Variation of serum hyaluronan with activity in individuals with knee osteoarthritis

SummaryPurposeSerum hyaluronan (HA) was evaluated for diurnal variation in participants with osteoarthritis (OA) of the knee.MethodsTwenty 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 5h 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 4h (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 30min 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.ResultsSerum levels of HA increased significantly from T0 to T1 (P