Endocrine Abstracts

Introduction: 2nd generation ‘Intact’ PTH assays currently available, measure 1–84 PTH and additional fragments. Recently a third generation kit developed which detects only active.

1–84 PTH molecule, based on an immuno-radiometric sandwich assay.

Design: Evaluation took place in an HMO central lab. 240 plasma samples collected. One hundred and sixty-one randomly out patients and 78 hospitalized nephrologic patients. Patients samples, controls and NEQAS samples tested by CLIA.

Method: DiaSorin LIAISON 1–84 PTH assay, DiaSorin LIAISON N-TACT PTH II, SIEMENS Centaur iPTH and DiaSorin IRMA N-tact PTH SP (‘Gold Standard’). Results were compared with laboratory parameters and patients clinical status.

Results: Correlation between LIAISON 1–84 PTH and LIAISON N-TACT PTH II showed R=0.9164, slope=0.9076. Correlation between LIAISON 1–84 PTH and Centaur iPTH showed R=0.98, slope=2.7622. Correlation between LIAISON 1–84 PTH and IRMA N-tact PTH SP showed R=0.97, slope=1.0893. The following LIAISON 1–84 PTH parameters obtained: samples and controls within run precision showed 2.58 and 5.34% CV. Samples and controls between run precision showed 4.03 and 4.65% CV. Functional sensitivity matched manufacturer claim at 4 pg/ml. Recovery between 77 and 101%. Clinical agreement between LIAISON 1–84 PTH and IRMA N-tact PTH SP on nephrologic patients was 97.5%. Three discrepant patients were clinical matched with LIAISON 1–84 PTH results. From the healthy out patients tested samples 54% were found high with SIEMENS Centaur iPTH and 16% were high with LIAISON 1–84 PTH. The same behavior observed with NEQAS data.

PTH levels were influenced similarly by low Ca levels.

Conclusions: High diagnostic correlation was observed between IRMA N-tact PTH SP and LIAISON 1–84 PTH together with high clinical correlation of patients status. It is concluded that the LIAISON 1–84 PTH can be used as a reliable and accurate kit for setting up a clinical and high throughput laboratory.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.