title: Determination of the biological variation of S100β and lactate dehydrogenase in disease-free patients with malignant melanoma.
abstract: BACKGROUND
  Biological variation is important for determining analytical goals and for establishing the magnitude of change between two consecutive measurements. The aim of this study was to determine the biological variation for S100β and lactate dehydrogenase in patients diagnosed with malignant melanoma but without evidence of disease recurrence.
  
  
  METHODS
  The biological variation of S100β and lactate dehydrogenase was estimated from a mean of four consecutive measurements in 32 patients diagnosed with malignant melanoma but without evidence of disease recurrence, 3 months after tumor resection or 4 months after finishing adjuvant treatment. The mean sampling interval was 3 months.
  
  
  RESULTS
  Mean concentrations of S100β and lactate dehydrogenase were 0.0557 μg/L and 6.3 μkat/L, respectively. Between-run analytical variation was 3.5% at 0.181 μg/L for S100β and 3.5% at 2.83 μkat/L for lactate dehydrogenase. Biological variations obtained for S100β and lactate dehydrogenase were 14.2% and 8.2%, respectively. The analytical goals (defined as 50% of biological variation) were 7.1% for S100β and 4.1% for lactate dehydrogenase.
  
  
  CONCLUSIONS
  The estimation of biological variation allows us to calculate analytical goals and reference change values. These are necessary tools for the correct interpretation of serial measurements in patient follow-up.
authors: Service of Clinical Chemistry, Department of Biological Diagnosis, Althaia, Xarxa Assistencial de Manresa, Manresa, Spain. jtrape@althaia.cat
authors: Jaume
authors: J
authors: Trapé
authors: Jesús
authors: J
authors: Montesinos
authors: Josefina
authors: J
authors: Franquesa
authors: Maria
authors: M
authors: Sala
authors: Cristina
authors: C
authors: Fígols
authors: Ana
authors: A
authors: Miguel
authors: Montserrat
authors: M
authors: Domenech
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis; D019963:Clinical Chemistry Tests / Q000379:methods* / Q000592:standards; D018572:Disease-Free Survival; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000032:analysis*; D008545:Melanoma / Q000737:chemistry* / Q000628:therapy; D008875:Middle Aged; D009414:Nerve Growth Factors / Q000032:analysis*; D012016:Reference Values; D012306:Risk; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins / Q000032:analysis*
chemical_list: D014408:Biomarkers, Tumor; D009414:Nerve Growth Factors; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins; D007770:L-Lactate Dehydrogenase