Anti-thyroid antibodies: methodological aspects and diagnostic significance

Since the first publication, more than 40 years ago, laboratory tests for the presence of antibodies (Ab) to thyroid antigens (Ag) have played a pivotal position in the diagnosis of thyroid diseases. Thyroid is a common target for autoimmune diseases, hence the interest in the definition of the thyroid Ag that could be involved in the process. The first Ag to be recognized was thyroglobulin, followed by the microsomal Ag, later identified with thyroid peroxidase, the TSH receptor and, more recently, other Ag like the sodium/iodide symporter (NIS). The methodologies employed evolved from the initial hemaglutination assays, to the present use of recombinant Ag, alternative labels and transfected cells. Today the clinical uses of a test to detect the presence of Ab against thyroid Ag are very well defined. The most useful test is the detection of anti-peroxidase Ab, the test with greatest sensitivity and specificity for the presence of autoimmune thyroid diseases. The anti-thyroglobulin test is mandatory as a complement for the measurement of thyroglobulin in the follow-up of patients with differentiated thyroid cancers. The anti-TSH receptor test has its main use in the definition of the presence of Graves disease. Tests for the presence of Ab against other thyroid Ag have no clear indication at the moment. The continuous methodological developments will certainly increase the utility of tests for anti-thyroid Ab.Desde sua descrição, há mais de 40 anos, a pesquisa de anticorpos (Ac) contra antígenos (Ag) tiroideanos tem tido papel importante no diagnóstico da patologia tiroideana. A tiróide é freqüentemente acometida por doenças autoimunes, daí o interesse pela definição dos Ag tiroideanos que podem estar envolvidos no processo. O primeiro Ag reconhecido foi a tireoglobulina, seguido do fator microssomal, mais tarde identificado como a peroxidase tiroideana, o receptor de TSH e mais recentemente outros Ag como o cotransportador de sódio e iodo (sodium/iodide symporter, NIS). As metodologias evoluíram dos ensaios iniciais por hemaglutinação até o emprego atual de Ag recombinantes, marcadores alternativos e células transfectadas. Atualmente as indicações clínicas da pesquisa de Ac anti-tiroideanos são bem definidas, sendo o de maior aplicação a pesquisa de Ac anti-peroxidase, que é o que apresenta maior especificidade e sensibilidade para a definição da presença de doença autoimune tiroideana. A pesquisa de Ac anti-tireoglobulina é fundamental como complemento da dosagem de tireoglobulina no acompanhamento de pacientes com carcinoma diferenciado de tiróide. Já a pesquisa de Ac anti-receptor de TSH tem indicação precisa na definição da presença de doença de Graves. As indicações de pesquisa de Ac contra outros Ag tiroideanos não têm, atualmente, indicações comprovadas. A contínua evolução metodológica deverá aumentar ainda mais as indicações e utilidades da pesquisa de Ac contra Ag tiroideanos.Universidade Federal de São Paulo (UNIFESP) EPM Departamento de MedicinaUNIFESP, EPM, Depto. de MedicinaSciEL

HNF1A gene polymorphisms and cardiovascular risk factors in individuals with late-onset autosomal dominant diabetes: a cross-sectional study

<p>Abstract</p> <p>Background</p> <p>Type 2 diabetes mellitus (T2DM) is a genetically heterogeneous disease, hepatocyte nuclear factor-1 homeobox A (<it>HNF1A</it>) single-nucleotide polymorphisms (SNPs) playing a minor role in its pathogenesis. <it>HNF1A </it>is a frequent cause of monogenic diabetes, albeit with early-onset. Some uncommon subgroups like late-onset autosomal dominant diabetes mellitus (LOADDM) may present peculiar inheritance patterns with a stronger familial component. This study aims to investigate the relationship of <it>HNF1A </it>SNPs with cardiovascular risk factors in this group, as well as to characterize them in contrast with classical T2DM (CT2DM).</p> <p>Methods</p> <p>eighteen LOADDM (age at onset > 40 y.o.; diabetes in 3 contiguous generations, uniparental lineage) along with 48 CT2DM patients and 42 normoglycemic controls (N group) have been evaluated for cardiovascular risk factors and SNPs of <it>HNF1A</it>.</p> <p>Results</p> <p>LOADDM showed significantly higher frequencies of SNPs A98V (22.2% vs 2.1%, p = 0.02) and S487N (72.2% vs 43.8%, p = 0.049) of <it>HNF1A </it>compared to CT2DM. I27L did not show significant difference (66.7% vs 45.8%), but associated with lower risk of hypertriglyceridemia (OR 0.16, 95% CI 0.04–0.65, p = 0.01). "Protective effect" was independent from other well-known predictive risk factors for hypertriglyceridemia, such as waist circumference (OR 1.09 per 1 cm increase, p = 0.01) and HDL (OR 0.01 per 1 mmol/l, p = 0.005), after logistic regression.</p> <p>Conclusion</p> <p>Late onset autosomal dominant diabetes mellitus is clinically indistinguishable from classical type 2 diabetes individuals. However, LOADDM group is enriched for common <it>HNF1A </it>polymorphisms A98V and S487N. I27L showed "protective effect" upon hypertriglyceridemia in this sample of individuals, suggesting a role for <it>HNF1A </it>on diabetic individuals' lipid profile. These data contribute to the understanding of the complex interactions between genes, hyperglycemia and cardiovascular risk factors development in type 2 diabetes mellitus.</p

Desenvolvimento, caracterização e validação clínica de um novo ensaio sensível para a dosagem da tiroglobulina sérica

OBJECTIVE: In the last decade, data published stressed the role of highly-sensitive thyroglobulin (Tg) assays in the follow-up of differentiated thyroid carcinoma (DTC) patients. The present study describes a new, highly-sensitive Tg assay, compares it with an available commercial assay, and validates it in the follow-up of DTC patients. SUBJECTS AND METHODS: The immunofluorometric high-sensitivity Tg assay is based on monoclonal and polyclonal antibodies produced at our laboratories. It was validated in 100 samples of 87 patients with DTC submitted to total thyroidectomy, 87% of whom also received radioiodine. For correlation, all samples were also tested using a commercial Tg assay (Beckman Access) with functional sensitivity (FS) of 0.1 ng/mL. RESULTS: The new method showed FS of 0.3 ng/mL. The correlation between the two methods was good (r = 0.74; p < 0.0001). The diagnostic sensitivity was 88.9%, and it was increased to 100% when combined with neck US. CONCLUSION: This new, high-sensitivity Tg assay presented a good correlation with Beckman Access assay and with the clinical outcome of the patients. The continuous availability of a validated assay is an additional advantage for long term follow-up of DTC patients. Arq Bras Endocrinol Metab. 2012;56(9):658-65OBJETIVO: Na última década, estudos mostraram a importância dos ensaios de tiroglobulina (Tg) com melhor sensibilidade funcional no seguimento dos pacientes com carcinoma diferenciado de tiroide (CDT). Neste estudo, descrevemos o desenvolvimento de um novo ensaio de Tg de alta sensibilidade, que foi validado no seguimento de pacientes com CDT e correlacionado com um ensaio comercialmente disponível. SUJEITOS E MÉTODOS: O ensaio imunofluorométrico de Tg baseia-se em anticorpos, um monoclonal e um policlonal desenvolvidos em nosso laboratório. Avaliamos 100 amostras de soro de 87 pacientes com CDT submetidos à tiroidectomia total, sendo que 87% deles também receberam 131I. A Tg foi dosada também em ensaio comercial (Beckman Access). RESULTADOS: A correlação entre os dois métodos foi de 0,74 (p < 0,0001). O novo ensaio mostrou uma sensibilidade funcional de 0,3 ng/mL. A sensibilidade diagnóstica foi de 88,9%, que aumentou para 100% quando associada ao ultrassom cervical (US). CONCLUSÃO: O novo método de dosagem de Tg mostra boa correlação com o ensaio comercial Beckman Access e com a evolução clínica dos pacientes. O novo ensaio será fundamental no seguimento dos nossos pacientes com CDT. Arq Bras Endocrinol Metab. 2012;56(9):658-65Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Universidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de MedicinaUNIFESP, EPM, Depto. de MedicinaSciEL

Macrocalcitonin Is a Novel Pitfall in the Routine of Serum Calcitonin Immunoassay

Context: Calcitonin (CT) is a sensitive marker of medullary thyroid carcinoma (MTC) and is used for primary diagnosis and follow-up after thyroidectomy. However, persistently elevated CT is observed even after complete surgical removal without evidence of a recurrent or persistent tumor. Objective: To investigate the presence of assay interference in the serum CT of MTC patients who are apparently without a structural disease. Patients and Methods: We studied three index MTC cases for CT assay interference and 14 patients with metastatic MTC. The CT level was measured using an immunofluorometric assay. Screening for assay interference was performed by determination of CT levels before and after serum treatment with polyethylene glycol. Additionally, samples were analyzed by chromatography on ultra-performance liquid chromatography and protein A-Sepharose. Results: Patients with biochemical and structural disease showed CT mean recovery of 84.1% after polyethylene glycol treatment, whereas patients suspected of interference showed recovery from 2-7%. The elution profile on UPLC showed that the immunometric CT from these three patients behaved like a high molecular mass aggregate (>300 kDa). Additionally, when these samples were applied to the protein A-Sepharose, CT immunoreactivity was retained on the column and was only released after lowering the pH. Conclusions: For the first time, our results show the presence of a novel pitfall in the CT immunoassay: "macrocalcitonin." Its etiology, frequency, and meaning remain to be defined, but its recognition is of interest and can help clinicians avoid unnecessary diagnostic investigations and treatment during the follow-up of MTC.Sao Paulo State Research Foundation-FAPESPFAPESPFederal Agency of Support and Evaluation of Postgraduate Education (Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior)National Council for Scientific and Technological DevelopmentUniv Fed Sao Paulo, Escola Paulista Med, Div Endocrinol, Dept Med,Thyroid Dis Ctr, BR-04039032 Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Escola Paulista Med, Div Endocrinol, Dept Med,Lab Mol & Translat Endocrinol, BR-04039032 Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Escola Paulista Med, Dept Biochem, Div Mol Biol, BR-04044020 Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Escola Paulista Med, Div Endocrinol, Dept Med,Thyroid Dis Ctr, BR-04039032 Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Escola Paulista Med, Div Endocrinol, Dept Med,Lab Mol & Translat Endocrinol, BR-04039032 Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Escola Paulista Med, Dept Biochem, Div Mol Biol, BR-04044020 Sao Paulo, SP, BrazilFAPESP: 2006/60402-1FAPESP: 2010/51547-1FAPESP: 2010/19478Web of Scienc

Low iodine diet does not improve the efficacy of radioiodine for the treatment of Graves&apos; disease

ABSTRACT Objective: Consuming a low-iodine diet (LID) is a widely accepted practice before administering radioiodine ( 131 I) to evaluate and to treat thyroid disease. Although this procedure is well established for the management of patients with differentiated thyroid cancer, its use in patients with benign disease is unclear. So, we aimed to evaluate the influence of a LID on the outcome in patients with Graves&apos; disease (GD) treated with 131 I. Subjects and methods: We evaluated 67 patients with GD who were divided into 2 groups: one group (n = 31) consumed a LID for 1-2 weeks, and the second group (n = 36) was instructed to maintain a regular diet (RD). Results: The LID group experienced a 23% decrease in urinary iodine after 1 week on the diet and a significant 42% decrease after 2 weeks on the diet. The majority (53%) of the patients in the LID group had urinary iodine levels that were consistent with deficient iodine intake. However, there was no difference in the rate of hyperthyroidism&apos;s cure between the LID and the RD groups 6 months after 131 I therapy. Furthermore, the therapeutic efficacy did not differ in patients with varying degrees of sufficient iodine intake (corresponding urinary iodine levels: &lt; 10 μg/dL is deficient; 10-29.9 μg/dL is sufficient; and &gt; 30 μg/dL is excessive). Conclusion: In the present study, we demonstrated that although a LID decreased urinary iodine levels, those levels corresponding with sufficient or a mild excess in iodine intake did not compromise the therapeutic efficacy of 131 I for the treatment of GD. Arch Endocrinol Metab. 2015;59(6):501-