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Analytical and clinical evaluation of a new Roche electrochemiluminescence immunoassay for the determination of total P1NP

OBJECTIVE: Analytical and clinical evaluation of the total procollagen 1 amino-terminal propeptide (P1NP) electrochemiluminescence immunoassay on a Roche Elecsys 2010 immunoassay analyzer. MATERIALS AND METHODS: The analytical evaluation was performed according to standardized protocol based on the concepts of ECCLS documents. Imprecision studies were carried out using control materials and human pool sera. Intra- assay imprecision was tested on 20 replicates per analysis for 2 days. Interassay imprecision was tested using control material in duplicate for 10 days and the mean value was used for inaccuracy assessment. Interferences were investigated for hyperbilirubinemia, lipemia and hemolysis. For clinical evaluation, 3 groups of patients: I, secondary hyperparathyroidism due to hemodialysis (n=30) ; II, women on treatment for osteoporosis (n=26) ; and III, patients after bone fracture (n=11), were tested along with healthy volunteers (n=50). RESULTS: Imprecision studies yielded intra-assay CVs of 2.4-2.5% and interassay CVs of 2.2-3.4%. Inaccuracy was 6.2-9.2%. Interferences from triglycerides (<9.8 mmol/L), bilirubin (<750 µ ; ; ; ; ; mol/L) and hemoglobin (<4 g/L) were undetectable. The medians in groups I, II, III and control group were 338.6, 40.5, 166.1 and 51.7, respectively. With 95%CI, maximal diagnostic efficiency for groups I, II and III were reached at >89.3 ng/ml (specificity 94% ; sensitivity 100%), ≤ 32.5 (specificity 92% ; sensitivity 40.7%) and >147 (specificity100% ; sensitivity 60%), respectively. The respective AUCs were 0.994, 0.649 and 0.742. CONCLUSION: The new Roche electrochemiluminescence immunoassay for P1NP yields precise and accurate results, mostly free from interferences. P1NP could be a useful biochemical tool in assessing bone turnover in patients on hemodialysis and after bone fracture as well as a marker of therapeutic efficacy for osteoporosis.

P1NP; bone turnover; osteoporosis; hemodialysis; bone fracture

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