Analytical requirements for biochemical bone marker assays

Abstract

New markers measuring an imbalance of the bone modeling process have been established in research and in clinical studies, but not yet within the routine laboratories. The improvement of clinical utility by both better interlaboratory comparability as well as minimization of assay influences would facilitate the acceptance in the routine laboratory.

Using two specifically developed monoclonal antibodies, a new osteocalcin assay in an Enzymun-Testr` format has become capable to measure intact as well as the stable N-Mid fragment of osteocalcin. This improvement allows the precise measurement of bone turnover through a stable measuring signal during sample storage compared to the signal of an assay that measure only the intact osteocalcin. The accuracy of the assay allows the follow-up measurement of the dose-dependent effect of the Ibandronate (an advanced bisphosphonate) treatment of patient with bone disease.

The measurement of urinary degradation products of the C-telopeptides of type I collagen as performed in the CrossLaps® ELISA has proven to be a sensitive and specific index of the bone resorption. A new technology (Elecsysr`) was used to realize the measurement of the CrossLaps® also in serum samples. The assay precision below 5% and an increased test component stability improve the laboratory quality, reliability and efficiency in order to adapt this serum assay to routine lab conditions.

Key Words:

• CrossLaps™
• Elecsys®
• Enzymun-Test®
• N-Mid Osteocalcin
• Osteoporosis Care