Performance evaluation of automated magnetic beads extraction method for the measurement of catecholamine metabolites analyzed by liquid chromatography tandem mass spectrometry / 中华检验医学杂志

Objective:To evaluate the performance of magnetic beads extraction method (MGE) for the measurement of catecholamine metabolites by liquid chromatography tandem mass spectrometry.Methods:This is a methodological evaluation study. The linearity, limit of quantitation, recovery, precision, and matrix effect of catecholamine metabolites 3-methoxyepinephrine (MN), 3-methoxynorepinephrine (NMN) and 3-methoxytyramine (3-MT) extracted by MGE method were evaluated according to CLSI C62-A. Consensus of method development and validation of liquid chromatography-tandem mass spectrometry in clinical laboratories and other guidelines, 132 clinical residual plasma samples were collected and extracted by automated MGE and traditional solid phase extraction (SPE) method to compare the harmonization of the two extraction methods.Results:The linearity of MN, NMN and 3-MT extracted by automated MGE was>0.99, and the LOQ for MN, NMN and 3-MT were 0.033 5 nmol/L, 0.054 7 nmol/L and 0.011 0 nmol/L, respectively. The repeatability of MN, NMN and 3-MT were 1.3%-5.1%, 2.2%-5.6% and 1.7%-7.1%, respectively. The total imprecision in the laboratory were 1.5%-8.2%, 2.2%-7.7%, 2.1%-11.2%. Although the absolute recovery is low, the average relative recoveries of MN, NMN and 3-MT were 91.5%-108.5%, 92.0%-108.6%, and 89.3%-104.1%, respectively, and the percentage deviation from the expected concentration was within 15%. After isotope internal standard correction, the relative matrix effect is close to 100%, which can compensate for the potential matrix effect. The results of MGE and SPE of MN, NMN and 3-MT showeda good correlation (correlation coefficient r>0.99). The average relative deviations of MN, NMN and 3-MT were 0.2%, -1.4% and 1.0%, respectively. Conclusion:The automatic MGE method hasa good performance in extracting catecholamine metabolites, and is expected to be used in high-throughput analysis of samples in clinical in the future.

Pheochromocytomas: diagnosis and treatment / Feocromocitomas: diagnóstico y tratamiento

Pheochromocytomas are neoplasms that have their origin in chromaffin cells of the adrenal medulla. 80 to 90% of these are located in one of the adrenal glandules. This pathology is characterized by multiple symptoms that constitute a complex, heterogeneous clinical frame with a high rate of cardiovascular morbidity and mortality. The main secretion is catecholamine metabolites: metanephrine and normetanephrine. Diagnosis is carried out by determining free metanephrines in plasma (not conjugated) and fractioned metanephrines in 24-hour urine collection. Its location through different image procedures is fundamental. Preoperative treatment is initiated with a adrenergic antagonist and by adding, after a week, b adrenergic antagonists. Trans-operative treatment requires a multidisciplinary team of medical experts. This treatment is of vital importance and depends on the size and existence of metastasis. In some cases, adrenal retroperitoneal laparoscopy is preferred. However, an anterior approach is used when the tumor is > 6 cm, but other physicians have considered a 6 cm to 15 cm size. Transoperative follow up is a vital procedure for the patient. Paragangliomas are extra-adrenal ganglia pheochromocytomas.

Los feocromocitomas son neoplasias que tienen su origen en las células cromafines de la médula adrenal; 80 a 90% están localizados en una de las glándulas adrenales. Es una patología caracterizada por múltiples signos y síntomas que constituyen un cuadro clínico heterogéneo, complejo y con alto índice de morbilidad y mortalidad cardiovascular. La principal secreción son los metabolitos de las catecolaminas: metanefrina y normetanefrina. El diagnóstico se realiza con la determinación de metanefrinas libres en plasma (no conjugadas) y metanefrinas fraccionadas en orina de 24 horas; la localización es fundamental por diferentes procedimientos de imágenes. El tratamiento preoperatorio inicialmente es con antagonistas a adrenérgicos y agregándose una semana después antagonistas b adrenérgicos. El tratamiento transoperatorio requiere de un grupo de profesionales versados en la materia. El tratamiento transoperatorio es de vital importancia. Su tratamiento actual depende del tamaño y de la existencia o no de metástasis. Se ha preferido laparoscopia adrenal vía retroperitoneal; se utiliza la vía anterior cuando el tumor es > 6 cm; otros han considerado el tamaño de 6 cm a 15 cm. Los paragangleomas son feocromocitomas de los ganglios extra-adrenales.