Ann Lab Med.  2015 Sep;35(5):519-522. 10.3343/alm.2015.35.5.519.

Development and Validation of Liquid Chromatography-Tandem Mass Spectrometry Method for Quantification of Plasma Metanephrines for Differential Diagnosis of Adrenal Incidentaloma

• Lee SM
• Lee MN
• Oh HJ
• Cho YY
• Kim JH
• Woo HI
• Park HD
• Lee SY

• KMID: 2369768
• DOI: http://doi.org/10.3343/alm.2015.35.5.519

Abstract

High-resolution imaging techniques have increased the detection rate of adrenal incidentaloma. We developed a method of liquid chromatography-tandem mass spectrometry (LC-MS/MS) for detection of plasma free metanephrine (MN) and normetanephrine (NMN) and evaluated its analytical performance and clinical efficacy in differential diagnosis of adrenal incidentaloma. After solid-phase extraction, chromatographic isolation of the analytes and internal standard was achieved by column elution in the LC-MS/MS system. The analytes were detected in multiple-reaction monitoring mode by using positive electrospray ionization: MN, transition m/z 180.1-->165.1; NMN, m/z 166.1-->134.1. This method was validated for linearity, precision, accuracy, lower limits of quantification and detection, extraction recovery, and the matrix effect. Plasma concentrations of MN and NMN of 14 patients with pheochromocytoma were compared with those of 17 healthy volunteers, 10 patients with essential hypertension, and 60 patients with adrenal adenoma. The assay's linear range was 0.04-50.0 and 0.08-100.0 nmol/L for MN and NMN, respectively. Assay imprecision was 1.86-7.50%. The accuracy ranged from -7.50% to 2.00%, and the mean recovery of MN and NMN was within the range 71.5-95.2%. Our LC-MS/MS method is rapid, accurate, and reliable and useful for differential diagnosis of adrenal incidentaloma.

Keyword

Metanephrines; Plasma; Mass spectrometry; Validation; Pheochromocytoma

MeSH Terms

Adenoma
Diagnosis, Differential*
Healthy Volunteers
Humans
Hypertension
Mass Spectrometry*
Metanephrine
Normetanephrine
Pheochromocytoma
Plasma*
Metanephrine
Normetanephrine

Figure

• 

  Fig. 1 Chromatograms of (A) d3-metanephrine-HCl (0.4 ng/mL), (B) metanephrine (2.0 nmol/L), (C) d3-normetanephrine-HCl (0.8 ng/mL), and (D) normetanephrine (4.0 nmol/L).Abbreviation: MRM, multiple-reaction monitoring.

• 

  Fig. 2 Dot-box and whisker plots showing the distribution of the levels of plasma metanephrine (A) and normetanephrine (B) in healthy normotensive volunteers and in patients with essential hypertension, adrenal adenoma, or proven pheochromocytoma. The central box represents the values from the lower to upper quartiles (25th to 75th percentiles). The middle line represents the median. A line extends from the minimum to the maximum value, excluding "outside" values (greater than the upper quartile plus 1.5 times the interquartile range) and "outlying" values (greater than the upper quartile plus three times the interquartile range, marked as □), which are displayed as separate points.

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