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Context: The low-dose (1 μg) ACTH test (LDT) is widely used to assess central adrenal insufficiency (CAI); however, the serum cortisol cutoff value is controversial. Salivary cortisol (SC) may be a more accurate measurement for CAI. Objective: To assess a new maximum cutoff value of serum cortisol after LDT in pediatric patients, taking into account serum and SC measurements. Design and Setting: Prospective study in a pediatric tertiary referral center. Working Hypothesis: The combined analysis of serum and SC response to LDT might improve LDT for CAI diagnosis. Participant and Outcome Measurement: A total of 145 pediatric patients underwent LDT. Serum and SC levels were measured. A central adrenal sufficient (CAS) response was established according to the reference serum cortisol cutoff value of ≥497 nmol/L. Results: The LDT study showed central adrenal sufficiency in 72 patients and CAI in 73 patients. Considering the lower quartile of maximum SC value (21 nmol/L) in the CAS group, an intermediate CAI (InCAI) group and a real CAI (RCAI) group were defined. Regarding the median maximum value of serum cortisol levels in the InCAI group, a new serum cortisol cutoff value of 450 nmol/L was established. Furthermore, 91% of the patients in the RCAI group were below this cutoff value. Conclusion: The combined evaluation of maximum serum and SC levels to LDT might be useful to define an InCAI group and to avoid unnecessary hormone replacement therapy. However, rigorous patient follow-up is required © 2019 Fil: Vaiani, Elisa. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; Argentina Fil: Lazzati, Juan Manuel. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; Argentina Fil: Ramirez, Pablo. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; Argentina Fil: Costanzo, Mariana. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; Argentina Fil: Gil, Silvia. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; Argentina Fil: Dratler, Gustavo. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; Argentina Fil: Zaidman, Verónica. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; Argentina Fil: Chaler, Eduardo Adrian. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; Argentina Fil: Belgorosky, Alicia. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Hypothyroidism caused by Hashimoto's thyroiditis is the most common reason for thyroid dysfunction in children. Our objective was to analyze its impact on final stature in relation to height and pubertal stage at the time of diagnosis in children younger than 18 years with severe autoimmune hypothyroidism. Out of 79 patients, 78.5 % were girls. Those with goiter (56 %) had a better height at diagnosis than those without goiter (mean standard deviation score for height: 0.2 versus -2.42; p0.0001). Five girls (6.3 %) had precocious puberty. When considering the final stature of patients (n: 33), among those with short stature at the time of diagnosis, pubertal children had a significantly shorter final stature than prepubertal children (mean standard deviation score for height: -2.82 versus -1.52; p = 0.0311). The late diagnosis of severe hypothyroidism in pediatrics has a negative impact on final stature, especially in those who were pubertal patients at the time of diagnosis.El hipotiroidismo por tiroiditis de Hashimoto es la causa más frecuente de disfunción tiroidea en niños. Nuestro objetivo fue analizar el impacto en la talla final según la talla y el estadio puberal al momento del diagnóstico en menores de 18 años con hipotiroidismo grave de origen autoinmune. De los 79 pacientes, el 78,5 % fueron mujeres. Los que presentaron bocio (el 56 %) mostraron mejor talla en el diagnóstico que los que no lo tenían (puntaje de desvío estándar de media de talla: 0,2 vs. -2,42; p0,0001). Cinco niñas (el 6,3 %) presentaron pubertad precoz. De los pacientes con talla final (n: 33), dentro de los que presentaron talla baja al momento del diagnóstico, los púberes tuvieron una talla final significativamente menor que los prepúberes (puntaje de desvío estándar media: -2,82 vs. -1,52; p = 0,0311). El diagnóstico tardío de hipotiroidismo grave en pediatría tiene un impacto negativo en la talla final, especialmente, en los pacientes puberales al momento del diagnóstico.