Major depressive disorder laboratory findings

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Mitra Chitsazan, M.D.[2]

There are no diagnostic laboratory findings associated with major depressive disorder.

• There are no diagnostic laboratory findings associated with major depressive disorder. ^[1]
• Dexamethasone suppression test: ^[2]
  • About 50% of patients with major depressive disorder have abnormal dexamethasone suppression test. Nonsuppression (positive test result) shows cortisol hypersecretion secondary to a hyperactive hypothalamus-pituitary-adrenal axis.
  • However, dexamethasone suppression test is not routinely used in the diagnosis of major depressive disorders due to high rates of false positives and false negatives.
• Diminished TSH in response to TRH and decreased prolactin release in response to tryptophan have been reported in patients with major depression. However, the results are not definitive, and thus, are not used routinely used in clinical practice.