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Problems with the PTH assays
Etienne Cavalier1, Pierre Delanaye2, Laurent Nyssen3
1Department of Clinical Chemistry, CHU de Liège, Liège, Belgium; University of Liège, Liège, Belgium.
Insights
Determining parathyroid hormone (PTH) levels is challenging due to circulating fragments recognized by current assays. New methods aim to improve accuracy for better clinical use.
Area of Science:
- Clinical Chemistry
- Endocrinology
- Assay Development
Background:
- Parathyroid hormone (PTH) assays have limitations despite decades of development.
- Circulating PTH includes active hormone and fragments, complicating accurate measurement.
- Renal impairment leads to fragment accumulation, interfering with standard assays.
Purpose of the Study:
- To review the challenges and issues associated with parathyroid hormone (PTH) determination.
- To highlight the impact of PTH fragments on assay accuracy.
- To discuss the need for improved standardization and reference methods.
Main Methods:
- Literature review of PTH assay methodologies and challenges.
- Analysis of PTH fragment behavior in different assay generations.
- Discussion of standardization efforts and future directions.
Main Results:
- Second-generation "intact" PTH assays recognize various PTH fragments.
- Third-generation PTH assays offer improved specificity but are not universally available.
- Significant issues include lack of reference methods, standardization, and consistent ranges.
Conclusions:
- Accurate PTH measurement remains a significant clinical challenge.
- Fragment interference and assay variability necessitate further research and development.
- Standardization efforts are underway to improve PTH determination reliability.
Abstract:
Even if the first assay for parathyroid hormone (PTH) was published in the early 1960s, its determination remains a challenge even today. Indeed, in the circulation, PTH is present in its active form (PTH 1-84), but many PTH fragments can also be present. These fragments accumulate when renal function declines and are recognized, at different extents, by the 2nd generation ("intact") PTH assays that are widely used in the clinical laboratories. Some assays, called "3rd generation PTH" do not recognize these fragments, but are not available everywhere. Hence, different problems are also linked with PTH determination. Among them, one can cite the lack of a reference method, the lack of standardization of the assays and, sometimes, the lack of consistent reference range. We can also point out stability problems and a large intra-individual variation. A workgroup is working on these problems under the auspices of the IFCC and we hope that some of these problems will be resolved in the next years. In this article, we will discuss all the possible issues of PTH determination.
