RESUMEN
Thyroidal 99mTc uptake in the acute thyrotoxic phase of subacute thyroiditis (SAT) is always inhibited. However, a patient with SAT had signs in the right-side thyroid gland with transient thyrotoxicosis and slightly high 99mTc uptake levels in the right lobe, low 99mTc uptake in the left lobe, and normal overall uptake. Histological examination showed cellular destruction and granulomatous inflammatory changes in the right lobe, with marked interstitial fibrosis in the left lobe. The patient was thyrotrophin-receptor antibody (TRAb) positive. After a short course of prednisolone, SAT-like symptoms and signs improved. TRAb-positivity resolved spontaneously after 22 months, and TSH levels were slightly low for 22 months. Levels then kept normal in the following four years. In conclusion, high 99mTc uptake by the right lobe was due to the combined effects of TRAb and left thyroid gland fibrosis.
Asunto(s)
Compuestos de Tecnecio/farmacocinética , Glándula Tiroides/metabolismo , Tiroiditis/metabolismo , Adulto , Autoanticuerpos/análisis , Humanos , Masculino , Receptores de Tirotropina/inmunologíaRESUMEN
Thyroidal 99mTc uptake in the acute thyrotoxic phase of subacute thyroiditis (SAT) is always inhibited. However, a patient with SAT had signs in the right-side thyroid gland with transient thyrotoxicosis and slightly high 99mTc uptake levels in the right lobe, low 99mTc uptake in the left lobe, and normal overall uptake. Histological examination showed cellular destruction and granulomatous inflammatory changes in the right lobe, with marked interstitial fibrosis in the left lobe. The patient was thyrotrophin-receptor antibody (TRAb) positive. After a short course of prednisolone, SAT-like symptoms and signs improved. TRAb-positivity resolved spontaneously after 22 months, and TSH levels were slightly low for 22 months. Levels then kept normal in the following four years. In conclusion, high 99mTc uptake by the right lobe was due to the combined effects of TRAb and left thyroid gland fibrosis.
A absorção tiroidiana de 99mTc no estado tirotóxico agudo da tireoidite subaguda (SAT) é sempre inibida. Entretanto, um paciente com SAT apresentou sinais na tiroide direita, com tirotoxicose transitória e níveis levemente elevados de 99mTc no lobo direito, baixa absorção de 99mTc no lobo esquerdo e absorção geral normal. O exame histológico mostrou destruição celular e alterações inflamatórias granulomatosas no lobo direito, com fibrose intersticial marcada no lobo esquerdo. O paciente foi positivo para anticorpos antirreceptores da tireotropina (TRAb). Após um curto tratamento com prednisolona, os sintomas e sinais da SAT melhoraram. A positividade para TRAb foi resolvida espontaneamente em 22 meses. Os níveis de TSH permaneceram levemente baixos por 22 meses e, depois, se mantiveram normais nos quatro anos seguintes. Concluiu-se que a alta absorção de 99mTc pelo lobo direito foi devida à combinação entre TRAb e fibrose da tiroide esquerda.