Primary hypothyroidism is a common disorder in clinical practice. The management of most cases of hypothyroidism is usually straightforward, but the best approach in some special situations may raise questions among physicians. This position statement was prepared by experts from the Brazilian Society of Endocrinology and Metabolism to guide the management of three special situations, namely, hypothyroidism in the elderly, subclinical hypothyroidism in patients with heart disease, and difficult-to-control hypothyroidism. The authors prepared the present statement after conducting a search on the databases MEDLINE/PubMed, LILACS, and SciELO and selecting articles with the best evidence quality addressing the selected situations. The statement presents information about the current approach to patients in these special situations.

Desenvolvido pelo Departamento de Tireoide da Sociedade Brasileira de Endocrinologia e Metabologia (SBEM), o Guia Prático em Doenças da Tireoide está integrado ao rol de materiais de divulgação científica e educação médica lançados pela instituição nos últimos anos. Em 28 capítulos elaborados por professores, pesquisadores e endocrinologistas com reconhecimento mundial e larga experiência clínica, o guia contempla tópicos que se estendem da fisiologia tireoidiana à abordagem diagnóstica e terapêutica dos pacientes com as mais diversas doenças da tireoide. A confiabilidade dos dados compilados e o sólido conhecimento de seus colaboradores condicionam este livro como auxílio essencial para consulta durante o atendimento dos pacientes em consultórios, ambulatórios ou enfermarias, além de oportunidade única de atualização a estudantes, médicos residentes e profissionais com particular interesse na Tireoidologia.

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Objective: Our aim was to assess the ability of serum magnesium (Mg), measured on the first postoperative day (Mg1PO), to predict the need for calcium (Ca) replacement in patients undergoing total thyroidectomy (TT). Subjects and methods: Eighty patients undergoing TT, with Mg1PO and PTH dosage in the first (PTH1h) and eighth (PTH8h) hours after TT, were evaluated for the need for Ca replacement. Data were evaluated by uni/multivariate logistic regression and Receiver Operating Characteristic (ROC) curve. Results: 32 patients (40%) required Ca replacement. Median PTH1h, PTH8h and Mg1PO were higher in the no replacement group: 17 versus (vs) 3 pg/mL (p < 0.001), 18.2 vs 3.0 pg/mL (p < 0.001) and 2 vs 1.6 mg/dL (p < 0.001), respectively. Mg1PO was the isolated predictor for this replacement (odds ratio = 0.0004, 95% confidence interval: 0.000003-0.04; p = 0.001), with the cut-off value of 1.8 mg/dL showing sensitivity and specificity of 78.1% and 87.5%, respectively. Conclusions: In this group of patients, serum Mg1PO was the isolated predictor for the need for Ca replacement.

Objective: Although controversial, there may be a positive correlation between the body mass index (BMI) of individuals with obesity in euthyroidism and serum levels of thyroid stimulating hormone (TSH). This study aimed to evaluate the correlation between BMI and serum levels of TSH in individuals with morbid obesity undergoing bariatric surgery. Patients and methods: The medical records of patients treated between the years 2012 and 2016 were used. A total of 96 patients with obesity, pre-surgery BMI ≥ 40 kg/m2, being followed up in the endocrinology unit, with mean age of 50 years, were evaluated pre and post operatively. In addition to the plasma TSH dosage by IRMA and plasma free T4 by RIE, age, BMI and biochemical parameters (glycaemia, total cholesterol and triglycerides) were analyzed. Results: Patients with BMI > 40 kg/m2 prior to surgery showed higher serum TSH than subjects with a BMI <40 kg/m after surgery (2.48 ± 0.2 vs. 1.81 ± 0.25, p < 0.001). The decrease in BMI was accompanied by an improvement in the glycemic and lipid profiles, as well as free T4 and TSH levels are shown to accompany BMI. Conclusion: Bariatric surgery was efficient in controlling obesity, since 100% of the patients had their degree of obesity decreased with concomitant metabolic improvement. We found that BMI and TSH are positively related, as post-surgical patients had both BMI and TSH decreased.