PAX5 and chronic kidney disease: In kidney disease, PTH and BSAP are the most widely tested BTMs to assess bone turnover, and BSAP, vitamin D, calcium, and phosphorus are used to assess mineralization.8, 9, 10, 67, 119 Generally, extremes of PTH and BSAP identify bone turnover type based on bone biopsy finding in CKD and ESKD.