Your primary care physician may refer you to a specialist for one of several reasons. He or she may decide that a specialist is necessary to diagnose your illness. You may already have a diagnosis, but your physician may feel a specialist for that illness should care for you. Alternatively, your doctor may wish to arrange cooperative care with the specialist for that disease. Lastly, your primary care doctor may want you to be evaluated to rule out a rheumatologic disease or to confirm one that he or she plans to manage. Rheumatologists and most other specialists cannot assume your general medical care.
Though lab tests are an essential part of medical practice including rheumatology, pitfalls may occur when using these to evaluate patients with musculoskeletal or associated systemic issues. Simple tests such as the sedimentation rate (ESR) and C-reactive protein (CRP) often parallel disease activity in inflammatory conditions. These markers of inflammation may be useful in monitoring conditions such as rheumatoid arthritis, systemic lupus, and polymyalgia rheumatica. However, other conditions such as infection or malignancy can also elevate these in-office tests. These tests are routinely normal in patients with degenerative arthritis and may not accurately reflect disease activity in other rheumatic disease states. Rheumatoid factor (RF) and the anti-nuclear antibody test (ANA) are common tests used to evaluate a variety of joint and muscle symptoms. However, they are not necessarily diagnostic standing alone. The anti-nuclear antibody is often falsely positive and further detailed testing might be indicated depending on an individual situation. One can have active rheumatoid arthritis without a positive rheumatoid factor; this test might be more useful to identify someone with more severe disease potential.
A person may be referred because of abnormal blood tests when being "screened" for illness. The entire clinical picture needs to be taken into account when evaluating someone with a potential inflammatory process. No rheumatologic test is necessarily black or white. There are a number of other blood tests that a rheumatologist may obtain to help establish or negate a diagnosis or monitor a given condition yet the patient's story and physical findings are the essential and necessary parameters.