Thyroglobulin reference values in a pediatric infant population.

Few reports have addressed normal serum thyroglobulin (Tg) values in newborns and infants. In the present study, serum Tg was measured in 228 normal children (110 females and 118 males) aged from 3 to 180 days of life, all presenting normal age-related serum thyrotropin (thyroid-stimulating hormone [TSH]) values and negative anti-Tg and antithyroperoxidase antibodies. Serum Tg was measured by Radioimmunoassay (RIA) (two methods) and Immunometricassay (IMA) (three methods). Mean Tg values measured by the five methods exhibited among-method biases, although a significant positive correlation was observed. Serum Tg levels measured by the five methods showed a correlation with age, but not with TSH or gender. During the first days of life, relatively high mean Tg levels were observed, which progressively decreased until they reached a plateau. Therefore, with the aim of establishing reference values, the population was separated into two age groups: from 3 to 15 days of life (group A) and from 16 to 180 days of life (group B). Mean Tg concentration in group A was statistically higher than in group B. Tg centile distributions were calculated with the aim of establishing the normal levels of serum Tg for each method. We conclude that for a correct interpretation of serum Tg levels, the age and the methods used should be considered.

Decreased bone mineral density in HIV-infected patients is independent of antiretroviral therapy.

OBJECTIVE: To describe the alterations in the bone metabolism of HIV-seropositive patients and evaluate the effects of antiretroviral therapies. DESIGN: Cross-sectional analytical study. METHOD AND MATERIALS: A total of 142 subjects (113 male, 29 female), aged 20-45 years were divided into four groups: group A, 33 HIV-seropositive antiretroviral-naive patients; group B1, 36 HIV-seropositive patients on antiviral therapy for over 1 year, without protease inhibitors (PI); group B2, 42 HIV-seropositive patients on combined therapy containing PI for over 1 year; and group C, 15 healthy, HIV-seronegative subjects. Bone mineral density (BMD) were determined by dual energy X-ray absorptiometry in total body, lumbar spine and proximal femur; and evaluation of serum osteocalcin, d-pyridinoline, parathyroid hormone (THP), calcium and phosphate, and urine calcium. RESULTS: BMD was significantly lower in HIV-seropositive patients in comparison with healthy controls, in all sites studied. However, no statistical differences were observed among all groups of HIV-infected patients, independently of the antiretroviral therapy. There was a significantly higher occurrence of osteopenia and osteoporosis in HIV-infected patients in comparison with controls (P < 0.0001), with no differences among treatment-naive patients and either of the treatment groups. Bone formation and resorption markers were similar among all studied groups. There was a significant correlation in all bone sites between time of infection and BMD (P < 0.02). CONCLUSIONS: BMD was significantly lower in HIV-seropositive patients in comparison with controls in lumbar spine, proximal femur and total body, without significant differences among treatment-naive patients and either of the treatment groups. Only time with HIV infection and not specific therapy was associated with BMD decreases.

Clinical practice guidelines for the management of hypothyroidism.

INTRODUCTION: Hypothyroidism has long been known for its effects on different organ systems, leading to hypometabolism. However, subclinical hypothyroidism, its most prevalent form, has been recently related to cardiovascular risk and also to maternal-fetal complications in pregnant women. OBJECTIVES: In these clinical practice guidelines, several aspects of this field have been discussed with the clear objectives of helping physicians treat patients with hypothyroidism, and of sharing some of our Latin American-based clinical experience. MATERIALS AND METHODS: The Latin American Thyroid Society commissioned a Task Force on Hypothyroidism to develop evidence-based clinical guidelines on hypothyroidism. A systematic review of the available literature, focused on the primary databases of MedLine/PubMed and Lilacs/SciELO was performed. Filters to assess methodological quality were applied to select the best quality studies. The strength of recommendation on a scale from A-D was based on the Oxford Centre for Evidence--based Medicine, Levels of Evidence 2009, allowing an unbiased opinion devoid of subjective viewpoints. The areas of interest for the studies comprised diagnosis, screening, treatment and a special section for hypothyroidism in pregnancy. RESULTS: Several questions based on diagnosis, screening, treatment of hypothyroidism in adult population and specifically in pregnant women were posed. Twenty six recommendations were created based on the answers to these questions. Despite the fact that evidence in some areas of hypothyroidism, such as therapy, is lacking, out of 279 references, 73% were Grade A and B, 8% Grade C and 19% Grade D. CONCLUSIONS: These evidence-based clinical guidelines on hypothyroidism will provide unified criteria for management of hypothyroidism throughout Latin America. Although most of the studies referred to are from all over the world, the point of view of thyroidologists from Latin America is also given.

Undetectable pre-ablation thyroglobulin levels in patients with differentiated thyroid cancer: it is not always what it seems.

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.

Effect of environmental perchlorate on thyroid function in pregnant women from Córdoba, Argentina, and Los Angeles, California.

OBJECTIVE: To determine whether environmental perchlorate exposure adversely affects thyroid function in women in the first trimester of pregnancy. METHODS: First-trimester pregnant women were recruited from prenatal clinics in the Los Angeles County Hospital, Los Angeles, California, and in the Hospital Universitario de Maternidad dependent Universidad Nacional de Córdoba, Córdoba, Argentina, between 2004 and 2007. Spot urine and blood specimens were obtained during the clinic visit. Urinary perchlorate, iodine, and creatinine were measured, and thyroid function tests were performed. RESULTS: The study included 134 pregnant women from Los Angeles, California (mean gestational age ± SD = 9.1 ± 2.2 weeks), and 107 pregnant women from Córdoba, Argentina (mean gestational age = 10.0 ± 2.0 weeks). Median urinary iodine values were 144 µg/L in California and 130 µg/L in Argentina. Urinary perchlorate levels were detectable in all women (California: median, 7.8 µg/L [range, 0.4-284 µg/L] and Argentina: median, 13.5 µg/L [range, 1.1-676 µg/L]). Serum thyroperoxidase antibodies were detectable in 21 women from California (16%) and in 17 women from Argentina (16%). Using Spearman rank correlation analyses, there was no association between urinary perchlorate concentrations and serum thyrotropin, free thyroxine index, or total triiodothyronine values, including within the subset of women with urinary iodine values less than 100 µg/L. In multivariate analyses using the combined Argentina and California data sets and adjusting for urinary iodine concentrations, urinary creatinine, gestational age, and thyroperoxidase antibody status, urinary perchlorate was not a significant predictor of thyroid function. CONCLUSIONS: Low-level perchlorate exposure is ubiquitous, but is not associated with altered thyroid function among women in the first trimester of pregnancy.

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.

Clinical practice guidelines for the management of hypothyroidism / Diretrizes clínicas práticas para o manejo do hipotiroidismo

INTRODUCTION: Hypothyroidism has long been known for its effects on different organ systems, leading to hypometabolism. However, subclinical hypothyroidism, its most prevalent form, has been recently related to cardiovascular risk and also to maternal-fetal complications in pregnant women. OBJECTIVES: In these clinical practice guidelines, several aspects of this field have been discussed with the clear objectives of helping physicians treat patients with hypothyroidism, and of sharing some of our Latin American-based clinical experience. MATERIALS AND METHODS: The Latin American Thyroid Society commissioned a Task Force on Hypothyroidism to develop evidence-based clinical guidelines on hypothyroidism. A systematic review of the available literature, focused on the primary databases of MedLine/PubMed and Lilacs/SciELO was performed. Filters to assess methodological quality were applied to select the best quality studies. The strength of recommendation on a scale from A-D was based on the Oxford Centre for Evidence--based Medicine, Levels of Evidence 2009, allowing an unbiased opinion devoid of subjective viewpoints. The areas of interest for the studies comprised diagnosis, screening, treatment and a special section for hypothyroidism in pregnancy. RESULTS: Several questions based on diagnosis, screening, treatment of hypothyroidism in adult population and specifically in pregnant women were posed. Twenty six recommendations were created based on the answers to these questions. Despite the fact that evidence in some areas of hypothyroidism, such as therapy, is lacking, out of 279 references, 73% were Grade A and B, 8% Grade C and 19% Grade D. CONCLUSIONS: These evidence-based clinical guidelines on hypothyroidism will provide unified criteria for management of hypothyroidism throughout Latin America. Although most of the studies referred to are from all over the world, the point of view of thyroidologists from Latin America is also given.

INTRODUÇÃO: O hipotiroidismo é amplamente reconhecido por seus efeitos sobre os diferentes sistemas orgânicos, levando ao hipometabolismo. No entanto, o hipotiroidismo subclínico, sua apresentação mais prevalente, tem sido recentemente relacionado ao risco cardiovascular e também com complicações materno-fetais em gestantes. OBJETIVOS: Nestas diretrizes clínicas, vários aspectos do hipotiroidismo foram discutidos com objetivos claros de ajudar os médicos a tratar pacientes com hipotiroidismo e de compartilhar algumas das nossas experiências clínicas na América Latina. MATERIAIS E MÉTODOS: A Sociedade Latino-Americana de Tireoide formou uma Força-Tarefa para desenvolver diretrizes baseadas em evidências clínicas sobre o hipotiroidismo. Foi realizada uma revisão sistemática da literatura existente, com foco em bancos de dados primários do MedLine/PubMed e Lilacs/SciELO. Foram feitas análises para avaliar a qualidade metodológica no sentido de selecionar os melhores estudos. A força de recomendação em uma escala de A-D foi baseada no Centro de Oxford para a Medicina Baseada em Evidência - Níveis de Evidência 2009 - , permitindo uma opinião imparcial, desprovida de pontos de vista subjetivos. As áreas de interesse compreenderam estudos de diagnóstico, triagem, tratamento e uma seção especial de hipotiroidismo na gravidez. RESULTADOS: Foram feitos vários questionamentos relacionados ao diagnóstico, triagem e tratamento do hipotiroidismo na população adulta e, especificamente, em mulheres grávidas. Foram elaboradas vinte e seis recomendações baseadas nas respostas a essas perguntas. Apesar da falta de evidências em algumas áreas como o tratamento do hipotiroidismo, de 279 referências, 73% eram de Grau A e B, 8% de Grau C e 19% de Grau D. CONCLUSÕES: Essas diretrizes baseadas em evidências clínicas sobre o hipotiroidismo poderão fornecer um critério consensual de como tratar o hipotiroidismo na América Latina. Apesar de a maior parte dos estudos referidos ser da experiência internacional em hipotiroidismo, o ponto de vista dos tiroidologistas da América Latina foi contemplado.