Undetectable pre-ablation thyroglobulin levels in patients with differentiated thyroid cancer: it is not always what it seems / Níveis indetectáveis de tireoglobulina pré-ablação em pacientes com câncer de tireoide: nem sempre é o que parece

OBJECTIVE: To establish the frequency of U Tg (undetectable pre-ablation thyroglobulin) in TgAb- negative patients and to evaluate the outcome in the follow-up. SUBJECTS AND METHODS: We retrospectively reviewed 335 patients' records. Twenty eight patients (9%) had U Tg. Mean follow-up was 42 ± 38 months. All subjects had undergone total thyroidectomy, and lymph nodes were positive in 13 (46%) patients. Tg and TgAb levels were measured 4 weeks after surgery by IMA technology in hypothyroid state. No evidence of disease (NED) status was defined as undetectable (< 1 ng/mL) stimulated Tg and negative Tg-Ab and/or negative WBS, together with normal imaging studies. RESULTS: Seventeen patients (61%) were considered with NED. Four patients (14%) had persistent disease (mediastinum, n = 1, lung n = 2, unknown n = 1), and 7 (25%) had detectable TgAb by other method during their follow-up. CONCLUSIONS: U Tg levels usually is associated to a complete surgery. However, in a low percentage of patients, this may be related to false negative Tg or TgAb measurement.

OBJETIVO: Estabelecer a frequência de U Tg (tireoglobulina indetectável pré-ablação) em pacientes com TgAb negativo e avaliar o prognóstico no seguimento. SUJEITOS E MÉTODOS: Foram analisados retrospectivamente 335 registros de pacientes. Vinte e oito pacientes (9%) tiveram U Tg. O acompanhamento médio foi de 42 ± 38 meses. Todos os participantes receberam uma tireoidectomia total, e os linfonodos foram positivos em 13 (46%) pacientes. Tg e TgAb foram medidos quatro semanas após a cirurgia pelo método IMA em estado de hipotireoidismo. A não evidência de doença (NED) foi definida como níveis indetectáveis (<1 ng/mL) de Tg estimulada com anticorpos anti-Tg negativos e/ou PCI negativo, com estudos de imagem normais. RESULTADOS: Dezessete pacientes (61%) foram considerados com NED. Quatro pacientes (14%) tiveram doença persistente (mediastino, n = 1, pulmão n = 2, n = desconhecido 1), e 7 (25%) apresentavam anticorpos anti-Tg detectáveis por outro método durante acompanhamento. CONCLUSÕES: U Tg geralmente indica uma cirurgia completa. No entanto, em uma pequena porcentagem de pacientes, pode estar relacionada com uma medida de Tg ou de anticorpos anti-Tg falsamente negativos.

Prospective Observation of 5-Year Clinical Course of Subclinical Hypothyroidism in Korean Population

Subclinical hypothyroidism (SCH) is a common clinical condition, whereas it's natural course has not been identified distinctly. We evaluated the natural history of 169 SCH patients over 5-yr and the prognostic factors including thyroid autoantibodies and thyroid ultrasonographic (USG) findings related to develop overt hypothyroidism. After 5 yr, 47.3% of patients showed normalization of TSH, while 36.7% of patients remained persistence of high level of TSH, and overt hypothyroidism developed in 11.2% of patients. There were painless thyroiditis (2.9%) and hyperthyroidism (1.7%) during 5 yr follow-up. The thyroid nodule was seen in 48.6% of patients. Most of patients had 1 to 2 nodules whereas only 3% of patients with thyroid nodule had more than 6 nodules. Overt hypothyroidism patients had more heterogenous echogenecity in USG compared to patients with normalization or persistent SCH (76.5% vs 50.0% vs 35.0%, P = 0.048) and higher prevalence positive anti-thyroid peroxidase (anti-TPO Ab) and anti-thyroglobulin antibody (anti-Tg Ab) and titer of anti-TPO Ab than other two groups. The cut off values for prediction of overt hypothyroidism were TSH > 7.45 microIU/mL, free T4 560 IU/mL. SCH has various courses and initial TSH, free T4, presence of thyroid autoantibody, titer of thyroid autoantibody; and thyroid USG findings can serve as a prognostic factor for progression of overt hypothyroidism. These parameters suggest consideration to initiate thyroid hormone treatment in SCH.

Does undetectable basal Tg measured with a highly sensitive assay in the absence of antibodies and combined with normal ultrasonography ensure the absence of disease in patients treated for thyroid carcinoma? / Tireoglobulina basal indetectável medida com ensaio ultrassensível na ausência de anticorpos e combinada com ultrassonografia normal assegura ausência de doença em pacientes tratados de câncer de tireoide?

It has been proposed that, in patients treated for well-differentiated thyroid carcinoma, undetectable basal thyroglobulin (Tg) levels measured with a highly sensitive assay in the absence of anti-thyroglobulin antibodies (TgAb) and combined with negative neck ultrasonography (US) ensured the absence of disease. We report a series of five patients with well-differentiated (papillary) carcinoma submitted to total thyroidectomy with apparently complete tumor resection, followed by remnant ablation with 131I (100-150 mCi), who had no distant metastases upon initial post-therapy whole-body scanning. When tumor recurrence or persistence was detected, these patients presented undetectable basal Tg (0.1 ng/mL) in the absence of TgAb, and US showed no anomalies. Two patients had lymph node metastases, one had mediastinal metastases, bone involvement was observed in one patient, and local recurrence in one. We conclude that further studies are needed to define in which patients undetectable basal Tg (negative TgAb) combined with negative US is sufficient, and no additional tests are required.

Tem sido proposto que em pacientes tratados de carcinoma bem diferenciado da tireoide o encontro de valores basais indetectáveis de tireoglobulina (Tg), dosada por ensaios ultrassensíveis, na ausência de anticorpos antitireoglobulina (TgAc), e combinado à ultrassonografia (US) cervical negativa, asseguraria ausência de doença. Reportamos aqui uma série de cinco pacientes com carcinoma bem diferenciado (papilífero), submetidos à tireoidectomia total, com ressecção tumoral aparentemente completa, seguida da ablação de remanescentes com 131I (100-150 mCi), sem metástases distantes na pesquisa de corpo inteiro pós-dose inicial, que, na ocasião em que a recorrência ou persistência tumoral foi detectada, apresentavam Tg basal indetectável (0.1 ng/ml), TgAc negativos e US sem anormalidades. Dois pacientes tinham metástases linfonodais, um tinha mediastinal, outro acometimento ósseo e um recorrência local. Concluímos que mais estudos são necessários para a definição de que pacientes com Tg basal indetectável (sem TgAc) combinada à US sem anormalidades seria suficiente, dispensando testes adicionais.

Prevalência de disfunção tireoidiana e anticorpos antitireoidianos em pacientes portadores de diabetes melito tipo 1 e em seus familiares de primeiro grau / Prevalence of thyroid dysfunction and antithyroid antibodies in type 1 diabetic mellitus patients and their first degree relatives

O diabetes melito tipo 1 (DM1) freqüentemente encontra-se associado à doença auto-imune da tireóide (DAT). A prevalência de DAT varia de 3 por cento a 50 por cento entre diabéticos, e é maior também entre seus familiares, comparada à população geral. OBJETIVOS: Investigar a prevalência da DAT em pacientes com DM1, avaliar possíveis diferenças de comportamento clínico-evolutivo do DM1 entre diabéticos com e sem DAT e estudar a prevalência de DAT nos familiares dos pacientes diabéticos. MATERIAIS E MÉTODOS: Os prontuários de 124 diabéticos tipo 1 foram revisados e coletados os dados referentes à função e aos anticorpos tireoidianos; pacientes com e sem DAT foram comparados em relação à média de Hb glicosilada, complicações agudas e crônicas, idade ao diagnóstico e tempo de evolução do DM, dose de insulina e outros. Um estudo caso-controle foi realizado com 54 familiares em primeiro grau destes pacientes; foram avaliadas a função tireoidiana e a presença de anticorpos antitireoidianos em 32 familiares de diabéticos sem DAT e 22 familiares de diabéticos com DAT. RESULTADOS: As prevalências de DAT e de disfunção hormonal entre os diabéticos foram de 35,5 por cento e 19,3 por cento, respectivamente. Quanto à avaliação dos parâmetros de evolução do DM1, comportamento clínico e controle metabólico não houve diferenças significantes entre os diabéticos com e sem DAT. Houve maior prevalência de DAT nos familiares de diabéticos com DAT do que no grupo dos familiares dos diabéticos sem DAT, sem diferença significativa quanto à prevalência de disfunção hormonal. CONCLUSÕES: A prevalência de doença auto-imune de tireóide em diabéticos e em seus familiares é elevada, justificando-se, nesses casos, a investigação rotineira da função tireoidiana, particularmente dos familiares de primeiro grau de diabéticos com DAT.

Diabetes Mellius Type 1 (DM1) is frequently associated to Autoimmune Thyroid Disease (AITD). The prevalence of AITD among diabetic patients varies between 3 to 50 percent and the incidence is also big among their family members, when compared to the population in general. OBJECTIVES: To investigate the prevalence of AITD in patients with DM1; to evaluate possible differences concerning the clinical-evolutive behavior of DM1 among diabetic patients with or without AITD and to study the prevalence of AITD among the diabetes patients' relatives. MATERIALS AND METHODS: 124 prontuaries of diabetic patients (type 1) were revised and data was gathered concerning the thyroid function and the anti-thyroid antibodies. Patients with and without AITD were compared in relation to the level of glycosylated hemoglobin, the presence of acute and chronic complications, the age of the patient at the time of the diagnosis, time of evolution of the disease, daily dose of insulin and other factors. A control case study was conducted with 54 first degree relatives of the diabetic patients who took part in the study; the thyroid function as well as the presence of anti-thyroid antibodies were evaluated in 32 of those first degree relatives with AITD, and in 22 of those without AITD. RESULTS: The prevalence of AITD and of hormonal dysfunction among diabetic patients was 35.5 percent and 19.3 percent, respectively. No significant differences were found between groups in respect to clinical outcome or to diabetic chronic complications. However, prevalence of AITD and hormonal dysfunction were found to be higher among first degree relatives of diabetic patients with AITD than among relatives of diabetic patients without AITD. CONCLUSIONS: The prevalence of autoimmune thyroid disease in diabetic patients and in their first degree relatives is high. Thyroid function screening is therefore justified in these cases, especially in first degree relatives of diabetics ...

Avaliação da associação entre doença auto-imune de tireóide e urticária crônica idiopática / Assessment of association between autoimmune thyroid disease and chronic urticaria

Vários estudos encontraram maior prevalência de Doença Auto-imune de Tireóide (DAT) em pacientes com Urticária Crônica (UC). Essa relação pode ocorrer devido à possível etiologia auto-imune em até um terço dos casos de Urticária Crônica Idiopática (UCI). No entanto, a freqüência de DAT variou de 1,14 por cento a 28,6 por cento. O princípio deste estudo foi determinar se ocorre associação entre DAT e UCI em uma população atendida em um mesmo centro de saúde. Comparamos a freqüência de anticorpos anti-tireoidianos e disfunção tireoidiana entre 49 pacientes com UCI (grupo 1) e 112 controles (grupo 2). Com a finalidade de fortalecer o resultado encontrado, estudamos a prevalência de UCI em 60 pacientes com DAT (grupo 3) comparados com 29 com doença não auto-imune de tireóide (DNAT) (grupo 4). Não encontramos diferença estatística quanto à presença de anticorpos anti-tireoidianos ou disfunção tireoidiana entre os grupos 1 e 2 (12,24 por cento x 9,82 por cento e 12,24 por cento x 7,14 por cento, respectivamente). O mesmo ocorreu quanto à presença de UCI entre os grupos 3 e 4 (3,33 por cento x 3,44 por cento). Em nosso estudo não foi possível demonstrar uma relação entre DAT e UCI, o que significa que diferentes populações podem apresentar maior ou menor grau de associação entre essas doenças.

Several studies found a higher prevalence of Autoimmune Thyroid Disease (ATD) in patients with Chronic Urticaria (CU). This relationship may be due to the possible autoimmune etiology in up to one third of the cases of Chronic Idiopathic Urticaria (CIU). However, the frequency of ATD ranged from 1.14 percent to 28.6 percent. The study began by determining whether there is an association between ATD and CU, in a population seen at the same clinic. We compared the frequency of anti-thyroid antibodies and thyroid dysfunction in 49 patients with CIU (group 1) and 112 controls (group 2). In order to support the result found, we studied the prevalence of CIU in 60 patients with ATD (group 3) and compared with 29 patients who had non-immune thyroid disease (NITD) (group 4). We did not find a statistical difference for the presence of anti-thyroid antibodies or thyroid dysfunction between groups 1 and 2 (12.24 percent x 9.82 percent and 12.24 percent x 7.14 percent, respectively). The same occurred for the presence of CIU among groups 3 and 4 (3.33 percent x 3.44 percent). In our study it was not possible to demonstrate a relationship between ATD and CIU, which means that different populations may present a higher or lower degree of association between these illnesses.

Quantificação de anticorpos antitireoperoxidase e antitireoglobulina, tireotrofina e tiroxina livre em gestantes normais / Quantification of antithyroperoxidase and antithyroglobulin antibodies, and thyrotrophin and free thyroxine in normal pregnant women

OBJETIVO: verificar a presença de anticorpos antitireoperoxidase (anti-TPO) e antitireoglobulina (anti-TG) e as concentrações plasmáticas de tireotrofina (TSH) e tiroxina livre (T4L) em gestantes normais. MÉTODOS: estudo transversal realizado no ambulatório de Pré-Natal da Santa Casa de Misericórdia de São Paulo (SP), no período de janeiro de 2003 a setembro de 2004. Foram incluídas 127 grávidas, residentes em São Paulo, com idades entre 14 e 44 anos e idade gestacional igual ou superior a 16 semanas, determinada por ultra-sonografia realizada antes da 20ª semana de gestação. Foram excluídas gestantes em uso de medicamentos ou história de tireoidopatia. Foram quantificados os anticorpos antitireoperoxidase e antitireoglobulina por imunoensaio quimioluminescente. A técnica de imunofluorimetria por tempo resolvido foi empregada para a determinação de tireotrofina e tiroxina livre. Para análise dos resultados, aplicou-se o teste t de Student, com significância de 5 por cento. RESULTADOS: a freqüência dos anticorpos antitireoidianos foi 12,6 por cento (8,6 por cento de anticorpos anti-TPO, 4,6 por cento de anticorpos anti-TG). A média das concentrações de TSH foi de 2,1±1,0 µU/mL e a média de T4L foi de 0,9±0,5 ng/dL. Observou-se alteração da função tireoidiana em dez gestantes (8 por cento). Três delas tiveram diagnóstico de hipotireoidismo: uma na forma clínica da doença, com TSH aumentado e T4L diminuído; duas na forma subclínica, com TSH aumentado e T4L normal. Cinco mostraram valores de TSH diminuídos e de T4L aumentados, compatíveis com hipertireoidismo clínico, e duas tiveram diagnosticado hipertireoidismo subclínico, apenas com concentrações de TSH diminuídas. CONCLUSÕES: a freqüência de anticorpos antitireoidianos foi de 12,6 por cento em gestantes, sendo os anticorpos antitireoperoxidase predominantes sobre os anticorpos antitireoglobulina. Verificaram-se disfunções da tireóide em 8 por cento dos casos, com alterações...

PURPOSE: to quantify the presence of antithyroperoxidase (anti-TPO) and antithyroglobulin (anti-TG) antibodies, and the plasmatic concentrations of thyrotropin (TSH) and free thyroxine (FT4) in normal pregnant women. METHODS: a hundred twenty-seven pregnant women, residing in São Paulo, aged from 14 to 44 years old and gestational age > 16 weeks, determined by ultrasound performed before the 20th week of pregnancy were included in a transversal study performed in the prenatal clinic of Santa Casa de Misericórdia de São Paulo, from January 2003 to September 2004. Pregnant women using medicines or with thyroidopathy history were excluded. Antithyroperoxidase and antithyroglobulin antibodies were quantified by chemiluminescence immunoassay. The immunofluorimetry technique by time-resolved was used for determining the thyrotrophin and free thyroxine. The Student's t test, with significance of 5 percent, was used for analyzing the results. RESULTS: the frequency of antithyroid antibodies was 12.6 percent (8.6 percent of anti-TPO antibodies, and 4.6 percent of anti-TG antibodies). The average of TSH concentrations was 2.13±1.0 µU/ml, and the average of T4L was 0.9±0.5 ng/dl. It was observed alteration of the thyroid function in ten pregnant women (8 percent). Three of them had diagnosis of hypothyroidism: one in the clinical form of the disease, with increased TSH and decreased FT4; two in the subclinical form with increased TSH and normal FT4. Five presented decreased TSH and increased FT4, consistent with clinical hyperthyroidism and two were diagnosed with subclinical hyperthyroidism, with decreased TSH concentrations only. CONCLUSIONS: the frequency of antithyroid antibodies was 12.6 percent in pregnant women, the antithyroperoxidase antibodies being predominant over the antithyroglobulin antibodies. It was observed some thyroid dysfunction in 8 percent of the cases with alterations of TSH and/or T4L.

Hipotiroidismo congênito transitório: perfil das crianças identificadas no programa estadual de triagem neonatal de Minas Gerais, Brasil / Congenital transient hypothyroidism: characteristics of children identified at newborn screening program of the state of Minas Gerais, Brazil

O diagnóstico e o tratamento precoces do hipotiroidismo congênito (HC) constituem os principais objetivos dos programas de triagem neonatal. Neste estudo avaliou-se o perfil hormonal e os possíveis fatores responsáveis pelo HC transitório (HCT). Os dados foram colhidos dos prontuários das crianças acompanhadas no Hospital das Clínicas da UFMG, triadas pelo Programa Estadual de Triagem Neonatal de Minas Gerais. Para o diagnóstico de HCT considerou-se: exames de triagem e sérico confirmatório alterados; TSH e T4 livre normais em 4 e 8 semanas após suspensão do tratamento hormonal para avaliação etiológica. As 21 crianças com HCT representavam 4,23 por cento das crianças acompanhadas pelo Programa e receberam tratamento com L-tiroxina por um mês a três anos. Os valores de TSH no primeiro exame sérico variaram de 10,4 a 583,4æUI/ml, não se correlacionando, portanto, à gravidade da doença. Possivelmente a presença de anticorpos maternos em duas crianças, anti-TPO (anticorpo anti-tireoperoxidase) em uma e o anticorpo anti-receptor de TSH associado à exposição ao iodo em outra foram responsáveis pelo hipotiroidismo. Concluímos que o HCT é uma entidade importante na triagem neonatal, sendo essencial o tratamento hormonal nos primeiros meses de vida e que os níveis iniciais de TSH não são úteis para definir se a disfunção tiroidiana será transitória ou permanente.

Antithyroglobulin antibodies in patients with differentiated thyroid carcinoma: methods of detection, interference with serum thyroglobulin measurement and clinical significance

Anticorpos anti-tireoglobulina (TgAb) foram medidos por um imunoensaio de quimioluminescência (ICMA) e um teste de aglutinação. Avaliamos a interferência clínica e laboratorial dos TgAb com as medidas de Tg. A evolução da concentração dos TgAb e o estado da doença foram comparados durante 3 anos após o início do tratamento. O teste de aglutinação falhou em detectar todos o títulos <10UI/mL (ICMA). Interferência dos TgAb foi comum com títulos altos, mas mesmo títulos baixos dos anticorpos (<5UI/mL) interferiram na medida de Tg. Casos com metástases à distância e Tg indetectável (por IRMA) e aqueles aparentemente livres da doença e sem remanescentes tireoidenos com Tg >2ng/ml (por RIA) foram identificados entre pacientes com TgAb. O teste de recuperação da Tg exógena foi normal (>80%) por ambos os métodos em 22% dos pacientes com TgAb, confirmando a interferência laboratorial. Ausência de redução dos níveis de TgAb foi um marcador de persistência da doença. Em conclusão, TgAb deve ser determinada por imunoensaios; interferência com as medidas de Tg ocorreram principalmente mas não somente em altas concentrações, com um teste normal de recuperação de Tg não excluindo esta interferência. O comportamento dos TgAb está relacionado à persistência ou à cura da doença.

Localization of radiolabeled monoclonal antibodies in thyroid tumor xenografts.

Monoclonal antibodies to human thyroglobulin were produced using the hybridoma technique. Two monoclonal antibodies D5I and F9I were radiolabeled with 125I and used for radioimmunolocalization studies in an immunosuppressed animal model bearing xenografts of human thyroid tumor tissue. Biodistribution studies were carried out at various time intervals post-injection. Maximum tumor uptake was obtained at 72 hr after administration of the antibodies. The absolute tumor uptake (ATU) expressed as percentage of injected dose per gram of tissue (% ID/g) was 15.49 +/- 2.47, 4.51 +/- 0.69 and 2.50 +/- 0.41 for D5I, F9I and control Igs respectively. The tumor to blood ratios (T/B) obtained were 3.01 +/- 0.43 for D5I, 0.98+/-0.2 for F9I and 0.47 +/- 0.12 for control Igs. ATU as well as T/B ratio obtained with D5I was significantly higher as compared to F9I and control Igs. The results indicated the potential application of radiolabeled monoclonal antibodies to human thyroglobulin for tumor targetting in patients of differentiated thyroid carcinoma, particularly those metastases which did not concentrate radioiodine.

Frequency and clinical Importance of Anti - TG auto antibodies [ATG]

To note the frequency of anti thyroglobulin autoantibodies [ATG] and its clinical importance in 25 follow-up cases of differentiated thyroid cancer [DTC]. Design: A case control study. Place and Duration of Study: The total duration of study was one year [September 2000 to August 2001]. Majority of the patients included were the routine follow-up cases at IRNUM, Peshawar. However, few of the cases were also included from NORI, Islamabad and AFIP, Rawalpindi. Subjects and All the patients who had undergone sub-total or total thyroidectomy followed by I-131 ablation therapy were selected for this study. Thyroglobulin [Tg] and ATG were measured using immunometric assay technique with reference range of non-detectable to 40 IU/L. Patients with serum Tg level ' 10 ng/mL were included in group-1 [n=15] and all the remaining [n=10] in group-2. Overall, 11 patients showed ATG titer above the pre-defined threshold level. In group -1 patients, 8 had positive anti-Tg antibodies in their sera while in group-2, it was positive in only 3 cases. Risk of relapsing metastatic/recurrent disease in association with ATG was calculated which showed that patients with positive ATG have almost seven - fold increased risk of having recurrent/metastatic disease than those who do not. Samples for s-Tg measurements must also be evaluated for ATG status because more than one-third of these patients have positive ATG titer in their sera. Although in the presence of positive ATG, the risk of concurrent metastatic/recurrent thyroid disease is increased but still more studies are required to support its significance

Prevalence of thyroid microsomal and thyroglobulin autoantibodies in goitrous lesions

This prospective study was done to evaluate the serum levels of Microsomal and Thyroglobulin autoantibodies in patients with toxic diffuse goiter and nodular goitre [non-toxic] undergoing radio-iodine therapy and thyroidectomy respectively. Forty eight patients suffering from thyroid disorders, 29 with nodular goiter and 19 with toxic diffuse goitre [TDG] and 15 age and sex-matched normal controls were studied. Thyroid microsomal [MSAb] and thyroglobulin autoantibodies [TGAb] were estimated in the sera of all the subjects using the commercially available kits based on tanned red cell hemaglutination technique. MSAb seropositivity in TDG and nodular goitre was found to be 78.9% and 51.7% respectively. On the other hand, TGAb seropositivity was 57.9% and 27.6% in cases of TDG and nodular goitre. 13.3% and 6.7% of the normal controls were positive for MSAb and TGAb respectively. These findings indicate that autoimmunity is implicated in the genesis of commonly occurring thyroid disorders

Autoanticuerpos anti-tiroglobulina: detección y posible interferencia en la medición de tiroglobulina en suero / Thyroglobulin autoantibodies: detection and possible interference in serum thyroglobulin measurement

Background: Thyroglobulin measurement is useful for the follow up of patients subjected to total thyroidectomy for differentiated thyroid carcinoma. Thyroglobulin autoantibodies may interfere with its determination. Aim: To measure thyroglobulin autoantibodies and their interference with thyroglobulin determination. Material and methods: The presence of thyroglobulin autoantibodies was investigated in 801 serum samples sent to the laboratory for measurement of thyroglobulin levels. A serum was considered positive for these autoantibodies when radioactivity corresponding to 125I-thyroglobulin bound to thyroglobulin autoantibodies, precipitated with human gamma globulin, exceeded in 1.4 times that of a negative sera pool. In positive sera, thyroglobulin autoantibody concentration was measured and its interference with thyroglobulin radioimmunoassay was assessed through a recuperation test using exogenous thyroglobulin. Results: Thyroglobulin autoantibodies were detected in 149 sera (18.6 percent). Of these, 65 had a recuperation that fluctuated between 1 and 80 percent. Thyroglobulin autoantibody concentration was negatively correlated with recuperation percentages (r= -0.64; p <0.001) but not with thyroglobulin concentrations (r= 0.08). Thyroglobulin was higher in positive sera with a recuperation over 80 percent than in sera with a recuperation of less than 80 percent (12.7 ñ 1.7 and 5.9 ñ 0.6 ng/ml, respectively; p <0.001). Conclusions: Thyroglobulin autoantibodies interfere with thyroglobulin measurement by radioimmunoassay, sequestering variable amounts of thyroglobulin. The presence of these autoantibodies must be investigated prior to thyroglobulin determination

Reactivity of anti-thyroid antibodies to thyroglobulin tryptic fragments: comparison of autoimmune and non-autoimmune thyroid diseases

Studies concerning the antigenicity of thyroglobulin fragments allow the characterization of the epitopes but do not consider the role of heavier antigenic fragments that could result in vivo from the action of endoproteases. Here we assess the relative importance of the fragments obtained from thyroglobulin by limited proteolysis with trypsin and compare by immunoblotting their reactivity to serum from patients with autoimmune (Graves' disease and Hashimoto's thyroiditis) and non-autoimmune (subacute thyroiditis) disease. The results showed no difference in frequency of recognition of any peptide by sera from patients with autoimmune thyroiditis. In contrast, sera from patients with subacute thyroiditis reacted more frequently with a peptide of 80 kDa. These results suggest the presence of antibody subpopulations directed at fragments produced in vivo by enzymatic cleavage of thyroglobulin. This fragment and antibodies to it may represent markers for subacute thyroiditis.

Desenvolvimento de um método imunofluorométrico para a medina de anticorpos séricos contra tiroglobulina / Development of an immunofluorometric method for measurement of serum antibodies against thyroglobulin

A pesquisa e quantificaçao de anticorpos séricos contra os antígenos tiroideanos tiroglobulina e tiroperoxidase apresenta grande interesse clínico. Neste trabalho descrevemos o desenvolvimento de um novo método para a pesquisa de anticorpos anti-tiroglobulina e a comparaçäo dos resultados obtidos com este método e os obtidos com um ensaio competitivo de referência para anticorpos anti-peroxidase tiroideana (anti-TPO). Tiroglobulina humana purificada é adsorvida em placas de microtitulaçäo e amostras ou controles säo adicionados numa diluiçäo de 1/100. Após duas horas de incubaçao a placa é lavada e acrescenta-se um monoclonal anti-IgG humana marcado com Európio. O monoclonal foi produzido em nossos laboratórios e reage com as quatro subclasses de IgG humano. A sensibilidade do método foi calculada em 40 UI/mL, e o erro interensaio é inferior a 5 por cento ao longo de toda a curva padräo. O método foi aplicado em 602 amostras de soro de rotina diagnóstica nos quais foi também realizada a pesquisa de anticorpos anti-TPO. Em 302 soros (50,2 por cento) ambos os testes foram negativos; em 178 (29,6 por cento) ambos foram positivos; em 62 (10,2 por cento) apenas o teste para anticorpos anti-tiroglobulina foi positivo e em 60 (10,0 por cento) apenas o teste para anticorpos anti-TPO foi positivo. O método nao sofre interferência de níveis elevados de tiroglobulina na amostra. Nossos achados sugerem que os resultados da pesquisa de anticorpos anti-tiroglobulina e anti-TPO com métodos sensíveis e específicos säo complementares no diagnóstico de doenças autoimunes da tiróide.

Evaluation of a new direct radioimmunoassay for serum thyroid peroxidase and thyroglobulin antibodies.

The measurement of serum TPO Ab and Tg Ab by a new direct sensitive RIA in this study are quantitative and provided a convenient system. When compared to the commonly used PH technique for TM Ab and Tg Ab, this RIA determination appears to be more sensitive than by PH, since it enabled detection of TPO Ab and/or Tg Ab in sera that were negative by PH. Thus, this RIA determination should be more widely used in a clinical laboratory.

Thyrotoxicosis--treatment by I131 therapy and early prediction of hypothyroidism following this therapy.

This study was undertaken in 68 thyrotoxic patients to assess the predictive value of various post treatment biochemical and immunological tests for early hypothyroidism after I131 therapy and to determine whether pretreatment with carbimazole protects against post I131 therapy hypothyroidism. Early changes observed in serum T3, T4, TSH, thyroid microsomal and thyroglobulin antibody levels were found to be of no predictive value. A sharp increase in TRAb levels around 3 months following I131 therapy indicated that hypothyroidism was likely to occur as this rise reflected a greater degree of thyroid damage. Lower levels of thyroglobulin in patients who became hypothyroid by 12 months after treatment would support this view. Carbimazole pretreatment for eight weeks did not appear to protect against hypothyroidism, in our study.

Anthyroid antibodies and thyroid dysfunction in Saudi children with Down Syndrome

Fifty children [ages seven months to nine years] with Down syndrome compared with age and sex matched controls were tested for antithyroid antibodies. Seven [14%] of the Down group were found to be seropositive; six [12%] for antimicrosomal antibodies; three for both antimicrosomal and antithyroglobulin; none was positive for antithyroglobulin alone. All the control group were seronegative and had no clinical evidence of thyroid disease. Three [6%] of the Down group had hypothyroidism, two due to autoimmune thyroiditis and one had thyroid dysgenesis; one of the previous two had insulin dependent diabetes mellitus. One child had Graves disease. Thyroid dysfunction was not previously suspected in the two symptomatic children. In view of our findings, recommendations are made to regularly screen these children for autoantibodies and evidence of thyroid dysfunction

A simple radioassay for detection of antithyroglobulin autoantibodies.

Radioassay technique for detection of anti-thyroglobulin autoantibodies (ATA) in serum samples using protein-A rich Staphylococcus aureus as an immune complex separating agent was comparable (r = 0.99; n = 42; P < 0.001) to that evaluated with anti-human gammaglobulin (AHGG). The inter- and intra-assay coefficient of variations were lower (7.4 and 2.2% respectively) using Staph. aureus as compared to that observed with AHGG (10.4 and 4.7% respectively). A highly significant correlation was observed (r = 0.53; n = 71; P < 0.001) between per cent bound radiolabel thyroglobulin in radioassay and log reciprocal titre of ATA by haemagglutination method. Radioassay scored more number of positive sera as compared to haemagglutination method for normal controls (6 vs 1; n = 46) and patients of thyroid diseases (151 vs 70; n = 238). Due to the relatively poor stability of tracer on storage larger inter-assay coefficient of variations were observed with the radiolabelled preparations older than 10-12 days. The radioassay method evaluated is sensitive, reproducible and useful in detecting presence of anti-thyroglobulin autoantibodies.

Alteración de la inmunidad humoral en diabéticos tipo II con dificultad en su control metabólico / Changes of humoral immunity in type II diabetic patients with a poor metabolic control

Se estudiaron 72 pacientes diabéticos tipo II (no insulinodependientes) con una duración de la enfermedad de 7,5 ñ 6,1 años y subdivididos en 2 grupos en dependencia de los valores de su hemoglobina glicosilada al momento de tomar la muestra. Se consideró un buen control metabólico el de aquellos enfermos con valores de hemoglobina glicosilada inferiores al 8 % y con mal control, el de aquéllos con valores iguales o superiores al 8 %. Se detectaron anticuerpos contra el citoplasma de las células insulares pancreáticas (ICA) en el 21,73 % de los pacientes con dificultades en el mantenimiento de un buen control metabólico y en ninguno de los que no presentaban dificultades. La presencia de ICA en diabéticos de difícil control metabólico con dieta e hipoglicemiantes orales, puede orientar al médico a la implantación de la terapia insulínica con críterios más objetivos