Rheumatic diseases, which primarily target the locomotor system, affect multiple organs and systems, which their fluctuating course demanding constant clinical and laboratory follow-up. Laboratory tests, however, may remain unchanged in people with definite rheumatic disease, while many normal people may show false-positive results. On the other hand, symptoms may precede laboratory alterations in weeks or even months, making a thorough knowledge of such interplay essential for the assistant doctor ordering these exams.