Serum hyaluronan (HA) was determined in 37 patients suffering from psoriatic arthritis (PSA), 39 patients with rheumatoid arthritis (RA), 31 with osteoarthritic joint disease (OA) and 26 healthy controls (C) in order to examine earlier reports that HA levels are increased in the serum of RA and to assess whether this finding is also relevant for PSA, another inflammatory joint disease, since HA in serum is considered a sign of inflammation in general.
HA in the serum samples was measured with an enzyme linked microplate assay.
Sera from PSA, RA and OA patients showed a significantly higher HA concentration than those of healthy controls (56.0 +/- 16.0 micrograms/l). The serum HA concentration in PSA patients amounted to 107.8 +/- 57.2 micrograms/l, which was not significantly different from OA patients (104.9 +/- 16 micrograms/l). A significant difference, however, could be observed between the HA concentrations of the PSA subgroups: the mean HA level of patients suffering from symmetrical polyarthritis was 134 +/- 79.6 micrograms/l, which turned out to be significantly higher than in patients suffering from symmetrical oligoarthritis (89.9 +/- 42.8 micrograms/l; P < 0.04), but was insignificantly increased in comparison to patients with ankylosing spondylitis as the predominant feature (109 +/- 27.8 micrograms/l; P = 0.49). The mean HA concentration for RA sera was 197.1 +/- 122.9 micrograms/l, which was statistically significantly increased compared to PSA (P < 0.001) and OA (P < 0.001) sera. The sera of seropositive RA patients showed significantly higher HA levels than PSA patients with symmetrical polyarthritis (P < 0.04).
The data obtained support recent studies which have shown HA levels to be higher in RA patients than in OA patients. Seronegative and seropositive RA patients showed the same HA concentrations, while patients suffering from "seronegative" PSA were found to have lower HA concentrations. Therefore, HA serum levels may reflect cartilage degradation in general or the degree of articular inflammatory processes, indicating different pathogenetic pathways.