How is Axial Spondyloarthritis diagnosed
Most patients with AS can be diagnosed on the basis of history, physical examination, and the finding of sacroiliitis on radiographs, obviating the need for HLA testing.
A negative HLA-B27 dramatically reduces the likelihood of axSpA/AS in white patients. Up to 75% of AS patients will have an elevated ESR or CRP, and an elevated CRP modestly predicts response to TNF inhibitors.
However, many patients with AS will have normal ESR and CRP levels. Rheumatoid factor and antinuclear antibodies are typically negative.
IgA levels are frequently elevated in AS patients who develop an IgA nephropathy.
