Laboratorio de función tiroidea en pediatría. Ventajas y limitaciones de los métodos indirectos para la obtención de intervalos de referencia / Thyroid function laboratory in pediatrics. Advantages and limitations of indirect methods to obtain reference intervals

Obtener intervalos de referencia (IRs) confiables para pruebas de laboratorio en pediatría es particularmente complejo y costoso. Una alternativa a este problema es el uso de métodos indirectos, donde se usan grandes bases de datos preexistentes de pacientes. Nuestros objetivos fueron: calcular IR para TSH y hormonas tiroideas (Perfil tiroideo, PT) en población pediátrica que asiste al Hospital de Pediatría Juan P. Garrahan, por método indirecto y verificar la confiabilidad de los mismos para su aplicación. Se recolectaron datos de 19.842 pacientes entre enero de 2020 y diciembre de 2021. Se aplicaron filtros para eliminar los pacientes que pudieran tener afectado el PT. Los 4.861 pacientes incorporados al análisis fueron divididos en 3 grupos: G1: 0-12 meses (n: 551), G2:13 meses- 7 años (n: 1347) y G3: 8 -18 años (n: 2963). Los IR fueron calculados por 2 métodos: el de Hoffman adaptado y el de CLSI EP28A3, para cada grupo de edad. TSH, TT3 y T4L se analizaron con Architect i4000-Abbott y TT4 con Immulite 2000XPi-Siemens. Para la primera etapa de verificación se utilizaron 20 sueros de pacientes provenientes de análisis prequirúrgicos. Los outliers se detectaron aplicando el método de Tukey. Los datos fueron procesados según CLSI EP28A3c. Los IR obtenidos fueron similares a los previamente publicados obtenidos por método directo. Los resultados de la verificación fueron en su mayoría aceptados. Por lo tanto, los métodos indirectos son una buena alternativa de cálculo de IR en pediatría (AU)

Obtaining reliable reference ranges (RRs) for laboratory tests in pediatrics is particularly complex and costly. An alternative to this problem is to use of indirect methods, where large pre-existing patient databases are used. Our aims were to calculate RRs for TSH and thyroid hormones (thyroid profile, PT) in children seen at Hospital de Pediatría Juan P. Garrahan by indirect methods and to verify their reliability for their application. Data were collected from 19,842 patients seen between January 2020 and December 2021. Filters were applied to eliminate patients in whom the PT was potentially affected. The remaining 4,861 patients included in the analysis were divided into 3 groups: G1: 0-12 months (n: 551), G2: 13 months-7 years (n: 1347) and G3: 8-18 years (n: 2963). RRs were calculated by 2 methods: the adapted Hoffman method and the CLSI EP28A3 method, for each age group. TSH, TT3, and FT4 were analyzed with Architect i4000-Abbott and TT4 with Immulite 2000XPi-Siemens. For the first stage of verification, 20 patient sera from pre-surgical analysis were used. Outliers were detected by applying the Tukey method. The data were processed according to CLSI EP28A3c. The RRs obtained were similar to those previously published using the direct method. The verification results were mostly acceptable. Therefore, indirect methods are a good option for calculating RRs in children (AU)

Uso adecuado de las pruebas de laboratorio para la evaluación de la función tiroidea en pediatría / Appropriate use of laboratory tests for evaluation of thyroid function in pediatrics

Las pruebas de función tiroidea (PFT) son esenciales para el diagnóstico preciso y el seguimiento eficaz de la disfunción tiroidea. Existe un incremento progresivo y estable de los pedidos de PFT, incluso se han incorporado las mismas a los exámenes de salud anuales en niños sanos. Representan más del 60% de las pruebas realizadas en el laboratorio de endocrinología, tanto en adultos como en los laboratorios especializados en pediatría. Para hacer un uso eficiente de las PFT, antes de solicitarlas debemos preguntarnos… ¿Para quién? ¿Cuándo solicitarlas? ¿Qué pruebas solicitar? ¿Cómo solicitarlas? y ¿Cómo interpretar correctamente los resultados? Un resultado anormal en las PFT no siempre implica patología tiroidea asociada. Las PFT tienen importante variabilidad intra e interindividual lo que hace más compleja su correcta interpretación. La pesquisa de enfermedad tiroidea neonatal es un importante aporte a la prevención de la deficiencia mental en la infancia, su aplicación obligatoria posibilita un diagnóstico temprano, para asegurar su éxito debe considerarse en el marco de un programa integral de detección con estrategias de confirmación, tratamiento temprano y seguimiento a corto, mediano y largo plazo. No debe hacerse un uso indiscriminado de la prueba de estímulo con TRH en el diagnóstico de la patología tiroidea. En pediatría la estrategia de tamiz de enfermedad tiroidea es conveniente realizarla mediante la medición de por lo menos TSH y T4 libre e incluir la determinación de ATPO en grupos de riesgo, a diferencia de la determinación aislada de TSH como es recomendado en adultos. (AU)

Thyroid function tests (TFTs) are essential for accurate diagnosis and effective monitoring of thyroid dysfunction. There is a progressive and steady increase in requests for TFTs, and they have even been incorporated into annual health examinations in healthy children. They represent more than 60% of the tests performed in the endocrinology laboratory, both in adults and in specialized pediatric laboratories. To efficiently use TFTs, before requesting them we should ask ourselves... For whom? When to request them? Which tests to request? How to request them? and How to correctly interpret the results? An abnormal TFT result does not always imply thyroid disease. TFTs have significant intra- and inter-individual variability, which makes their correct interpretation more complex. Screening for newborn thyroid disease is an important contribution to the prevention of intellectual disability in childhood and its mandatory use enables early diagnosis; however, to ensure the test to be successful, it should be considered within the framework of a comprehensive screening program with strategies for confirmation, early treatment, and short-, medium-, and long-term follow-up. The TRH stimulation test in the diagnosis of thyroid disease should not be used indiscriminately. In children, the screening strategy for thyroid disease should be performed by measuring at least TSH and free T4 and include the measurement of TPO-ab in risk groups, as opposed to the isolated measurement of TSH as recommended in adults. (AU)

A multi-center analysis of thyroid-stimulating hormone level in apparently healthy elderly population in China / 南方医科大学学报

OBJECTIVE@#To investigate serum thyroid stimulating hormone (TSH) level and its changes with age in apparently healthy Chinese elderly population and analyze the differences between TSH levels detected using Roche and Snibe electrochemiluminescence immunoassay analyzers.@*METHODS@#General clinical data and frozen fasting serum samples were collected from 5451 apparently healthy Chinese elderly individuals (> 60 years) from 10 centers in different geographic regions in China. Thyroid function indexes including TSH level were detected using Roche and Snibe electrochemiluminescence immunoassay analyzer, and the median (2.5% and 97.5% quantiles) TSH level was calculated. The variations of TSH level among the participants with geographic regions, gender, and age (with an interval of 5 years) were analyzed to determine the influence of these factors on TSH level.@*RESULTS@#The reference ranges of serum TSH level established using Roche and Snibe electrochemiluminescence immunoassay analyzers were 0.42-9.47 mU/L and 0.36-7.98 mU/L, respectively, showing significant differences between the two methods (P < 0.001). The TSH levels measured at two centers in Western China were significantly higher than those at the other centers (P < 0.05). In elderly male population, serum TSH level tended to increase with age, which was not observed in elderly female population. At the age of 60-75 years, women generally had higher serum TSH level than men, but this difference was not observed in the population beyond 75 years.@*CONCLUSION@#In elderly population, serum TSH level can vary with geographic region, gender, and age, but there was no need for establishing specific reference ranges for these factors. The differences between different detection methods should be evaluated when interpreting the detection results of TSH level.

Prevalencia de hipotiroidismo subclínico y biomarcadores de riesgo cardiovascular en pacientes del Hospital General de Riobamba / Prevalence of subclinical hypothyroidism and biomarkers of cardiovascular risk in patients of the General Hospital of Riobamba

El Hipotiroidismo subclínico (HSC) es definido bioquímicamente por una elevación en la concentración sérica de la hormona TSH con niveles normales de T4 libre. El objetivo de este estudio fue determinar la prevalencia de HSC en los pacientes que asistieron a la consulta de medicina interna del Hospital General IESS de Riobamba. Así como, analizar la correlación entre los parámetros hormonales y ciertos marcadores bioquímicos asociados con el incremento de riesgo cardiovascular. Se realizó una investigación de tipo descriptiva, observacional, con un diseño no experimental de corte transversal, que abarcó el periodo comprendido desde enero de 2019 hasta septiembre de 2021. 245 pacientes fueron diagnosticados con HSC, lo cual representó el 10.58 % del universo poblacional estudiado, 61.2% eran del sexo femenino, mientras que el 38.8% del sexo masculino. El mayor número de casos (59.61 %) se observó en el grupo etario mayor de 65 años, distribuidos de la siguiente manera: (22.86% hombres y 36.75% mujeres), también se encontró que el HSC está asociado con un perfil lipídico aterogénico, caracterizado por un incremento en la concentración de colesterol total y LDL los cuales se correlacionaron positivamente con las concentraciones de TSH.

Subclinical hypothyroidism (SH) is biochemically defined by an elevation in the serum concentration of TSH hormone with normal levels of free T4. The aim of this study was to determine the prevalence of SH in patients attending the internal medicine clinic of the General Hospital IESS of Riobamba. Also, to analyze the correlation between hormonal parameters and certain biochemical markers associated with increased cardiovascular risk. A descriptive, observational, non-experimental cross-sectional design was performed, covering the period from January 2019 to September 2021. 245 patients were diagnosed with SH, which represented 10.58 % of the population universe studied, 61.2% were female, while 38.8% were male. The highest number of cases (59.61 %) was observed in the age group over 65 years, distributed as follows: (22.86% men and 36.75% women), it was also found that SH is associated with an atherogenic lipid profile, characterized by an increase in the concentration of total cholesterol and LDL which correlated positively with TSH concentrations.

Hipotiroidismo subclínico en el embarazo / Subclinical hypothyroidism in pregnancy

Las alteraciones de la función tiroidea incluida el hipotiroidismo subclínico son unas de las patologías más frecuentes durante el embarazo, y se asocian a importantes complicaciones maternas, fetales y neonatales. Se han desarrollado múltiples guías de práctica clínica por sociedades internacionales en busca de unificar el enfoque diagnóstico y terapéutico de las patologías tiroideas durante la gestación, sin embargo hay evidencia insuficiente sobre la realización de tamizaje y aún más sobre las intervenciones terapéuticas en caso del hipotiroidismo subclínico, se presenta la siguiente revisión de la literatura para vislumbrar a la luz de información actualizada como realizar el abordaje integral de las pacientes gestantes con hipotiroidismo subclínico (AU)

Alterations in thyroid function, including subclinical hypothyroidism, are one of the most frequent pathologies during pregnancy, and are associated with important maternal, fetal, and neonatal complications. Multiple clinical practice guidelines have been developed by international societies in search of unifying the diagnostic and therapeutic approach of thyroid pathologies during pregnancy, however there is insufficient evidence on screening and even more on therapeutic interventions in case of subclinical hypothyroidism , the following review of the literature is presented to envision in the light of updated information how to carry out a comprehensive approach to pregnant patients with subclinical hypothyroidism (AU)

Incremento de la proteína C reactiva ultrasensible en pacientes con hipotiroidismo subclínico y su posible relación con el desarrollo de daño cardiovascular / Increase in high sensitivity C-reactive protein in patients with subclinical hypothyroidism and its possible relationship to the development of cardiovascular damages

INTRODUCCIÓN: El hipotiroidismo subclínico (HSC) se define bioquímicamente por una elevación en la concentración sérica de la hormona estimulante de la tiroides (TSH), con niveles normales de tiroxina libre (T4L). La asociación entre el HSC y el daño cardiovascular ha sido un tema controversial. OBJETIVO: determinar la asociación entre el HSC y el desarrollo de la enfermedad cardiovascular mediante la cuantificación de la proteína C reactiva ultrasensible PCR-us y la determinación de lípidos circulantes asociados a la enfermedad cardiovascular y la ateroesclerosis. MÉTODOS: Estudio descriptivo, correlacional de corte transversal realizado en el Hospital IESS de Riobamba, Ecuador en el periodo comprendido desde enero a diciembre de 2019. Se estudiaron 70 individuos (40 pacientes con HSC y 30 controles) con edades entre 18 y 75 años. Se realizaron las historias clínicas y el examen físico a cada paciente y la toma de las muestras sanguíneas para determinar la concentración sérica de los siguientes parámetros bioquímicos y hormonales: colesterol total, triglicéridos, HDL colesterol y LDL colesterol, TSH, T4L y PCR-us. RESULTADOS: Se encontró un incremento significativo en la concentración de colesterol total (p<0.0001), LDL colesterol (p<0.01) y PCR-us (p<0.0001) en los pacientes con HSC vs los controles. Se observó una correlación positiva (p<0.0001; r=0.9148) entre la TSH y la PCR-us en los pacientes con HSC. CONCLUSIÓN: los pacientes con HSC experimentan una elevación en los niveles séricos de PCR-us la cual está correlacionada con un incremento en la concentración sérica de TSH. Estos parámetros asociados a un aumento del colesterol total y de la LDL colesterol sugieren un estado inflamatorio de bajo grado que podría estar asociado con el desarrollo de aterosclerosis y daño cardiovascular.

INTRODUCTION: Subclinical hypothyroidism (SH) is defined biochemically by an elevation in serum thyroid stimulating hormone (TSH) concentration, with normal levels of free thyroxine (T4L). The association between SH and cardiovascular damage has been a controversial issue. OBJECTIVE: to determine the association between SH and the development of cardiovascular disease through the quantification of the high sensitivity C-reactive protein (hs-PCR) and the determination of circulating lipids associated to cardiovascular disease and atherosclerosis. METHODS: Observational, correlational cross-sectional study with patients captured in the internal medicine office as well as those attending screening activities at the IESS Hospital in Riobamba- Ecuador, in the period from January to December 2019. Seventy individuals (40 patients with SH and 30 controls) between the ages of 18 and 75 years were studied. Each patient's medical history and physical examination were performed, and blood samples were taken to determine the serum concentration of the following biochemical and hormonal parameters: total cholesterol, triglycerides, HDL cholesterol and LDL cholesterol, TSH, T4L and hs-PCR. RESULTS: A significant increase in the concentration of total cholesterol (p<0.0001), LDL cholesterol (p<0.01) and hs-PCR (p<0.0001) was found in patients with SH vs. controls. A positive correlation (p<0.0001; r=0.9148) was observed between TSH and hs-PCR in patients with SH. CONCLUSION: patients with SH experience an elevation in serum hs-PCR levels which is correlated with an increase in serum TSH concentration. These parameters associated with an increase in total cholesterol and LDL cholesterol suggest a low-grade inflammatory state that may be associated with the development of atherosclerosis and cardiovascular damage.

Impact of the reduction in TSH cutoff level to 6 mIU/L in neonatal screening for congenital hypothyroidism in Santa Catarina: final results

ABSTRACT Oubjective: To assess the implications of changing the cutoff level of TSH from 10 to 6 mIU/L. Subjects and methods: The study population was constituted by 74.123 children screened for congenital hypothyroidism by the National Screening Program in Santa Catarina, from March 2011 to February 2012. The cutoff of TSH was 6 mIU/L. If TSH between 6-10 mIU/L, the newborn was recalled for a second TSH measurement on filter paper. If TSH > 6 mIU/L in the second sample, the child was sent for medical evaluation. In children with normal topic thyroid, levothyroxine was suspended for 1 month at the age of 3 years for identification of the etiology and evaluation of the need to continue treatment. Results: Among the children screened, 435 were recalled for presenting TSH between 6 and 10 mIU/L in the first sample, 28 remained TSH > 6 mIU/L in the second sample. Among these, 11 had a final diagnosis of dyshormonogenesis, two of ectopic thyroid, two of thyroid hypoplasia and one of transient hypothyroidism. Ten children presented normal TSH levels on the first medical evaluation and two lost follow-up. Conclusion: A decrease in the TSH cutoff level from 10 to 6 mIU/L in a neonatal screening program for congenital hypothyroidism reduced the number of false-negative results, increasing the sensitivity of the test, but increased the number of false-positive results and recalls. Since a TSH cutoff level of 6 mIU/L detects thyroid function abnormalities requiring treatment, the adoption of this cutoff level is justified.

The Difference in Thyroid Stimulating Hormone Levels between Differentiated Carcinoma and Benign Enlargement

Abstract Introduction Papillary and follicular thyroid carcinoma are common head and neck cancers. This cancer expresses a thyroid stimulating hormone (TSH) receptor that plays a role as a cancer stimulant substance. This hormone has a diagnostic value in the management of thyroid carcinoma. Objective The present study aimed to determine the difference in TSH levels between differentiated thyroid carcinoma and benign thyroid enlargement. Methods The present research design was a case-control study. The subjects were patients with thyroid enlargement who underwent thyroidectomies at the Dr. Sardjito General Hospital, Yogyakarta, Indonesia. Thyroid stimulating hormone levels were mea- sured before the thyroidectomies. The inclusion criteria for the case group were: 1) differentiated thyroid carcinoma, and 2) complete data; while the inclusion criteria for the control group were: 1) benign thyroid enlargement, and 2) complete data. The exclusion criteria for both groups were: 1) patients suffering from thyroid hormone disorders requiring therapy before thyroidectomy surgery, 2) patients receiving thyroid suppression therapy before the thyroidectomy was performed, and 3) patients suffering from severe chronic diseases such as renal insufficiency, and severe liver disease. Results There were 40 post-thyroidectomy case group patients and 40 post-thyroidect- omy control group patients. There were statistically significant differences in TSH levels between the groups with differentiated thyroid carcinoma and benign thyroid enlargement (p = 0.001; odds ratio [OR] = 8.42; 95% confidence interval [CI]: 3.19-36.50). Conclusion Based on these results, it can be concluded that there were significant differences in TSH levels between the groups with differentiated thyroid carcinoma and benign thyroid enlargement.

Relationship of gender and age on thyroid hormone parameters in a large Chinese population

ABSTRACT Objective This study aimed to present the impact of age and gender on thyroid hormone levels in a large Chinese population with sufficient iodine intake. Subjects and methods A total of 83643 individuals were included and were stratified by age and gender. The median, 2.5th and 97.5th of thyrotropin (TSH), free triiodothyronine (FT3), free thyroxine (FT4) and FT3/FT4 ratio were calculated for both genders for every decade from 18 to over 80 years. TSH, FT3, FT4, FT3/FT4 distribution in each age group was evaluated for females and males using smoothing splines in the generalized additive models (GAM). TSH concentrations were compared in the different age groups in gender. Results In the over 80s age group, the TSH level (median: 2.57 mIU/L, 2.5th-97.5th: 0.86-7.56 mIU/L) was significantly higher than other age groups, irrespective to gender (P<0.001). Females had a higher TSH value than males in all age groups (P<0.001). Results of the smoothing curves showed that TSH increased with age, FT3 concentration was higher in males than in females and the tendency of the FT3/FT4 ratio was basically similar to that of FT3. TSH concentration in the 50s age group (median 2.48 mIU/L for females versus 2.00 mIU/L for males) was significantly higher than that in the 30s age group (median 2.18 mIU/L for females versus median 1.85 mIU/L for males). Conclusions In accord with increasing TSH values during aging, females and older adults have lower FT3 values and lower FT3/FT4 ratios, while the FT4 values remain stable.

Evaluation of the structure, autoimmunity, and functions of the thyroid gland in familial Mediterranean fever patients

ABSTRACT Objective Familial Mediterranean fever (FMF) is an autosomal recessive autoinflammatory disorder that is frequently seen in the eastern Mediterranean region. The thyroid gland can be affected in FMF patients through autoimmunity or amyloidosis. Here, we aimed to evaluate the structure and functions of the thyroid gland in addition to possible autoimmunity in FMF patients. Subjects and methods The study was conducted by the Endocrinology and Metabolism and Internal Medicine Departments. Thirty FMF patients and 30 age and gender-matched healthy controls were enrolled in the study. Free thyroxin (fT4), free triiodothyronine (fT3), thyroid-stimulating hormone (TSH), and anti-thyroid peroxidase (anti-TPO) autoantibodies were investigated. Detailed thyroid grayscale and Doppler Ultrasonography examinations and shear-wave elastosonography (SWE) were performed in the patient and control groups. Results Anti-TPO was detected in 24% (n = 7) of the patients. On the grayscale US, mean thyroid volumes were similar between the FMF and the control groups (p > 0.05). By Doppler US, thyroid vascularity observed was detected in 10.3% (n = 3) of the patients. SWE revealed that the mean velocity value of right vs. left lobe in the patient group was 1.77 ± 0.45 m/s and 1.95 ± 0.51 m/s, respectively. Compared to the control group, the mean velocity values were significantly higher in the right (p = 0.004) and left (p = 0.01) lobes of the patient group. The mean stiffness value in the patient group was also significantly higher in the right and left lobes [10.13 ± 5.65 kPa (p = 0.005) and 12.24 ± 6.17 kPa (p = 0.02), respectively]. Conclusion Recognizing the complications of FMF early in the course of the disease is as important as the early diagnosis of the disorder. Based on this, thyroid functions and changes in its structure should be evaluated carefully for early diagnosis of a possible coexisting thyroid disorder. Arch Endocrinol Metab. 2020;64(1):66-70

Use of strain ultrasound elastography versus fine-needle aspiration cytology for the differential diagnosis of thyroid nodules: a retrospective analysis

OBJECTIVE: Fine-needle aspiration cytology is the risk stratification tool for thyroid nodules, and ultrasound elastography is not routinely used for the differential diagnosis of thyroid cancer. The current study aimed to compare the diagnostic parameters of ultrasound elastography and fine-needle aspiration cytology, using surgical pathology as the reference standard. METHODS: In total, 205 patients with abnormal thyroid function test results underwent ultrasound-guided fine-needle aspiration cytology on the basis of the American College of Radiology Thyroid Imaging-Reporting and Data System classification and strain ultrasound elastography according to the ASTERIA criteria. Histopathological examination of the surgical specimens was performed according to the 2017 World Health Organization classification system. Moreover, a beneficial score analysis for each modality was conducted. RESULTS: Of 265 nodules, 212 measured ≥1 cm. The strain index value increased from benign to malignant nodules, and the presence of autoimmune thyroid diseases did not affect the results (p>0.05 for all categories). The sensitivities of histopathological examination, ultrasound elastography, and fine-needle aspiration cytology for detection of nodules measuring ≥1 cm were 1, 1, and 0.97, respectively. The working area for detecting nodule(s) in a single image was similar between strain ultrasound elastography and fine-needle aspiration cytology for highly and moderately suspicious nodules. However, for mildly suspicious, unsuspicious, and benign nodules, the working area for detecting nodule(s) in a single image was higher in strain ultrasound elastography than in fine-needle aspiration cytology. CONCLUSION: Strain ultrasound elastography for highly and moderately suspicious nodules facilitated the detection of mildly suspicious, unsuspicious, and benign nodules.

Hipertiroidismo como clave diagnóstica de un coriocarcinoma avanzado: Una asociación inusual / Hyperthyroidism as a diagnostic key to advanced choriocarcinoma. An unusual association

El hipertiroidismo es una condición relativamente frecuente con múltiples etiologías. La más común es la enfermedad de Graves, seguida del bocio multinodular y el adenoma tóxico. La asociación entre hipertiroidismo y cáncer es infrecuente en la práctica clínica. Presentamos el caso de un varón de 42 años con síntomas de hipertiroidismo de dos meses de evolución. Al examen físico se constató una marcada hepatomegalia de consistencia duro pétrea. El examen de testículos se reveló normal. Se llevó a cabo el diagnóstico de hipertiroidismo a través del dosaje hormonal. Los estudios por imágenes mostraron la presencia de múltiples lesiones sólidas compatibles con metástasis hepáticas. Luego de descartar las causas habituales de hipertiroidismo y las neoplasias primarias de la glándula tiroides, se consideró la posibilidad de mimetismo molecular a través de la producción ectópica de gonadotrofina coriónica humana. Se obtuvieron valores críticamente elevados de esta hormona y en un segundo tiempo se confirmó el diagnóstico histológico de coriocarcinoma a través de una biopsia hepática. Consideramos que el reconocimiento de este mecanismo poco frecuente de hipertiroidismo, puede ser una clave diagnóstica para arribar rápidamente al diagnóstico correcto, particularmente en los tumores extragonadales.

Hyperthyroidism is a relatively frequent condition with multiple causes. The most common cause is Graves' disease; followed by hyperthyroid multinodular goiter and toxic adenoma. Association between hyperthyroidism and cancer is infrequent in daily practice. We present the case of a 42-year-old man who developed severe symptoms of hyperthyroidism within a period of two months. Physical examination revealed significant hepatomegaly. Testicular examination proved normal. Imaging studies showed the presence of multiple hepatic solid lesions consistent with metastases. After discarding the most common causes of hyperthyroidism and primary thyroid gland neoplasm, the possibility of molecular mimicry was considered through human chorionic gonadotrophin production. Critical high values of this hormone were found and choriocarcinoma histological diagnosis was confirmed through a liver biopsy. We consider that the recognition of this rare mechanism of hyperthyroidism may be a clue permitting a faster diagnosis, particularly when extragonadal tumors are present.

Anticuerpos anti-estreptavidina: Confusión diagnóstica por interferencia bioquímica / Anti-estreptavidin antibodies. Diagnostic confusion by biochemical interference

Se presenta el caso de una paciente que, durante los estudios por búsqueda de fertilidad y posterior embarazo, mostraba un perfil tiroideo alterado con niveles elevados de T4 libre y TSH normal. Luego de descartar un adenoma tirotropo y ante la ausencia de sintomatología clínica de hipertiroidismo, se investigó la posibilidad de interferencias analíticas en los inmunoensayos utilizados para la medición de las hormonas. Se han descrito interferencias causadas por anticuerpos heterófilos, macro TSH, anticuerpos anti-tiroideos, biotina, y en menor medida anticuerpos anti-estreptavidina y anti-rutenio. Los análisis de la paciente se realizaron en autoanalizador cuya plataforma emplea el sistema estreptavidina-biotina que es muy susceptible a varios interferentes. Un algoritmo propuesto incluye una serie de pruebas simples de realizar e interpretar que permiten detectar o descartar la presencia de interferentes. De acuerdo al mismo, se efectuó la comparación con una plataforma analítica diferente (que no utiliza el sistema estreptavidina-biotina), diluciones seriadas, precipitación con polietilenglicol 6000 y tratamiento con micropartículas recubiertas con estreptavidina. Los resultados obtenidos confirmaron la presencia de anticuerpos anti-estreptavidina en el suero de la paciente. Ante discordancias entre las manifestaciones clínicas y los resultados de laboratorio, se debe investigar la posibilidad de interferencias metodológicas para evitar el riesgo iatrogénico potencial que implica una interpretación bioquímica errónea.

We present the case of a patient who, during studies for fertility and subsequent pregnancy, showed an altered thyroid profile with elevated levels of free T4 and normal TSH. After ruling out a thyrotropic adenoma and in the absence of clinical symptoms of hyperthyroidism, the possibility of analytical interference in the immunoassays used to measure hormones was investigated. Interferences caused by heterophile antibodies, macro TSH, anti-thyroid antibodies, biotin, and to a lesser extent anti-streptavidin and anti-ruthenium antibodies have been described. The analysis of the patient was carried out in a self-analyzer whose platform uses the streptavidin-biotin system that is very susceptible to several interferents. A proposed algorithm includes a series of simple tests to perform and interpret that allow detecting or ruling out the presence of interferents. Accordingly, a comparison was made with a different analytical platform (which does not use the streptavidin-biotin system), serial dilutions, precipitation with polyethylene glycol 6000 and treatment with microparticles coated with streptavidin. Results obtained confirmed the presence of anti-streptavidin antibodies in the patient's serum. In the case of disagreements between clinical manifestations and laboratory results, the possibility of methodological interferences should be investigated in order to avoid the potential iatrogenic risk involved in an erroneous biochemical interpretation.

Prevalence of antithyroperoxidase antibodies in a multiethnic Brazilian population: The ELSA-Brasil Study

ABSTRACT Objective In this study, we aimed to describe the prevalence and distribution of positive antithyroperoxidase antibodies (TPOAb) according to sex, age strata, and presence of thyroid dysfunction using baseline data from the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). Materials and methods Thyroid hormone tests were obtained from each study participant at baseline. Levels of thyroid-stimulating hormone (TSH) and free thyroxine (FT4) were measured using a third-generation immunoenzymatic assay. Antithyroperoxidase antibodies were measured by electrochemiluminescence and were considered to be positive when ≥ 34 IU/mL. Results The prevalence of TPOAb among 13,503 study participants was 12%. Of participants with positive TPOAb, 69% were women. Almost 60% of the individuals with positive TPOAb were white. The presence of positive TPOAb was associated with the entire spectrum of thyroid diseases among women, but only with overt hyperthyroidism and overt hypothyroidism in men. Conclusion The distribution of positive TPOAb across sex, race, age, and thyroid function in the ELSA-Brasil study is aligned with the worldwide prevalence of positive TPOAb reported in iodine-sufficient areas. In women, the presence of TPOAb was related to the entire spectrum of thyroid dysfunction, while in men, it was only related to the occurrence of overt thyroid disease.

Stress-induced hashitoxicosis: case report and relative HLA serotype and genotype

SUMMARY OBJECTIVE Even though stress has been long known as a provocative factor for Graves' disease, its relationship with Hashimoto's thyroiditis is more controversial. Studies on this topic are scanty. This paper aims to report a case of stress-induced Hashitoxicosis. RESULTS Here we report a case of Hashitoxicosis induced by a psychological stressful event in a 28-year-old woman with Hashimoto's thyroiditis. She had remained stably euthyroid for 12 years. She was first observed in April 2016, while euthyroid. She came back after 11 months because of fatigue and palpitations, in the absence of neck pain. Thyroid function tests revealed moderate thyrotoxicosis (undetectable TSH; FT4 36.94 pmol/L, normal values 9.0-24.46; FT3 13.50 pmol/L, normal values 3.07-6.14) with negative TSH-receptor antibodies. In the previous three months, she had experienced a psychological stressful event. Inflammatory markers were negative, and the white cell count was normal. Thyroid ultrasound revealed a modest increase in vascularization. Transient subclinical hypothyroidism ensued after seven weeks and spontaneously recovered. On the last visit, the patient was still on euthyroidism. (TSH 1.01 mU/L; FT4 9.22 pmol/L; FT3 3.98 pmol/L). We also performed HLA serotyping and genotyping. CONCLUSION This case demonstrates that, similarly to Graves' disease, Hashitoxicosis can also be triggered by stressful life events.

RESUMO OBJETIVO Mesmo que o estresse seja conhecido há muito tempo como um fator provocativo para a doença de Graves, sua relação com a tireoidite de Hashimoto é mais controversa. Estudos sobre esse tema são escassos. O objetivo deste artigo é relatar um caso de Hashitoxicose induzida por estresse. RESULTADOS Aqui nós relatamos um caso de Hashitoxicose induzido por um evento psicológico estressante em uma mulher de 28 anos com tireoidite de Hashimoto. Ela permaneceu estável eutireoidiana por 12 anos. Ela veio a nossa observação pela primeira vez em abril de 2016, enquanto eutireoidiana. Voltou após 11 meses por causa de fadiga e palpitações, na ausência de dor no pescoço. Testes de função tireoidiana revelaram uma tireotoxicose moderada (TSH indetectável; T4F 36,94 pmol/L, valores normais 9,0-24,46; FT3 13,50 pmol/L, valores normais 3,07-6,14) com anticorpos negativos para o receptor de TSH. Nos últimos três meses ela experimentou um evento psicológico estressante. Os marcadores inflamatórios foram negativos e a contagem de leucócitos foi normal. A ultrassonografia da tireoide revelou um aumento modesto da vascularização. Hipotireoidismo subclínico transitório ocorreu após sete semanas e se recuperou espontaneamente. Na última visita, a paciente ainda estava em eutireoidismo. (TSH 1,01 mU/L; FT4 9,22 pmol/L; FT3 3,98 pmol/L). Também realizamos a sorotipagem e a genotipização do HLA. CONCLUSÃO Este caso demonstra que, similarmente à doença de Graves, também a Hashitoxicose pode ser desencadeada por eventos estressantes da vida.

Relación deltre hipotiroidismo subclínico y bocio con el origen del agua consumida por una población del conurbano bonaerense / Relationship of subclinical hypothyroidism and goiter with the origin of water consumed by a population of the Buenos Aires suburbs

El hipotiroidismo subclínico (HS), elevación de tirotrofina con hormonas tiroideas normales, junto al bocio, aumentó la frecuencia en las últimas décadas. Con el objetivo de relacionar la prevalencia de bocio y HS con el consumo de agua subterránea como factor de riesgo etiológico poblacional, se analizaron 879 historias clínicas de un centro médico de Glew, en el conurbano bonaerense Sur. Se estudió la población según edad (20-60 y 12-19 años) y tipo de agua consumida (potabilizada o napa subterránea). El agua subterránea fue consumida por el 70.5% del grupo de 20 a 60 años (n = 559, 79.9% mujeres) y por el 66.3% del grupo de 12 a 19 años (n = 57, 81.4% mujeres). En el grupo de 20 a 60 años la prevalencia de HS en consumidores de agua potabilizada y subterránea fue del 1% y 57.8% (p < 0.0001) y la de bocio de 3.8% y 38.9% (p < 0.0001), respectivamente; con un riesgo atribuible al agua subterránea de 57% para HS y 35% para bocio. En el grupo de 12 a 19 años, la prevalencia de HS fue 6.9% y 52.6% (p < 0.0001) y de bocio 13.8% y 77.2% para los grupos de agua potabilizada y subterránea, (p < 0.0001) respectivamente; con un riesgo atribuible al agua subterránea de 46% para HS y 61% para bocio. El análisis fisicoquímico mostró presencia de nitratos (entre 24 y 83 mg/l) en aguas de pozos y ausencia en agua potable. La prevalencia aumentada de HS y bocio podrían deberse a la acción disruptora tiroidea de los nitratos.

Subclinical hypothyroidism (SH), elevation of the level of thyrotrophin with normal thyroid hormones, along with goiter (glandular size > 25g), increased in recent decades. In order to relate the prevalence of goiter and SH with the consumption of groundwater, as a population etiological risk factor, we analyzed 879 clinical histories from a medical center in the city of Glew in the South Buenos Aires suburbs. The population was studied according to age (20 to 60 and 12 to 19 years) and type of water consumed (potable water or groundwater). Groundwater was consumed by 70.5% of the group from 20 to 60 years old (n = 559, 79.9% women) and by 66.3% of the group from 12 to 19 years old (n = 57, 81.4% women In the group of 20 to 60 years, the prevalence of SH in potable water and groundwater users was 1% and 57.8% (p < 0.0001) and the goiter rate of 3.8% and 38.9% (p < 0.0001) respectively; with an attributable risk to groundwater of 57% for HS, and 35% for goiter In the group of 12 to 19 years, the prevalence of SH was 6.9% and 52.6% (p < 0.0001) and goiter 13.8% and 77.2% for the water and groundwater groups (p>0.0001) respectively, with an attributable risk of 46% for HS y 61% for goiter. The physicochemical analysis showed the presence of nitrates in the range of 24 to 83 mg/l in groundwater and absence in potable water. The increased prevalence of HS and goiter could be due to the thyroid disrupting action of nitrates.

Hipotireoidismo congênito como fator de risco para os transtornos do processamento auditivo central / Congenital hypothyroidism as a risk factor for central hearing process disorders

RESUMO Objetivo: Investigar a manifestação de sintomas do transtorno do processamento auditivo central em crianças com hipotireoidismo congênito. Métodos: Estudo de caráter exploratório, descritivo e transversal com 112 pacientes com hipotireoidismo congênito com idade ≥5 anos. Realizou-se entrevista com os pais/cuidadores no momento da espera da consulta médica. Portadores de outras afecções médicas foram excluídos. Como instrumento de pesquisa utilizou-se o protocolo estruturado de anamnese para avaliação do processamento auditivo rotineiramente empregado por audiologistas. A análise estatística utilizou o teste Qui-quadrado. Resultados: A distribuição por sexo foi semelhante (meninas: 53,3%). Os casos não-disgenesia constituíram a forma fenotípica mais prevalente para o hipotireoidismo congênito (88,4%), e verificou-se que 65,3% das crianças apresentavam algum episódio de níveis séricos irregulares de hormônio tireoestimulante. Dentre as manifestações mais frequentes dos sintomas do transtorno do processamento auditivo central, as queixas relaciondas às funções cognitivas auditivas, como: figura-fundo (83,0%), atenção auditiva (75,9%) e memória auditiva (33,0%) foram as mais evidentes. Reclamações relacionadas ao rendimento escolar foram reportadas em 62,3%. Conclusões: Os dados obtidos evidenciaram altas frequências de sintomas de defasagem nas funções cognitivas relacionadas ao processamento auditivo central, em especial na atenção auditiva, figura-fundo e memória auditiva nos portadores do hipotireoidismo congênito.

ABSTRACT Objective: To investigate the presence of central auditory processing disorder symptoms in children with congenital hypothyroidism. Methods: An exploratory, descriptive, cross-sectional study of 112 patients with congenital hypothyroidism aged ≥5 years old. An interview was held with the parents/caregivers at the time of the medical consultation. Patients with other medical conditions were excluded. As a research instrument, the structured protocol of anamnesis was used to evaluate the auditory processing routinely used by audiologists. For statistical analysis, the chi-square test was used. Results: Sex distribution was similar in both boys and girls (girls: 53.3%). The most prevalent phenotypic form of congenital hypothyroidism was no dysgenesis (88.4%), and 65.3% of the children had an episode of irregular serum thyroid-stimulating hormone (TSH) levels. Among the manifestations of the most frequent central auditory processing disorder symptoms, problems were reported with regard to cognitive functions, as they related to hearing, such as figure-background ability (83.0%), auditory attention (75.9%) and auditory memory (33.0%). Complaints related to school performance were reported in 62.3% of the cases. Conclusions: The data obtained show a high frequency of lag symptoms in cognitive functions related to central auditory processing, particularly with regard to auditory attention, figure-background ability and auditory memory in patients with congenital hypothyroidism.

Selective screening for thyroid dysfunction in pregnant women: How often do low-risk women cease to be treated following the new guidelines of the American Thyroid Association?

ABSTRACT Objective: Universal screening for thyroid dysfunction in pregnant women is not recommended by the American Thyroid Association (ATA) or the American Association of Clinical Endocrinologists (AACE). This study evaluated the frequency of pregnant women that would have an indication for levothyroxine (L-T4) according to the new ATA/AACE guidelines among low-risk women without an indication for screening with TSH. Subjects and methods: The sample consisted of 412 pregnant women ranging in age from 18 to 30 years. These women were considered to be at low risk for thyroid dysfunction according to ATA/AACE and would not be candidates for screening with TSH. Anti-thyroid peroxidase antibodies (TPOAb) and TSH were measured. Women who had TSH > 2.5 mIU/L or TPOAb in the first trimester were submitted to subsequent evaluations in the second and third trimester. Results: In the first trimester, none of the pregnant women would have L-T4 therapy "recommended" and treatment would be "considered" in only two. In the second trimester, pregnant women with positive TPOAb or TSH > 2.5 mIU/L in the first trimester (n = 30) were reevaluated. L-T4 treatment would be "recommended" in only one woman and would be "considered" in two others. The 28 women that were not treated in the second trimester were reevaluated in the third trimester, but none of them would have L-T4 "recommended". Conclusion: The findings of the study suggest that selective screening, recommended by ATA/AACE does not result in a significant loss of pregnant women with an indication for L-T4 treatment.

Conversion to Graves disease from Hashimoto thyroiditis: a study of 24 patients

ABSTRACT Objective: The conversion of Hashimoto's thyroiditis (HT) to hyperthyroidism due to thyrotropin receptor antibodies is intriguing and considered rare. The contribution of TSH receptor blocking antibodies (TRAb), which may be stimulators (TSAb) or blockers (TBAb), is suspected. We describe clinical and biological variables in a series of patients switching from Hashimoto's thyroiditis to Grave's disease. Subjects and methods: Retrospective case study of 24 patients with Hashimoto's thyroiditis followed during 48 ± 36 months that developed later Graves' disease (GD). These variables were analysed in the hypo and hyperthyroid phase: age, sex, initial TSH, free triiodothyronine (fT3), free thyroxine (fT4), anti-TPO, TBII antibodies, parietal cell autoantibodies, time between hypo and hyperthyroidism, thyroid volume and levothyroxine doses (LT). Results: In HT, mean TSH was 9.4 ± 26.1 UI/L and levothyroxine treatment was 66.2 ± 30.8 µg/day. The switch to GD was observed 38 ± 45 months after HT diagnosis. As expected, we found significant differences on TSH, FT3, FT4 and TBAb levels. Three out of 14 patients had parietal cell autoantibodies. In two of these three cases there was an Helicobacter pylori infection. There were no significant differences between HT and GD groups with respect to thyroid volume. Conclusions: To our knowledge, large series documenting the conversion of HT to GD are scarce. Although rare, this phenomenon should not be misdiagnosed. Suspicion should be raised whenever thyroxine posology must be tapered down during the follow-up of HT patients. Further immunological and genetic studies are needed to explain this unusual autoimmune change.

Heart rate response to graded exercise test of elderly subjects in different ranges of TSH levels

ABSTRACT Objective: Life expectancy is increasing worldwide and studies have been demonstrating that elevated serum thyroid stimulating hormone (TSH) concentration in elderly is associated with some better health outcomes. This elevation is somewhat physiological as aging. The aim of this study was to investigate the heart rate (HR) response during a graded exercise test and its recovery in healthy elderly, comparing subjects within serum TSH in the lower limit of reference range to those within the TSH in the upper limit. Subjects and methods: A cross-sectional study was conducted with 86 healthy elderly aged 71.5 ± 5.1 years, with serum TSH between 0.4 - 4.0 mUl/mL. The participants were divided into two groups according to TSH level: < 1.0 mUl/mL (n = 13) and ≥ 1.0 µUI/mL (n = 73). All participants performed an ergometric test on a treadmill. The HR was recorded and analyzed at rest, during exercise and during the three minutes immediately after exercise. Results: No differences were observed in relation to HR at peak of exercise (TSH < 1.0 µUI/mL: 133.9 ± 22.5 bpm vs. TSH ≥ 1.0 µUI/mL: 132.4 ± 21.3 bpm; p = 0.70) and during the first minute of recovery phase (TSH < 1.0 µUI/mL: 122.3 ± 23.1 bpm vs. TSH ≥ 1.0 µUI/mL: 115.7 ± 18.4 bpm p = 0.33). The groups also presented similar chronotropic index (TSH < 1.0 µUI/mL: 78.1 ± 30.6 vs. TSH ≥ 1.0 µUI/mL: 79.5 ± 26.4; p = 0.74). Conclusion: In this sample studied, there were no difference between lower and upper TSH level concerning HR response during rest, peak of exercise and exercise recovery.