RESUMO
OBJECTIVE: To determine the usefulness of thyroglobulin (Tg) stimulation in low-risk patients with undetectable Tg on T4 and negative neck ultrasound (US) after initial therapy of thyroid carcinoma. METHODS: We evaluated 122 consecutive patients classified as low risk 6 months to 1 year after total thyroidectomy and remnant ablation. All patients had a normal clinical exam, Tg < or = 1 ng/ml during suppressive therapy (TSH < 0.1 mIU/l), and undetectable antithyroglobulin antibodies. RESULTS: After T4 withdrawal and elevation of TSH to values > 30 mIU/l, 26 patients (21.3%) converted Tg to levels > 1 ng/ml. Metastases were detected in 10 patients, nine showing stimulated Tg levels > 1 ng/ml. Cervical metastases were observed in 9/10 patients and lung metastases in one patient. Neck US identified all cervical metastases. Seventeen patients with stimulated Tg levels > 1 ng/ml initially showed no apparent disease, with a reduction in Tg being observed upon subsequent measurements, and 13 patients presented undetectable Tg off T4 at the end of the study. Undetectable Tg on T4 showed a high negative predictive value (NPV; 91.8%), which increased to 99.1% when combined with neck US. Stimulated Tg levels < 1 ng/ml presented a 98.9% NPV. A total of 113 patients with undetectable Tg on T4 and negative US had to be exposed to hypothyroidism in order to diagnose one further case of metastases. CONCLUSION: Undetectable Tg on T4 combined with negative neck US presented a high NPV in low-risk patients and Tg stimulation might be avoided in these patients.
Assuntos
Recidiva Local de Neoplasia/diagnóstico , Tireoglobulina/sangue , Neoplasias da Glândula Tireoide/sangue , Tireotropina , Tiroxina/uso terapêutico , Adulto , Idoso , Anticorpos Monoclonais/sangue , Feminino , Seguimentos , Humanos , Radioisótopos do Iodo/uso terapêutico , Metástase Linfática/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Pescoço , Recidiva Local de Neoplasia/sangue , Recidiva Local de Neoplasia/diagnóstico por imagem , Proteínas Recombinantes , Medição de Risco , Estimulação Química , Tireoglobulina/imunologia , Glândula Tireoide/diagnóstico por imagem , Neoplasias da Glândula Tireoide/diagnóstico por imagem , Neoplasias da Glândula Tireoide/terapia , Tireoidectomia , Ultrassonografia , Contagem Corporal TotalRESUMO
OBJECTIVE: To determine the sensitivity of thyroglobulin (Tg), iodine scanning, and sonography in the diagnosis of cervical recurrence of thyroid cancer. METHODS: This prospective study assessed 81 patients with cervical metastases or extrathyroid invasion at first appearance who underwent clinical examination, scanning, measurement of Tg after thyroxine withdrawal, and sonography about 8 months after thyroidectomy followed by radioiodine treatment. Only patients without distant metastases and without anti-Tg antibodies were included. RESULTS: Fifty patients showed persistence of the disease in the cervical region, with only 16% of them having had a suspicion on clinical examination, 33 with Tg levels of 2 ng/mL or greater (66% sensitivity), and 29 with positive scan findings (58% sensitivity). A combination of the 2 methods detected disease in 40 (80%) of 50 patients but failed to show 20% of cases that were identified by sonography and confirmed by fine-needle aspiration. Sonography had sensitivity of 96%. Specificity values for Tg, iodine scanning, and sonography were 80.6%, 90.3%, and 87%, respectively. CONCLUSIONS: Classic follow-up methods may not detect cervical disease in some patients with differentiated thyroid carcinoma, and sonography is necessary even in patients apparently free of the disease.