title: Comparison of simple acid-ethanol precipitation with gel exclusion chromatography for measuring leptin binding in serum of normal subjects and cancer patients.
abstract: BACKGROUND
  In humans, leptin circulates in a free form and is also bound to macromolecules. The aim of the present study was to compare a rapid acid-ethanol precipitation (AEP) method of measuring bound leptin with the more laborious gel exclusion chromatography (GEC) reference procedure. Serum samples collected from healthy subjects and cancer patients were used in this comparison.
  
  
  METHODS
  AEP and GEC methods for measuring leptin binding in serum (from 14 healthy volunteers and 14 patients with advanced non-small cell lung cancer) were adapted from previously published procedures.
  
  
  RESULTS
  Intra- and inter-assay precision of the AEP method were 6% (n = 10) and 8% (n = 10), respectively. Bland-Altman analysis of results obtained from the AEP and GEC methods indicated no significant difference in healthy controls. However, significantly higher results were obtained by the AEP method in the cancer patients.
  
  
  CONCLUSIONS
  Evaluation of the AEP method revealed that on examination of normal subjects the method was less precise than had previously been reported. Moreover, the method gave differing results in the cancer patients when compared with the GEC method. This study indicates that careful evaluation of any new method for measuring leptin binding requires comparison with a GEC method using the sample matrix of interest.
authors.affiliation: University Department of Surgery, Royal Infirmary, Glasgow, G31 2ER, UK. nigeljamieson@yahoo.com
authors.forename: Nigel B
authors.initials: NB
authors.lastname: Jamieson
authors.forename: Donald C
authors.initials: DC
authors.lastname: McMillan
authors.forename: Duncan J F
authors.initials: DJ
authors.lastname: Brown
authors.forename: A Michael
authors.initials: AM
authors.lastname: Wallace
mesh_terms: D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000097:blood; D016022:Case-Control Studies; D002624:Chemistry, Clinical / Q000379:methods*; D002845:Chromatography; D000431:Ethanol / Q000494:pharmacology*; D005260:Female; D006801:Humans; D020738:Leptin / Q000097:blood / Q000378:metabolism*; D008175:Lung Neoplasms / Q000097:blood; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D013223:Statistics as Topic
chemical_list: D020738:Leptin; D000431:Ethanol