The Usefulness of Thyroid Antibodies in the Diagnostic Approach to Autoimmune Thyroid Disease.

Autoimmune thyroid disease (AITD) refers to a spectrum of various diseases, with two extremes of clinical presentation, hypothyroidism (Hashimoto's thyroiditis (HT) and hyperthyroidism (Graves-Basedow disease (GBD)). Both conditions are characterized by presenting a cellular and humoral autoimmune reaction, with an increase in the synthesis and secretion of antibodies directed toward various thyroid antigens, together with a phenomenon of thyrocyte necrosis and apoptosis (in HT) and a persistent thyrotropin-receptor stimulation (in GBD). The diagnosis of both entities is based on clinical, laboratory, and imaging findings. Three major anti-thyroid antibodies have been described, those directed against the TSH receptor (TRAb), against thyroid peroxidase (TPOAb), and against thyroglobulin (TgAb). Each of these autoantibodies plays a fundamental role in the diagnostic approach of autoimmune thyroid disease. TRAbs are the hallmark of GBD, and additionally, they are predictors of response to disease treatment, among other utilities. Likewise, TPOAb and TgAb allow for identifying individuals with a higher risk of progression to hypothyroidism; the positivity of one or both autoantibodies defines the presence of thyroid autoimmunity. In this review, the usefulness of anti-thyroid antibodies in the diagnostic approach to autoimmune thyroid disease is described.

Relationship of Subclinical Hypothyroidism on Epicardial Adipose Tissue: A Systematic Review and Meta-Analysis.

Accumulation of epicardial adipose tissue (EAT) and Subclinical hypothyroidism (SH) are associated with increased cardio-metabolic risk. The objective of this study was to quantitatively compare EAT thickening between patients with SH and healthy controls. Therefore, after searching the PubMed/MEDLINE, Embase, Science Direct, Scopus, Google Scholar, and Cochrane databases; we analyzed a group of observational studies who compare the EAT changes between SH vs control groups. A total of 9 studies were included in the final analysis, for a total of 424 patients with SH and 330 controls. Random or fixed effects models were used. Pooled analysis revealed that HS increased EAT (MD: 1.0 mm [0.40; 1.50]; P < 0.01). This meta-analysis suggests that the amount of EAT is significantly increased in SH patients. EAT might be a marker of cardiovascular risk in patients with SH.

Optimal levothyroxine dose to achieve euthyroidism in patients with primary hypothyroidism: analysis according to etiology.

INTRODUCTION: Levothyroxine (LT4) has been considered the standard of care for treatment of hypothyroidism. Current recommendations suggest a LT4 dose between 1.6-1.8 µg/kg/day. The aim of this study was to evaluate the LT4 dose for adult patients with primary hypothyroidism of different etiologies who reached euthyroidism. METHODS: A cross-sectional study was performed from the retrospective review of the charts of patients with primary hypothyroidism in treatment with LT4. Subjects were classified according to TSH level in overtreated (TSH < 0.4 µIU/ml), euthyroid (TSH 0.40-4.20), and undertreated (TSH >4.2) and according to the etiology of hypothyroidism. A stepwise logistic regression model was performed to evaluate the variables associated with TSH<0.4 µIU/ml. RESULTS: 955 patients were included. 75.13% of the patients had an adequate LT4 replacement. LT4 dose to achieve euthyroidism was higher in patients with a history of radioiodine therapy (1.92 µg/kg) and thyroid surgery (1.52 µg/kg), while the LT4 dose required to achieve euthyroidism in patients with Hashimoto's thyroiditis and atrophic thyroiditis was lower than that reported in previous studies (1.25 and 1.08 µg/kg, respectively). The variables that were associated with a higher probability of TSH<0.4 µIU/ml were male gender, Hashimoto's thyroiditis, radioiodine therapy, and thyroid surgery. MAJOR CONCLUSION: LT4 dose required to achieve euthyroidism in patients with hypothyroidism varies according to the etiology, being higher in patients with hypothyroidism due to radioiodine therapy and thyroid surgery. Patients with hypothyroidism due to Hashimoto's thyroiditis and atrophic thyroiditis require a lower dose than current recommendations.

Introducción: La levotiroxina (LT4) se considera el estándar de tratamiento del hipotiroidismo. Las recomendaciones actuales sugieren una dosis de LT4 entre 1,6-1,8 µg/kg/día. El objetivo de este estudio fue evaluar la dosis de LT4 en pacientes adultos con hipotiroidismo primario de diferentes etiologías que alcanzaron el eutiroidismo. Métodos: Estudio transversal a partir de la revisión retrospectiva de historias clínicas de pacientes con hipotiroidismo primario en tratamiento con LT4. Los sujetos se clasificaron según el nivel de TSH en sobretratados (TSH<0,4 µUI/ml), eutiroideos (TSH 0,40-4,20) y subtratados (TSH>4,2) y según la etiología del hipotiroidismo. Se realizó un modelo de regresión logística escalonada para evaluar las variables asociadas con TSH <0,4 µUI/ml. Resultados: Se incluyeron 955 pacientes. El 75,13% tuvo un reemplazo adecuado de LT4. La dosis de LT4 para lograr el eutiroidismo fue mayor en pacientes con antecedentes de terapia con yodo radiactivo (1,92 µg/kg) y cirugía de tiroides (1,52 µg/kg), mientras que la dosis de LT4 para lograr el eutiroidismo en pacientes con tiroiditis de Hashimoto y tiroiditis atrófica fue menor que el reportado en estudios previos (1,25 y 1,08 µg/kg, respectivamente). Las variables que se asociaron con una mayor probabilidad de TSH<0,4 µUI/ml fueron el sexo masculino, tiroiditis de Hashimoto, terapia con yodo radiactivo y cirugía de tiroides. Conclusión principal: La dosis de LT4 necesaria para alcanzar el eutiroidismo en pacientes con hipotiroidismo varía según la etiología, siendo mayor en pacientes con hipotiroidismo por tratamiento con yodo radiactivo y cirugía tiroidea. Los pacientes con hipotiroidismo debido a tiroiditis de Hashimoto y tiroiditis atrófica requieren una dosis más baja que las recomendaciones actuales.

The influence of age and body weight on levothyroxine replacement dosage to achieve euthyroidism in patients with primary hypothyroidism.

INTRODUCTION: Although, it is generally held that the levothyroxine (LT4) dose tends to decrease with age, this theory remains controversial. Our objective was to assess whether the LT4 dose required to achieve euthyroid status varies according to age, body weight (BW), sex, menopausal status, or antibody status. MATERIALS AND METHODS: A cross-sectional study was performed from the retrospective review of the charts of patients with a previous diagnosis of primary hypothyroidism in treatment with LT4 and in a euthyroid state. Sex, age, actual body weight (ABW), TSH, and LT4 dose were recorded. Patients were grouped according to age ranges (18-44, 45-65, and over 65 years). A euthyroid state was defined as a serum TSH within the range of 0.4-4µIU/ml. A multiple linear regression model was performed to assess the LT4 dose and age, gender, antibody status, and ABW. RESULTS: A total of 882 charts of patients were reviewed. 586 patients met the inclusion criteria. The median age was 55 years. There was no correlation between the LT4 dose and age. A positive correlation was observed between the LT4 dose and ABW, but not with the ideal BW. Linear regression analysis showed that positivity antibody and ABW have a significant effect on the LT4 dose. Comparison of the LT4 dose between the different age groups showed no difference. CONCLUSION: Our study demonstrates that the dose of LT4 necessary to achieve euthyroidism is influenced by ABW and the presence of antibodies. Age and menopause did not influence the required daily dose of LT4.

The influence of age and body weight on levothyroxine replacement dosage to achieve euthyroidism in patients with primary hypothyroidism.

INTRODUCTION: Although, it is generally held that the levothyroxine (LT4) dose tends to decrease with age, this theory remains controversial. Our objective was to assess whether the LT4 dose required to achieve euthyroid status varies according to age, body weight (BW), sex, menopausal status, or antibody status. MATERIALS AND METHODS: A cross-sectional study was performed from the retrospective review of the charts of patients with a previous diagnosis of primary hypothyroidism in treatment with LT4 and in a euthyroid state. Sex, age, actual body weight (ABW), TSH, and LT4 dose were recorded. Patients were grouped according to age ranges (18-44, 45-65, and over 65 years). A euthyroid state was defined as a serum TSH within the range of 0.4-4µIU/ml. A multiple linear regression model was performed to assess the LT4 dose and age, gender, antibody status, and ABW. RESULTS: A total of 882 charts of patients were reviewed. 586 patients met the inclusion criteria. The median age was 55 years. There was no correlation between the LT4 dose and age. A positive correlation was observed between the LT4 dose and ABW, but not with the ideal BW. Linear regression analysis showed that positivity antibody and ABW have a significant effect on the LT4 dose. Comparison of the LT4 dose between the different age groups showed no difference. CONCLUSION: Our study demonstrates that the dose of LT4 necessary to achieve euthyroidism is influenced by ABW and the presence of antibodies. Age and menopause did not influence the required daily dose of LT4.

Radioiodine thyroid remnant ablation after recombinant human thyrotropin or thyroid hormone withdrawal in patients with high-risk differentiated thyroid cancer.

To supplement limited relevant literature, we retrospectively compared ablation and disease outcomes in high-risk differentiated thyroid carcinoma (DTC) patients undergoing radioiodine thyroid remnant ablation aided by recombinant human thyrotropin (rhTSH) versus thyroid hormone withdrawal/withholding (THW). Our cohort was 45 consecutive antithyroglobulin antibody- (TgAb-) negative, T3-T4/N0-N1-Nx/M0 adults ablated with high activities at three referral centers. Ablation success comprised negative (<1 µg/L) stimulated serum thyroglobulin (Tg) and TgAb, with absent or <0.1% scintigraphic thyroid bed uptake. "No evidence of disease" (NED) comprised negative unstimulated/stimulated Tg and no suspicious neck ultrasonography or pathological imaging or biopsy. "Persistent disease" was failure to achieve NED, "recurrence," loss of NED status. rhTSH patients (n = 18) were oftener ≥45 years old and higher stage (P = 0.01), but otherwise not different than THW patients (n = 27) at baseline. rhTSH patients were significantly oftener successfully ablated compared to THW patients (83% versus 67%, P < 0.02). After respective 3.3 yr and 4.5 yr mean follow-ups (P = 0.02), NED was achieved oftener (72% versus 59%) and persistent disease was less frequent in rhTSH patients (22% versus 33%) (both comparisons P = 0.03). rhTSH stimulation is associated with at least as good outcomes as is THW in ablation of high-risk DTC patients.