Perspective and priorities for improvement of parathyroid hormone (PTH) measurement – A view from the IFCC Working Group for PTH

Abstract

Parathyroid hormone (PTH) measurement in serum or plasma is a necessary tool for the exploration of calcium/phosphate disorders, and is widely used as a surrogate marker to assess skeletal and mineral disorders associated with chronic kidney disease (CKD), referred to as CKD-bone mineral disorders (CKD-MBD). CKD currently affects >10% of the adult population in the United States and represents a major health issue worldwide. Disturbances in mineral metabolism and fractures in CKD patients are associated with increased morbidity and mortality. Appropriate identification and management of CKD-MBD is therefore critical to improving clinical outcome. Recent increases in understanding of the complex pathophysiology of CKD, which involves calcium, phosphate and magnesium balance, and is also influenced by vitamin D status and fibroblast growth factor (FGF)-23 production, should facilitate such improvement. Development of evidence-based recommendations about how best to use PTH is limited by considerable method-related variation in results, of up to 5-fold, as well as by lack of clarity about which PTH metabolites these methods recognise. This makes it difficult to compare PTH results from different studies and to develop common reference intervals and/or decision levels for treatment. The implications of these method-related differences for current clinical practice are reviewed here. Work being undertaken by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) to improve the comparability of PTH measurements worldwide is also described.

Vitamin K Supplementation Modulates Bone Metabolism and Ultra-Structure of Ovariectomized Mice

“…Studies of VK-4 supplementation into women under hormone replacement therapy, carried out by Ishida and Kawai [24] have shown significant improvement of BMD parallel to raise into osteocalcin in serum. Also, the same study have shown a decrease into number of fractures in such women [24][25][26]. These data corroborate our experiments were carried in a mouse model.…”

“…to be used to reduce bone loss in women with osteoporosis [26][27][28]. In this paper we showed that OVX led to significant decreased in BMD.…”

Critical Governance Issue of Parathyroid Hormone Assays and its Selection in the Management of Chronic Kidney Disease Mineral and Bone Disorders

“…A significant variation can be seen when the same sample is measured with different i‐PTH assay kits using different readout systems. Although the results of different i‐PTH assays generally correlate well with each other, there was significant discrepancy between the i‐PTH assays in i‐PTH concentrations in CKD patients .…”

Harmonization in laboratory medicine: more than clinical chemistry?

“…This complexity, in turn, can hinder our current understanding of whether one, several or all forms of a measurand are of clinical interest. Of the many examples, human chorionic gonadotropin (HCG) [5], troponin [56] and PTH [69] represent paradigmatic and commonly requested laboratory measurands. In the last few years, the increased awareness of the lack of clearly defined measurands, reference methods and/or reference materials for many measurands of absolute clinical value has prompted further efforts to achieve harmonization, particularly as the final goal is to assure the comparability not only of analytical results but also of the ultimate laboratory information and not only in clinical chemistry but also in all fields of laboratory medicine.…”