Diseases That Are Difficult to Diagnose

The common symptoms of fibromyalgia, including widespread pain, fatigue, sleep problems, and cognitive difficulties like confusion and forgetfulness, are shared with many other conditions. Because there are no specific imaging or diagnostic tests for fibromyalgia, doctors often try to rule out other conditions first.

To complicate matters, some fibromyalgia symptoms fade over time, and new symptoms can develop. Someone with fibromyalgia may receive different diagnoses throughout their lifetime, depending on their symptoms at the time of their appointment.

Multiple sclerosis (MS) is a chronic disease that affects the brain and the spinal cord, but it looks different in everyone. MS can be episodic, with symptoms coming and going. Some people have very mild symptoms, while others lose the ability to walk or speak.

Because these symptoms vary drastically, both in type and severity, it can be challenging to distinguish MS from other disorders affecting the central nervous system. An MRI can usually confirm an MS diagnosis, but some people need further testing.

Lupus is a chronic autoimmune disease that can affect the skin, kidneys, eyes, and joints. One common symptom that points to a lupus diagnosis is a red butterfly-shaped rash over the nose and cheeks, but if a person happens not to develop this rash, the diagnosis can be particularly tricky.

Lupus symptoms flare up and recede, making it difficult to pinpoint the problem. The disease often develops slowly and can take years to make itself known, and then taking up to two years to diagnose.

There is a reason it takes between six and ten years for someone with celiac disease to be correctly diagnosed. Celiac disease is an immune reaction to gluten that causes inflammation in the small intestine, leading to various symptoms.

The digestive system has a profound impact on many other areas of health, so celiac disease can cause joint pain, headaches, and itchy skin, too, which can easily be mistaken for something else. Celiac disease has a relatively low rate of diagnosis—doctors don't always consider it a possibility due to the wide range of symptoms. Blood tests are helpful, but current experts recommend an intestinal biopsy to confirm a diagnosis.

Even though hypothyroidism is relatively common and easily treatable, it is still challenging to diagnose, especially in the early stages. The most common symptoms are non-specific and include lethargy, fatigue, weight gain, constipation, and dry skin. Symptoms differ depending on many factors, and elderly patients often have fewer classic signs than younger people.

While an increase in the severity of symptoms may increase the likelihood of a diagnosis, one study showed that none of 34 symptoms related to hypothyroidism appeared in patients who actually had the condition and that 15 percent of people were asymptomatic.

Someone with hyperthyroidism may feel anxious, nervous, or irritable with unusual sweating, a high heart rate, and weight loss, which are symptoms that can also indicate a mood or anxiety disorder. Doctors commonly use blood tests to diagnose hyperthyroidism, but research shows that, in some cases, patients get results that mimic those "generally found in subclinical or mild hypothyroidism," which can lead to a misdiagnosis.

Acquired central hyperthyroidism is generally uncovered when patients are tested for other things, like pituitary or hypothalamic dysfunction.

Early symptoms of rheumatoid arthritis (RA), like general joint stiffness, pain, tenderness, and fatigue, are vague enough to be mistaken for other conditions. Advanced symptoms can affect the central nervous system, eyes, kidneys, and lungs. Studies show rheumatoid arthritis presents in different ways, too, which can make it hard to pin down as a diagnosis.

African Americans may have positive blood tests for rheumatoid factor without showing signs of severe disease, and the main skin manifestation of RA, rheumatoid nodules, only appears in 30 percent of people with the disease. Patients with RA are twice as susceptible to depression as the general population and have an increased mortality risk, making early detection even more critical.

Irritable bowel syndrome (IBS) is sometimes called a "diagnosis of elimination" because there are no diagnostic tests to confirm it. IBS does not have any specific chemical or structural abnormalities, and the physical symptoms mimic those of many other conditions, like food allergies, celiac disease, or inflammatory bowel disease, making it a challenging diagnosis for doctors.

Most people know to look for a ring-like rash as a tell-tale sign of Lyme disease, but it only appears in 70 to 80 percent of cases. The other symptoms of Lyme, like fever, headaches, chills, and fatigue, are very general without the bullseye rash; this can make it challenging to diagnose, particularly in children.

Research shows direct detection methods like bacterial cultures [citation href="https://pubmed.ncbi.nlm.nih.gov/33861032/' title="Epidemiological review" desc="Challenges and new methods in the diagnosis of Lyme disease in children"]may be inadequate in children, and testing spinal fluid may be necessary.

Both types of inflammatory bowel disease—Crohn's disease and ulcerative colitis—cause inflammation in the gastrointestinal tract. Symptoms include diarrhea, constipation, abdominal pain, nausea, and vomiting, the same symptoms as many gastrointestinal disorders.

There is no definitive test for inflammatory bowel disease, so doctors may make a diagnosis by eliminating everything else. Diagnosing inflammatory bowel disease requires a combination of lab markers and clinical findings. Imaging can assess for bowel obstruction and other complications.