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Abstract Introduction
Catecholamines[epinephrine(E), norepinephrine(NE),and dopamine(DA)] along with their metabolites [metanephrine(MN), normetanephrine(NMN), and 3-methoxytyramine(3-MT)] play important roles in humans as neuromodulators and hormones in the blood circulation. Their extremely high levels can indicate the presence of neuroendocrine tumors. Accurate and rapid quantitation of catecholamines is useful in the differential diagnosis of neuroendocrine tumors.
Methods
200 μL plasma were firstly diluted using isotope labelled internal standards(IS), and then extracted using solid phase extraction. The performance of the isotope diluted liquid chromatography tandem mass spectrometry(ID-LC-MS/MS) was thoroughly evaluated. The method was applied for evaluating the level of catecholamines and metabolites in 73 apparently healthy adults.
Results
The total analysis time of the method was 4 mins. The ID-LC-MS/MS method was highly sensitive, with an limit of quantification(LOQ) for E, MN, NMN, 3-MT, and E of 1 pg/mL, and an LOQ for DA of 5 pg/mL, and NE of 10 pg/mL. After correction using IS, no significant matrix effects were observed. Good reproducibility was obtained, with total CVs of 3.2-13.1%,4.8%-10.0%, 6.2%-6.9%,3.8%-7.9%,4.1%-8.8%,3.4%-8.9% for DA, E, NE, MN, NMN, and 3-MT, respectively. Recoveries were in the range of 91.1 to 109.7% for the six analytes. The mean levels of MN, NMN, 3-MT, DA, E, and NE in the volunteers were 22.9±7.2 pg/mL, 41.4±17.2 pg/mL, 2.34±2.01 pg/mL, 10.2±4.6 pg/mL, 29.3±14.2 pg/mL, and 427.0±190.6 pg/mL, respectively.
Conclusions & Discussion
A reliable ID-LC-MS/MS method for the determination of catecholamines and metabolites using small volume of plasma was verified. The method is quick, simple, could serve as an essential diagnostic tool for neuroendocrine tumors in clinical practice. |
= Discovery stage.
= Translation stage.
= Clinically available.
