title: A method comparison of total and HMW adiponectin: HMW/total adiponectin ratio varies versus total adiponectin, independent of clinical condition.
abstract: BACKGROUND
  Total and high-molecular-weight (HMW) adiponectin have been associated with endocrine and cardiovascular pathology. As no gold standard is available, the discussion about biological relevance of isoforms is complicated. In our study we perform a method comparison between two commercially available assays measuring HMW and total adiponectin, in various patient groups, thus contributing further to this discussion.
  
  
  METHODS
  We determined levels of HMW and total adiponectin using assays by Lumipulse® and Millipore® respectively, in 126 patients with different clinical characteristics (n=29 healthy volunteers, n=22 dialysis patients, n=25 elderly with body mass index (BMI) <21kg/m2, n=25 elderly with BMI 30-35kg/m2, n=26 children).
  
  
  RESULTS
  The Passing & Bablock regression analysis resulted in HMW adiponectinLUMIPULSE∗0.5-0.9=total adiponectinMILLIPORE, albeit with significant deviation from linearity (p<0.001). Pearson's correlation was R=0.987 (p=0.000). No significant differences between patient groups were observed (p=0.190).
  
  
  CONCLUSIONS
  The HMW/total adiponectin ratio varies with total adiponectin concentration independent of clinical conditions studied. Our results imply that total and HMW adiponectin have similar utility when assessing adiponectin levels in blood, as the ratio is independent of clinical condition.
authors.affiliation: Department of Internal Medicine, Endocrine Section, VU University Medical Center, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands. Electronic address: m.vanandel@vumc.nl.
authors.forename: Merel
authors.initials: M
authors.lastname: van Andel
authors.affiliation: Department of Internal Medicine, Endocrine Section, VU University Medical Center, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands; Department of Clinical Neuropsychology, VU University, De Boelelaan 1105, 1081 HV Amsterdam, The Netherlands. Electronic address: ML.Drent@vumc.nl.
authors.forename: Madeleine L
authors.initials: ML
authors.lastname: Drent
authors.affiliation: Department of Laboratory Medicine, Radboud University Medical Center, Geert Grooteplein 10, 6525 GA Nijmegen, The Netherlands. Electronic address: Teun.vanHerwaarden@radboudumc.nl.
authors.forename: Antonius E
authors.initials: AE
authors.lastname: van Herwaarden
authors.affiliation: Department of Clinical Chemistry, Laboratory of Endocrinology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands. Electronic address: m.t.ackermans@amc.uva.nl.
authors.forename: Mariëtte T
authors.initials: MT
authors.lastname: Ackermans
authors.affiliation: Department of Clinical Chemistry, Endocrine Laboratory, VU University Medical Center, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands. Electronic address: a.heijboer@vumc.nl.
authors.forename: Annemieke C
authors.initials: AC
authors.lastname: Heijboer
mesh_terms: D052242:Adiponectin / Q000097:blood* / Q000378:metabolism; D000293:Adolescent; D015992:Body Mass Index; D002648:Child; D003956:Dialysis; D006801:Humans; D007124:Immunoenzyme Techniques / Q000379:methods; D008163:Luminescent Measurements / Q000379:methods*; D008875:Middle Aged; D008970:Molecular Weight; D020033:Protein Isoforms / Q000097:blood / Q000378:metabolism; D011863:Radioimmunoassay / Q000379:methods*
chemical_list: C499918:ADIPOQ protein, human; D052242:Adiponectin; D020033:Protein Isoforms
keywords: Adiponectin isoforms; Cardiovascular disease; High molecular weight/total adiponectin ratio; Method comparison; Patient characteristics