Mass spectrometric quantification of salivary metanephrines—A study in healthy subjects

Abstract

Determination of metanephrine (MN), normetanephrine (NMN) and 3-methoxytyramine (3-MT) in saliva could be of diagnostic value in patients with pheochromocytoma. This preliminary study was set out to determine metanephrine concentrations in saliva from healthy subjects compared to their simultaneously measured plasma levels. In addition, we studied the possible influence of pre-analytical conditions such as a collection device, awakening, position, and eating on the salivary metanephrine levels. We included 11 healthy volunteers. Fasting blood and saliva samples were collected in seated position and after 30 minutes of horizontal rest. Saliva samples 30 minutes after eating were also collected. Saliva was collected with and without the use of a polyethylene salivette. Plasma and salivary MN, NMN and 3-MT concentrations were determined using a High-Performance Liquid Chromatography tandem mass spectrometric technique (LC-MS/MS) with automated solid phase extraction sample preparation. Metanephrines were detectable in saliva from all participants both in seated and the supine position. We found no significant correlation between the MN, NMN and 3-MT concentrations in saliva and plasma in the seated or supine position. In addition, there was no difference between MN, NMN and 3-MT concentrations collected with or without a collection device. Plasma MN, NMN, 3-MT and salivary NMN concentrations collected in seated position were significantly higher compared concentrations of samples collected in supine position (all P<.05). In conclusion, salivary metanephrines can be detected with LC-MS/MS with sufficient sensitivity and precision. Our findings warrant evaluation of salivary metanephrine measurement in the work-up of patients who are suspected to harbor pheochromocytoma.

Effect of Supplementation with Saccharomyces Boulardii on Academic Examination Performance and Related Stress in Healthy Medical Students: A Randomized, Double-Blind, Placebo-Controlled Trial

“…Metanephrine is released to circulation as a relatively stable and inactive metabolite of catecholamine epinephrine [32], the major enhancer of heart rhythm [33], and the level of metanephrine correlates with respective catecholamine [34]. Unconjugated metanephrine is easily transported over the salivary gland membrane and is detectable in saliva; however, conflicting results regarding plasma-saliva metanephrine correlation have been published [35,36].…”

Diagnostic Accuracy of Salivary Metanephrines in Pheochromocytomas and Paragangliomas

“…Recovery was 106% (SD: 10%) for MN and 101% (SD: 5%) for NMN. Linearity was excellent over the different calibration ranges (MN: 0.03-10 nmol/L; NMN: 0.035-26 nmol/L) with R 2 > 0.99 (13).…”

“…The analytical method, extensively validated for plasma free metanephrines, was validated for saliva as described previously, using saliva pools with low, medium, and high concentrations of MN and NMN (13).…”

“…Metanephrines also pass across the acinar cells via ultrafiltration into saliva through gap junctions between cells of secretory units (12). Previously, we showed that high-performance LC-MS/MS was a highly sensitive technique that enabled the measurement of very low concentrations of catecholamines and metanephrines in saliva (13). Because saliva can be collected at home, specimen collection could also be more convenient.…”

Computational Analysis Of Potential Key Genes Associated With Dopamine Neurotransmission In Pheochromocytoma And Paraganglioma

“…pinephrine (NE), epinephrine (EPI), and dopamine (DA) that are mainly synthesized and released from the adrenal medulla (chromaffin cells) [5]. Specifically, DA acts as a neurotransmitter and neurohormone that modulates cognition, motivation, food intake, appetite, sexual behavior, emotion, reward system, motor activity, and prolactin secretion in the central nervous system [6,7]. Moreover, DA participates in the regulation of inhibition of aldosterone secretion, vasodilation, inhibition of insulin secretion, diuresis, phagocytic inhibition, IgM and IgG secretion, and natriuresis in the periphery [6].…”