A Specific Laboratory Test for the Diagnosis of Melancholia

TLDR

The study standardized a dexamethasone suppression test (DST) by administering it overnight to 438 subjects to diagnose melancholia. The DST, using a 1‑mg dose and two samples at 4 and 11 PM, identified melancholia with 67 % sensitivity and 96 % specificity, using a 5 µg/dL cortisol cutoff, and abnormal results were almost exclusive to melancholic patients, with no association to demographics or symptom severity.

Abstract

• Four hundred thirty-eight subjects underwent an overnight dexamethasone suppression test (DST) to standardize the test for the diagnosis of melancholia (endogenous depression). Abnormal plasma cortisol concentrations within 24 hours after dexamethasone administration occurred almost exclusively in melancholic patients. The best plasma cortisol criterion concentration, above which a DST result may be considered abnormal, was 5 ug/dL. The optimal dose of dexamethasone was 1 rather than 2 mg. Two blood samples obtained at 4 and 11 PM after dexamethasone administration detected 98% of the abnormal test results. This version of the DST identified melancholic patients with a sensitivity of 67% and a specificity of 96%. Baseline nocturnal plasma cortisol concentrations were not useful. Abnormal DST results were found with similar frequency among outpatients and inpatients with melancholia; but they were not related to age, sex, recent use of psychotropic drugs, or severity of depressive symptoms. Extensive evidence validates this practical test for the diagnosis of melancholia.