It seems reasonable to assume that after a full evaluation, your doctor will know the cause of your symptoms. And the process itself is straightforward: If you have a problem, you go to the doctor, he or she finds the cause, and makes recommendations about how to treat it.
However, the notion that your doctor knows the cause of your condition is often a medical myth. In fact, the amount of uncertainty present in most medical care is probably underestimated and underappreciated. The best health care providers recognize they are dealing with possibilities and probabilities and learn to accept uncertainty — certain fields of medicine have more uncertainty than others.
For example, a cancer diagnosis based on a biopsy is typically less open for debate than what is causing a headache. In medical training, future physicians learn to create a "differential diagnosis" — a list of reasonable explanations for the problem at hand with some attempt to identify the most probable. The ability to promptly whittle this list down to one diagnosis with confidence is more often the exception than the rule.
Some exceedingly common problems are poorly understood. Here are three standouts.
If you are one of the millions of back-pain sufferers, one doctor may diagnose "back strain." However, another doctor may tell you arthritis is causing your pain, while yet another diagnoses you with disk disease. They may all be exceptional physicians. But the scary thing is they may all be wrong. The fact is, most back pain cannot be definitively diagnosed. Despite all the fancy tests we could order, doctors are much better at telling people with back pain what they don't have (such as a fracture or tumor) than what they do have.
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If you put your arm in a sling for two weeks and then take if off, your shoulder will be quite stiff. In fact, you might lose motion in your shoulder, which makes it hard to reach up to high shelves. That lost motion may never return. Just to be clear: Don't try this experiment at home.
The condition is called "frozen shoulder." It may affect anyone who does not move their shoulder for a prolonged period. Sometimes it develops for no apparent reason. Bursitis, tendinitis, rotator cuff injury may all cause pain in the shoulder. If the pain is great enough, you may avoid moving your shoulder and it may "freeze." Getting motion back may be very difficult or even impossible. Physical therapy is commonly recommended when you have shoulder pain (for any reason) to prevent or reduce the loss of motion that often follows, especially if the painful condition lasts more than a week or two. It is also the reason to avoid prolonged use of a shoulder sling.
One theory about why frozen shoulder develops includes the release of substances within the joint that lead to scarring and constriction of tissues around the shoulder joint. There are risk factors, such as diabetes or fracture of the upper arm. But the root causes of frozen shoulder and the underlying triggers in some cases, such as bursitis or tendinitis, are unknown.
Gout is a common form of arthritis. Crystals of uric acid deposit in one or more joints, causing sudden inflammation and pain. Uric acid is a waste product of normal metabolism. We all have a certain amount of it circulating in our bloodstreams. If you've ever had gout, you may wonder why you got it. Risk factors associated with gout include being male, having hypertension or kidney disease, using diuretics, drinking too much alcohol, eating a diet high in meat or seafood, and having a high uric acid in the blood. But most people with these risk factors never develop gout. So, to answer why one person has attacks of gout and another does not: No one knows for certain.
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The Bottom Line
If uncertainty is so rampant in medical care, you may wonder why you should see your doctor at all. There are some very good reasons:
- While identifying the definite cause of symptoms may be impossible, making sure there is nothing dangerously wrong is also important. This can usually be done with relative certainty. Remember, doctors are often better at telling you what you do not have than what you do have.
- There are many conditions that can be diagnosed with certainty and readily treated. This includes many types of thyroid disease, heart disease and diabetes to name a few.
- Your doctor can check for conditions that cause no symptoms. Checking the blood pressure for hypertension (high blood pressure) is a good example. Early diagnosis and treatment can prevent serious problems later.
- It's an excellent opportunity to review preventive measures that have been proven health benefits, such as screenings for breast, cervical or colon cancers.
Perhaps the most important point to make here is that expectations of certainty from your health care professional may be unrealistic. If you have back pain, gout or shoulder pain and there's no clear answer about your condition, a second-opinion is a reasonable option to consider. But don't be surprised if the additional evaluation simply confirms the uncertainty of the situation.
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Robert H. Shmerling, M.D. is associate physician at Beth Israel Deaconess Medical Center and associate professor at Harvard Medical School. He has been a practicing rheumatologist for over 20 years at Beth Israel Deaconess Medical Center. He is an active teacher in the Internal Medicine Residency Program, serving as the Robinson Firm Chief. He is also a teacher in the Rheumatology Fellowship Program.