Serum hyaluronic acid levels are elevated in arthritis patients, but normal and not associated with clinical data in patients with fibromyalgia syndrome.

BACKGROUND: Fibromyalgia syndrome (FM) is a disease with widespread chronic pain and many nonspecific symptoms. Hyaluronic acid (HA) is a disputed marker for the diagnosis of FM. The aim of the study is to clarify the discrepant results reported so far.
METHODS: Serum concentrations of HA were measured with a radiometric assay (Pharmacia & Upjohn, Sweden) in 41 patients with FM (38 females), 48 with arthritis (35 females) and 31 control subjects (28 females). Correlations of HA levels with clinical parameters (duration of disease, age, gender, medication) and scores of disease severity (e.g. depression and pain) were calculated. If appropriate, partial correlations and analysis of covariance adjusted for confounding variables (e.g. age) were used.
RESULTS: HA levels were confirmed to be age-related in the whole study group (r(s) = 0.54; P < 0.001) and each subgroup. Association between HA levels and gender, drug therapy, clinical or psychometric data could not be demonstrated in patients suffering from FM. Analyzing all study participants, HA levels were correlated with the pain disability index (PDI) (r(tau) = 0.27; P < 0.02) and, in arthritis patients only, with duration of disease (r(tau) = 0.82; P < 0.001). Moreover, analysis of covariance revealed that patients with FM had normal HA values as compared with control subjects and only patients with arthritis had significantly higher levels than both other groups.
CONCLUSIONS: The present study with a quite large cohort including patients with arthritis and FM demonstrates that serum levels of HA in FM are neither elevated nor associated with any relevant clinical data of this disease and, therefore, have no diagnostic or prognostic value in Germans.