Nieren- und Hochdruckkrankheiten 01/2011; 40(05):190-200. DOI:10.5414/NHP40190
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ABSTRACT: Assessment of bone turnover for management of renal osteodystrophy is part of routine care in chronic kidney disease Stage 5 (CKD-5) patients. Measurement of intact parathyroid hormone (iPTH) is the most commonly used surrogate marker for bone turnover in these patients. The current study was conducted to evaluate the predictive value of the five most commonly used iPTH assays for bone turnover.
In a cross-sectional study, 84 CKD-5 patients underwent bone biopsy and blood drawings for determination of iPTH and total serum alkaline phosphatase (AP).
Histologically, patients presented with a broad range of bone turnover abnormalities as determined by activation frequency and bone formation rate/bone surface. Results of the five iPTH assays in each patient correlated but were significantly different. There were also significant differences between iPTH measurements at the same bone turnover level. Using Kidney Disease Outcome Quality Initiative recommended iPTH ranges, all assays showed comparably poor diagnostic performance. At 80% specificity, cut-off values of the 5 iPTH assays for low bone turnover varied from 165 to 550 pg/ml and for high bone turnover from 404 to 1,003 pg/ml. Sensitivities at these cutoffs remained below acceptable standards. Addition of AP measurements to iPTH did not improve diagnostic accuracy.
Precise assessment of bone turnover will require utilization of established and novel bone markers reflecting effects of bone turnover rather than measuring only iPTH or other effectors.
Clinical nephrology 08/2009; 72(1):5-14. DOI:10.5414/CNP72005 · 1.23 Impact Factor
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ABSTRACT: Cinacalcet lowers plasma parathyroid hormone (PTH) levels in patients with secondary hyperparathyroidism (sHPT), but the bone histologic response has not been described. This prospective, double-blind, placebo-controlled trial assessed the effects of cinacalcet on bone histology and serum markers of bone metabolism in dialysis patients with sHPT.
Patients with intact PTH (iPTH) > or = 300 pg/ml were randomly assigned 2:1 to receive cinacalcet or placebo with concurrent vitamin D and/or phosphate binder therapy. Cinacalcet (30 - 180 mg/day) was used to achieve iPTH levels < or = 200 pg/ml. Bone biopsies were performed before and after one year of treatment.
Baseline and end-of-study data were available from 32 patients (19 cinacalcet, 13 placebo). Baseline bone turnover was elevated in 27, reduced in 3 and normal in 2 patients. Serum bone-specific alkaline phosphatase (BSAP) and N-telopeptide (NTx) were elevated. Cinacalcet treatment decreased PTH and diminished activation frequency, bone formation rate/bone surface, and fibrosis surface/bone surface. Adynamic bone was observed in three patients receiving cinacalcet; in two of these, PTH levels were persistently low (< 100 pg/ml). The histomorphometric parameter changes in bone corresponded to PTH, BSAP and NTx reductions. Bone mineralization parameters remained normal.
Treatment with cinacalcet lowered PTH and reduced bone turnover and tissue fibrosis among most dialysis patients with biochemical evidence of sHPT.
Clinical nephrology 04/2008; 69(4):269-78. DOI:10.5414/CNP69269 · 1.23 Impact Factor