5 Diseases Doctors Often Get Wrong

— -- intro: When you experience strange pains, mysterious digestive issues, or other unexplained symptoms, you'd hope a trip to the doctor would solve your health woes. But sometimes, doctors have just as much trouble identifying certain disorders and conditions as their patients.

"A lot of symptoms are nonspecific and variable, depending on the person," says David Fleming, MD, president of the American College of Physicians and a professor of medicine at the University of Missouri. "On top of that, many diagnostic tests are expensive and aren't done routinely, and even then they don't always give us a black and white answer."

The following five conditions are notoriously difficult to pin down.

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quicklist: 1category: Diseases Doctors Often Get Wrongtitle: Irritable bowel syndromeurl:text: Some conditions are difficult to diagnose because there is no real test to prove their existence; rather, they require a "diagnosis of elimination," says Dr. Fleming, as doctors rule out all other possibilities.

Irritable bowel syndrome (IBS)—a chronic condition that affects the large intestine and causes abdominal pain, cramping, bloating, diarrhea, and/or constipation—is one of these cases. According to diagnostic criteria, a patient should have symptoms for at least six months before first being seen for a formal evaluation, and discomfort should be present at least three days a month in the last three months before being diagnosed with IBS.

quicklist: 2category: Diseases Doctors Often Get Wrongtitle: Celiac diseaseurl:text: So much confusion surrounds celiac disease—an immune reaction to gluten that triggers inflammation in the small intestine—that it takes the average patient six to 10 years to be properly diagnosed.

Celiac sufferers would, in theory, have digestive problems when eating gluten-containing foods like wheat, barley, and rye, but in fact, only about half of people diagnosed with the disease have experienced diarrhea and weight loss. Celiac disease can also cause itchy skin, headaches, joint pain, and acid reflux or heartburn, and it's all too easy to blame these symptoms on other things.

A blood test can diagnose celiac disease no matter what symptoms are present, and an endoscopy can determine any damage that's been done to the small intestine.

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quicklist: 3category: Diseases Doctors Often Get Wrongtitle: Fibromyalgiaurl:text: Fibromyalgia, which is characterized by widespread musculoskeletal pain, involves "medically unexplained symptoms"—a term doctors use to describe persistent complaints that don't appear to have an obvious physical cause.

When doctors can't find a root cause for a patient's chronic pain and fatigue, they often settle on this diagnosis. This may involve seeing specialists and ruling out other diseases, some of which prove equally difficult to diagnose, says Eugene Shapiro, MD, deputy director of the Investigative Medicine Program at Yale University.

"There are studies that show that people with certain symptoms who show up at a rheumatologist will be diagnosed with fibromyalgia, but if the same patients show up at a gastroenterologist they'll be diagnosed as having irritable bowel syndrome."

quicklist: 4category: Diseases Doctors Often Get Wrongtitle: Rheumatoid arthritisurl:text: Unexplained aches and pains may also be caused by rheumatoid arthritis (RA), an autoimmune disorder.

Unlike osteoarthritis (the "wear and tear" kind that appears as people get older), RA causes inflammation and painful swelling of joints and can occur at any age.

"Early stages of RA can mimic many other conditions—sometimes it's just a sense of aches or stiffness in the joints, which could be caused by a lot of different things," says Dr. Fleming.

Blood tests can help detect the presence of inflammation in the body, he says, but an exact diagnosis of RA also must take into account a patient's medical history and a doctor's careful physical exam.

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quicklist: 5category: Diseases Doctors Often Get Wrongtitle: Multiple sclerosisurl:text: Another autoimmune disease, multiple sclerosis (MS) occurs when the immune system attacks the body's own nerve cells and disrupts communication between the brain and the rest of the body. Some of the first symptoms of MS are often numbness, weakness, or tingling in one or more limbs, but that's not always the case.

"Multiple sclerosis can be episodic; the disease waxes and wanes," says Dr. Shapiro. Depending on the number and location of lesions in the brain, he adds, signs and symptoms may be more or less severe in different people. Once a doctor does suspect MS, however, a spinal tap or MRI can help confirm the diagnosis.

15 Diseases Doctors Often Get Wrong originally appeared on Health.com.