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10
| 4 | 2003
Klinisk Biokemi i Norden
1. DEKS, 54 M1, University Hospital Herlev,
Denmark
2. Fürst Medical Laboratory, Oslo, Norway
3. Department of Clinical Chemistry, Malmö
University Hospital, Sweden
Summary
An overview of the background,
manufacturing and traceability of
the NFKK Reference Serum X is
presented, as well as a reprint of
the certified and indicative values
from the official certificate. The
intended use and a suggestion for
the practical use are described.
Introduction
NFKK reference serum X (hereafter called X) is
an unmodified fresh-frozen human serum without
additives. X is a reference material and comes with
a certificate [1]. X carries 14 assigned property val-
ues traceable to the highest available metrological
order and 12 indicative values.
X is the result of a cooperation between NFKK,
EQAnord and especially the participating laborato-
ries in the Nordic Reference Interval Project (NORIP)
[2] and in The Nordic Trueness Project (NTP)[3].
X is intended for evaluation and verification
of trueness of measurement procedures, usually
involving
in-vitro
diagnostic (IVD) medical devices.
Primarily X is intended to work as trueness control
when laboratories implement the common Nordic
reference intervals. Also X could be the answer to
the growing need for certified reference materials
with traceable values of higher order.
X is available from each of the national External
Quality Assurance (EQA) Organisers in the Nordic
countries.
Links to other projects
X was first included in NORIP in 2000 as a control
material, but also as the heir to CAL, the primary
calibrator in the project. Later in 2002 in NTP, a
Nordic expansion of the International Measurement
Evaluation Programme round 17 (IMEP-17), X and
CAL were measured again along with IMEP-17
Material 1 [4], a master material with assigned
values of the highest available metrological order
and assumed to involve none or negligible com-
mutability problems. The measuring in parallel after
common protocols enabled the transfer of values
and uncertainties from the IMEP-17 Material 1 to
X directly or via CAL. The transfer of the directly
assigned reference measurement procedure values
from CAL to X was also possible.
Background of the material
Material X is an unmodified fresh frozen human
serum. The material is a pool of fresh frozen human
sera isolated from donors’ blood by Hjørring County
Hospital in 2000. The blood was collected from
healthy blood donors according to WHO recom-
mendations. Each individual donation, as well as
the final pool, was tested and found negative for
anti-HIV, anti-HCV and HBsAG. The pool (~21 L)
was further treated by DEKS¹ in collaboration with
Statens Seruminstitut (SSI), Copenhagen, Denmark. It
was left unmodified and carefully mixed and sterile-
filtered (0,22 µm) before transferring 5 mL into each of
4200 polypropylene vials. The vials were closed with
a Teflon-coated stopper and an outer metal seal, and
stored at -80 °C [5].
The long-term stability (10 years) at -20, -80 and
-150 °C is monitored by DEKS [6].
The homogeneity has been verified and found suf-
ficient for this material [3], as well as other materials
manufactured in a similar way, e.g. IMEP 17 Material 1,
have also proved to be sufficiently homogenous [5;7]
No specific commutability study has been provid-
ed for X, but the material is assumed to have no or
NFKK Reference Serum X
Morten M. Pedersen¹, Pål Rustad², Per Simonsson³
(morten.pedersen@deks.dk)
1 Danish Institute for External Quality Assurance for laboratories
in Health Care
