Diagnostic value of PTH total kit for estimation of bone turnover in children with chronic renal failure

The aim of the study was to estimate the usefulness of total PTH and 1-84 molecule (CAP) assay in clinical practice. 118 children with chronic renal failure aged 13.8 +/- 4.5 years were examined: 69 on conservative treatment with creatinine clearance 40.7 +/- 20 ml/min/1.73 m2, 31 on peritoneal dialysis and 16 on hemodialysis. In all patients the following parameters were assessed: serum levels of calcium (sCa), phosphorus (sP), PTH intact (PTHs) by chemiluminescence method (Immulite analyzer), total PTH (PTHc) and CAP with Duo PTH Assay (Scantibodies Laboratories, USA). The value of CIP as the difference between total PTH and CAP was calculated. For the evaluation of bone turnover the serum level of osteocalcin (OC) with IRMA, (OsteoRiact, CIS, F) and activity of serum alkaline phosphatase (AP) were determined. The correlations between parameters were calculated by Pearson's correlation coefficient (r).Significant correlation were found between PTHs and PTHc (r=0.84, p=0.0000), CAP (r=0.79, p=0.0000) and CIP. The increase of PTHs, PTHc, CAP, CIP, sP, OC and percentage of CIP were noticed, when parallel increase of creatinine level was found. The negative correlation between creatinine level and CAP/CIP was observed. The similar correlations between level of PTHs, PTHc, CAP and OC level were observed (r=0.55, 0.49 and 0.50 respectively).The assay of total PTH and CAP fragment is not usefull in clinical practice for estimation of bone turnover in children with chronic renal failure.