Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (18 page)

   Laboratory Findings

   Positive ANA test, with high titers and a fine speckled staining pattern by IFA, is found in two thirds of patients.

   Anti-SSA/Ro and Anti-SSB/La antibodies are frequently detected in the serum of patients with SjS, and their presence supports the diagnosis. These antibodies are also detected in patients with SLE.

   RF is frequently positive because of the association of SjS with rheumatoid arthritis.

   CRP and ESR are typically elevated.

   Other laboratory tests are indicated to evaluate systemic and extraglandular involvement, and they include serum electrolytes, anticardiolipin antibodies, lupus anticoagulant, cryoglobulins, liver function tests, and urinalysis.

   Imaging studies and specific diagnostic tests of the glands can help with the diagnosis. Tests commonly used include Schirmer test to measure tear production, rose bengal test to assess the damage to epithelial cells in the cornea and conjunctivae, and tear breakup time test to measure overall lacrimal function.

Suggested Reading

Shiboski SC, Shiboski CH, Criswell L, et al. American College of Rheumatology classification criteria for Sjögren’s syndrome: a data-driven, expert consensus approach in the Sjögren’s International Collaborative Clinical Alliance cohort.
Arthritis Care Res.
2012;64(4):475–487.

SYSTEMIC LUPUS ERYTHEMATOSUS

   Definition

   SLE is a chronic autoimmune disease characterized by multisystem involvement and a variable clinical course. A prominent feature of SLE is the production of a number of antinuclear antibodies. The autoantibodies and immune complexes bind to various tissues, with resulting damage.

   According to the ACR classification criteria for SLE, a person is said to have SLE if any four or more of the following 11 criteria are present, serially or simultaneously, during any interval of observation:

   Malar rash

   Discoid rash