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Am Fam Physician. 2001;64(5):857-858

Laboratory tests for diagnosing Lyme disease remain controversial because of the variability of test sensitivity and specificity, nonstandardized reagents, and variations within and between laboratories. Klempner and associates conducted a study to determine the diagnostic reliability of a serologic and a urine test for Lyme disease. Each test was performed in a reference laboratory.

Ten control subjects who had never had Lyme disease and 21 patients with a history of acute Lyme disease and post-treatment symptoms of at least six months' duration (despite antibiotic therapy) were included in the study. Post-treatment symptoms included fatigue, musculoskeletal pain and neurocognitive impairment. Serum samples were collected from each participant in the study. Midstream clean-catch urine samples were collected from the control subjects. An immunoglobulin G western blot assay, testing for antibodies to Borrelia burgdorferi, was performed to test the serum samples. An antigen capture-inhibition enzyme-linked immunosorbent assay (ELISA) test was used to test the urine samples. ELISA test results were based on the antigen level in the sample: less than 20 ng per mL was considered negative, 20 to 31 ng per mL was borderline, 32 to 45 ng per mL was positive and a level more than 45 ng per mL was highly positive.

Results of the immunoglobulin G Western blot assay on the serum samples of the 10 control subjects were negative; however, results were mixed in the patients with known Lyme disease (14 positive; 7 negative). The results of the ELISA tests on the urine samples were unreliable, with extremely variable antigen levels and inconsistent interpretation of results.

The authors conclude that an immunoglobulin G Western blot test is the most appropriate serologic test to perform in a patient with chronic (for at least six months) symptoms of Lyme disease. This is also the recommendation of the Centers for Disease Control and Prevention. The authors further conclude that the urine antigen test is unreliable and should not be used to diagnose Lyme disease.

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