PREDICTIVE VALUE OF SERUM PARATHYROID-HORMONE LEVELS FOR BONE TURNOVER IN PATIENTS ON CHRONIC MAINTENANCE DIALYSIS

With the increasing occurrence of adynamic bone disease, it is essenti al to determine the level of bone turnover in chronically dialyzed pat ients before instituting vitamin D therapy, To assess the value of ser um parathyroid hormone (PTH) levels for prediction of bone turnover, w e determined sensitivity, specificity, and predictive value positive o f serum PTH, alone or in combination with other variables, in 79 patie nts who underwent one or two bone biopsies, Serum PTH levels were dete rmined by a radioimmunometric assay and were obtained at the time of b one biopsies, Patients were classified into (1) low or normal and (2) high bone turnover according to the value of activation frequency of b one, There were 57 biopsy specimens taken from hemodialysis patients a nd 39 specimens from continuous ambulatory peritoneal dialysis patient s (CAPD), All patients with serum PTH levels within or below the norma l range had low or normal bone turnover, Values of serum PTH above 450 pg/mL were 100% and 95.5% specific for high. bone turnover in hemodia lysis and CAPD patients, respectively, Values of serum PTH between 65 and 450 pg/mL had worse predictive value positive in CAPD patients (48 .6% to 78.6%) than in hemodialysis patients (67.3% to 87.1%), When oth er characteristics of the patients were taken into consideration, only age in hemodialysis patients and serum ionized calcium in CAPD patien ts improved the predictive value of serum PTH, All hemodialysis patien ts younger than 45 years of age with serum PTH levels above 65 pg/mL ( n = 15) had high bone turnover, and CAPD patients with low or normal b one turnover had higher serum ionized calcium, However, overall, bone turnover could not be predicted by serum PTH measurements in 30% of he modialysis and 51.3% of CAPD patients, The data suggest that for patie nts with serum PTH levels between 65 and 450 pg/mL, bone biopsies are indicated to precisely assess bone turnover prior to initiation of vit amin D therapy. (C) 1995 by the National Kidney Foundation, Inc.