PTH and chronic kidney disease: Regarding the biochemical parameters of CKD-mineral and bone disorder (MBD), patients with higher CKD stages were likely to have elevated serum levels of phosphate (P < 0.001), calcium × phosphate (Ca × P) product (P < 0.001), and intact PTH (P < 0.001), whereas they were likely to have decreased serum levels of calcium (P < 0.001).