Preanalytical considerations in parathyroid hormone measurement

Automated immunoassays used to evaluate parathyroid function are vulnerable to different types of interference, which can affect clinical practices. This review provides a detailed overview of the six main types of interference known to affect the measurement of parathyroid hormone (PTH): heterophilic antibodies, biotin, PTH fragments, oxidized PTH (oxPTH), phosphorylated PTH, and some preanalytical factors. Because the prevalence of some of these conditions has been reported to approach 11.7%, and the frequency of testing for parathyroid function is important, the scale of the problem might be tremendous. Potential interference in parathyroid function testing should always be suspected whenever clinical or biochemical discrepancies arise. Their identification typically relies on additional laboratory tests, including method comparison, serial dilution, blocking reagent studies, affinity adsorption, and polyethylene glycol precipitation. Moreover, some of these issues can be mitigated with the development of mass spectrometry. This review also evaluated the clinical impact of parathyroid interference on immunoassays, including misdiagnosis, inappropriate parathyroidectomy; and delay in receiving appropriate therapy. Hence, strong communication should be maintained between the clinician and laboratory to avoid such scenarios.

Automated summary

Automated immunoassays used for evaluating parathyroid function are prone to various types of interference, which can have an impact on clinical practices. This review provides a comprehensive overview of six main types of interference affecting parathyroid hormone (PTH) measurement: heterophilic antibodies, biotin, PTH fragments, oxidized PTH (oxPTH), phosphorylated PTH, and certain preanalytical factors. The prevalence of some of these conditions has been reported to be as high as 11.7%, indicating a potentially significant problem due to the importance of parathyroid function testing. Identification of potential interference typically requires additional laboratory tests, such as method comparison and polyethylene glycol precipitation.