[Comparative study of the serum measurement of PTH on Roche Cobas e411^® versus the Abbott Architect ci8200^®]

Parathormone (PTH) is the main hormone of phosphocalcic homeostasis. It is synthesized and secreted by the parathyroid glands. PTH has become a routine test in the medical biology laboratory. However, its measurement presents analytical difficulties with the various marketed kits. The aim of this work is to present the results of a comparative study between the PTH measurment on Abbott architect ci8200 and on Roche's Cobas e411 automaton. It is a prospective study carried out for 252 hospitalized patients in the various departments of the University Hospital Center Mohammed VI of Oujda. The "intact" PTH tests were performed on two automata: Abbott Architect ci8200 and Roche Cobas e411. The first uses chemiluminescent microparticle immunoassay. The second uses electrochemiluminiscence sandwich enzyme immunoassay. The agreement of the results between the different techniques was evaluated using the Bland-Altman difference diagram and the Passing-Bablok and Deming regression line (MedCalc software version 14.8.1.0^®). By analyzing the diagram of Bland-Altman, we note that the average bias between both methods is of the order of 193.9 pg/mL. As for the equation of the right of Passing-Bablok, it is: Y(Architect) = 3.11 X (Cobas) - 12.26. In conclusion, our study shows a great discrepancy between the results of the PTH assay on the Architect ci8200 versus the Cobas e411, hence the biologist's indisputable role in the control and evaluation of the kits marketed through the various validation tests.