão do exame em 6 meses, houve normalizacão. Os seis pacientes masculinos tinham LH e testosterona normais. Nossa avaliacão não revelou sinais de fibrose pulmonar secundária ao tratamento nos 10 casos com metástases captantes neste órgão. Nossos dados sugerem que a terapia ablativa com dose de 100 a 300mCi é segura em jovens, mas complicacões persistentes como disfuncão salivar e conjuntivite podem ocorrer.

Valor da varredura com iodo antes da terapia ablativa em pacientes com carcinoma de tireóide / Usefulness of iodine scanning before ablative therapy in patients with thyroid carcinoma

OBJETIVO: Avaliar a relevância clínica da varredura pré-dose ablativa em pacientes com carcinoma diferenciado de tireóide. MATERIAIS E MÉTODOS: Analisamos a varredura com 131I e a tireoglobulina (Tg) sérica em hipotireoidismo antes da primeira terapia ablativa em 100 pacientes submetidos a tireoidectomia total, considerando a varredura clinicamente importante quando revelou metástases ressecáveis ou que foram tratadas com doses maiores que a inicialmente proposta (100 mCi de 131I), além dos casos sem captação e com Tg < 5 ng/ml, que não receberam radioiodoterapia. RESULTADOS: A varredura revelou captação correspondente a metástases linfonodais em dez pacientes (10 por cento), metástases distantes em cinco (5 por cento), apenas em leito tireoidiano em 76 (76 por cento) e foi negativa em nove (9 por cento), sendo clinicamente relevante (indicando cirurgia, aumento da dose ou dispensando a radioiodoterapia) em 18 por cento dos pacientes. Nos pacientes com Tg > 10 ng/ml a varredura influenciou a conduta em 41 por cento dos casos pela presença de metástases, e naqueles com Tg < 10 ng/ml em apenas 10 por cento, na maioria por não receberem radioiodo. CONCLUSÃO: A varredura pré-dose ablativa fornece informacões clinicamente importantes (presença de metástases) em muitos pacientes com Tg > 10 ng/ml, sendo indicada nesta condição.

TSH recombinante no tratamento e seguimento de pacientes com carcinoma diferenciado de tireóide: uso na prática clínica / Recombinant TSH in ablative therapy and follow-up of patients with differentiated thyroid carcinoma

Os estudos que avaliaram a eficácia e segurança do TSH recombinante no preparo dos pacientes com carcinoma diferenciado de tireóide (CDT) para o tratamento ablativo e no seguimento com tireoglobulina sérica (Tg) e varredura de corpo inteiro com iodo-131 foram revisados neste artigo. No acompanhamento após a terapia inicial, o TSH recombinante é eficaz na geração da Tg e para realização da varredura de corpo inteiro com radioiodo e apresenta vantagens sobre o hipotireoidismo iatrogênico, poupando os pacientes dos sintomas de hipotireoidismo e da piora da qualidade de vida induzida pela suspensão da levotiroxina, resultando em menor exposição a um TSH elevado, e reduzindo o período de afastamento das atividades. TSH recombinante é a forma de preparo indicada para o diagnóstico de metástases, tanto em pacientes de baixo (Tg após TSH recombinante), quanto de moderado ou alto risco (Tg e varredura com iodo-131 após TSH recombinante). Para terapia ablativa, os resultados são promissores com a dose de 100mCi na ablação de remanescentes, mas o hipotireoidismo ainda é preferível, exceto em pacientes que não alcançam a elevação desejada do TSH após a retirada da levotiroxina, com doenças de base que são agravadas pelo hipotireoidismo agudo e severo (cardiopatia e doença pulmonar graves, coronariopatia, função renal comprometida, passado de psicose por mixedema), indivíduos debilitados por doença avançada e idosos. Os estudos também mostram que a administração do TSH recombinante é segura, com poucos efeitos adversos leves ou moderados.

Revisitando a tireoglobulina sérica no seguimento de pacientes com carcinoma diferenciado de tireóide / Revisiting serum thyroglobulin in the follow-up of patients with differentiated thyroid carcinoma

Este estudo avaliou a tireoglobulina (Tg) sérica dosada em hipotireoidismo em 207 pacientes com carcinoma diferenciado de tireóide tratados com tireoidectomia total e ablação com radioiodo e anticorpos anti-Tg indetectáveis. O estadiamento da doença foi definido pelo exame clínico, Tg estimulada, varredura com radioiodo pré e/ou pós-terapia ablativa e outros métodos de imagem (RX, US, TC e varredura com sestamibi). O intervalo médio desde a terapia inicial foi de 2,3 anos. Dos pacientes, 153 (74 por cento) não apresentavam doença evidente, 34 (16,4 por cento) tinham metástases (Mt) cervicais ou mediastinais e 20 (9,6 por cento) Mt distantes. O valor de 1ng/ml da Tg foi o que melhor discriminou pacientes com e sem doença aparente, com 100 por cento de sensibilidade para Mt distantes, 88,2 por cento para doença em leito tireoidiano ou linfonodos e especificidade de 88,8 por cento para Mt de qualquer natureza, e 74,8 por cento considerando apenas Mt distantes. Dos pacientes com Tg <1ng/ml, 2,8 por cento apresentavam Mt cervicais. Doença cervical ou mediastinal representou 26 por cento dos casos com valores de Tg entre 1 e 5ng/ml. Tg entre 5 e 10ng/ml foi associada a Mt distantes em 14,2 por cento dos casos, os demais apresentavam Mt linfonodais. Mt distantes foram diagnosticadas em 51,3 por cento dos pacientes com Tg >10ng/ml. Sugerimos a necessidade de US cervical mesmo em pacientes com Tg <1ng/ml; que pacientes com Tg <5ng/ml sejam investigados apenas com US cervical e TC de mediastino; e que a terapia empírica fique reservada aos casos com Tg no mínimo >5ng/ml.