ABD is a serious complication of ESRD that leads to soft tissue/vascular calcification and ultimately to myocardial infarction, the leading cause of death in ESRD patients. Proper diagnosis of ABD is important because administration of potent vitamin D analogs to a patient with ABD (as would be appropriate for a patient with high bone turnover) must be avoided. The gold standard for diagnosing ABD is the invasive bone biopsy. Measurements of serum calcium and alkaline phosphatase are not reliable for ABD. However, bone-specific alkaline phosphatase can be used as a marker of ABD. Bone biopsy studies have demonstrated that iPTH is nondiagnostic for ABD when concentrations are >10.6 pmol/L; however, if iPTH is <10.6 pmol/L, there is a >85% probability of ABD (1). The Roche Elecsys iPTH assay was calibrated to the former Nichols Allegro iPTH IRMA (the assay on which treatment guidelines are based), whereas the Siemens DPC iPTH assay generates values that are on average 50% higher than the Roche assay. Therefore, the case study patient can be reliably concluded to have ABD, and the DPC iPTH should not be used to guide therapy.
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Authors’ Disclosures of Potential Conflicts of Interest: Upon manuscript submission, all authors completed the Disclosures of Potential Conflict of Interest form. Potential conflicts of interest:
Employment or Leadership: T. Cantor, Scantibodies Laboratory.
Consultant or Advisory Role: None declared.
Stock Ownership: None declared.
Honoraria: None declared.
Research Funding: None declared.
Expert Testimony: None declared.
Role of Sponsor: The funding organizations played no role in the design of study, choice of enrolled patients, review and interpretation of data, or preparation or approval of manuscript.
- © 2009 The American Association for Clinical Chemistry