PREVALENCE OF AUTOIMMUNE THYROIDITIS AND THYROID DYSFUNCTION IN HEALTHY ADULT MEXICANS WITH A SLIGHTLY EXCESSIVE IODINE INTAKE.

OBJECTIVE: the purpose of this study was to evaluate the prevalence of autoimmune thyroiditis and thyroid dysfunction in healthy individuals with no previously known thyroid disease, in an urban area of Mexico City. SUBJECTS AND METHODS: the study was conducted on volunteers with no known thyroid disease. We recruited 427 subjects among the hospital's medical and administration personnel. All underwent thyroid ultrasound (US) and TSH, free T4 (FT4), total T3 (TT3), thyroid anti-peroxidase (TPOAb) and anti-thyroglobulin (TgAb) antibodies were measured. Hypoechogenicity and thyroid volume were determined by US. Urinary iodine (UI) excretion was also measured. RESULTS: the frequency of autoimmune thyroiditis was 8.4% (36/427) and women were most commonly affected than men (11.6 vs. 4.3% respectively, P = 0.008); when including cases of atrophic thyroid, the frequency increased to 15.7% (67/427). Clinical hypothyroidism was detected in 1.2% (5/427) and it was sub-clinical in 5.6% of individuals. A goiter was present in 5.9% (25/427) of volunteers. Median UI was 267 µg/L, (IQR 161.3 - 482.5). CONCLUSIONS: in spite of our study's limitations, the frequency of autoimmune thyroiditis is clearly elevated in the studied population. Further studies are necessary in order to define the prevalence of autoimmune thyroid disease as well as the current iodine nutritional status in our country.

Objetivo: el objetivo del presente estudio fue evaluar la prevalencia de tiroiditis autoinmune y disfunción tiroidea en individuos sanos sin enfermedad tiroidea conocida, de un área urbana de la ciudad de México. Material y métodos: el estudio se realizó en voluntarios sin enfermedad tiroidea conocida. Se reclutaron 427 individuos entre personal médico y administrativo del hospital. A todos se les realizó ultrasonido (US) tiroideo, TSH, T4 libre (FT4), T3 total (TT3), anticuerpos anti-peroxidasa tiroidea (TPOAb) y anti tiroglobulina (TgAb). Dentro de la evaluación por US se incluyó la hipoecogenicidad y el volumen tiroideo. También se midió la excreción urinaria de yodo (UI). Resultados: la frecuencia de tiroiditis autoinmune fue de 8,4% (36/427), las mujeres fueron más afectadas que los hombres (11,6 vs. 4,3%, respectivamente, P = 0,008), cuando se sumó la tiroides atrófica, esta frecuencia se elevó al 15,7% (67/427) de los estudiados. El hipotiroidismo clínico fue detectado en el 1,2% (5/427) y el subclínico en el 5,6%. El hipertiroidismo clínico solo se observó en el 0,5% (2/427) y el subclínico en el 1,9%. El bocio se identificó en el 5,9% (25/427) de los voluntarios. La mediana de la UI fue de 267 µg/L, RIQ (161,3 ­ 482,5). Conclusiones: a pesar de las limitaciones de nuestro estudio, es clara la frecuencia incrementada de tiroiditis autoinmune en la población estudiada. Son necesarios más estudios que definan tanto la prevalencia de enfermedad tiroidea autoinmune como el estatus nutricional de yodo actual en nuestro país.

Prevalence of autoimmune thyroiditis and thyroid dysfunction in healthy adult Mexicans with a slightly excessive iodine intake / Prevalencia de tiroiditis autoinmune y disfunción tiroidea en adultos mexicanos sanos, con una ingestión de yodo levemente excesiva

Objective: the purpose of this study was to evaluate the prevalence of autoimmune thyroiditis and thyroid dysfunction in healthy individuals with no previously known thyroid disease, in an urban area of Mexico City. Subjects and methods: the study was conducted on volunteers with no known thyroid disease. We recruited 427 subjects among the hospital’s medical and administration personnel. All underwent thyroid ultrasound (US) and TSH, free T4 (FT4), total T3 (TT3), thyroid anti-peroxidase (TPOAb) and anti-thyroglobulin (TgAb) antibodies were measured. Hypoechogenicity and thyroid volume were determined by US. Urinary iodine (UI) excretion was also measured. Results: the frequency of autoimmune thyroiditis was 8.4% (36/427) and women were most commonly affected than men (11.6 vs. 4.3% respectively, P=0.008); when including cases of atrophic thyroid, the frequency increased to 15.7% (67/427). Clinical hypothyroidism was detected in 1.2% (5/427) and it was sub-clinical in 5.6% of individuals. A goiter was present in 5.9% (25/427) of volunteers. Median UI was 267 µg/L, (IQR 161.3 - 482.5). Conclusions: in spite of our study’s limitations, the frequency of autoimmune thyroiditis is clearly elevated in the studied population. Further studies are necessary in order to define the prevalence of autoimmune thyroid disease as well as the current iodine nutritional status in our country

Objetivo: el objetivo del presente estudio fue evaluar la prevalencia de tiroiditis autoinmune y disfunción tiroidea en individuos sanos sin enfermedad tiroidea conocida, de un área urbana de la ciudad de México. Material y métodos: el estudio se realizó en voluntarios sin enfermedad tiroidea conocida. Se reclutaron 427 individuos entre personal médico y administrativo del hospital. A todos se les realizó ultrasonido (US) tiroideo, TSH, T4 libre (FT4), T3 total (TT3), anticuerpos anti-peroxidasa tiroidea (TPOAb) y anti tiroglobulina (TgAb). Dentro de la evaluación por US se incluyó la hipoecogenicidad y el volumen tiroideo. También se midió la excreción urinaria de yodo (UI). Resultados: la frecuencia de tiroiditis autoinmune fue de 8,4% (36/427), las mujeres fueron más afectadas que los hombres (11,6 vs. 4,3%, respectivamente, P=0,008), cuando se sumó la tiroides atrófica, esta frecuencia se elevó al 15,7% (67/427) de los estudiados. El hipotiroidismo clínico fue detectado en el 1,2% (5/427) y el subclínico en el 5,6%. El hipertiroidismo clínico solo se observó en el 0,5% (2/427) y el subclínico en el 1,9%. El bocio se identificó en el 5,9% (25/427) de los voluntarios. La mediana de la UI fue de 267 µg/L, RIQ (161,3 - 482,5). Conclusiones: a pesar de las limitaciones de nuestro estudio, es clara la frecuencia incrementada de tiroiditis autoinmune en la población estudiada. Son necesarios más estudios que definan tanto la prevalencia de enfermedad tiroidea autoinmune como el estatus nutricional de yodo actual en nuestro país

Determination of thyrotropin reference values in an adult Mexican population / Determinación de los valores de referencia para la tirotropina en una población mexicana adulta

BACKGROUND AND OBJECTIVE: The upper limit of TSH reference level is controversial. The purpose of our study was to determine TSH reference values in a Mexican population in accordance with the National Academy of Clinical Biochemistry (NACB) criteria and in correlation with thyroid ultrasound (US) examination. PATIENTS AND METHODS: The study was conducted in volunteers with no known thyroid disease. We recruited 482 subjects, most of them medical or administrative staff from our hospital. They answered a questionnaire on demographic data, family history, co-morbidities, and drug use. Their thyroid hormone levels and thyroid antibodies were determined, and a complete physical examination and thyroid US were performed. The population used to establish the TSH reference intervals was selected according to the NACB criteria and their normal thyroid structural and echogenic characteristics in US examination. RESULTS: Among 482 subjects (209 males) with a median age of 26 years, prevalence rates of TPOAb and TgAb were 9.3% and 10.3% respectively. Mean TSH level in the overall population was 1.90 ± 1.94, with a 97.5 th percentile of 6.76 mIU/L. The reference population was limited to 282 subjects (41.5% were excluded) with a mean TSH of 1.86 ± 1.63 and a 97.5 th percentile of 4.88 mIU/L. No sex difference was found (p = 0.287). Median urinary iodine level in the reference population was 267¿g/L IQR (161.3-482.5). CONCLUSIONS: The TSH reference interval in the reference population was 0.71 (CI 0.65 - 0.77) to 4.88 mIU/L (CI 4.5 - 5.3); these limits may be influenced by iodine nutritional status in this population

ANTECEDENTES Y OBJETIVO: Existe controversia respecto al límite superior de referencia para TSH. El objetivo del estudio fue determinar los valores de referencia para TSH en una población mexicana de acuerdo con los criterios de la National Academy of Clinical Biochemistry (NACB) y en correlación con el examen ultrasonográfico (US) tiroideo. PACIENTES Y MÉTODOS: El estudio se realizó en voluntarios sin enfermedad tiroidea conocida. Se reclutaron 482 individuos, personal sanitario y administrativo del hospital, que respondieron un cuestionario sobre datos demográficos, antecedentes familiares, co-morbilidades y medicamentos consumidos, y a los que se les practicó determinación de hormonas tiroideas, anticuerpos anti-tiroideos, exploración y US tiroideo. La población escogida para establecer los intervalos de referencia de TSH fue seleccionada con los criterios de la NACB más la normalidad estructural y ecogénica del tiroides por US. RESULTADOS: En los 482 sujetos (209 hombres) con mediana de edad de 26 años, la prevalencia de TPOAb fue de 9,3% y TgAb 10,3%. La media de TSH para la población total fue 1,90n ± 1,94, con percentil 97,5 de 6,76 mUI/L. La población de referencia se limitó a 282 sujetos (41,5% fueron excluidos); la TSH media de esta población fue de 1,86±1,63, con percentil 97,5 de 4,88 mUI/L, sin diferencia entre géneros (p = 0,287). La mediana para la yoduria de la población referencia fue 267¿g/L RIQ (161,3-482,5). CONCLUSIONES: El intervalo de referencia para la TSH fue de 0,71 (IC 0,65 - 0,77) a 4,88 mUI/L (IC 4,5 - 5,3); el resultado posiblemente está influido por el estado nutricional de yodo de esta población

Determination of thyrotropin reference values in an adult Mexican population.

BACKGROUND AND OBJECTIVE: The upper limit of TSH reference level is controversial. The purpose of our study was to determine TSH reference values in a Mexican population in accordance with the National Academy of Clinical Biochemistry (NACB) criteria and in correlation with thyroid ultrasound (US) examination. PATIENTS AND METHODS: The study was conducted in volunteers with no known thyroid disease. We recruited 482 subjects, most of them medical or administrative staff from our hospital. They answered a questionnaire on demographic data, family history, co-morbidities, and drug use. Their thyroid hormone levels and thyroid antibodies were determined, and a complete physical examination and thyroid US were performed. The population used to establish the TSH reference intervals was selected according to the NACB criteria and their normal thyroid structural and echogenic characteristics in US examination. RESULTS: Among 482 subjects (209 males) with a median age of 26 years, prevalence rates of TPOAb and TgAb were 9.3% and 10.3% respectively. Mean TSH level in the overall population was 1.90±1.94, with a 97.5th percentile of 6.76 mIU/L. The reference population was limited to 282 subjects (41.5% were excluded) with a mean TSH of 1.86±1.63 and a 97.5th percentile of 4.88 mIU/L. No sex difference was found (p=0.287). Median urinary iodine level in the reference population was 267 µg/L IQR (161.3-482.5). CONCLUSIONS: The TSH reference interval in the reference population was 0.71 (CI 0.65-0.77) to 4.88 mIU/L (CI 4.5-5.3); these limits may be influenced by iodine nutritional status in this population.

Urinary iodine excretion in healthy Mexican adults / Excreción urinaria de yodo en adultos sanos mexicanos

The iodine nutritional status of a population is mainly measured by urinary iodine excretion (UI) and thyroid volume determined by ultrasound (US). The surveillance of nutritional iodine levels in the Mexican population has been insufficient. Our aim was to determine the UI in random samples from adults living in an urban area. We selected a sample of healthy individuals over the age of 18 that were students, physicians or administrative personnel at our Institution and had no known thyroid disease. Thyroid volume was determined by ultrasound in all volunteers as well as thyroid hormones and antithyroid antibodies and a urine sample was obtained. One hundred and two volunteers with a median age of 29, participated in the study. The group’s median UI was 221 μg/L,interquartile range (IQR)(135.0 to 356.8) and no differences were observed between genders: women had a UI of 218.0 μg/L IQR (129.0 a 351.0) vs. 223.0 μg/L IQR (138.0 to 374.0) in males, p 0.941. Excessive dietary iodine intake was established in 31.4% of all volunteers according to their UI, placing them at risk of thyroid dysfunction. It is fundamental to evaluate the national iodine nutritional status in Mexico. We discuss the current status of the nutritional state in the Americas, emphasizing that in Latin America and the observed tendency in the region to ingest a diet high in iodine.

El estatus nutricional del yodo en una población, principalmente es medido por la excreción del yodo urinario (UI) y el cálculo del volumen tiroideo por ultrasonido (US). La vigilancia nutricional del yodo en la población en México ha sido escasa. El objetivo fue determinar la UI en una muestra casual en adultos sanos que habitan en un área urbana. Se seleccionó una muestra de individuos mayores de 18 años, entre estudiantes, médicos y trabajadores administrativos de nuestra institución, sanos, sin enfermedad tiroidea conocida. A todos los voluntarios se les determinó el volumen tiroideo por US, hormonas y anticuerpos antitiroideos y se les solicitó una muestra de orina. Participaron 102 voluntarios, mediana de 29 años. La mediana de la UI del grupo fue 221 μg/L, rango intercuartílico (RIQ) (135.0 a 356.8), no hubo diferencias entre géneros, las mujeres tuvieron una UI de, 218.0 μg/L RIQ (129.0 a 351.0) vs 223.0 μg/L RIQ (138.0 a 374.0) p 0.941. El 31.4% de los voluntarios mostraron una ingestión excesiva de yodo en la dieta de acuerdo a la UI, lo cual los coloca en riesgo de sufrir disfunción tiroidea. Es necesario considerar la evaluación Nacional del estatus nutricional del yodo, en México. En el artículo se discute la situación actual del estatus nutricional en las Américas, haciendo énfasis en Latinoamérica y a la tendencia de la región a la dieta excedida en yodo.

Urinary iodine excretion in healthy Mexican adults.

The iodine nutritional status of a population is mainly measured by urinary iodine excretion (UI) and thyroid volume determined by ultrasound (US). The surveillance of nutritional iodine levels in the Mexican population has been insufficient. Our aim was to determine the UI in random samples from adults living in an urban area. We selected a sample of healthy individuals over the age of 18 that were students, physicians or administrative personnel at our Institution and had no known thyroid disease. Thyroid volume was determined by ultrasound in all volunteers as well as thyroid hormones and antithyroid antibodies and a urine sample was obtained. One hundred and two volunteers with a median age of 29, participated in the study. The group's median UI was 221 µg/L, interquartile range (IQR) (135.0 to 356.8) and no differences were observed between genders: women had a UI of 218.0 µg/L IQR (129.0 a 351.0) vs. 223.0 µg/L IQR (138.0 to 374.0) in males, p 0.941. Excessive dietary iodine intake was established in 31.4% of all volunteers according to their UI, placing them at risk of thyroid dysfunction. It is fundamental to evaluate the national iodine nutritional status in Mexico. We discuss the current status of the nutritional state in the Americas, emphasizing that in Latin America and the observed tendency in the region to ingest a diet high in iodine.

Effect of 1110 MBq Radioiodine in Reducing Thyroid Volume in Multinodular Goiter: A New Protocol.

BACKGROUND: There is no consensus on the optimal treatment of multinodular goiter (MNG), but in the past few years, the use of radioiodine has increased. This study's objective was to evaluate adjuvant methimazole (MMI) therapy to increase and standardize radioiodine uptake (RAIU) with a fixed therapeutic (131)I dose of 1110 MBq (30 mCi). METHODS: Our study included 5 women with MNG treated with MMI, 10 - 15 mg/day for 2 to 4 months, prior to the administration of 1110 MBq (131)I (30 mCi); none of the patients developed hypothyroidism during MMI therapy and had average basal TSH levels of 0.32 ± 0.39 mIU/L that increased to 2.6 ± 0.9 mIU/L (P = 0.07). RESULTS: RAIU increased from 25.6 ± 8.7% to 49.2 ± 8.3% (P = 0.003). All patients were followed for 12 months: median thyroid volume (TV) decreased from 77.2 mL (32.9 - 124.2) to 48.8 ml (12.4 - 68.9) with an average decrease of 46.4 ± 14.8% (P = 0.01). All patients developed hypothyroidism during the first 6 months after radioiodine therapy. CONCLUSIONS: This new therapeutic protocol using MMI as adjuvant therapy is effective in increasing RAIU as well as the deleterious effects of (131)I, without increasing the required dose, but leading to thyroid volume decreases similar to those reported with the use of recombinant human thyrotropin (rhTSH) or higher radioiodine doses.