title: Social peptides: measuring urinary oxytocin and vasopressin in a home field study of older adults at risk for dehydration.
abstract: OBJECTIVE
  We present the novel urine collection method used during in-home interviews of a large population representative of older adults in the United States (aged 62-91, the National Social Life, Health and Aging Project). We also present a novel assay method for accurately measuring urinary peptides oxytocin (OT) and vasopressin (AVP), hormones that regulate social behaviors, stress, and kidney function.
  
  
  METHODS
  Respondents in a randomized substudy (N = 1,882) used airtight containers to provide urine specimens that were aliquoted, stored under frozen refrigerant packs and mailed overnight for frozen storage (-80 °C). Assays for OT, AVP, and creatinine, including freeze-thaw cycles, were refined and validated. Weighted values estimated levels in the older U.S. population.
  
  
  RESULTS
  Older adults had lower OT, but higher AVP, without the marked gender differences seen in young adults. Mild dehydration, indicated by creatinine, specific gravity, acidity, and AVP, produced concentrated urine that interfered with the OT assay, yielding falsely high values (18% of OT). Creatinine levels (≥ 1.4 mg/ml) identified such specimens that were diluted to solve the problem. In contrast, the standard AVP assay was unaffected (97% interpretable) and urine acidity predicted specimens with low OT concentrations. OT and AVP assays tolerated 2 freeze-thaw cycles, making this protocol useful in a variety of field conditions.
  
  
  CONCLUSIONS
  These novel protocols yielded interpretable urinary OT and AVP values, with sufficient variation for analyzing their social and physiological associations. The problem of mild dehydration is also likely common in animal field studies, which may also benefit from these collection and assay protocols.
authors.affiliation: Department of Comparative Human Development, University of Chicago, Illinois. Institute for Mind and Biology, University of Chicago, Illinois. teofilo@uchicago.edu.
authors.forename: Teófilo L
authors.initials: TL
authors.lastname: Reyes
authors.affiliation: Center on Demography and Economics of Aging, University of Chicago, Illinois.
authors.forename: Adena M
authors.initials: AM
authors.lastname: Galinsky
authors.affiliation: Institute for Mind and Biology, University of Chicago, Illinois.
authors.forename: Joscelyn N
authors.initials: JN
authors.lastname: Hoffmann
authors.affiliation: Institute for Mind and Biology, University of Chicago, Illinois.
authors.forename: Hannah M
authors.initials: HM
authors.lastname: You
authors.affiliation: Wisconsin National Primate Research Center, University of Wisconsin-Madison.
authors.forename: Toni E
authors.initials: TE
authors.lastname: Ziegler
authors.affiliation: Department of Comparative Human Development, University of Chicago, Illinois. Institute for Mind and Biology, University of Chicago, Illinois.
authors.forename: Martha K
authors.initials: MK
authors.lastname: McClintock
mesh_terms: D000367:Age Factors; D000368:Aged / Q000706:statistics & numerical data; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D003404:Creatinine / Q000652:urine; D003681:Dehydration / Q000453:epidemiology / Q000652:urine*; D005260:Female; D006801:Humans; D007668:Kidney / Q000502:physiology; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010121:Oxytocin / Q000652:urine*; D012307:Risk Factors; D012737:Sex Factors; D012919:Social Behavior; D013315:Stress, Psychological / Q000652:urine; D014481:United States / Q000453:epidemiology; D059349:Urine Specimen Collection / Q000379:methods*; D014667:Vasopressins / Q000652:urine*
chemical_list: D014667:Vasopressins; D010121:Oxytocin; D003404:Creatinine
keywords: Creatinine; Dehydration; Social behavior; Stress.; Urinary oxytocin assay; Vasopressin