Evaluation of serum interleukin-1 receptor antagonist levels in major depressive disorder: A case-control study.

Background And Aims: Major depressive disorder (MDD) is characterized by the occurrence of one or more depressive episodes lasting a minimum of 2 weeks and is marked by a persistently low mood and a lack of enjoyment in daily activities. The diagnosis of MDD is not possible by a well-established laboratory test or biomarker. A wide range of potential biomarkers for depression have been proposed by many studies, but none of them has adequately described the correlation between the biomarkers and depression.