PTH and depressive symptom measurement: Possible factors of reduced BMD in depression patients are the hypothalamic-pituitary-adrenal (HPA) axis: cortisol, leptin, and immune factor levels; cytokine, vitamin D, and parathyroid hormone levels; gender, lifestyle factors, the effect of antidepressants on BMD, osteoporotic fractures, and other comorbid psychiatric conditions [6].