Beck Depression Inventory ( BDI ) score and serum levels of C-reactive protein ( CRP ) , interleukin ( IL ) -6 , IL-10 , tumor necrosis factor ( TNF ) - , ferritin , intact parathyroid hormone ( iPTH ) , and ratios of IL-10 to IL-6 and IL-10 to TNF - were measured at baseline and at the end of the study .