Prevalence of thyroid dysfunction in healthy adults according to the estimated iodine intake in 24-hour urine samples: The SALMEX cohort.

PURPOSE: The aim of this study was to evaluate the prevalence of thyroid dysfunction in a cohort of healthy individuals in Mexico City, as well as to investigate the potential associations of these results with their estimated iodine intake (EII) as reflected by their 24-hour urinary iodine excretion (24-h UIE). METHODS: From the SALMEX cohort, 683 adults provided an appropriate 24-h urine sample. Thyroid function tests and thyroid antibody concentrations were determined in the participants' sera. We analyzed discrepancies between the commonly used urinary parameters to determine the iodine intake status and the performance of thyroglobulin (Tg) as a biomarker of its status in the adult population. RESULTS: The prevalence of dysthyroidism was high, being similar to other studies. Subclinical hypothyroidism was detected in 5.0% of individuals, clinical hypothyroidism in 1.8% of individuals, and sub-clinical hyperthyroidism in 2.8% of individuals. The median EII was 285 µg/d (IQR 215.0-369.0); 94% of individuals had EII >150 µg/d recommended daily allowance (RDA) in adults. The urinary iodine concentration (UIC) and the UIE had relative biases in their averages of 34.4%. The Tg median was 7.21 ng/mL. The prevalence of increased Tg was 6.15%. There was no correlation between Tg and EII (r= 0.019, p= 0.606). CONCLUSIONS: Thyroid dysfunction was highly prevalent in this population. Our cohort revealed a slight discrepancy between dysthyroidism manifestations and iodine intake markers; the latter represent a population with adequate iodine intake. Further studies are necessary to clearly define the prevalence of thyroid dysfunction as well as the iodine nutritional status in Mexico.

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.

The sum of us: considerations on physician-industry relationships. / La suma de nosotros: una reflexión sobre las relaciones médico-industria.

This essay describes critically the physician-industry relationships and how the latter influences economically in the realization of continuing medical education (CME), industry expenses in sponsoring the academic events of medical societies, travel costs and enrollment, payment for consultants and speakers. It also refers to the movements that have been created in the academic world to counteract this influence, such as No Free Lunch (Spanish version “NoGracias”) and PharmFree. And the struggles between major scientific medical journals, with editorials and among editorialists on the concept of conflicts of interest. All this seen through the existence of an academic institution in Mexico and the exemplary life of one of its members.

En este ensayo se describen de forma crítica las relaciones médico-industria, su influencia económica en la realización de la educación médica continua, los gastos de la industria en el patrocinio de los eventos académicos de las sociedades médicas, los costos de sus inscripciones y los viajes asociados a ellos, el pago por consultorías y “conferencistas a sueldo” (speakers). También hace referencia a los movimientos que se han creado en el mundo académico para contrarrestar esta influencia, como el No Free Lunch (su versión española No Gracias) y PharmFree. Asimismo, se alude a las pugnas entre las grandes revistas médicas científicas, con editoriales y entre editorialistas sobre el concepto del conflicto de intereses. Todo ello es visto a través de la existencia de una institución académica en México y la vida ejemplar de uno de sus miembros.

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.

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.

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.

Developing thyroid disorders is associated with poor prognosis factors in patient with stable chronic heart failure.

We sought to assess the developing of thyroid disorders in forty eight patients with chronic stable heart failure and without thyroid abnormalities during six months follow-up. Thyroid function disorders were observed in 27.1% of the subjects: sick euthyroid syndrome (12.5%), subclinical hypothyroidism (10.4%) and overt hypothyroidism (6.2%). Subjects with higher thyroid stimulating hormone (TSH) levels at the end of the study had more hospitalizations. The developing of altered thyroid profile was related to lower hemoglobin levels, smaller phase angle with bioelectrical impedance method and more fatigue perception by the patients. This abnormal thyroid function behavior on stable chronic heart failure and was observed as part of the disease progress and was associated to worse prognosis factors as lower phase angle and anemia.

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.

Evidence of linkage between neurocardiogenic dysfunction and reactive hypoglycemia / Evidencia de una posible asociación entre disfunción neurocardiogénica e hipoglicemia reactiva

La hipoglucemia reactiva es un problema común en la práctica clínica cuya patofisiología es motivo de controversia. El objetivo del presente estudio fue investigar la prevalencia de anormalidades del sistema nervioso autónomo en pacientes con hipoglucemia reactiva comparada con controles sanos. Material y métodos. Se incluyeron para el estudio a seis mujeres con hipoglucemia reactiva con edad media de 31 ñ 5 años y 5 mujeres sanas con edad media de 24 ñ 4 años. Se investigó la variabilidad de la frecuencia cardiaca y los cambios en la presión arterial después de una prueba de inclinación con y sin isoproterenol. Se definió como prueba positiva a la presencia de síncope o presíncope asociados a bradicardia, hipotensión o ambas. Resultados. En respuesta a la prueba de inclinación con o sin isoproterenol 5 de 6 pacientes comparado con 1 de 5 controles sanos presentaron una prueba positiva. Las pacientes presentaron un tono hiperadrenérgico con una relación simpático/parasimpático de 2.3 ñ 0.8 en condiciones basales y 10.1 ñ 4.1 durante la infusión de isoproterenol, en comparación a 0.7 ñ 0.3 (p = 0.06) y 0.5 ñ 0.1 (p < 0.01) respectivamente en el grupo control. Conclusiones. Los pacientes con hipoglucemia reactiva pueden estar en un extremo de variabilidad biológica normal. Pueden cursar con un tono hiperadrenérgico y después de un estímulo provocativo la descarga simpática o la liberación sináptica de norepinefrina pueden ser insuficientes para mantener un tono vascular adecuado. Otra posibilidad es que la respuesta vascular a norepinefrina esté alterada. No se observó una respuesta vasovagal paradójica o excesiva.