Estimación de masa grasa en niños chilenos: ecuaciones de pliegues subcutáneos vs densitometría de doble fotón / Estimation of body fat in Chilean children: comparing subcutaneous fold equations amd doble photon densitometry

Estimation of thickness of subcutabeous folds (SqF) is a simple way to estimate body composition in children, although it has its limitations. Double photon densitometry (DXA) is considered a new standard. Objective: To compare the precision of estimation of body fat by SqF and DXA in a population of Chilean children. Patients and Methods: Body fat was estimated in 128 eutrophic healthy children (70 females, 58 males), between 2 and 18 y.o. through SqF equations and DXA. Differences between both methods were evaluated through the Bland and Altman method and Lin concordance coefficient. Results: Most SqF equations had poor concordance with DXA. There was better concordance if the Westrate and Deurenberg equation was used among prepuberal and children of all ages (average difference of 2,96 +/- 1,20 percent and 4,92 +/- 0,98 percent and Lin concordance index of 0,50 +/- 0,22 and 0,43 +/- 0,88, respectively). Conclusions: Body fat estimated through subcutaneous fold measurements is poorly correlated with double photon densitometry among Chilean children. However, until more precise equations are developed, Westrate and Deurenberg for all ages, and Westrate/Deurenberg specific for pre-puberal age can be used.

La estimación del grosor de pliegues subcutáneos (PS) es una manera simple de estimar composición corporal en niños, sin embargo, tiene limitaciones. La densitometría de doble fotón (DXA) es considerada como el nuevo estándar de referencia. Objetivo: Comparar la precisión de la estimación del porcentaje de masa grasa por PS con la obtenida por DXA en población infantil chilena. Pacientes y Método: Se estimó el porcentaje de masa grasa en 128 niños (70 mujeres y 58 hombres) sanos, eutróficos, entre 2 y 18 años, por diversas ecuaciones de PS y se comparó con DXA. La diferencia entre ambos mediciones fue evaluada mediante el método de Bland y Altman y el coeficiente de concordancia de Lin. Resultados: La mayoría de las ecuaciones de PS tuvieron un pobre nivel de concordancia con DXA. Sin embargo, existe una mejor concordancia entre lo calculado según PS y DXA tanto en niños pre-puberales con la fórmula específica de Westrate y Deurenberg y en niños de todas las edades, con la ecuación general de Westrate y Deurenberg (diferencia promedio de 2,96 +/- 1,20 por ciento y 4,92 +/- 0,98 por ciento e índice de concordancia de Lin de 0,50 +/- 0,22 y 0,43 +/- 0,88, respectivamente) Conclusiones: La estimación del porcentaje de masa grasa a partir de los PS, tiene una baja concordancia, sin embargo, mientras no se desarrollen ecuaciones con una precisión más alta se podrían utilizar las ecuaciones de Westrate y Deurenberg a todas las edades y la de Westrate y Deurenberg específica para la edad pre-puberal.

Avances en el diagnóstico de las alteraciones del eje somatotrófico que causan retardo del crecimiento / An update on the diagnosis of growth hormone axis disturbances that cause stunting

Human growth is a complex process regulated by several genes, most of which are unknown. Recently, our knowledge regarding the etiology of genetically determined causes of short stature has greatly increased, so molecular analysis is becoming essential for the diagnosis of growth retardation. The advances in our understanding of the molecular mechanisms involved in the function of the somatotrophic axis have resulted in a dramatic enhancement of our ability to diagnose and treat growth disorders. We hope that in the next few years improved methods for identifying specific abnormalities which cause short stature will expand our ability to diagnose other causes of growth retardation, and reduce the proportion of patients with "idiopathic" short stature.

Hiperinsulinismo neonatal persistente: análisis del diagnóstico diferencial a propósito de dos casos clínicos / Persistent neonatal hyperinsulinism: report of two cases

Persistent neonatal hyperinsulinism is the most common cause of refractory hypoglycemia during the first year of life. Inadequate insulin secretion is associated to mutations of four different genes, that can be diagnosed to orient patient management. We report two patients: a female newborn that presented a hypoglycemia of 16 mg/dl two hours after birth, was subjected to a subtotal pancreatectomy that did not correct hypoglycemia, requiring a total pancreatectomy. Pathological study of the pancreas showed a focal adenomatous hyperplasia. At the present time, she is three years of age and maintains euglycemia with fractionated feeding. A male newborn that had seizures at 28 hours of life and a hypoglycemia of 15 mg/dl was detected. He was also subjected to a subtotal pancreatectomy, that did not correct hypoglycemia and had to be extended to a total pancreatectomy. At the present time, he is 3 years and 11 months of age and has a normal psychomotor development (Rev Méd Chile 2004; 132: 995-1000).

Tiroiditis aguda supurada en un paciente pediátrico / Acute suppurative thyroiditis: report of a pediatric case

Acute suppurative thyroiditis (AST) is an uncommon condition because thyroid gland is remarkably resistant to infections. In children, anatomic defects such as a left pyriform sinus fistula or a thyroglossal duct remnant predispose to this infection. Once the diagnosis is confirmed by ultrasound or computed tomography, antimicrobial therapy based on the culture and Gram staining must be started. After two or three weeks of treatment, predisposing anatomic defects must be sought cautiously. We report a 13 years old girl presenting with cervical pain and fever. A cervical ultrasound showed an enlarged thyroid lobule with hypoecogenic zones that suggested a supurative collection. Cefotaxime and cloxacillin were started. A needle aspiration of the collection obtained a purulent material. The culture of this material yielded a Streptococcus Pneumoniae. The clinical condition of the patient improved and she was discharged in good conditions. Two months later a contrast esophagus X ray did not show predisposing anatomic defects.