As with most mental disorders, there are no blood tests or other "hard and fast" ways to diagnose agoraphobia. A doctor will ask many questions to find out whether you have the symptoms and signs of agoraphobia and to make sure that it isn't another mental health condition.
In particular, agoraphobia should be distinguished from social phobia (social anxiety disorder), where avoidance is limited to social situations due to fear of embarrassment – treatment interventions for social phobia are different from treatments for agoraphobia.
In addition, it's important to be sure that the anxiety isn't being caused by a medication, drug abuse or addiction, or a medical condition. A doctor may refer someone to a psychiatrist or another therapist who specializes in recognizing and treating anxiety disorders, including agoraphobia.