title: Liquid chromatography-tandem mass spectrometry method for the measurement of serum mevalonic acid: a novel marker of hydroxymethylglutaryl coenzyme A reductase inhibition by statins.
abstract: BACKGROUND
  Mevalonic acid (MVA) is synthesized at an early and rate-limiting step in the biosynthesis of cholesterol by the enzyme hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase, and is a useful measure of statin efficacy or treatment. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the measurement of serum MVA has been developed.
  
  
  METHODS
  Following the in vitro conversion of MVA to mevalonic acid lactone (MVAL) in the serum, MVAL and a deuterated internal standard were extracted using an online solid-phase extraction procedure. Chromatographic separation was achieved using a Luna PFP column (Phenomenex), with enhanced selectivity and improved resolution for polar compounds. A gradient system was used, with mobile phase comprising methanol and water (5 mmol/L ammonium formate buffer, pH 2.5). Analysis was performed using an API 5000 tandem mass spectrometer (Applied Biosystems) in positive electrospray ionization mode.
  
  
  RESULTS
  The method showed excellent recoveries (98 ± 8%) and imprecision (intra-assay coefficient of variation of 2.2% [6.5 ng/mL] and 2.6% [10.5 ng/mL], and inter-assay coefficient of variation of 9% [10.5 ng/mL]). The assay provides a calibration range up to 50 ng/mL with a limit of detection at 0.1 ng/mL.
  
  
  CONCLUSIONS
  A simple, rapid and analytically specific method has been developed for the measurement of serum MVA, in the form of MVAL. The high analytical sensitivity of the method allows for accurate quantitation of MVAL in serum samples, both at the endogenous levels found in healthy individuals and in statin-treated patients where normal levels are expected to be greatly reduced through the inhibition of HMG-CoA reductase.
authors.affiliation: Department of Biochemistry and Immunology, Birmingham Heart of England NHS Foundation Trust, Bordesley Green East, Birmingham B9 5SS, UK. jenna.waldron@nhs.nhs.net
authors.forename: Jenna
authors.initials: J
authors.lastname: Waldron
authors.forename: Craig
authors.initials: C
authors.lastname: Webster
mesh_terms: D015415:Biomarkers / Q000097:blood; D001774:Blood Chemical Analysis / Q000379:methods* / Q000592:standards; D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods* / Q000592:standards; D005260:Female; D006801:Humans; D006903:Hydroxymethylglutaryl CoA Reductases / Q000378:metabolism*; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D006949:Hyperlipidemias / Q000097:blood / Q000188:drug therapy; D008297:Male; D008798:Mevalonic Acid / Q000031:analogs & derivatives / Q000097:blood*; D008875:Middle Aged; D012016:Reference Values; D053719:Tandem Mass Spectrometry / Q000379:methods* / Q000592:standards
chemical_list: D015415:Biomarkers; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; C015367:mevalonolactone; D006903:Hydroxymethylglutaryl CoA Reductases; D008798:Mevalonic Acid