The serum parathyroid hormone (PTH) rises in chronic kidney disease (CKD) and induces renal bone disease as well as other organ damage. The bone disease guidelines were released by the K-DOQI in 2003 in order to help physicians to improve bone management at all different CKD stages. However, many different PTH commercial assays are available today and some questions are raised concerning the interpretation, the validity and the practical choice of these different measurements. After reviewing PTH biosynthesis and metabolism, we will describe the regulation of different PTH fragments (particularly 1-84 and 7-84) and the various types of PTH assays. In compromised clinical situations, bone biopsy still remains the golden standard assessment of bone disease, and it will be helpful to clarify the interest of new 3rd generation PTH measurements. At present, we do not dispose of valid therapeutic recommendations using 3rd generation tests, as well as the relevance of the ratio PTH 1-84/7-84.