In Matrix Derivatization Combined with LC-MS/MS Results in Ultrasensitive Quantification of Plasma Free Metanephrines and Catecholamines.

Plasma-free metanephrines and catecholamines are essential markers in the biochemical diagnosis and follow-up of neuroendocrine tumors and inborn errors of metabolism. However, their low circulating concentrations (in the nanomolar range) and poor fragmentation characteristics hinder facile simultaneous quantification by liquid chromatography and tandem mass spectrometry (LC-MS/MS). Here, we present a sensitive and simple matrix derivatization procedure using propionic anhydride that enables simultaneous quantification of unconjugated l-DOPA, catecholamines, and metanephrines in plasma by LC-MS/MS. Dilution of propionic anhydride 1:4 (v/v) in acetonitrile in combination with 50 µL of plasma resulted in the highest mass spectrometric response. In plasma, derivatization resulted in stable derivatives and increased sensitivity by a factor of 4-30 compared with a previous LC-MS/MS method for measuring plasma metanephrines in our laboratory. Furthermore, propionylation increased specificity, especially for 3-methoxytyramine, by preventing interference from antihypertensive medication (ß-blockers). The method was validated according to international guidelines and correlated with a hydrophilic interaction LC-MS/MS method for measuring plasma metanephrines (R2 > 0.99) and high-performance liquid chromatography with an electrochemical detection method for measuring plasma catecholamines (R2 > 0.85). Reference intervals for l-DOPA, catecholamines, and metanephrines in n = 115 healthy individuals were established. Our work shows that analytes in the subnanomolar range in plasma can be derivatized in situ without any preceding sample extraction. The developed method shows improved sensitivity and selectivity over existing methods and enables simultaneous quantification of several classes of amines.

Comparative efficacy of vasoactive medications in patients with septic shock: a network meta-analysis of randomized controlled trials.

BACKGROUND: Catecholamines, especially norepinephrine, are the most frequently used vasopressors for treating patients with septic shock. During the recent decades, terlipressin, vasopressin V1A agonist, and even Ca2+ sensitizer were increasingly used by physicians. The aim of this study is to compare the efficacy of such different kinds of vasoactive medications on mortality among patients with septic shock. METHODS: Relevant randomized controlled trials were identified by searching PubMed, Embase, Web of Science, and the Cochrane Central Register of Controlled Trials updated to February 22, 2018. A network meta-analysis was performed to evaluate the effect of different types of vasoactive medications. The primary outcome was 28-day mortality. Intensive care unit (ICU) mortality, hospital and ICU length of stay (LOS), and adverse events were also assessed. RESULTS: A total of 43 trials with 5767 patients assessing 17 treatment modalities were included. Treatments ranking based on surface under the cumulative ranking curve values from largest to smallest were NE/DB 85.9%, TP 75.1%, NE/EP 74.6%, PI 74.1%, EP 72.5%, VP 66.1%, NE 59.8%, PE 53.0%, DA 42.1%, DX 38.2%, SP 27.0%, PA 24.3%, EX 22.8%, LE 21.5%, and DB 13.3% for 28-day mortality. Treatments ranking for ICU mortality were TP/NE 86.4%, TP 80.3%, TP/DB/NE 65.7%, VP/NE 62.8%, NE 57.4%, VP 56.5%, PE 48.4%, DA 33.0%, PA 27.5%, LE 22.1%, and DB 9.9%. The incidence of myocardial infarction was reported with NE/EP 3.33% (n = 1 of 30), followed by EP 3.11% (n = 5 of 161), and then VP 3.10% (n = 19 of 613), NE 3.03% (n = 43 of 1417), DA 2.21% (n = 19 of 858), NE/DB 2.01% (n = 4 of 199), LE 1.16% (n = 3 of 258), and PA 0.39% (n = 1 of 257). The incidence of arrhythmia was reported with DA 26.01% (n = 258 of 992), followed by EP 22.98% (n = 37 of 161), and then NE/DB 20.60% (n = 41 of 199), NE/EP 20.0% (n = 6 of 30), NE 8.33% (n = 127 of 1525), LE 5.81% (n = 15 of 258), PA 2.33% (n = 6 of 257), and VP 1.67% (n = 10 of 600). CONCLUSIONS: The use of norepinephrine plus dobutamine was associated with lower 28-day mortality for septic shock, especially among patients with lower cardiac output.

Reference intervals for urinary catecholamines and metabolites from birth to adulthood.

OBJECTIVE: To establish reference intervals for urinary excretion of biogenic amines from birth to adulthood. DESIGN AND METHODS: 865 outpatients were categorized into nine groups ranging from birthday to 25 years. Free catecholamines, total metanephrines, vanillylmandelic and homovanillic acids were determined in urine samples by HPLC with amperometric detection. RESULTS: The ratio of each analyte-to-creatinine declined gradually from birth to 15-18 years reaching adults values. No difference was observed by sex except a lower excretion of epinephrine and metanephrine in girls than in boys below 1 year. CONCLUSION: Our data provide age-appropriate reference ranges for the diagnosis of tumors from neural crest in children.

Paediatric reference values for urinary catecholamine metabolites evaluated by high performance liquid chromatography and electrochemical detection.

The majority of the published reference range data on catecholamines excretion by healthy children is incomplete and often contradictory (1). We assayed in the urines of 127 healthy children the values of the catecholamines (norepinephrine, epinephrine, dopamine) and their methylated metabolites (normetanephrine, metanephrine, 3-methoxytyramine) for the determination of paediatric reference ranges. Data were expressed as micrograms/24 h, mumol/24 h and mmol/mol creatinine. An isocratic HPLC procedure by ion-pair reversed phase chromatography on a C18 column, using a single mobile phase containing formic acid, acetonitrile, diethylamine and octane sulphonic acid (ion pairing agent), permitted the separate assay of the various fractions of total catecholamines. The relations between each biogenic amine and age were studied and reference values were determined as a function of age.