title: Limited preanalytical requirements for insulin measurement.
abstract: OBJECTIVE
  To evaluate the stability of insulin in serum and plasma under conditions relevant for the transport of samples from outpatient clinics to a centralized laboratory.
  
  
  METHODS
  Venous blood samples were taken from 15 volunteers and processed either immediately or after storage at room temperature for 24 h. The effect of EDTA or sodium fluoride on insulin results was investigated.
  
  
  RESULTS
  Insulin was found to be stable in EDTA-containing tubes at room temperature for at least 24 h, whereas significantly lower concentrations were found if samples without additives or potassium fluoride as an additive were used.
  
  
  CONCLUSIONS
  If shipment of patients' samples for insulin measurement from an outpatient clinic to a centralized laboratory can be performed within 24 h, centrifugation and freezing of plasma is not required. These findings facilitate a widespread application of insulin measurements to characterize and follow-up individual insulin sensitivity.
authors.affiliation: Institute of Clinical Chemistry, Hospital of the University of Munich, Marchioninistrasse 15, D-81377 Munich, Germany. Michael.Vogeser@med.uni-muenchen.de
authors.forename: Michael
authors.initials: M
authors.lastname: Vogeser
authors.forename: Klaus G
authors.initials: KG
authors.lastname: Parhofer
mesh_terms: D001800:Blood Specimen Collection / Q000379:methods*; D004355:Drug Stability; D004492:Edetic Acid / Q000494:pharmacology; D005069:Evaluation Studies as Topic; D006801:Humans; D007328:Insulin / Q000097:blood*; D012969:Sodium Fluoride / Q000494:pharmacology; D013048:Specimen Handling / Q000379:methods*; D013696:Temperature; D013997:Time Factors
chemical_list: D007328:Insulin; D012969:Sodium Fluoride; D004492:Edetic Acid