PTH and chronic kidney disease: Most importantly, mineralization is a significant abnormality in children with CKD [73], and is seen even in the early stages of CKD, before abnormalities in serum calcium, phosphate or PTH manifest, increasing as the eGFR decreases (29% of those in CKD stage 2, 42% in CKD stage 3, and 79% in CKD stages 4/5) [46].