The pathway through LC-MS method development: in-house or ready-to-use kit-based methods?

Historically, the determination of low concentration analytes was initially made possible by the development of rapid and easy-to-perform immunoassays (IAs). Unfortunately, typical problems inherent to IA technologies rapidly appeared (e.g. elevated cost, cross-reactivity, lot-to-lot variability, etc.). In turn, liquid chromatography tandem mass spectrometry (LC-MS/MS) methods are sensitive and specific enough for such analyses. Therefore, they would seem to be the most promising candidates to replace IAs. There are two main choices when implementing a new LC-MS/MS method in a clinical laboratory: (1) Developing an in-house method or (2) purchasing ready-to-use kits. In this paper, we discuss some of the respective advantages, disadvantages and mandatory requirements of each choice. Additionally, we also share our experiences when developing an in-house method for cortisol determination and the implementation of an "ready-to-use" (RTU) kit for steroids analysis.

Bone alkaline phosphatase: An important biomarker in chronic kidney disease - mineral and bone disorder.

Increased cardiovascular morbidity and mortality in chronic kidney disease (CKD) represents an emerging major health problem. Indeed, disturbances in mineral and bone metabolism occur frequently in CKD and are termed chronic kidney disease - mineral and bone disorder (CKD-MBD). These can lead to cardiovascular pathology, resulting in an increased cardiovascular risk. Bone alkaline phosphatase (BALP) is essential for biomineralization. Recent findings demonstrate a crucial role for BALP in the pathogenesis of vascular calcification and identified it as a promising predictor of mortality in CKD. In conjunction with parathyroid hormone (PTH), serum BALP has been suggested as a biomarker of bone turnover in CKD-MBD. In contrast to PTH, serum BALP demonstrates a lower variability and may thus be better suited for the diagnosis and longitudinal follow-up of bone turnover. The linear association with mortality, compared to the U-shaped curve for PTH, is an additional advantage, making BALP more suitable than PTH as a treatment target in CKD. Here we review the main characteristics of alkaline phosphatase isozymes/isoforms and the various assays currently used in clinical routine laboratories. We also discuss the role of BALP in both physiological and pathological mineralization, and the clinical benefit of BALP determination in CKD.