RESUMO
El cáncer diferenciado de tiroides (CDT) es el cáncer endocrinológico más frecuente y en las últimas décadas su incidencia ha aumentado. El seguimiento de la enfermedad se efectúa con la medición de tiroglobulina (Tg) sérica, ecografía cervical y barrido corporal total diagnóstico. Los métodos de Tg han evolucionado a través del tiempo. Actualmente, los ensayos inmunométricos de Tg se clasifican en 1.ª y 2.ª generación (1.ª G y 2.ª G). Comprobamos que los ensayos de 2.ª G alcanzan una precisión adecuada para medir valores del orden de 0,1 ng/ml y los de 1.ª G de 1 ng/ml. La bibliografía señala que en el caso de los pacientes de bajo riesgo, una Tg bajo levotiroxina indetectable por un método de 2.ª G puede evitar la realización de Tg estimulada, sea por la suspensión de la terapia hormonal como por el empleo de la TSH recombinante humana, debido a su mayor sensibilidad. Sin embargo, por su menor especificidad, un valor detectable no asegura la presencia de enfermedad, y debería confirmarse. Para optimizar la utilidad clínica de dicha medición se podrían emplear valores de cortes de acuerdo con la población y el método en lugar de la sensibilidad funcional o límite de cuantificación del mismo. Se señalan también otros aspectos críticos en la medición de Tg como son la discordancia entre distintas metodologías y las interferencias en su medición, principalmente por anticuerpos antitiroglobulina. En presencia de interferencias pierden utilidad los ensayos de Tg de 1.ª y 2.ª G. El seguimiento de los pacientes con Tg interferida tiene limitaciones todavía no resueltas. Es importante consensuar entre médicos y bioquímicos las dificultades técnicas y los criterios de interpretación de los valores de Tg en el seguimiento de los pacientes con CDT.
Differentiated thyroid cancer (DTC) is the most common endocrine cancer (tumour) and its incidence has risen in the past decades. Its follow-up includes measuring serum thyroglobulin (Tg), performing neck ultrasound and a diagnostic whole-body scan. Tg assays have evolved with time. At present immunoassays for Tg are classified as 1 st and 2 nd generation assays (1 st G and 2 nd G). 2 nd G assays show an adequate (good) precision at levels close to 0.1 ng/ml and 1 st G assays at levels close to 1 ng/ml. The literature shows that for low risk patients on levothyroxine treatment, who undetectable levels by 2 aG assays can avoid the stimulation test performed by thyroid hormone withdrawal or after recombinant human TSH, due to better sensitivity. However, due to lower specificity, detectable levels do not confirm the presence of disease (tumour), and should be confirmed. To optimise the clinical usefulness of the test, cut-off values specific for population and method should be used, instead of functional sensitivity or quantification limit. Critical issues for measuring Tg are discussed, such as non-harmonisation of methods, and interferences, mainly by antithyroglobulin antibodies (ATg). 1 st and 2 nd G assays are less useful in presence of ATg, and follow up of such patients is limited. Consensus between physicians and the laboratory on technical issues and interpretation criteria of Tg values is of outmost importance in the follow-up of DTC patients.
Assuntos
Humanos , Tireoglobulina/análise , Testes de Função Tireóidea/métodos , Neoplasias da Glândula Tireoide/diagnóstico , Sensibilidade e Especificidade , Limite de Detecção , Razão Sinal-RuídoRESUMO
OBJECTIVE: To examine the association between thyroid profile and morbidity/mortality (MM) in hospitalized older patients. DESIGN: This is a retrospective study of patients over the age of 60 yr admitted to the Dr. Cesar Milstein Hospital between 2009 and 2010 and who had thyroid function tests (TFT). The patients were grouped as per their thyroid tests and their clinical characteristics and MM was associated with their TFT. High MM was defined as mortality, intensive care unit (ICU) requirement or prolonged hospital stay (>18 days, 75th percentile), and mortality assessed during an 18-month follow-up period after their hospital discharge. RESULTS: Out of 2599 older patients admitted to our hospital, 7% had TFT performed for various reasons. The patients who had TFT were mostly women and presented in a more serious clinical condition compared to the rest of the patients. The patients were grouped as per their thyroid values as follows: 61% of them had a non-thyroidal illness, 25% were euthyroid,7% had overt hyperthyroidism, 5% overt hypothyroidism and 1% had subclinical hyper- or hypothyroidism. The hypothyroid patients had a worse clinical outcome compared to the others. Patients with increased MM exhibited higher TSH and lower TT4 (p<0.005). Short-term MM (OR=2.0,95%CI=1.1-3.6, p<0.01) was associated with the decrease of TT4 adjusted by age, sex, T3 and TSH, while for long-term MM the increase in TSH (OR=1.6,95%CI 1.1-2.3, p<0.05) was also significant. CONCLUSION: Among hospitalized older patients who had TFT tests, low TT4 and high TSH were associated with a worse prognosis. We propose that TFT be used as an additional tool in assessing MM in elderly hospitalized patients.
