The physician will take a careful medical and personal history, perform a physical examination, and order laboratory tests as needed. There is no one laboratory test that can be used to diagnose anxiety, but tests may provide useful information about a medical condition that may be causing physical illness or other anxiety symptoms.

To be diagnosed with generalized anxiety disorder (GAD), a person must:

Excessively worry and be anxious about several different events or activities on more days than not for at least six months
Find it difficult to control the worrying
Have at least three of the following six symptoms associated with the anxiety on more days than not in the last six months: restlessness, fatigue, irritability, muscle tension, difficulty sleeping, difficulty concentrating
Generally, to be diagnosed with GAD, symptoms must be present more often than not for six months and they must interfere with daily living, causing the sufferer to miss work or school.

If the focus of the anxiety and worry is confined to a particular anxiety disorder, GAD will not be the diagnosis. For example, a physician may diagnose panic disorder if the anxiety is focused on worrying about having a panic attack, social phobia if worrying about being embarrassed in public, separation anxiety disorder if worrying about being away from home or relatives, anorexia nervosa if worrying about gaining weight, or hypochondriasis if worrying about having a serious illness.

Patients with anxiety disorder often present symptoms similar to clinical depression and vice-versa. It is rare for a patient to exhibit symptoms of only one of these.

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