3) You were diagnosed by a physician working outside his or her specialty.

For many people, the first doctor they see when they get sick is a family practice physician. Family practice doctors, by necessity and training, have to know how to spot the most common symptoms of many different diseases. But if you have a complicated case, it may be not be easy for such a generalist to reach the right diagnosis.

In one 2003 study, for example, researchers at McGill University in Montreal, Quebec, followed all new patients referred to the university’s rheumatology clinic. Seventy-six patients were told by their primary care physicians that they probably had fibromyalgia. Rheumatologists subsequently determined that only about one-third of those patients actually met the diagnostic criteria for the condition. About two-thirds of those patients had another rheumatic disease that accounted for their symptoms.

“There are millions and millions of people who have chronic pain where doctors have trouble figuring out what that chronic pain is due to,” says Dr. Goldenberg. “And in that situation, the rheumatologist probably would be helpful early on in figuring out the problem.”

Even if a primary care physician has correctly diagnosed your condition, you may get added benefits from having a rheumatologist on your team. Research has shown that early, aggressive treatment of inflammatory forms of arthritis, like rheumatoid or psoriatic arthritis, can prevent permanent disability. Rheumatologists are specialists in the treatments and complications of diseases that affect the muscles and joints, and they can make sure you’re being treated appropriately.

4) A lab test is needed to make a definitive diagnosis, but your doctor never ordered it for you.

While a diagnosis should never be based exclusively on test results, there are some conditions that can’t be positively identified without specific tests.

“If your doctor told you that you had gout, for example, but he failed to draw fluid from the joint to check for uric acid crystals, then you might not have gout,” Dr. Schiff says.

Other diseases mimic gout, including bursitis, OA, and pseudogout, which is caused by deposits of calcium, rather than uric acid crystals, and they require different treatments.

How are you, the patient, supposed to know when a test is required? This is where preparation and education can pay off. Check reputable sources of information, including the Centers for Disease Control and Prevention, the National Institute of Arthritis, Musculoskeletal and Skin Diseases, the Arthritis Foundation and Arthritis Today. Find out what tests are typically ordered to aid your doctor in a diagnosis of your condition, and check with your doctor to see if you need them.

5) Your symptoms don’t match your diagnosis.

Many doctors are so busy that it’s easy for them to fall into the bad habit of listening to one or two of a patient’s complaints before they start down a diagnostic path, and the result may be a conclusion that doesn’t quite fit.

Dr. Goldenberg says he sees many patients who have run into this problem.