A diagnosis of Parkinson's disease is based on your medical history and a thorough neurological exam. Your doctor also may check your sense of smell. Sometimes, your doctor will have you try a medicine for Parkinson's disease. If that medicine helps your symptoms, it may help the doctor find out if you have Parkinson's disease.

There are no lab tests that can diagnose Parkinson's disease. If your symptoms and the doctor's findings during the examination are not entirely typical of Parkinson's disease, certain tests may be done to help diagnose other conditions with similar symptoms. For instance, blood tests may be done to check for abnormal thyroid hormone levels or liver damage. An imaging test (such as a CT scan or an MRI) may be used to check for signs of a stroke or brain tumor.

Another type of imaging test, called PET, sometimes may detect low levels of dopamine in the brain, a key feature of Parkinson's disease. However, PET scanning is not commonly used to evaluate Parkinson's disease because it is very expensive, is not available in many hospitals, and is only used experimentally.

Early Detection

For some diseases, doctors can do tests to look for problems or diseases before you have any symptoms. This is called screening. But there is no screening test for Parkinson's disease at this time.