title: Variation of serum hyaluronan with activity in individuals with knee osteoarthritis.
abstract: OBJECTIVE
  Serum hyaluronan (HA) was evaluated for diurnal variation in participants with osteoarthritis (OA) of the knee.
  
  
  METHODS
  Twenty participants with radiographic OA of at least one knee were admitted overnight to the General Clinical Research Center for serial serum sampling. Serum was obtained between 6:00 p.m. and 8:00 p.m. on Day 1 (T3) after a day of normal activity. During the night of bed rest, participants remained supine for a minimum of 5 h between the hours of 3:00 a.m. and 8:00 a.m. Blood was drawn prior to arising from bed (T0), and 1h (T1) and 4 h (T2) after arising and performing usual morning activities, including eating breakfast. During the morning, participants were encouraged to remain physically active and were not permitted to sit for more than 30 min at a time. Serum HA was measured by enzyme-linked immunosorbent assay. Results were analyzed using non-parametric Freidman's test with Dunn's post-hoc Multiple Comparison test.
  
  
  RESULTS
  Serum levels of HA increased significantly from T0 to T1 (P < 0.01). There were no other significant changes in serum HA levels observed between any of the other time points.
  
  
  CONCLUSIONS
  Although a rise in serum HA with activity and eating has been demonstrated previously in individuals with rheumatoid arthritis, this is the first study to demonstrate a similar rise in individuals with OA. These results suggest that serum sampling for HA in OA clinical trials should be performed more than 1h after arising in the morning and at least 1h after breaking an overnight fast.
authors.affiliation: Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: Lisa G
authors.initials: LG
authors.lastname: Criscione
authors.forename: Alan L
authors.initials: AL
authors.lastname: Elliott
authors.forename: Thomas
authors.initials: T
authors.lastname: Stabler
authors.forename: Joanne M
authors.initials: JM
authors.lastname: Jordan
authors.forename: Carl F
authors.initials: CF
authors.lastname: Pieper
authors.forename: Virginia B
authors.initials: VB
authors.lastname: Kraus
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D004435:Eating; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D006820:Hyaluronic Acid / Q000097:blood*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000097:blood*; D018401:Sample Size; D018709:Statistics, Nonparametric
chemical_list: D015415:Biomarkers; D006820:Hyaluronic Acid