Preanalytical considerations in parathyroid hormone measurement

Area of Science:

• Clinical Chemistry
• Laboratory Medicine
• Endocrinology

Background:

• Automated immunoassays for parathyroid hormone (PTH) assessment are susceptible to various interferences.
• These interferences can significantly impact clinical decision-making and patient care.
• Understanding these interferences is vital given the high frequency of parathyroid function testing.

Purpose of the Study:

• To provide a comprehensive review of known interferences affecting PTH immunoassays.
• To discuss the clinical implications of these interferences, including misdiagnosis and treatment delays.
• To highlight methods for identifying and potentially mitigating assay interference.

Main Methods:

• Literature review of interference types affecting PTH measurement.
• Discussion of diagnostic laboratory techniques for interference identification (e.g., method comparison, serial dilution, blocking reagents).
• Evaluation of emerging technologies like mass spectrometry for interference mitigation.

Main Results:

• Six primary interference types identified: heterophilic antibodies, biotin, PTH fragments, oxidized PTH (oxPTH), phosphorylated PTH, and preanalytical factors.
• Prevalence of some interferences can be as high as 11.7%, indicating a potentially widespread issue.
• Clinical impacts include misdiagnosis, unnecessary parathyroid surgery, and delayed treatment.

Conclusions:

• Interference in PTH immunoassays poses a significant risk to patient management.
• Suspecting interference is essential when clinical and laboratory findings are discordant.
• Close collaboration between clinicians and laboratories is necessary to prevent adverse patient outcomes.