Possible clinical applications of laboratory tests in depression.

The diagnosis of depression has traditionally been based on clinical history and behavioral observations. While objective laboratory tests will further our understanding of the pathophysiology and perhaps aid in the management of depression, a critical examination of the application of these techniques in clinical psychiatry is warranted by their increasing use. The utility for clinicians of the dexamethasone suppression test (DST), urinary MHPG assay, and tricyclic antidepressant plasma level assay is reviewed.