Método indirecto para la verificación del intervalo de referencia del perfil lipídico / Indirect method for the verification of the lipid profile reference range

Introducción: La dislipidemia es uno de los problemas más frecuentes en los niños y adolescentes y su estudio es importante debido a su fuerte correlación con la enfermedad cardiovascular aterosclerótica en adultos. Muchos países desarrollaron valores de referencia nacionales investigando los lípidos séricos utilizando datos basados en la población nacional propia. Nuestro objetivo fue verificar el intervalo de referencia del perfil lipídico calculando las curvas de percentiles a través del método indirecto en nuestra población pediátrica. Materiales y métodos: Se analizaron los resultados de nuestra base de datos utilizando el método indirecto. Luego de aplicar filtros y criterios de exclusión se calcularon los percentiles 25, 50, 75, 95 y 99 para colesterol total (CT), colesterol HDL (C-HDL), colesterol no HDL (C-no-HDL), triglicéridos (TG) y colesterol LDL (C-LDL) y para el C-HDL además se calculó el percentil 10. El valor de referencia para el cambio (RCV) se utilizó para determinar si existía diferencia clínicamente significativa entre los valores de percentiles obtenidos y los utilizados en el consenso de la SAP. Resultados: No se evidenció diferencia clínicamente significativa contra los valores propuesto por la SAP, excepto para los TG para las edades 1,5,7 años en el percentil 95 y para la edad de 8 años en el percentil 75 y 95; para el C-HDL en el percentil 10 para las edades 1,16 y 17 años. Discusión: Se obtuvieron los percentiles de los lípidos y se compararon con los valores de referencia utilizados por el consenso en el que están basados las guías (AU)

Introduction: Dyslipidemia is one of the most common problems in children and adolescents and its study is important because of its strong correlation with atherosclerotic cardiovascular disease in adulthood. Many countries have developed national reference values investigating serum lipids using data based on their own national population. Our aim was to verify the lipid profile reference range by calculating percentile curves through the indirect method in our pediatric population. Materials and methods: The results of our database were analyzed using the indirect method. After applying filters and exclusion criteria, the 25th, 50th, 75th, 95th, and 99th percentiles were calculated for total cholesterol (TC), HDL cholesterol (HDL-C), non-HDL cholesterol (non-HDL-C), triglycerides (TG), and LDL cholesterol (LDL-C); for HDL-C, the 10th percentile was also calculated. The reference change values (RCV) were used to determine whether there was a clinically significant difference between the percentile values obtained and those used in the consensus of the Argentine Association of Pediatrics (SAP). Results: There was no clinically significant difference with the values proposed by the SAP, except for TG for ages 1, 5, and 7 years at the 95th percentile and for age 8 years at the 75th and 95th percentile; and for HDL-C at the 10th percentile for ages 1, 16, and 17 years. Discussion: Lipid percentiles were obtained and compared with the reference values used by the consensus on which the guidelines are based (AU)

Análisis clínicos en pediatría: la necesidad de minimizar las horas de ayuno / Clinical analysis in pediatrics: the need to minimize fasting hours

Los informes de laboratorio tienen impacto en las decisiones médicas. El ayuno es un factor preanalítico "controlable" que influye en los distintos parámetros bioquímicos. El objetivo del presente trabajo es poner en discusión la realización en pediatría de análisis clínicos con la indicación de un ayuno fisiológico , analizando resultados obtenidos por diferentes autores y evaluando las diferencias clínicas encontradas según los criterios de calidad establecidos por el laboratorio de Química Clínica. La mayoría de los individuos durante el día se encuentran en estado postprandial. Los resultados del perfil lipídico en ayunas no representan las concentraciones reales promedios de los lípidos plasmáticos de un paciente. El ayuno no sería crítico en la etapa de pesquisa , pero puede ser relevante para establecer un diagnóstico certero o inicio de tratamiento. En el caso de la glucemia si se indica en el control rutinario del paciente, y no hay sospecha de alteraciones en el metabolismo de los hidratos de carbono la glucemia sin ayuno puede ser solicitada comparando la misma con valores de corte adecuado. Las diferentes guías nacionales e internacionales recomiendan que la elección de la métrica para la evaluación, control y seguimiento de pacientes con diagnóstico de diabetes se realicen según el objetivo terapéutico. En los trabajos analizados, observamos que varios parámetros bioquímicos presentaron diferencias estadísticas, aunque las diferencias clínicas no fueron relevantes y permanecieron dentro de los intervalos de referencia. El factor limitante para evaluar parámetros bioquímicos sin ayuno es la falta de valores de referencia adecuados. Hay evidencia suficiente para que tanto el perfil lipídico, la glucemia como el resto de los parámetros bioquímicos del laboratorio de química clínica, sean solicitados con la indicación de un ayuno fisiológico de 2, 4 o 6 horas, dependiendo siempre del motivo de consulta y/o la edad del paciente. Es esencial extender la evaluación a otros analitos en población pediátrica, así como evaluar nuevos puntos de corte para parámetros bioquímicos sin ayuno (AU)

Laboratory reports have an impact on medical decision-making. Fasting is a "controllable" preanalytical factor that influences the different biochemical parameters. The aim of this study is to discuss the performance of clinical analyses in pediatrics with the indication of physiological fasting, analyzing results obtained in different disciplines, and evaluating the clinical differences found according to the quality criteria established by the clinical chemistry laboratory. During the day, most patients are in a postprandial state. Fasting lipid profile results do not represent the actual average plasma lipid concentrations of a patient. Fasting would not be critical in the screening stage, but it may be relevant to establish an accurate diagnosis or initiate treatment. Regarding glycemia, if it is indicated in the routine control of the patient and there is no suspicion of alterations in carbohydrate metabolism, non-fasting glycemia can be requested, comparing it with adequate cut-off values. Different national and international guidelines recommend that the choice of metrics for the evaluation, control, and follow-up of patients with diabetes should be made according to the therapeutic objective. In the studies analyzed, we found that several biochemical parameters presented statistical differences, although the clinical differences were not relevant and remained within the reference range. The limiting factor in the evaluation of biochemical parameters without fasting is the lack of adequate reference values. There is sufficient evidence that the lipid profile, glycemia, and the remaining biochemical parameters of the clinical chemistry laboratory should be requested with the indication of a physiological fast of 2, 4, or 6 hours, always depending on the reason for consultation and/or the patient's age. It is essential to extend the evaluation to other analytes in the pediatric population, as well as to evaluate new cut-off points for biochemical parameters without fasting (AU)

Further improvements in the application of high-performance liquid chromatography, capillary electrophoresis and capillary electrochromatography to the analysis of algal toxins in the aquatic environment.

The presence of algal toxins in the aquatic environment represents an important socioeconomic concern in many places worldwide, due to the toxicity that these compounds can induce in seafood or freshwater organisms at very low levels. Several analytical alternatives have been proposed over the last years for the control of these contaminants, which acute or chronic toxicity requires low detection levels and demands for the search of sensitive methods for their detection and determination. HPLC has been widely used for this purpose, although several alternatives such as CE or capillary electrochromatography (CEC) are being lately developed with this aim. In this work we report on the application of improved HPLC, as well as CE and CEC, for the analysis of diarrhetic shellfish poisoning toxins, amnesic shellfish poisoning (ASP) toxins and microcystins (MCs) present in different matrices such as water, shellfish or algae. Improvements in sample preparation for increasing sensitivity and selectivity are also shown. While UV and fluorimetric detection are the detection methods generally used, mass spectrometric detection was also applied for ASP toxins and MCs, especially for confirmatory purposes. From the results obtained it can be concluded that both HPLC and CE offer a good potential for a sensitive and selective determination of these algal toxins in such complex matrices. The results obtained for CEC allow also to conclude that this technique can result in a promising technique for such application.

Capillary electrophoresis with diode array detection as an alternative analytical method for paralytic and amnesic shellfish toxins.

In recent years the marine environment has been seriously damaged by the presence of several toxic phytoplanktonic species, such as dinoflagellates and other toxic algae, which contaminate shellfish and other marine products. Amnesic and paralytic shellfish toxins are examples of these contaminants. The search for sensitive methodologies for the analysis of such compounds is one of the aims of researchers working in the marine environment. High-performance liquid chromatographic methods have been used for this purpose, allowing the detection of very low levels of these toxins. Recently, capillary electrophoresis (CE) has been used as an alternative for the separation and analysis of these compounds. In this paper, we report the optimization of CE procedures for their analysis. Due to the complexity of the matrix, clean-up procedures are required for removing interferences which affect the electrophoretic resolution. The influences of electrophoretic parameters such as voltage, buffer concentrations and organic modifiers, were studied in order to optimize the electrophoretic system to achieve high resolution as well as an accurate quantitation. Extraction and other steps such as clean-up of samples prior to the electrophoretic analysis have been also studied. Different buffers and organic modifiers were used in order to improve the separation of the toxic components, and consequently to obtain accurate quantitative information about the amount of toxins present in the contaminated samples.