title: Stability of Phosphatidylethanol in Dry Blood Spot Cards.
abstract: BACKGROUND
  The analysis of phosphatidylethanol, a promising direct ethanol metabolite, in dry blood spots (PEth-DBS) is advantageous due to ease of storage, transportation and minimal invasiveness of capillary blood collection. One potential application of PEth-DBS is to confirm prenatal alcohol exposure in newborns suspected of FASD; however, stability of PEth-DBS is largely unknown.
  
  
  METHODS
  Phlebotomized samples from 31 adults with a history of alcoholism, admitted to the University of New Mexico Emergency Department, were analyzed for blood alcohol content and pipetted onto DBS cards (13 spots per patient). The first spot was analyzed within 2 weeks of collection for a baseline PEth; the remaining 12 spots were allocated into three temperature conditions (room temperature, 4°C, -80°C) for the repeated measures analysis. In addition, 5 newborn DBS samples with a baseline PEth>LOD were obtained from a prospective cohort at UNM and re-analyzed at 4 months after storage at -80°C. A mixed linear model was fitted to examine the effects of temperature, time and temperature-time interaction on PEth degradation over the first 9 months.
  
  
  RESULTS
  The baseline PEth levels were 592.8 ± 86.7 ng/ml and 18.3 ± 4.8 ng/ml in adult and newborn samples, respectively. All DBS samples remained positive in successive samples in all temperature conditions. Results of mixed linear model demonstrated a significant effect of temperature (P < 0.001) on PEth degradation over 9 months.
  
  
  CONCLUSIONS
  PEth-DBS appears to be relatively stable, especially when stored at lower temperatures. These initial results are encouraging and highlight the PEth-DBS potential in retrospective assessment of alcohol exposure.
authors.affiliation: Department of Pharmacy Practice and Administrative Sciences, UNM, Albuquerque, NM, USA Department of Family and Community Medicine, UNM, Albuquerque, NM, USA lbakhireva@salud.unm.edu.
authors.forename: Ludmila N
authors.initials: LN
authors.lastname: Bakhireva
authors.affiliation: Department of Pharmacy Practice and Administrative Sciences, UNM, Albuquerque, NM, USA.
authors.forename: Shikhar
authors.initials: S
authors.lastname: Shrestha
authors.affiliation: Department of Pharmacy Practice and Administrative Sciences, UNM, Albuquerque, NM, USA.
authors.forename: Hilda L
authors.initials: HL
authors.lastname: Gutierrez
authors.affiliation: Department of Emergency Medicine, UNM, Albuquerque, NM, USA.
authors.forename: Mike
authors.initials: M
authors.lastname: Berry
authors.affiliation: Department of Pharmacy Practice and Administrative Sciences, UNM, Albuquerque, NM, USA.
authors.forename: Cheryl
authors.initials: C
authors.lastname: Schmitt
authors.affiliation: Department of Emergency Medicine, UNM, Albuquerque, NM, USA.
authors.forename: Dusadee
authors.initials: D
authors.lastname: Sarangarm
mesh_terms: D000328:Adult; D000428:Alcohol Drinking / Q000097:blood*; D000437:Alcoholism / Q000097:blood*; D000067401:Blood Alcohol Content; D059788:Dried Blood Spot Testing / Q000379:methods*; D005260:Female; D020404:Glycerophospholipids / Q000097:blood* / Q000737:chemistry*; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D011446:Prospective Studies; D013696:Temperature; D013997:Time Factors
chemical_list: D000067401:Blood Alcohol Content; D020404:Glycerophospholipids; C051521:phosphatidylethanol