Serum level of intact parathyroid hormone and other markers of bone metabolism in dialyzed patients.

In the present study, we evaluated and compared serum markers of bone turnover in dialyzed patients with serum intact parathyroid hormone (iPTH) < 100 pg/mL (LBT group, n = 9), 100-150 pg/mL (MIX group, n = 6), and iPTH > 150 pg/mL (non-LBT group, n = 15). Laboratory parameters included iPTH; cyclase activating parathyroid hormone (CAP); osteoprotegerin (OPG); OPG ligand (OPGL); inorganic phosphates; total Ca, urea, and creatinine; alkaline phosphatase activity; and blood pH. Cyclase inactive parathyroid hormone (CIP) was calculated by subtraction of CAP from iPTH. When results were adjusted for sex, age, dialysis modality, and dialysis duration, only CAP and CIP were significantly different between the groups. For the LBT MIX, and non-LBT groups respectively, mean serum values for CAP were 20.3 pg/mL (range: 6.53-50.7 pg/mL), 79.3 pg/mL (range: 53.4-99.0 pg/mL), and 343.3 pg/mL (range: 102.1-887.9 pg/mL) and for CIP they were 7.74 pg/mL (range: 2.41-48.4 pg/mL), 50.2 pg/mL (range: 29.5-68.0 pg/mL), and 129.0 pg/mL (range: 62.4-399.0 pg/mL). In a selection of dialyzed patients, serum CAP and CIP concentrations--but not CAP/CIP ratio, OPG, OPGL, and OPGL/OPG ratio--can, like iPTH values, be used to categorize those suspected of having adynamic bone.