What do laboratory studies and joint radiographs show in intermittent hydrarthrosis?
Laboratory tests, including the erythrocyte sedimentation rate (ESR), are normal even during an attack. Synovial fluid is normal or mildly inflammatory (white blood cells [WBCs], 5000/mm 3 ) with a slight increase in polymorphonuclear leukocytes. An effusion may be seen on radiographs, but no other abnormalities are seen even after years of attacks. Recently, some patients have been found to be heterozygous for MEFV gene mutations without other features of familial Mediterranean fever (FMF). This suggests that some patients with intermittent hydrarthrosis may have a mild autoinflammatory syndrome that can be colchicine-responsive.
