Data di Pubblicazione:
2013
Citazione:
Commutability of two reference materials for two commercial lithium assays / E. Frusciante, I. Infusino, C.A. Ferrero, M. Panteghini. - In: BIOCHIMICA CLINICA. - ISSN 0393-0564. - 37:suppl.13(2013), pp. T257.S420-T257.S420. (Intervento presentato al convegno EUROMEDLAB tenutosi a Milano nel 2013).
Abstract:
is ensured by the availability in the JCTLM database of two
secondary reference materials (RM), i.e. the NIST SRM 956c
(electrolytes in frozen human serum) and the IRMM BCR-304
(lyophilised human serum). As these RM are intended for use
in the calibration and traceability validation of commercial
systems, information on their commutability is central. Here we
tested the commutability of these RM using two commercial
methods measuring serum lithium, based on direct
potentiometry (Ion-Selective Electrodes Direct, Roche Cobas
Integra 400) and on a colorimetric approach (Multigent Lithium,
Abbott Architect c16000), respectively. Methods: A total of 27
leftover human serum samples were collected, aliquoted and
stored at -80 °C until their use. We measured lithium
concentrations with the two systems in each biological sample,
in SRM 956c (3 levels) and in BCR-304 in duplicate in two
different runs on the same day. Manufacturer’s control
materials were used to validate analytical runs. The
commutability of RM was estimated from Deming regression
analysis of the measured results in native samples using the
95% prediction interval (95PI) and multiples of the standard
error of regression (Sy-x), in accordance with the CLSI C53-A
standard. Results: The SRM 956c results did not fall inside the
95PI based on the results for the native clinical samples. In
addition, using an acceptance criterion for commutability of ±3
times the experimental Sy-x (±0.066), the relative residuals (rr)
for SRM 956c (−2.956 level 1, −4.044 level 2, −3.209 level 3)
were all outside the acceptable range. On the other hand, BCR-
304 results fall inside the 95PI, but its rr (−0.197) was not within
the acceptable range. Conclusions: Our results show that SRM
956c was not commutable between the methods evaluated.
BCR-304 showed better, although not perfect, commutability
and should be preferred to align lithium assays to higher-order
references. The uncertainty of BCR-304 (2.9%) is however
relatively high and this may become an issue for fulfilling the
goal of acceptable uncertainty of lithium measurement for
clinical laboratories (±4.3%), as calculated assuming a time
interval between doses of 12h and a drug average half-life of
24h.
Tipologia IRIS:
01 - Articolo su periodico
Elenco autori:
E. Frusciante, I. Infusino, C.A. Ferrero, M. Panteghini
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