Preanalytical validation and reference values for a mass spectrometric assay of serum vanillylmandelic acid for screening of catecholamine secreting neuroendocrine tumors

Clin Chim Acta. 2015 Jun 15;446:206-12. doi: 10.1016/j.cca.2015.03.041. Epub 2015 Apr 18.

Abstract

Background: Urinary vanillylmandelic acid (VMA) is used to diagnose and monitor catecholamine secreting neuroendocrine tumors (NETs). We developed and validated a new liquid chromatography tandem mass spectrometry (LC-MS/MS) assay for determination of serum VMA.

Methods: We used serum samples from healthy volunteers (n=314) and patients suspected for NET (n=36). Deuterated VMA as an internal standard was added to samples before solid phase extraction (SPE) and LC-MS/MS analysis. We studied the effects of sample storage, sampling device and a meal on serum VMA and metanephrine concentrations. Diurnal variation and age-dependent reference intervals were established. The diagnostic performance was compared with a urinary HPLC assay for VMA and metanephrines and a serum metanephrine LC-MS/MS assay.

Results: Serum VMA is stable at least for one day at +4°C, seven days at room temperature and 98 days at -20°C. Type of sampling device was not critical, but elevated serum VMA occurs after a meal (p = 0.031). Serum VMA increased with age. Therefore, we suggest clinical cut-off values of 62 nmol/L, 80 nmol/L and 108 nmol/L for age groups 18-50 yrs, 51-70 yrs and > 70 yrs, respectively. Comparison between a urinary VMA HPLC assay and serum VMA LC-MS/MS assay showed good correlation.

Conclusions: Our LC-MS/MS assay is fast and sensitive and suits well for use in a clinical laboratory. Compared to 24-h urine collection our serum assay enables well controlled sampling and convenient preanalytical steps.

Keywords: LC–MS/MS; Metanephrines; Neuroblastoma; Paraganglioma; Pheochromocytoma; Vanillylmandelic acid.

Publication types

  • Research Support, Non-U.S. Gov't
  • Validation Study

MeSH terms

  • Adenoma / blood*
  • Adenoma / diagnosis
  • Adenoma / urine
  • Adolescent
  • Adrenal Gland Neoplasms / blood*
  • Adrenal Gland Neoplasms / diagnosis
  • Adrenal Gland Neoplasms / urine
  • Adult
  • Aged
  • Biological Assay*
  • Biomarkers, Tumor / blood*
  • Biomarkers, Tumor / urine
  • Case-Control Studies
  • Chromatography, Liquid
  • Female
  • Humans
  • Male
  • Metanephrine / blood
  • Metanephrine / urine
  • Middle Aged
  • Neuroblastoma / blood*
  • Neuroblastoma / diagnosis
  • Neuroblastoma / urine
  • Paraganglioma / blood*
  • Paraganglioma / diagnosis
  • Paraganglioma / urine
  • Reference Values
  • Sensitivity and Specificity
  • Tandem Mass Spectrometry
  • Vanilmandelic Acid / blood*
  • Vanilmandelic Acid / urine

Substances

  • Biomarkers, Tumor
  • Metanephrine
  • Vanilmandelic Acid