A National Laboratory Perspective: The Impact of the Covid-19 Pandemic on the Management of Patients With Non-Communicable Disease in South Africa: Impact of COVID-19 on patients with noncommunicable diseases.

OBJECTIVE: The aim of this study was to determine the impact of the COVID-19 pandemic on test requests for the diagnosis and routine care of patients with various non-communicable diseases (NCD) across South Africa (SA). METHODS: A retrospective audit of laboratory test requests received from hospital outpatient departments and primary healthcare facilities across SA was performed. The following analytes were studied: glycated hemoglobin (HbA1c), lipids profiles, thyroid-stimulating hormone (TSH), and thyroxine (fT4), as well as triiodothyronine (fT3), serum protein electrophoresis (SPE), serum free light chains (SFLC), and prostate specific antigen (PSA); these tests were used as a proxy of NCD detection and follow-up. Requests received during the 3 waves of the pandemic were compared to requests received within the same period during 2017 - 2019. RESULTS: During the first wave, requests for all analytes were reduced, with the biggest reduction observed for SPE (- 37%); TSH (- 29%); fT4 (- 28%); and HbA1c (- 25%). Requests received from urban facilities showed a larger decrease compared to those from rural facilities. During the third wave there was an increase in requests for all analytes; the biggest increase observed was for fT3 (21%) and HbA1c (18%). CONCLUSIONS: The COVID-19 pandemic had a significant impact on the South African population receiving care in the public healthcare sector.

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)

Factores clínicos y ambientales asociados a la tiroiditis de Hashimoto / Clinical and environmental factors associated with Hashimoto's thyroiditis

Introducción: La tiroiditis de Hashimoto es una enfermedad tiroidea autoinmune poligénica y multifactorial resultante de una interacción compleja de factores genéticos y ambientales. Objetivo: Determinar la posible asociación de los factores clínicos y ambientales con los niveles de anticuerpos antitiroideos y las pruebas de función tiroidea en la tiroiditis de Hashimoto. Métodos: Estudio observacional, descriptivo y transversal con 120 personas con diagnóstico de tiroiditis de Hashimoto. Variables estudiadas: edad, sexo, color de la piel, estado nutricional, paridad, hábito de fumar, consumo de alcohol, preparados estrogénicos, antecedentes familiares de enfermedad autoinmune tiroidea y personales de otras enfermedades autoinmunes. Se realizaron determinaciones de anticuerpos AbTPO, TSH, T3 y T4. Resultados: Predominio del sexo femenino (92,5 por ciento), de pacientes de piel blanca (50,8 por ciento) y con sobrepeso corporal (40 por ciento). El 73 por ciento no consumían preparados estrogénicos. El 20 por ciento tenían antecedentes familiares de enfermedad tiroidea y personales de diabetes mellitus tipo 1 (7,5 por ciento). La media del anticuerpo en pacientes con antecedentes de infecciones virales fue superior a los que no tuvieron este antecedente (732,6 vs. 624,6). El resto de las variables no mostraron diferencias entre las medias del anticuerpo. Ninguno de los factores estudiados mostró asociación con el estado de la función tiroidea. (p>0,05). Conclusiones: No existió asociación entre los factores clínicos y ambientales en relación a los niveles de Ac TPO y el estado de la función tiroidea, con predominio del hipotiroidismo manifiesto al diagnóstico de la TH(AU)

Introduction: Hashimoto's thyroiditis is a polygenic and multifactorial autoimmune thyroid disease, resulting from a complex interaction of genetic and environmental factors. Objective: To determine the possible association of clinical and environmental factors with antithyroid antibody levels and thyroid function tests in HT. Methods: An observational, descriptive, cross-sectional study was carried out with 120 subjects diagnosed with Hashimoto's thyroiditis. We studied variables such as age, sex, skin color, nutritional status, parity, smoking, alcohol consumption, estrogen preparations, family history of autoimmune thyroid disease and personal history of other autoimmune diseases. Additionally, AbTPO, TSH, T3 and T4 antibody determinations were made. Results: Predominance of the female sex (92.5 percent), white skin (50.8 percent) and body overweight (40 percent). 73 percent did not consume estrogenic preparations. Twenty percent had family history of thyroid disease and personal history of type 1 diabetes mellitus (7.5 percent). The mean antibody in patients with history of viral infections was higher than those without this history (732.6 vs. 624.6). The rest of the variables did not show differences between the means of the antibody. None of the factors studied showed association with the state of thyroid function. (p > 0.05). Conclusions: There was no association between clinical and environmental factors in relation to Ac TPO levels and the state of thyroid function, with a predominance of overt hypothyroidism at diagnosis of HT(AU)

Outpatient analytic assessment of anorexia nervosa — the importance of venous blood gases / Avaliação laboratorial em ambulatório na anorexia nervosa: a importância da gasometria venosa

ABSTRACT Objective: To evaluate serum biochemical parameters' evolution, especially venous blood gas (VBG), in anorexia nervosa (AN), correlating with clinical parameters. Methods: Retrospective study including out-patient AN adolescents, between January 2014 and May 2017. Three evaluations were compared: t1) first consultation; t2) consultation with the lowest body mass index (BMI) z-score and t3) with the highest BMI z-score. Results: A total of 24 adolescents (87.5% females) were included, mean age of presentation of 14.9±1.7 years, onset of symptoms 6.4±3.2 months before the first visit. In t1, BMI z-score of -1.91±1.11 kg/m2 and ideal weight % of 84.3±9.2. Amenorrhea was present in 88%. In t2 the analytical alterations were: altered VBG in 100%, altered ferritin (72% elevated), altered thyroid function (53% with thyroxine decrease), dyslipidemia (31% elevation of high density lipoprotein, 25% hypercholesterolemia), elevation of urea (25%), elevation of alanine aminotransferase (14%), hypoglycemia (14%), anemia (9%). Respiratory acidosis was present in 91% in t1, 100% in t2 and 94% in t3. There was a significant decrease between t2 and t3 in mean pCO2 (57.2 versus 53.6 mmHg; p=0.009) and mean HCO3 (30.0 versus 28.8 mEq/L; p=0.023). Conclusions: Respiratory acidosis and increased ferritin were common in this group. Respiratory acidosis was the most frequent abnormality with significant pCO2 and HCO3 variation in the recovery phase. VBG should be considered in AN evaluation, once it seems to be important in assessing the severity of the disease and its subsequent follow-up.

RESUMO Objetivo: Avaliar a evolução laboratorial, particularmente da gasometria venosa, na anorexia nervosa (AN), correlacionando os achados com parâmetros clínicos. Métodos: Estudo retrospetivo com adolescentes com AN seguidos em ambulatório, entre janeiro de 2014 e maio de 2017. Foram comparadas três avaliações: (t1) primeira consulta; (t2) consulta com escore Z de índice de massa corpórea (IMC) mais baixo; e (t3) consulta com escore Z de IMC mais elevado. Resultados: Incluídos 24 adolescentes, 87,5% do sexo feminino, idade média de apresentação de 14,9±1,7 anos, início dos sintomas 6,4±3,2 meses antes da primeira consulta. Em t1, escore Z de IMC de -1,91±1,11 kg/m2 e % de peso ideal de 84,3±9,2. Tinham amenorreia 88%. Em t2 as alterações laboratoriais encontradas foram: gasometria venosa alterada em 100%, ferritina alterada (72% elevada), função tiroideia alterada (53% com diminuição da tiroxina), dislipidemia (31% com elevação de lipoproteína de alta densidade, 25% com hipercolesterolemia), elevação da ureia (25%), elevação da alanina aminotransferase (14%), hipoglicemia (14%) e anemia (9%). A acidose respiratória esteve presente em 91% em t1, 100% em t2 e 94% em t3. Verificou-se diminuição significativa entre t2 e t3 da pressão parcial de CO2 (pCO2) média (57,2 versus 53,6 mmHg; p=0,009) e HCO3 médio (30,0 versus 28,8 mEq/L; p=0,023). Conclusões: A acidose respiratória e o aumento da ferritina foram comuns nesse grupo. Acidose respiratória foi a alteração mais frequente, com variação significativa de pCO2 e HCO3 na fase de recuperação. A gasometria venosa deve ser considerada na avaliação laboratorial na AN, pois parece ser importante na avaliação da gravidade e monitorização da doença.

Métodos de tiroglobulina de primera y segunda generación: su utilidad en pacientes con cáncer diferenciado de tiroides / First and second generation thyroglobulin measurement methods: Their usefulness in patients with thyroid cancer

El cáncer diferenciado de tiroides (CDT) es el cáncer endocrinológico más frecuente y en las últimas décadas su incidencia ha aumentado. El seguimiento de la enfermedad se efectúa con la medición de tiroglobulina (Tg) sérica, ecografía cervical y barrido corporal total diagnóstico. Los métodos de Tg han evolucionado a través del tiempo. Actualmente, los ensayos inmunométricos de Tg se clasifican en 1.ª y 2.ª generación (1.ª G y 2.ª G). Comprobamos que los ensayos de 2.ª G alcanzan una precisión adecuada para medir valores del orden de 0,1 ng/ml y los de 1.ª G de 1 ng/ml. La bibliografía señala que en el caso de los pacientes de bajo riesgo, una Tg bajo levotiroxina indetectable por un método de 2.ª G puede evitar la realización de Tg estimulada, sea por la suspensión de la terapia hormonal como por el empleo de la TSH recombinante humana, debido a su mayor sensibilidad. Sin embargo, por su menor especificidad, un valor detectable no asegura la presencia de enfermedad, y debería confirmarse. Para optimizar la utilidad clínica de dicha medición se podrían emplear valores de cortes de acuerdo con la población y el método en lugar de la sensibilidad funcional o límite de cuantificación del mismo. Se señalan también otros aspectos críticos en la medición de Tg como son la discordancia entre distintas metodologías y las interferencias en su medición, principalmente por anticuerpos antitiroglobulina. En presencia de interferencias pierden utilidad los ensayos de Tg de 1.ª y 2.ª G. El seguimiento de los pacientes con Tg interferida tiene limitaciones todavía no resueltas. Es importante consensuar entre médicos y bioquímicos las dificultades técnicas y los criterios de interpretación de los valores de Tg en el seguimiento de los pacientes con CDT.

Differentiated thyroid cancer (DTC) is the most common endocrine cancer (tumour) and its incidence has risen in the past decades. Its follow-up includes measuring serum thyroglobulin (Tg), performing neck ultrasound and a diagnostic whole-body scan. Tg assays have evolved with time. At present immunoassays for Tg are classified as 1 st and 2 nd generation assays (1 st G and 2 nd G). 2 nd G assays show an adequate (good) precision at levels close to 0.1 ng/ml and 1 st G assays at levels close to 1 ng/ml. The literature shows that for low risk patients on levothyroxine treatment, who undetectable levels by 2 aG assays can avoid the stimulation test performed by thyroid hormone withdrawal or after recombinant human TSH, due to better sensitivity. However, due to lower specificity, detectable levels do not confirm the presence of disease (tumour), and should be confirmed. To optimise the clinical usefulness of the test, cut-off values specific for population and method should be used, instead of functional sensitivity or quantification limit. Critical issues for measuring Tg are discussed, such as non-harmonisation of methods, and interferences, mainly by antithyroglobulin antibodies (ATg). 1 st and 2 nd G assays are less useful in presence of ATg, and follow up of such patients is limited. Consensus between physicians and the laboratory on technical issues and interpretation criteria of Tg values is of outmost importance in the follow-up of DTC patients.

The value of red blood cell distribution width in subclinical hypothyroidism / O valor da amplitude de distribuição de eritrócitos no hipotireoidismo subclínico

Objective : Therefore, we evaluated the relationship between the subclinical hypothyroidism and red cell distribution width (RDW) levels in a healthy population. Subjects and methods : The medical records of 23,343 consecutive health subjects were reviewed. Subjects were classified into four thyroid stimulating hormone (TSH) groups to determine the correlation between TSH and other variables in detail (0.3 to < 2.5 mU/L, 2.5 to < 5 mU/L, 5 to < 7.5 mU/L, and ≥ 7.5 mU/L). Results : In the multivariate linear regression analysis, RDW was associated with TSH levels, and e-GFR was inversely associated with TSH levels, respectively (standardized beta coefficient = 0.102, -0.019; p < 0.001, p < 0.001). After adjusting for age and sex, in the four groups, TSH levels were significantly correlated with RDW, estimated glomerular filtration rate (e-GFR), and free thyroxine (fT4) levels in all groups. Furthermore in the 4 th group, RDW levels were more strongly associated with TSH levels than in the other groups (p = 0.006). Conclusions : RDW levels are correlated with euthyroid and subclinical thyroid status. Notably, RDW is more correlated with subclinical hypothyroidism than the euthyroid status. This study presents the relationship between the RDW levels and thyroid function using TSH level in a large healthy population. .

Objetivo : Avaliamos a relação entre o hipotireoidismo subclínico e os níveis de distribuição do tamanho dos eritrócitos (RWD) em uma população saudável. Pacientes e métodos : Foram revisadas as fichas médicas de 23.343 sujeitos saudáveis consecutivos. Os sujeitos foram classificados em quatro grupos de nível de hormônio tireoestimulante (TSH) para se determinar a correlação entre o TSH e outras variáveis, em detalhe (0,3 a < 2,5 mU/L; 2,5 a < 5 mU/L; 5 a < 7,5 mU/L; e ≥ 7,5 mU/L). Resultados : Na análise de regressão linear múltipla, a distribuição do tamanho dos eritrócitos (RWD) foi associada aos níveis de TSH, e a taxa estimada de filtração glomerular (e-GFR) foi inversamente associada aos níveis de TSH, respectivamente (coeficiente betapadronizado = 0,102; -0,019; p < 0,001; p < 0,001). Depois do ajuste para idade e sexo, nos quatro grupos, os níveis de TSH se correlacionaram significativamente com os níveis de RDW, e-GFR e tiroxina livre (fT4) em todos os grupos. Além disso, no quarto grupo, os níveis de RDW estiveram mais fortemente associados aos níveis de TSH do que nos outros grupos (p = 0,006). Conclusões : Os níveis de RDW estão correlacionados com o estado eutiroide e com o hipotireoidismo subclínico. Notavelmente, a RDW é mais correlacionada com o hipotireoidismo subclínico do que com o estado eutiroide. Este estudo apresenta uma relação entre os níveis de RDW e a função tiroidiana por meio da concentração de TSH em um grande número de indivíduos saudáveis. .

Clinical evaluation with self-sequential longitudinal reference intervals: pregnancy outcome and neonatal thyroid stimulating hormone level associated with maternal thyroid diseases / Evaluación clínica con intervalos de referencia longitudinal auto-secuencial: evolución clínica del embarazo y niveles de la hormona estimulante de la tiroides en neonatos asociados con enfermedades tiroideas maternas

OBJECTIVE: We attempted to evaluate maternal thyroid function in a new self-sequential longitudinal reference interval (SLRI) which we established recently. By this method, we analysed the correlation between pregnancy outcome, neonatal thyroid stimulating hormone (TSH) level and maternal thyroid diseases. METHODS: A total of 1744 pregnant women participated in the study and 1747 babies were born from those women (three bore twins). The levels of TSH, free thyroxine (FT4) and thyroid peroxidase antibodies (TPO-Ab) of mothers were quantified by electrochemistry immunoassay (ECL). The levels of neonatal blood TSH were detected by time-resolved fluorescence immunoassay (TRFIA). All data were collected and statistically analysed by SPSS 13.0 software. RESULTS: With our new SLRI method, we found that 0.11%~3.84% pregnant women would get thyroid diseases. Subclinical hypothyroidism was the most common maternal thyroid disorder. Being positive for thyroid peroxidase antibodies was a significant risk factor of subclinical hypothyroidism during pregnancy. The median, P2.5~P97.5, and interquartile range (IQR) of neonatal TSH (N-TSH) of 1747 babies were 2.72 mIU/L, 0.10~8.01 mIU/L and 2.62 mIU/L, respectively; 28.6% of pregnant women with thyroid diseases developed pregnancy complications. The prevalence was significantly higher than in the normal thyroid function group (p< 0.001). The levels of N-TSH were low correlated with maternal TSH levels (p < 0.05), but there were no significant correlations between N-TSH and maternal FT4 and maternal TPO-Ab (p > 0.05). CONCLUSIONS: Thyroid disorders, especially subclinical hypothyroidism, are common in pregnant women. These disorders are associated with pregnancy and fetal outcome. Routine maternal thyroid function screening is important and should be recommended.

OBJETIVO: Intentamos evaluar la función tiroidea materna en un nuevo intervalo de referencia longitudinal auto-secuencial (SLRI) que establecimos recientemente. Por este método, analizamos la correlación entre el resultado del embarazo, el nivel de la hormona estimulante de la tiroides (TSH) en neonatos, y las enfermedades tiroideas maternas MÉTODOS: Un total de 1744 mujeres embarazadas participó en el estudio y 1747 bebés nacieron de esas mujeres (tres de ellas tuvieron gemelos). Los niveles de TSH, la tiroxina libre (FT4), y los anticuerpos de la peroxidasa tiroidea (TPO-Ab) de las madres, fueron cuantificados mediante inmunoensayo electroquímico (ECL). Los niveles de TSH en la sangre de los neonatos, fueron determinados mediante inmunoensayo por fluorescencia resuelto en el tiempo (TRFIA). Todos los datos fueron recogidos y analizados estadísticamente usando el software SPSS 13.0 RESULTADOS: Con nuestro nuevo método SLRI, encontramos que 0.11%~3.84% de las mujeres embarazadas contraerán enfermedades tiroideas. El hipotiroidismo subclínico fue el trastorno de la tiroides materna más común. Ser positivo a los anticuerpos de la peroxidasa tiroidea fue un factor de riesgo significativo del hipotiroidismo subclínico durante el embarazo. La mediana, P2.5~P97.5, y el rango intercuartil (IQR) de la TSH (N-TSH) neonatal de los 1747 bebés fueron 2.72 mIU/L, 0.10~8.01 mIU/L y 2.62 mIU/L respectivamente. El 28.6% de las mujeres embarazadas que tenían enfermedades tiroideas, desarrollaron complicaciones del embarazo. La prevalencia fue significativamente más alta que en el grupo con función tiroidea normal (p < 0.001). Los niveles de N-TSH fueron bajos en correlación con los niveles de TSH maternos (p < 0.05), pero no hubo ninguna correlación significativa entre la N-TSH y la FT4 materna, y la TPO-Ab materna (p > 0.05). CONCLUSIÓNS: Los trastornos tiroideos, especialmente el hipotiroidismo, son comunes en las mujeres embarazadas.Estos trastornos se hallan asociados con el resultado del embarazo y el resultado fetal. El tamizaje de rutina de la función tiroidea materna es importante y debe recomendarse.

Resección de recaídas de cáncer diferenciado de tiroides mediante cirugía radioguiada / Resection for recurrent differentiated thyroid cancer with radioguided surgery

Durante el seguimiento a los pacientes con cáncer diferenciado de tiroides se pueden encontrar recaídas en el cuello entre el 10% y el 60% de los casos. Durante el seguimiento se hace obligatoria la detección de enfermedad en dicha localización. Consecuentemente, se hace búsqueda estricta con ecografías de alta resolución, las cuales son las que más a menudo detectan tempranamente nodos linfáticos metastásicos de escasos milímetros. Cuando tales nódulos están presentes, se realizan disecciones de cuello, pero con cirugía previa se dificulta mucho su extirpación, por la fibrosis y las adherencias. Con el fin de facilitar estos procedimientos se ha planteado el uso de la técnica ROLL (radioguided occult lesion localization) para resecar de forma precisa y segura estos ganglios enfermos. Recientemente, se usó dicha técnica por primera vez en Colombia, y en el Instituto Nacional de Cancerología (INC), hasta donde el equipo a cargo del presente trabajo tiene conocimiento, para intervenir a una paciente con recaída en el cuello por cáncer papilar de tiroides.

During follow up of patients with differentiated thyroid cancer it is possible to find recurrence in the neck in 10% to 60% of cases. During follow up it is requisite to seek out the disease in said location. Consequently, a rigorous search is made with high resolution sonogram, which can most frequently detect early lymphatic node metastasis of scant length in millimeters. If such nodes are detected, neck dissections are performed; but where surgery has previously been carried out, extirpation is difficult due to adherence and fibrosis. In order to facilitate these procedures, the ROLL technique (radio-guided-occult-lesion-localization) is recommended as a means for achieving precise and safe resection of these diseased ganglia. This technique was recently put to use for the first time in Colombia at the National Cancer Institute (NCI) by the authors of this paper whose knowledge of the technique allowed them to perform surgery on a patient with papillary thyroid cancer recurrence in the neck.

Guia de consenso para el diagnostico y seguimiento de la enfermedad tiroidea Parte 2 de 3 / Antibodies cyclical citrulinado anti-peptide: a new marker in reumatoide arthritis

Nota del Editor:Medicina & Laboratorio ha recibido autorización de Academia Nacional de Bioquimica Clinica para reproducir, en su totalidad, la ®Guia de Consenso para el Diagnostico y Seguimiento de la Enfermedad Tiroidea¼, como una excelente herramienta de mejoramiento continuo en el manejo de las pruebas tiroideas, de vital importancia para la region, documento que llegara en tres entregas consecutivas. Demers LM, Spencer CA. Guía de consenso para el diagnostico y seguimiento de la enfermedad tiroidea. Medicina & Laboratorio 2005; 11: 11-38.Módulo 28 (Guías de manejo), número 1 (1/3). Editora Médica Colombiana S.A., 2005.

Guía de consenso para el diagnóstico y seguimiento de la enfermedad tiroidea / Guide of consensus for the diagnosis and pursuit of the tiroidea disease Part 1 of 3

Nota del Editor:Medicina & Laboratorio ha recibido autorización de Academia Nacional de Bioquímica Clínca para reproducir, en su totalidad, la ®Guía de Consenso para el Diagnóstico y Seguimiento de la Enfermedad Tiroidea¼, como una excelente herramienta de mejoramiento continuo en el manejo de las pruebas tiroideas, de vital importancia para la región, documento que llegará en tres entregas consecutivas. Demers LM, Spencer CA. Guía de consenso para el diagnóstico y seguimiento de la enfermedad tiroidea. Medicina & Laboratorio 2005; 11: 11-38.

Estado actual y perspectiva de las pruebas relacionadas con el estudio de la función tiroidea / Present state and prospects of tests related to the thyroid function study

Las enfermedades tiroideas pueden ser diagnosticadas, en la mayoría de los casos, por la clínica. Sin embargo, existen situaciones que requieren de las pruebas de función tiroidea con el fin de valorar correctamente al paciente en las etapas iniciales de la disfunción de esta glàndula, con el fin de establecer el tratamiento adecuado de forma individual y el seguimiento de la evolución de la enfermedad. En esta revisión hacemos referencia a las pruebas empleadas para valorar el estado de la función tiroidea y se señalan sus ventajas, limitaciones y tendencias actuales. La determinación de TSH por procederes de segunda y tercera generaciones permite establecer el diagnóstico del hipertiroidismo e hipotiroidismo primarios, aún en las formas subclínicas de ambos, al mostrar inhibición o hipersecreción, respectivamente, así como la dosis adecuada de l-levotiroxina y orientar a una causa hipofisaria de esta disfunción. La determinación de T4 es de gran valor para conocer la intensidad de la disfunción tiroidea y para valorar la eficacia del tratamiento en las primeras semanas de iniciado. La determinación de T3 tiene su principal indicación ante la sospecha de la presencia del llamado hipertiroidismo por T3. La determinación de T4 y T3 totales da lugar a una interpretación incorrecta en cuanto a las situaciones que modifican la globulina transportadora de tiroxina (TBG). La tendencia actual es al empleo de TSHs como prueba inicial para el diagnóstico de la disfunción tiroidea, la cual se debe indicar teniendo siempre en cuenta la clínica y, de ser necesario, asociarla a la determinación de T4 o T3 libres(AU)

The thyroid diseases may be diagnosed in most of cases by the clinics. However, there are circumstances that required thyroid function tests to correctly assess the patient in initial stages of thyroid dysfunction and give an adequate treatment on an individual basis and the follow-up of the disease. This review makes reference to the tests used to assess the condition of the thyroid function and mentions their advantages, limitations and present trends. The determination of TSH by second and third generation procedures allow setting up diagnoses of primary hyperthyroidism and hypothyroidism, even in the subclinical forms of both entities since or hypersecretion or inhibition are respectively exposed, and they also allow prescribing the right dose of 1-Levothyroxine and orienting towards a hypophyseal cause of thyroid dysfunction. T4 determination is of great value for finding out the intensity of thyroid dysfunction and furthermore assessing the effectiveness of the treatment in the first weeks. T3 determination is mainly indicated when the so-called T3-caused hyperthyroidism is suspected. The determination of total T4 and T3 gives rise to a wrong interpretation regarding the conditions that change the thyroxine-transporting globulin (TBG). The present trend is the use of TSH as an initial test for diagnosing the thyroid dysfunction, which should be indicated taking the clinic into account, and if necessary, it should be associated with the determination of free T4 or free T3(AU)

Fatores interferentes na interpretaçäo de dosagens laboratoriais no diagnóstico de hiper e hipotireoidismo / Interfering factors in the laboratory dosage interpretation in the diagnosis of hyper and hypothyroidism

Desde os primeiros relatos na literatura médica, descrevendo os quadros clínicos de hiper e hipotireoidismo, muito pouco mudou no cenário da semiologia destas entidades e mesmo na sua abordagem terapêutica. As mudanças que assistimos nos últimos anos se relacionam às ferramentas laboratoriais utilizadas no diagnóstico destas disfunçöes. Paralelamente a estes desenvolvimentos, passamos a entender melhor os fatores que interferem na interpretaçäo das dosagens laboratoriais no diagnóstico do hiper e hipotireoidismo. Neste artigo avaliaremos a utilizaçäo das medidas séricas de TSH e dos hormônios tireoideanos, bem como as armadilhas e interferências encontradas no seu uso cotidiano.

Interferência de anticorpos em testes de funçäo tireoidiana: relato de caso / Antibodies interference in thyroid function tests: repost of case

Na avaliaçäo da funçäo tireoideana utiliza-se como método diagnóstico as medidas de TSH, T4 e T3 totais e livres. Entretanto, em alguns casos acorre a ligaçäo näo específica com reagentes dos ensaios que väo, desta forma, interferir com as medidas destes hormônios. Estas interferências iräo resultar em concentraçöes séricas anormais de hormônios tireoideanos, näo consistentes com a avaliaçäo clínica e demais exames laboratoriais destes pacientes. Auto-anticorpos anti-hormônio tireoideano säo a classe de fatores que mais frequentemente interferem com vários ensaios. Relatamos o caso de uma paciente de 62 anos, com queixas de ansiedade e palpitaçöes e exame físico normal. na avaliaçäo laboratorial detectamos níveis séricos persistentemente elevados de T3 total, com níveis séricos normais de TSH e T4 total. A presença de anticorpos anti-T3 foi confirmada por radioimunoprecipitaçäo. Resultados que parecem ser inconscientes ou imcompatíveis com os demais exames laboratoriais, na presença ou näo de sintomas em geral inespecíficos, devem levantar a suspeita da presença de fatores interferentes no ensaio. Desta forma, evita-se o diagnóstico errôneo de disfunçäo tireoideana e, consequentemente, um tratamento desnecessário e até mesmo deletério.

Hipertiroidismo gestacional: análisis a propósito de un asociado a mola / Gestational hyperthyroidism associated to molar pregnancy: a case report

We report a 18 years old woman that was admitted with a history of four days of cardiac failure with acute pulmonary edema, high blood pressure, left ventricular dilatation and moderate to severe systolic dysfunction. Twenty four hours after admission she had a miscarriage, expelling a mole. The diagnosis of hyperthyroidism caused by a mole and early pre eclampsia was confirmed and the patient was managed with diuretics and dopamine. Symptoms abated, thyroid function tests, cardiac function and size returned to normal values and the patient was discharged asymptomatic, ten days after admission

Pruebas de función tiroidea en embarazadas normales, tercer trimestre y embarazadas con colestasis gravídica o con hepatitis aguda / Thyroid function tests in normal pregnancy women, third trimester and in women with intrahepatic cholestasis of pregnancy or with acute hepatitis in pregnancy

Background: Intrahepatic cholestasis of pregnancy (ICP) is a disease of unknown cause characterized by pruritus and biochemical cholestasis in the 3rd trimester of pregnancy. Its pathogenesis may be due to the interaction of abnormalities in the metabolism of estrogens and progesterone, while still unknown environmental factor (s) modulate the expressivity of a genetic predisposing trait. Aims: To verify if thyroid function tests (TFT) are altered in ICP as in other hepatic diseases and whether a dietary iodine deficiency could be involved. Material and methods: From 1983 to 1986, 13 normal pregnancies (3rd trimester), 26 ICP patients (with 30 pregnancies) and 4 patients with acute non-A non-B hepatitis in pregnancy, were studied. Serum T3, rT3, T4, fT4 and TSH (before and after TRH) were measured by RIA; in ICP patients, measurements were repeated in puerperium. Urinary 24 h iodine excretion was measured in normal pregnancies and in 6 ICP patients. Results: In normal pregnancies, T3 (3.00ñ0.22 nmol/L) and rT3 (0.40ñ0.03 nmol/L) were higher than the values detected in non-pregnant women; other TFT were unchanged. Urinary iodine excretion was normal in all individuals tested. Patients with acute hepatitis in pregnancy or with ICP had lower T3 than normal pregnancies (1.82ñ0.19 nmol/L in hepatitis; 2.24ñ0.12 nmol/L in ICP; p<0.01) and higher rT3 (0.80ñ0.25 nmol/L in hepatitis; 0.54ñ0.05 nmol/L in ICP; p<0.05), while other TFT were unchanged. None of them had clinical signs of hypo or hyperthyroidism. A "euthyroid sick syndrome" was detected in 2 ICP patients and in 2 acute hepatitis in pregnancy. In puerperium of ICP patients, T3 and rT3 returned to levels in non-pregnant women. Conclusions: In ICP patients, TFT show similar trends than in more severe hepatic and non-hepatic diseases. Although thyroid binding-globulin was not measured in our patients, the pattern of TFT suggests that an impaired peripheral (hepatic?) deiodination of T4 is responsible for these changes. The influence of a dietary iodine deficiency can be ruled out

Pruebas de función tiroidea

Las pruebas de función tiroidea se han convertido en pruebas de rutina en los laboratorios clínicos, así como de común solicitud en las ordenes médicas, lo que hace necesario que los médicos tengan un dominio amplio y útil de las diferentes pruebas y técnicas que se utilizan para evaluar función tiroidea. La mejor comprensión de la fisiología y metabolismo de las hormonas T3 y T4, ha hecho que desde hace algunos años se venga haciendo énfasis en la mayor utilidad y especificidad de las fracciones libres, lo que ha mejorado el diagnóstico y seguimiento de los pacientes y ha llevado a una mejor utilización e interpretación del comportamiento de éstas en el paciente con una determinada enfermedad tiroidea. Se ha definido también la importancia de los anticuerpos, muy especificamente en las enfermedades tiroideas que tienen un componente autoinmune. Estas pruebas deben hacer parte de las pruebas de rutina solicitadas en la evaluación de los pacientes con afecciones tiroideas.

Función tiroidea en una población con aporte extra de yodo / Thyroid function in a population with an extra iodine intake

Background: After 20 years of iodine salt fortification, the prevalence of goiter has decreased significantly in the rural area of Pirque, central Chile. In this location, equipment has been installed that efficiently and economically adds 0.5 mg of elemental iodine per liter of water to render it potable. Aim: To study thyroid function and urinary iodine excretion in scbool age cbildren of this zone, after two years of extra iodine intake. Material and methods: One hundred thirty four children aged 6 to 12 years old were examined. In 56 randomly chosen children a morning urine sample was obtained to measure iodine excretion. In 45 children without goiter, a blood sample was obtained to measure TSH and thyroxin. Results: In nine cbildren (7 percent) a diffuse goiter was found. Median urinary iodine excretion was 158 ug/dl. Thyroxin and TSH levels were within normal limits (8.4Ý1.1 ug/dl and 2.2Ý1.5 uU/ml respectively). During the period of iodine water supplementation there were 47 births in the zone. All newborns had normal TSH values and none had goiter. Conclusions: When present results are compared with the period before water iodination (when the prevalence of goiter was 9.6 percent and mean urinary iodine excretion was 57.6 ug/dl), it can be concluded that extra iodine intake in this rural population has not caused additional thyroid problems

Determinación del anticuerpo antirreceptor de TSH: experiencia en pacientes con patología tiroídea y controles / Determination of TSH antireceptor antibody: experience in patients with thyroid pathology and controls

In order to measure TSH receptor antibodies (TRAb) we tried to set up a radioreceptor assay using human thyroid membranes. Due to lack of appropriate binding activity of the material obtained, we decided to use a kit which provides solubilized porcine membrane-receptors to TSH instead of human membranes, as well as calibrators that have been standarized in a receptor assay against MRC LATS std B. With these reactives we have measured TRAb in sera from 7 normal controls (C), 54 thyrotoxic patients (43 diffuse goiters [BDH], 8 multinodular goiters [BDH] and 3 subacute Thyroiditis [TSA], 3 patients with Hashimoto's Thyroiditis (TH) and 6 non-hyperthyroid Graves ophtalmopathy patients. Measurement were initially performed using calibrators and the results expressed as U/L; since a very good correlation between the expression U/L and the calculated inhibition Index (I.I.) was found (r=0.99, n=15, p<0,001), results are shown using latter. In C mean ñ SD value for I.I. was 3.4 ñ 2.37 percent so we decided to use, as cut off criteria for differentiating between normal and abnormal results, the figure 11 percent which represents the mean ñ 3 SD. According to this, 93 percent of BDH has elevated TRAb activity while only slightly more than one third of MBH had elevated values, this difference being highly significant (p<0,0001); both TSA and TH patients showed low TRAb activity while all Graves ophtalmopathy pts had elevated values, thus suggesting that they had a latent disease. We concluded that the methodology that is adequate and practical for clinical purposes. Our results show that measurement of TRAb activity is very useful in stablishing the etiology of hyperthyroidism in an individual patient. Also it provides help inthe differential diagnosis of patients with exoftalmus od unknown etiology. Its usefulness remains to be proved in the follow-up of BDH pts after been treated with antithyroid drugs