Diagnosis

There are no tests that a doctor can order to confirm that you are depressed. The doctor will make a diagnosis based on the symptoms you describe. It is therefore important to tell the doctor if you have been suffering with any of the symptoms of depression.
He or she will often perform a physical examination and some laboratory studies to rule out medical disorders that can lead to depression, such as thyroid dysfunction or infections. (About 10% to 15% of depression cases are caused by a medical illness, use of certain medications, alcohol, illegal drugs, or other conditions. If the underlying problem can be corrected, depression will often go away, too.)
The diagnosis of major depression is typically made after talking with you about how you are feeling physically and emotionally, listening to any complaints you have about your health or mental state, and taking note of your personal and family medical history. A doctor may also ask your family members and friends about how you've been doing lately in an effort to gather more information so an accurate diagnosis can be made.