Idiopathic

What does idiopathic mean?

Idiopathic is a word healthcare providers use to describe a disease or condition that doesn’t have a known cause. Your provider will say your condition is “idiopathic” after they’ve ruled out all known causes. Some conditions have “idiopathic” built into their name because the lack of a known cause is a defining feature. Juvenile idiopathic arthritis is one example.

If you hear your provider refer to your condition as “idiopathic,” you might feel anxious. After learning providers don’t know the cause, you might wonder how this happened or whether treatments can help you.

The first thing to do is talk to your provider about your diagnosis. Ask if they can explain more about possible causes or contributing factors. In some cases, lab or imaging tests may not reveal the exact cause, but providers may suspect a likely cause based on your symptoms or medical history.

Your provider can also tell you more about treatment options available to help you. Often, providers can treat signs or symptoms even if they can’t directly target the underlying cause. There may also be opportunities to take part in a clinical trial. Your provider will let you know what’s possible in your situation and offer resources to guide the way forward.

What are some examples of idiopathic diseases or conditions?

Examples of idiopathic conditions include:

• Chronic idiopathic urticaria. This is when you have hives that last a long time or go away and come back again (recur), but you can’t identify a trigger.
• Diffuse idiopathic skeletal hyperostosis (DISH). This is a type of arthritis involving excess bone growth. It causes pain and mobility problems.
• Idiopathic intracranial hypertension. This is when cerebrospinal fluid (CSF) builds up in your skull for no known reason, causing severe headaches and vision changes.
• Idiopathic pulmonary fibrosis. This involves scarring and thickening of lung tissue that gradually gets worse, leading to breathing problems. 
• Idiopathic scoliosis. This is a side-to-side curve of your spine without a known cause. It’s the most common type of scoliosis.
• Juvenile idiopathic arthritis. This is the most common type of arthritis affecting children and teens. It causes joint pain, swelling and tenderness.
• Ménière’s disease (idiopathic endolymphatic hydrops). This is a rare inner ear disorder. Experts believe a buildup of fluid (endolymph) in your inner ear causes symptoms (like vertigo and tinnitus), but they’re not sure exactly what causes the buildup.

Future research may uncover causes for these conditions. But for now, providers consider them idiopathic.

Conditions that are often idiopathic

Some conditions are often idiopathic, but providers can identify a specific cause in some people. Examples of such conditions include:

• Castleman disease. Providers sometimes find a cause in people who have the multicentric form of this disease (enlarged lymph nodes throughout their body). But usually, this condition is idiopathic.
• Normal pressure hydrocephalus (NPH). Certain medical conditions (like a brain aneurysm or brain tumor) can cause this buildup of cerebrospinal fluid. But about 50% of all cases are idiopathic.
• Parkinson’s disease. This degenerative brain disease can be either genetic or idiopathic. About 9 in 10 cases are idiopathic.
• Pericarditis. Plenty of things (from infections to chest injuries) can cause inflammation in the sac surrounding your heart. But in many cases, there’s no clear cause.
• Pulmonary arterial hypertension (PAH). Damage to small blood vessels in your lungs raises pressure in your pulmonary arteries. Providers can sometimes pinpoint what causes this damage, but more commonly, PAH is idiopathic.
• Uveitis. Infections, eye injuries and autoimmune diseases can lead to this inflammation of the middle layer of your eye (uvea). But it’s common for exams and testing to reveal no known cause.

Idiopathic vs. occult — what’s the difference?

Idiopathic and occult are two different medical terms with different meanings. Idiopathic means having an unknown cause, and providers use the word to describe medical conditions where all known causes have been ruled out. On the other hand, occult means hidden or unable to be seen. Providers typically use “occult” when referring to:

• The place in your body where cancer started. Occult primary cancer (also called cancer of unknown primary) is cancer that has spread to one or more sites throughout your body from an unknown site of origin. Testing or other methods aren’t revealing where the cancer started, so that site is occult, or hidden.
• Findings that are hard to see. For example, a fecal occult blood test looks for tiny traces of blood in your poop that you can’t see with just your eyes. Radiologists may use the word “occult” to describe issues that are hidden on one type of imaging test (like an X-ray) but visible on another type.