A 50-year-old female complains of dry mouth and foreign body sensation in her eyes. It is difficult for her to speak for more than a few minutes. There is no history of diabetes mellitus or neurological disease. The patient is on no medications. During clinical examination the buccal mucosa appears dry and the salivary glands are enlarged bilaterally. The next step in evaluation would be?

Primary Sjogren's syndrome, an autoimmune disease with presenting symptoms of dry eyes and dry mouth. Positive Schirmer test is an objective evidence of dry eyes. Autoantibodies are directed against non-organ-specific antigens such as immunoglobulins (rheumatoid factors) and extractable nuclear and cytoplasmic antigens (Ro/SS-A, La/SS-B). Lip biopsy also can prove the diagnosis of Sjogren's syndrome. Noninvasive tests like Schirmer test and measurement of autoantibodies should be the first step in the evaluation of primary Sjogren's syndrome.