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)

Historia familiar de enfermedad tiroidea y riesgo de hipotiroidismo congénito en neonatos con síndrome de Down / Family history of thyroid disease and risk of congenital hypothyroidism in neonates with Down syndrome

Resumen Introducción: La historia familiar de enfermedad tiroidea (HFET) como factor de riesgo para hipotiroidismo congénito (HC), en síndrome de Down (SD) aún no ha sido explorada. Objetivo: Determinar si la HFET está asociada a mayor riesgo de HC en neonatos con SD. Método: Estudio de casos y controles en 220 neonatos con SD. Se compararon las pruebas de función tiroidea (PFT) de 37 con SD e HFET (casos), frente a las PFT de 183 recién nacidos con SD sin HFET (grupo de referencia). Se realizó análisis de regresión logística multivariante y se calculó la razón de momios (RM) y sus respectivos intervalos de confianza del 95 % (IC 95 %). Resultados: Nueve casos HC (4.1 %). El HC mostró asociación con la HFET (RMa = 8.3, IC 95 %: 2.0-34.3), particularmente en los varones (RMa = 9.0, IC 95 %: 1.6-49.6). La ausencia de HFET tuvo una RM de protección para HC (RMa = 0.4, IC 95 %: 0.1-0.8). Conclusiones: La HFET puede es una estrategia fácil y accesible para identificar pacientes con SD con mayor riesgo de HC.

Abstract Introduction: Family history of thyroid disease (FHTD) as risk factor for congenital hypothyroidism (CH) in patients with Down syndrome (DS) has not yet been explored. Objective: To determine whether FHTD is associated with an increased risk for CH in DS. Method: Case-control study in 220 neonates with DS. Thyroid function tests of 37 infants with DS and FHTD (cases) were compared with those of 183 DS newborns without FHTD (reference group). Data were analyzed using multivariate logistic regression analysis and adjusted odds ratios (aORs) with their respective 95 % confidence intervals (CI) were calculated. Results: Nine newborns with DS in our sample had CH (4.1 %). FHTD showed an association with CH in neonates with DS (aOR = 8.3, 95 % CI: 2.0-34.3), particularly in males (aOR = 9.0, 95 % CI: 1.6-49.6). In contrast, newborns with DS without FHTD were less likely to suffer from CH (aOR = 0.4, 95 % CI: 0.1-0.8). Conclusions: FHTD detailed evaluation can be an easy and accessible strategy to identify those newborns with DS at higher risk for CH.

Hormonal dysfunction in patients with chronic obstructive pulmonary disease

Systemic response to chronic disease in COPD patients might cause hormonal imbalance which in turn affects the severity of the disease. The severity of hypoxia in COPD patients causes alterations in thyroid function tests and IGF-1 levels. This work was carried on 50 COPD patients diagnosed and classified according to GOLD criteria and 20 healthy controlled subjects. All subjected to full clinical history, examination, chest X-ray and spirometry. Levels of TT3, TT4, FT3, FT4, IGF-1 and insulin were measured. TT4, FT3, FT4, TSH, and insulin levels were normal in all COPD. Despite the TT3 hormone level were normal in all stages of COPD, there is reduction in hormone levels in stage III and stage IV than control subjects. There is also reduction in TT3/TT4 ratio in severe COPD and there is correlation between TT3/TT4 ratio and PaO2 in stage III and stage IV but no correlation between TT3/TT4 ratio and PaO2 in stage I and stage II. IGF-1 hormone levels were variable among different stages of COPD. There is was no significant difference between some hormonal levels in COPD and in controls, accordingly hormonal replacement therapy in these patients is doubtful

Hypothyroidism following thyroid surgery

Postsurgical hypothyroidism and its incidence has not been fully investigated. In this study, the incidence of hypothyroidism and its possible risk factors at Shariati Hospital was assessed. One hundred and two patients with benign thyroid diseases, who had undergone thyroidectomy, were investigated with regards to thyroid function profile during period of one year after the operation every three months with post-operative sample as the baseline. Hypothyroidism was developed in 36 patients [35.2%] on average 5 +/- 3.2 months after surgery. Factors such as increased age, operation type, histopathologic type, underlying disease, lymphocytic infiltration and use of levothyroxine before surgery were associated with the increased incidence of hypothyroidism. It seems that use of indicators such as Graves' disease and lymphocytic infiltration in pathologic specimens should be helpful in projecting the potential occurrence of hypothyroidism in patients undergoing thyroidectomy

study of serum zinc, copper and thyroid hormones in children with chronic renal failure

The study included 21 patients [13 males and 8 females, aged from 9-17ys] with chronic renal failure [CRF] on regular hemodialysis. In addition, 10 apparently healthy age-matched children were included as a control group. Serum levels of zinc [Zn], copper [Cu], tri-iodothyronine [T[3]], thyroxin [T[4]], thyroid stimulating hormone [TSH] and creatinine were measured in all studied cases and controls. Serum levels of Zn and Cu were significantly lower among the studied cases [96.76 +/- 41.4 micro g/dl and 82.33 +/- 16.4 micro g/dl, respectively], compared with the controls [134.4 +/- 43 micro g/dl and 100.2 +/- 14.4 micro g/dl respectively], p<0. 05 and p<0.01 respectively. As regards the studied thyroid hormones and TSH, the studied cases showed significant lower serum T[3] level [61.85 +/- 9.7 nano g/dI] compared with the control group [85.80 +/- 4.26 nano g/dl], p< 0.001. While no significant statistical differences were found between the studied cases and controls regarding T[4] and TSH serum level. On the other hand, the mean value of T[3]/T[4] ratio was significantly lower among studied patients [12.91 +/- 1.87] in comparison with the controls [16.23 +/- 2.63], p<0.001. Additionally, a significant positive correlation was found between T[3] and T[4] [r=0.645, p<0.01]. Serum Zn exhibited also positive significant correlation with T[3] and T[4] [r=-0.506 and r=0 .514 respectively], p<0.05 for each. However, no significant correlation was detected between serum Cu levels and thyroid hormones. In conclusion; patients with CRF had low levels of serum Zn and Cu. They may have a state of subclinical hypothyroidism. The significant decrease in the mean value of serum T[3] level, the insignificant decrease in the mean value of serum T[4] level, the significant low T[3]/T[4] ratio as well as the significant positive correlation between serum Zn and T[3] may reflect impaired peripheral conversion of T[4] to T[3] due to Zn deficiency

Voice changes after thyroidectomy: role of external laryngeal nerve

To evaluate a technique to protect the external laryngeal nerve during thyroidectomy.Randomized controlled trial. Patients randomized into group A or B using closed envelops method. Alexandria university hospital is a teaching hospital. It is the referral center serving seven million people. Forty four consecutive patients admitted to Alexandria university hospital for thyroidectomy. Fourpatients had voice abnormalities on preoperative voice analysis. They were excluded. All patients underwent thyroidectomy. Group A had conventional mass ligature of the superior poleof thyroid gland while group B had individual ligation of the branches of the superior thyroid artery afteridentification of the external laryngeal nerve whenever possible. Abnormal readings on postoperative voice analysis and abnormal electromyogram of thecricothyroid muscles. Observers performing voice analysis tests were blinded as regards patient group. Postoperativeelectromyography of the cricothyroid revealed signs of nerve injury in five patients of group A but none in groupB. Multi-dimensional voice program, fundamental frequency range, fundamental frequency and maximum pressurelevel all showed significant postoperative change in group A but not of those in group B [level of confidence95%].Identification of external laryngeal nerve and/or ligation of the terminal branches of the superiorthyroid vessels seems to help prevent external laryngeal nerve injury

Tratamiento quirúrgico de los bocios difusos hipertiroideos: experiencia del hospital de Valdivia / Surgical treatment of diffuse hyperthyroid goiter: experience at Valdivia hospital

The charts of 64 patients, 54 female, aged between 15 and 57 years old, operated between 1985 and 1995 were analyzed. The indication for surgical treatment was failure of medical treatment in 59 patients and a big goiter causing mechanical compression in 3 patients. A subtotal thyroidectomy was done after an abbreviated surgical preparation. The mean weight of the resected glands was 65.9 g. Four patients had transient hypocalcemia and 4 had surgical wound seromas. After a mean follow up of 31 months, 77 percent of patients remain euthyroid, hyperthyroidism relapsed in 13.1 percent and 10 percent became hypothyroid. Surgical treatment of hyperthyroid goiter is safe but the percentage of hyperfunction relapse is high

present state of radionuclide thyroid studies

Thyroid diseases are very frequently encountered disorders by endocrinologists, and thyroid dysfunction is often suspected by almost all clinicians. The diagnosis of thyroid disease represents, therefore, a major clinical problem. The proliferation of in vitro thyroid function tests has lead to such confusion of nomenclature that many doctors do not know what they are asking for, much less the limitation of the particular investigation in question. Effective treatment of thyroid disease is relatively simple; so early diagnosis is of great asset to the clinician. Diagnosis of thyroid disease begin as in other areas of medicine, with a careful clinical history, and physical examination. A good percentage of thyroid illnesses can be correctly diagnosed on clinical grounds. The Wayne's Index was advocated to transfer clinical findings into numbers. However laboratory tests to confirm the clinical diagnosis of thyroid disease are needed,since such diagnosis often necessitates surgery or medical treatment that extends over years or throughout the patients life. Furthermore, a significant fraction of thyroid illnesses can be diagnosed only on the basis of laboratory data, and in some instances laboratory diagnosis along might be an indication to therapy in the absence of clear clinical evidence of thyroid disease. Errors in diagnosis may be contributed by any laboratory method used and when investigations are carried out in the best laboratories, values outside the normal range occur in few euthyroid people. In addition, the tests themselves are subject to limitation, which are often not appreciated by those asking for them. Laboratory tests are liable to interference by many factors unrelated to the thyroid pathology