Abordagem clínica e laboratorial do bócio uninodular sólido: vantagens da determinação da calcitonina sérica por métodos distintos no rastreamento do carcinoma medular de tireóide, forma esporádica

Abstract

RESUMOA apresentação clínica mais freqüente da forma esporádica do carcinoma medular da tireóide (CMT) é o bócio uninodular sólido (BUS), apresentação esta semelhante aos demais tumores que afetam a glândula. O estabelecimento da freqüência de CMT em BUS apresenta implicações importantes não só diagnosticas, como também terapêuticas, visto a abordagem cirúrgica do CMT diferir de outros tumores tireoideanos. Para investigar a prevalência de CMT em BUS, dosamos calcitonina (CT) sérica, marcador bioquímico do CMT, por métodos distntos (RIA e IRMA) em 60 casos (55 mulheres; com idades entre 22 e 75 anos). A análise citológica obtida através de punção biópsia (PAAF) revelou 100% de especificidade e 67% de sensibilidade na detecção de carcinoma de tireóide. Considerando-se o grau de suspeita clínica para neoplasia tireoideana e os achados anatomopatológicos, houve 60% de correlação positiva. CMT foi diagnosticado através da elevação da CT sérica em um dos 59 casos (1,69%) e confirmado posteriormente pela PAAF e anatomopatológico. A incidência de CMT entre os casos de neoplasias tireoideanas nesta amostra foi de 12,5% (1/8). Concluímos que a dosagem rotineira da CT séri-ca em casos com BUS não só complementa o estudo desta doença, como auxilia fortemente no diagnóstico do CMT. Tanto o IRMA como o RIA mostraram-se métodos úteis no rastreamento do CMT. Entretanto, o RIA pode provavelmente detectar ainda mais precocemente a elevação de formas não monoméricas da molécula de CT, as quais nos casos de CMT são usualmente mais abundantes que as formas monoméricas. (Arq Bras Endocrinol Metab 1999;43/2: 104-13).Unitermos: Tireóide; Calcitonina; Bócio uninodular atóxico; Carcinoma medular de tireóide. ABSTRACTSporadic medullary thyroid carcinoma (MTC) usually presents as a single nodule (SNT), a presentation common to other thyroid tumors. The establishment of its frequency in SNT has diagnostic and therapeutic implications, since surgery for MTC differs from other tumors. Serum calcitonin (CT), the standard marker for MTC, were measured in 60 cases of SNT (55 females, 22-75 years of age). Fine needle aspiration biopsy (FNAB) of the nodules was also performed, being 100% specific and 67% sensitive for detecting thyroid carcinomas. Sixty percent of clinically suspected malignancies were confirmed post-surgically. MTC was diagnosed by serum CT in 1 of 59 cases (1.69%), confirmed by FNAB and submitted to appropriate surgery. It accounted for 12.5% of thyroid malignancies of this group, since 6 papillary and 1 undifferentiated cases were also diagnosed. Therefore, routine serum CT measurement in SNT is a strong tool in the diagnosis and adequate surgery of MTC. Both IRMA and RIA were useful in this screening. The latter, however, can detect MTC earlier, due to its ability to measure non-monomeric forms of CT, abundant in this condition. (Arq Bras Endocrinol Metab 1999;43/2: 104-13).

Screening of RET gene mutations in multiple endocrine neoplasia type-2 using Conformation Sensitive Gel Electrophoresis (CSGE)

“…All individuals have been followed at the Outpatient Service of the Division of Endocrinology, Hospital das Clínicas, University of Sao Paulo School of Medicine. Index cases were diagnosed by classical clinical, biochemical, and genetic parameters (2,3,(8)(9)(10)(11)(12)15).…”

“…Several Brazilian studies on MEN2 have been recently published, in which clinical and genetic aspects of MEN2 were extensively reviewed (2)(3)(4)(5)(7)(8)(9)(10)(11)(12)(13)(14). All clinical variants of MEN2 have a high penetrance rate for MTC and most (90%) RET mutation carriers will exhibit evidence for MTC during their lifetime (15).…”

Impact of Ret Proto-Oncogene Analysis on the Clinical Management of Multiple Endocrine Neoplasia Type 2

“…[28][29][30][31][32] At the stage of palpable thyroid nodules, MTC measures at least 1 cm, and 50% of patients already have local neck lymph node metastases and more rarely lung, liver, and bone metastases. 33,34 It has been suggested that routine calcitonin measurements should be performed in all patients with solid thyroid nodules, since this procedure would permit presurgical diagnosis of the sporadic form of MTC as well 35,36 Fine-needle biopsy followed by immunocytochemistry for calcitonin is also helpful for the presurgical diagnosis of MTC. 1,11,12,[37][38][39][40] Total thyroidectomy associated with extensive resection of neck lymph nodes is the only effective treatment for MTC, as the tumor is usually resistant to iodo-, chemo-, and radiotherapy.…”

Diagnóstico laboratorial do carcinoma medular de tiróide: calcitonina basal e testes de estímulo

“…Insuficiência renal pode estar associada a valores elevados de calcitonina em alguns casos e níveis elevados de pró-calcitonina podem levar a reatividade cruzada com a calcitonina a ser dosada (13,22,23). O aumento dos níveis basais de calcitonina em vigência de insuficiência renal é conhecido, e possivelmente está relacionado ao diminuído clearance renal de calcitonina observado nestes pacientes (24).…”