Biomedical subjects

Heinz-Jürgen Roth

Publications and source records attributed to Heinz-Jürgen Roth.

4 recordsLinked to original sources

PubMed2004

Evaluation of serum beta-carboxy-terminal cross-linking telopeptide of type I collagen as marker of bone resorption in chronic hemodialysis patients.

BACKGROUND: The carboxy-terminal cross-linking telopeptide of type I collagen (beta-CrossLaps, beta-CTX) is released into the circulation during degradation of type I collagen and serves as a marker of bone resorption. beta-CTX is known to undergo a diurnal rhythm in normal individuals and to accumulate in chronic renal failure. beta-CTX has a potential role in noninvasive diagnosis of renal bone disease. METHODS: Serum beta-CTX was compared to parathyroid hormone (PTH) and other biochemical bone markers in 90 unselected hemodialysis patients. RESULTS: Mean beta-CTX was elevated above the normal range (1.72 +/- 0.93 microg/l); there were large individual variations. Serum beta-CTX was significantly correlated with various PTH assays (r >0.56) and with tartrate-resistant acid phosphatase 5b (TRACP 5b, r = 0.629), bone-specific alkaline phosphatase (r = 0.404) and osteocalcin (r = 0.534, all correlations p < 0.001). The correlation between beta-CTX and PTH was significantly higher than the correlation between TRACP 5b and PTH. Several factors which could confound interpretation of serum beta-CTX were assessed in further studies: (i) There was no recognizable influence of the time of blood sampling (morning dialysis shift versus afternoon dialysis shift) on serum beta-CTX. (ii) Serum beta-CTX was not significantly related to residual diuresis of patients. CONCLUSIONS: We found a high association between beta-CTX and other established markers of bone and calcium metabolism demonstrating the potential utility of beta-CTX as marker of bone resorption in renal bone disease. However, further studies employing bone histology are still warranted to exactly define the influence of glomerular retention on serum beta-CTX in end-stage renal disease.

Adult↗

PubMed2004

Multicentre performance evaluation of the E170 module for modular analytics.

The E170 module was evaluated at 13 sites in an international multicentre study. The objective of the study was to assess the analytical performance of 49 analytes, and to collect feedback on the system's reliability and practicability. The typical, within-run coefficients of variation (CVs) for most of the quantitative assays ranged between 1 and 2% while a range of 2-4% was achieved with the infectious disease methods. Total precision CVs were found to be within the manufacturer's expected performance ranges, demonstrating good concordance of the system's measuring channels and a high reproducibility during the 2-4-week trial period. The functional sensitivity of 11 selected assays met the clinical requirements (e.g., thyreotroponin (TSH) 0.008 mU/l, troponin T 0.02 microg/l, total prostate-specific antigen (PSA) 0.03 microg/l). The E170 showed no drift during an 8-hour period and no relevant reagent carryover. Accuracy was confirmed by ring trial experiments and method comparisons vs. Elecsys 2010. The reliability and practicability of the system's hardware and software met with, or even exceeded, the evaluator's requirements. Workflow studies showed that E170 can cover the combined workload of various routine analysers in a variety of laboratory environment. Throughput and sample processing time requirements were achieved while personnel 'hands-on-time' could be reduced.

Calibration↗

PubMed2003

Influence of PTH assay methodology on differential diagnosis of renal bone disease.

BACKGROUND: Determination of plasma parathyroid hormone (PTH) is routinely performed to diagnose and monitor renal bone disease. Recently, a new PTH assay ('whole PTH') using an antibody directed specifically against PTH(1-4) has been introduced. It was the aim of the current study to evaluate whole PTH and parameters derived from whole PTH in renal bone disease. METHODS: The following measurements were carried out in blood samples from 141 unselected haemodialysis patients: three intact PTH assays (Nichols, Roche Elecsys), Scantibodies total); whole PTH (Scantibodies); bone-specific alkaline phosphatase (bAP); tartrate-resistant acid-phosphatase 5b (TRAP 5b); osteocalcin, 25-hydroxyvitamin D. Parameters derived from whole PTH were: (i) non-PTH(1-84), difference between intact PTH (Scantibodies assay) and whole PTH; (ii) whole PTH/non-PTH(1-84) ratio. RESULTS: The values generated by the intact PTH assays were comparable. The mean whole PTH concentration was lower than mean intact PTH concentrations (16.9+/-18.1 vs 26.4+/-30.5 pmol/l, Nichols, P<0.05). The correlation coefficients between all four PTH assays were comparable and were very high (r>0.96, ns). The rank order of values generated by the whole PTH assay was statistically not significantly different from the rank order generated by the Nichols intact PTH assay. The median non-PTH(1-84) concentration was 5.2 pmol/l (range 0-49.4). All PTH assays correlated highly significantly with non-PTH(1-84) (correlation coefficients 0.83-0.92). Corrected serum calcium was also associated with non-PTH(1-84) but the correlation was weaker (r=0.28). Regression analysis indicated that the non-PTH(1-84) concentration could be predicted by 76.6-84.6% by the prevailing intact PTH concentrations. Other parameters contributed only marginally to prediction of non-PTH(1-84). In the entire patient group, there was no statistically significant correlation between the whole PTH/non-PTH(1-84) ratio and any of the PTH assays or biochemical bone markers. Eight of 141 patients had a whole PTH/non-PTH(1-84) ratio <1. TRAP 5b, bAP and osteocalcin had high correlations with intact PTH assays and the whole PTH assay (correlation coefficients 0.51-0.56, no significant difference). None of the PTH assays was superior to any other PTH assay in predicting serum concentrations of the bone markers. Therapy with active vitamin D metabolites (n=70) did not alter the results of our analyses. CONCLUSIONS: With respect to information about bone turnover we were not able to find differences between whole PTH and intact PTH assays. Our data also suggest that whole PTH and intact PTH assays give similar information. (i) The correlation between all PTH assays was very high. (ii) The rank order between whole PTH and Nichols intact PTH assays was comparable. (iii) The association between intact PTH assays and non-PTH(1-84) was very high. Albeit non-PTH(1-84) was mostly determined by the prevailing intact PTH concentration, diagnostic information on parathyroid activity provided by whole PTH or intact PTH, respectively, may differ in individual patients. How often this would happen cannot be answered with the currently available data. Unequivocal structural identification of the non-PTH(1-84) fraction would facilitate the answer to that question. The use of the whole PTH/non-PTH(1-84) ratio as a biochemical bone marker in renal bone disease requires further investigation.

Chronic Kidney Disease-Mineral and Bone Disorder↗

PubMed2002

Multicenter evaluation of a new immunoassay for intact PTH measurement on the Elecsys System 2010 and 1010.

BACKGROUND AND OBJECTIVE: The determination of parathyroid hormone (PTH) is of great clinical relevance in the assessment of calcium metabolic disorders. Although PTH was one of the first hormones measured by immunoassays, there are still many difficulties in its determination due to the low concentration of the hormone in blood and due to the heterogeneity of PTH resulting from different circulating hormone fragments. The aim of our multicenter-study was to evaluate the technical performance and the clinical validity of a new immunoassay for intact PTH measurement on the Elecsys Systems 2010 and 1010. METHODS AND RESULTS: The multicenter evaluation was performed in 11 clinical laboratories. The Elecsys PTH assay is a one step sandwich electrochemiluminescence immunoassay based upon the streptavidin-biotin technology. Two monoclonal antibodies are used in the assay providing detection of intact PTH. The imprecision study yielded within-run and between-days coefficients of variation of 3.1% - 6.6% and 3.4% - 15.6%, respectively using a three level control (PreciControl Bone, Roche Diagnostics) and human pool sera at two different concentrations (HS-low: 20 - 60 pg/ml, HS-high > 65 pg/ml). The analytical sensitivity calculated as the mean value plus 2 standard deviations of a within-run imprecision was below 2.70 pg/ml using zero calibrator matrix. Dilution linearity was observed up to 4890 pg/ml using zero calibrator matrix or human pool sera. Recoveries ranged between 85% - 115%. Serum, EDTA- and heparin plasma were evaluated for PTH measurement. Due to a better analyte stability (48h at 21 degrees C; 3d at 4 degrees C) EDTA plasma was recommended for PTH measurement. Results of the Elec sys PTH immunoassay correlated well (r = 0.926 - 0.994) with three different immunoradiometric assays (N-tact PTH SP, DiaSorin; Nichols Allegro Intact PTH, Nichols Institute Diagnostics; ELSA-PTH, CISBio International) and two different immunochemiluminometric assays (PTH-Intact-Immulite, DPC Biermann; Nichols Advantage Intact PTH, Nichols Institute Diagnostics) in technical and clinical method comparisons. The Passing/Bablok regression analysis yielded slopes of 0.692 - 1.729 and intercepts of -13.982 - +15.763 pg/ml. Deviations from slope 1.0 and intercept 0.0 were not unexpected due to differences in immunoassay standardization and probably due to the presence of different PTH fragments and a variable affinity of the used antibodies to these PTH fragments. Highly similar PTH concentration pattern of the Elecsys immunoassay and the Quick-Intraoperative Intact PTH immunoassay (Nichols Institute Diagnostics) obtained from specimens taken intraoperatively support the applicability of the Elecsys immunoassay to monitor the success of parathyroid resection. A reference range of 12.3 - 56.0 pg/ml calculated from PTH values of 43 apparently healthy individuals confirms reference limits published in the literature. The partition of collectives according to age showed, that individuals > 50 years have slightly higher PTH concentrations, independently of gender. This shift could be due to age itself or to an increased prevalence of individuals without obvious calcium metabolic disorders in this collective. CONCLUSION: The Elecsys PTH assay is a useful and reliable tool for determination of intact PTH. Our data support the intended use of the assay in clinical applications related to disorders of calcium metabolism.

Adolescent↗