Increased incidence of recurrent hematuria in ankylosing spondylitis: a possible association with IgA nephropathy.

A retrospective analysis of our patients with ankylosing spondylitis revealed a 17.8% incidence of recurrent hematuria. Two of the five patients with recurrent hematuria had previously undergone renal biopsies showing a focal proliferative glomerulonephritis. The only specimen examined by immunofluorescent staining showed the typical changes of IgA nephropathy. A control group of patients with rheumatoid arthritis did not show recurrent hematuria. Recurrent hematuria may be a frequent occurrence in ankylosing spondylitis and may signify the presence of one of the glomerulonephritides such as IgA nephropathy.