context: If you are planning to see your doctor about depression, here is information about the kinds of tests your doctor might order. First, keep in mind that not every test is a "depression test." Some tests aren't used to diagnose clinical depression but rather to rule out other serious medical conditions that may cause similar symptoms. In most cases, the doctor will do a physical exam and ask for specific lab tests to make sure your depression symptoms aren't related to a condition such as thyroid disease, vitamin D deficiency, or another medical problem. If your symptoms are related to another serious illness, treating that illness may also help ease the depression. Again, the goal with a physical exam is usually to rule out another medical cause for depression. When performing the physical exam, the doctor may focus primarily on the neurological and endocrine systems. The doctor will try to identify any major health concerns that may be contributing to symptoms of clinical depression. For example, hypothyroidism -- caused by an underactive thyroid gland -- is the most common medical condition associated with depressive symptoms. Other endocrine disorders associated with depression include hyperthyroidism -- caused by an overactive thyroid -- and Cushing's disease -- a disorder of the adrenal gland. Many central nervous system illnesses and injuries can also lead to depression. For example, depression might be associated with any of the following conditions: Central nervous system tumors Head trauma Multiple sclerosis Stroke Syphilis Various cancers (pancreas, prostate, breast) Corticosteroid medications such as prednisone, which people take for diseases such as rheumatoid arthritis or asthma, are also associated with depression. Other drugs, including illegal steroids and amphetamines and over-the-counter appetite suppressants, may cause depression on withdrawal. Your doctor can usually tell if you have depression by asking you specific questions and doing a physical exam. Your doctor may, however, ask for lab tests to rule out other diagnoses. Your doctor will likely do blood tests to check for medical conditions that may cause depressive symptoms. He or she will use the blood tests to check for such things as anemia as well as thyroid or possibly other hormones, and sometimes calcium and vitamin D levels. The doctor may include other standard tests as part of the initial physical exam. Among them may be blood tests to check electrolytes, liver function, toxicology screening, and kidney function. Because the kidneys and liver are responsible for the elimination of depression medications, impairment to either of these two organs may cause the drugs to accumulate in the body. Other tests may sometimes include: CT scan or MRI of the brain to rule out serious illnesses such as a brain tumor Electrocardiogram ( ECG) to diagnose some heart problems Electroencephalogram ( EEG) to record electrical activity of the brain After discussing your mood and the way it affects your life, your doctor may also ask you questions that are used specifically to screen for depression. It's important to keep in mind that the inventories and questionnaires the doctor may use are just one part of the medical process of diagnosing depression. These tests, however, can sometimes give your doctor better insight into your mood. He or she can use them to make a diagnosis with more certainty. One example of a screening test is a two-part questionnaire that has been shown to be highly reliable in identifying the likelihood of depression. When you take this test, you will be asked to answer two questions: During the past month, have you been bothered by feeling down, depressed, or hopeless? During the past month, have you been bothered by little interest or pleasure in doing things? Your answer to the two questions will determine what the doctor does next. The doctor may ask you additional questions to help confirm a diagnosis of depression. Or if your answers indicate you do not have depression, the doctor may review your symptoms again to continue the effort to find the cause. Studies show that these two questions, especially when used with another test as part of the assessment process, are highly effective tools for detecting most cases of depression. Your doctor may use other depression screening instruments that measure the presence and severity of depression symptoms. Examples include: The Patient Health Questionnaire-9 ( PHQ-9) -- a 9-item self-administered diagnostic screening and severity tool based on current diagnostic criteria for major depression Beck Depression Inventory ( BDI), -- a 21-question multiple-choice self-report that measures the severity of depression symptoms and feelings Zung Self- Rating Depression Scale -- a short survey that measures the level of depression, ranging from normal to severely depressed Center for Epidemiologic Studies- Depression Scale ( CES- D) -- an instrument that allows patients to evaluate their feelings, behavior, and outlook from the previous week Hamilton Rating Scale for Depression ( HRSD), also known as the Hamilton Depression Rating Scale ( HDRS) or abbreviated to HAM- D -- a multiple choice questionnaire that doctors may use to rate the severity of a patient's depression When you take a test or inventory, you may feel uncomfortable responding honestly to questions or statements that are made. The person who administers the test will be asking about depression and mood, depression and cognition, and the physical feelings of depression such as lack of energy, sleep disturbance, and sexual problems. Try to be as honest as you can when assessing your symptoms. Questionnaires and screening tools can help a mental health professional in making a diagnosis, but rating scales in themselves are not a substitute for a clinical diagnosis made from a thorough interview. Once your doctor has made an accurate diagnosis he or she can then prescribe an effective treatment. Depression is treatable. Consequently, a depression diagnosis can start you on the road to a healthier life without feelings of helplessness, hopelessness, and worthlessness. Once your doctor makes a depression diagnosis, you need to follow the treatment program to get better. It's important to take the medications as prescribed. You also need to follow through on making lifestyle changes and working with a psychotherapist if that's what your doctor recommends. Millions of people with depression suffer needlessly because they don't get professional help that starts with a doctor's diagnosis.