The relationship between intact PTH and biointact PTH (1–84) with bone and mineral metabolism in pre-dialysis chronic kidney disease (CKD)

Abnormalities in PTH are implicated in the pathogenesis of bone abnormalities in chronic kidney disease (CKD)–mineral bone disorder (CKD–MBD). PTH concentrations are important in clinical decision and management. This emphasises the importance of providing an assay which measures biologically active PTH. We compared concentrations of intact PTH with biointact PTH (1–84) in CKD and end stage renal disease (ESRD) and investigated the relationship between the 2 PTH assays with bone and mineral laboratory parameters and bone mineral density (BMD) in CKD. We assessed 140 patients (61 in ESRD and 79 with CKD stages 1–4) in this cross-sectional study. We measured biointact PTH (1–84) as well as routine biochemical parameters on all subjects. In the CKD cohort, bone turnover markers; bone alkaline phosphatase (BAP) and tartrate resistant acid phosphatase (TRACP)-5b and bone mineral density (BMD) were also determined. In ESRD, intact PTH concentration was significantly higher compared to biointact PTH (1–84) (422 [443] v/s 266 [251] pg/mL, (p