title: Immunological and mass spectrometric assays of SHBG: consistent and inconsistent metabolic associations in healthy men.
abstract: BACKGROUND
  SHBG concentrations correlate inconsistently with metabolic parameters.
  
  
  OBJECTIVE
  SHBG assay platforms contribute to nonuniformities according to the literature.
  
  
  METHODS
  The design of the study was a noninterventional quantification of SHBG by two immuno- and two mass spectrometric assays and abdominal visceral fat by computed tomography scan.
  
  
  METHODS
  The study was conducted at the Center for Translational Science Activities.
  
  
  METHODS
  Healthy men (n=120) aged 18-80 years with a body mass index of 20-43 kg/m2 participated I the study.
  
  
  RESULTS
  Outcomes of the study included a correlation of log SHBG with age, metabolic surrogates [body mass index, albumin, glucose, insulin, abdominal (total and visceral) fat, homeostasis model assessment insulin resistance index], sex steroids (estrone, 17β-estradiol, T, and dihydrotestosterone by mass spectrometry), and adipocytokines (IL-1β, IL-6, IL-8, IL-10 and IL-12, TNF-α, and adiponectin).
  
  
  RESULTS
  By univariate regression, age (P<10(-4)), dihydrotestosterone (P<10(-4)), T (P≤.00022), and adiponectin (P≤.0084) were positive correlates, and insulin and homeostasis model assessment insulin resistance index were negative correlates (P≤.0060) of SHBG in all four assays. Stepwise multivariate analysis unveiled that age and T together could explain 38.1%-52.5% of the statistical variance in SHBG in all assays (P<10(-11)). Multivariate regression without sex steroids unveiled that age (P<10(-5)) and insulin (P<10(-3)) are jointly associated with SHBG levels in the four assays with overall R2=0.215-0.293 and P<10(-6). In one immunological SHBG assay each, abdominal visceral fat and adiponectin were weak multivariates also.
  
  
  CONCLUSIONS
  Immunological and mass spectrometric SHBG assays yield both consistent and inconsistent correlations with key metabolic variables in healthy men, thereby potentially explaining earlier inconsistencies in the literature.
authors.affiliation: Endocrine Research Unit (J.D.V.), Mayo School of Graduate Medical Education Center for Translational Science Activities, Immunochemical Laboratory (R.B.D.), and Departments of Neurology (S.A.T.) and Laboratory Medicine and Pathology (J.D.V., O.P.B., E.W.K., R.J.S., G.G.K.), Mayo Clinic, Rochester, Minnesota 55905.
authors.forename: Johannes D
authors.initials: JD
authors.lastname: Veldhuis
authors.forename: Olga P
authors.initials: OP
authors.lastname: Bondar
authors.forename: Roy B
authors.initials: RB
authors.lastname: Dyer
authors.forename: Sergey A
authors.initials: SA
authors.lastname: Trushin
authors.forename: Eric W
authors.initials: EW
authors.lastname: Klee
authors.forename: Ravinder J
authors.initials: RJ
authors.lastname: Singh
authors.forename: George G
authors.initials: GG
authors.lastname: Klee
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006262:Health; D006801:Humans; D007118:Immunoassay / Q000379:methods; D008297:Male; D013058:Mass Spectrometry / Q000379:methods; D008659:Metabolic Diseases / Q000097:blood* / Q000453:epidemiology / Q000209:etiology; D008875:Middle Aged; D012737:Sex Factors; D012738:Sex Hormone-Binding Globulin / Q000032:analysis* / Q000378:metabolism*; D055815:Young Adult
chemical_list: D012738:Sex Hormone-Binding Globulin