Endothelin and leptin within serum, and myeloperoxidase and midkine within urine, seemed to be more involved in women’s MDD pathophysiology, whereas apolipoprotein A1, EGF and myeloperoxidase within serum and cortisol, substance P and thromboxane B2 seemed to be more involved within men′s MDD pathophysiology. Here, LEP is linked to major depressive disorder.