Abstract: FR-PO287

Accuracy, Precision, and Stability of the LIAISON 1-84 PTH 3rd Generation Assay: Comparison to Existing Intact PTH Assays

Session Information

Category: Mineral Disease

  • 1202 Mineral Disease: Vitamin D, PTH, FGF-23

Authors

  • Valcour, Andre, LabCorp, Burlington, North Carolina, United States
  • Martin, Kevin J., Saint Louis University Med Ctr, St. Louis, Missouri, United States
  • Rao, Sudhaker D., Henry Ford Health System, Detroit, Michigan, United States
  • Hawkins, Douglas M, Scottsdale Scientific LLC, Scottsdale, Arizona, United States
  • Blocki, Frank A., DiaSorin Inc., Stillwater, Minnesota, United States
  • Zierold, Claudia, DiaSorin Inc., Stillwater, Minnesota, United States
  • Bonelli, Fabrizio, DiaSorin spa, Stillwater, Minnesota, United States
Background

Over the past few decades, PTH immunoassays have progressed through successive generations resulting in increased specificity and accuracy for detecting circulating PTH. With the introduction of 3rd generation assays, in which the biologically active PTH (1-84) is specifically targeted, the PTH (7-84) and other fragments are not detected. The specific recognition of PTH (1-84) whole molecule allows standardization and calibration with existing standards.

Methods

Samples from patients on hemodialysis, with primary hyperparathyroidism, and apparently healthy subjects were examined in different collection tubes (plasma, unspun plasma, and SST) stored for 0, 24, or 72h at room temperature to reflect the prevailing sample collection methods, shipping, and processing conditions of centralized labs in the US. Samples were analyzed by the LIAISON 1-84 PTH and the N-TACT assays, and three additional commercially available intact PTH methods.

Results

PTH is stable for up to 72 hours in plasma, but less stable in serum (SST) beyond 24h (% change from 0h in Table). Both the LIAISON assays (1-84 and N-TACT) demonstrated good precision. Furthermore, defined samples, prepared using two different standards (WHO 95/646 international standard and the synthetically synthesized Bachem PTH(1-84)), read accurately with the LIAISON 1-84 PTH assay, but not with the intact PTH assays (5-9% vs. 54-142% bias).

Conclusion

The FDA-approved LIAISON 1-84 PTH assay is accurate and precise and reliably measures the biologically active PTH molecule in serum or plasma stored at room temperature for up 72h in plasma, and 24h in serum.

% Change in PTH from T=0h
MethodSample Type24h72h
LIAISON 1-84 PTHplasma
SST
1.1%
-0.9%
-1.3%
-18.5%
LIAISON N-TACT PTHplasma
SST
0.5%
0.9%
-1.3%
-18.3%
Method A iPTHplasma
SST
-0.9%
-0.6%
-2.1%
-13.7%
Method B iPTHplasma
SST
-2.6%
-11.0%
-5.1%
-28.6%
Method C iPTHplasma
SST
20.0%
-17.8%
27.3%
-21.6%

Funding

  • Commercial Support