title: Within- and between-subject variation in commonly measured anthropometric and biochemical variables.
abstract: BACKGROUND
  The biological variation of some commonly assessed metabolic variables in healthy subjects has not been studied extensively. The aim of the study was to assess, in 12 healthy subjects (6 male and 6 female; mean (SD) age; 22.7 (1.5) years) following an overnight fast, the day-to-day variation of body fat (impedance method), triglycerides, nonesterified fatty acid (NEFAs), glycerol, 3-hydroxybutyrate (3-OHB), lactate, glucose, insulin (RIA), C-peptide, and glucagon on 12 consecutive days.
  
  
  METHODS
  Between- and within-subject coefficients of variation (CVG and CVW) were estimated using a random effects analysis of variance, and assay variation was subtracted to give the coefficient of within-subject biological variation (CVI). Individuality indices were calculated as CVW/CVG.
  
  
  RESULTS
  The overall means, CVI, and individuality indices were as follows: for body fat, 24.2%, 10%, and 0.3; for triglycerides, 0.61 mmol/L, 21%, and 1.1; for NEFAs, 376 micromol/L, 45%, and 1.4; for glycerol, 48 micromol/L, 36%, and 0.8; for 3-OHB, 43 micromol/L, 61%, and 1.5; for lactate, 0.88 mmol/L, 31%, and 1.1; for glucose, 4.9 mmol/L, 4.8%, and 0.7; for insulin, 52 pmol/L, 26%, and 1.0; for C-peptide, 0.39 nmol/L, 24%, and 0.9; and for glucagon, 53 ng/L, 19%, and 0.8.
  
  
  CONCLUSIONS
  The data presented here are necessary for the evaluation of several important metabolic variables in individual and group studies. The biological variation of some metabolites makes it difficult to characterize the status of healthy subjects with a single measurement.
authors: Department of Clinical Endocrinology, Hannover Medical School, 30625 Hannover, Germany.
authors: A
authors: A
authors: Widjaja
authors: R J
authors: RJ
authors: Morris
authors: J C
authors: JC
authors: Levy
authors: K N
authors: KN
authors: Frayn
authors: S E
authors: SE
authors: Manley
authors: R C
authors: RC
authors: Turner
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000097:blood; D000273:Adipose Tissue / Q000737:chemistry; D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D002096:C-Peptide / Q000097:blood; D002624:Chemistry, Clinical / Q000592:standards*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005934:Glucagon / Q000097:blood; D005990:Glycerol / Q000097:blood; D006801:Humans; D007206:Individuality; D007328:Insulin / Q000097:blood; D019344:Lactic Acid / Q000097:blood; D008297:Male; D011863:Radioimmunoassay; D012016:Reference Values; D014280:Triglycerides / Q000097:blood
chemical_list: D001786:Blood Glucose; D002096:C-Peptide; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D014280:Triglycerides; D019344:Lactic Acid; D005934:Glucagon; D005990:Glycerol; D020155:3-Hydroxybutyric Acid