Journal of Analytical Sciences, Methods and Instrumentation, 2013, 3, 163-166
http://dx.doi.org/10.4236/jasmi.2013.33020 Published Online September 2013 (http://www.scirp.org/journal/jasmi)
163
Determination of Total Galactose from Dried Blood
Spots—Extensive Assay Evaluation of a CE-Marked
Test-Kit
Ralph Fingerhut, Toni Torresani
Swiss Newborn Screening Laboratory, Children’s Research Center (CRC), University Children’s Hospital, Zurich, Switzerland.
Email: ralph.fingerhut@kispi.uzh.ch
Received July 12th, 2013; revised August 20th, 2013; accepted August 29th, 2013
Copyright © 2013 Ralph Fingerhut, Toni Torresani. This is an open access article distributed under the Creative Commons Attribu-
tion License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly
cited.
ABSTRACT
Most newborn screening laboratories use CE-marked or FDA-approved test-kits, like in routine clinical chemistry. Na-
tional regulations require only minimal evaluation from the customer, if the test-kits are used as specified by the manu-
facturer. The microtiter-based kit-concept is often based on the perception, that the laboratory always processes whole
microtiter plates. However, in the daily routine, this is rather a rare exception, which leads to much higher costs per
newborn, compared to the costs per assay in the test-kits. In addition, the amount of wasted resources is quite high. Per-
formance of the Neonatal Total Galactose kit from Perkin Elmer was tested. We have determined specificity, limit of
detection (LOD), limit of quantitation (LOQ), intra and inter assay variation, recovery, stability of measuring signal and
reagents. Results were also compared with the Astoria Pacific Spot Check System. In addition, we had (by chance) the
opportunity to test 2 kits, which were already expired for more than 3 years. LOD was 165 - 306 µmol/L and LOQ 475
- 703 µmol/L, depending on the definition of LOD/LOQ. Mean recovery was 112.8%, intra assay CVs were 11.3, 7.3,
4.0, and 3.0, and inter assay CVs 28.7, 15.9, 7.8, and 9.3, at 220, 590, 1200, and 2060 µmol/L respectively. Reconsti-
tuted and mixed reagents must be used within some hours, and were unstable even if stored at −20˚C. However, if the
reconstituted galactose substrate reagent and galactose oxidase reagent were only mixed according to the daily require-
ments, and the rest stored separately at −20˚C, they were stable for at least 12 days. The performance of the expired
test-kits did not differ from the others. The performance of the Total Galactose kit is comparable to other tests used for
newborn screening. However, we could significantly reduce the costs per newborn and reduce unnecessary production
of waste, by thorough validation and modification of the assay procedures.
Keywords: Newborn Screening; Galactosemia; Total Galactose
1. Introduction
Newborn Screening for Galactosemia was introduced in
the 1970s [1]. While the classical “Beutler-Test” can only
detect newborns with classical galactosaemie [2], the
determination of total galactose [3,4] will also detect
newborns with galactokinase deficiency and uridine di-
phosphate galactose-4-epimerase deficiency.
Most newborn screening laboratories use CE-marked
or FDA-approved test-kits, like in routine clinical chem-
istry. National regulations require only minimal evalua-
tion from the customer if the test-kits are used as speci-
fied by the manufacturer. The microtiter-based kit-con-
cept is often based on the perception, that the laboratory
always processes whole microtiter plates. However, in
the daily routine of newborn screening laboratories, this
is rather a rare exception, which leads to much higher
costs per newborn, compared to the costs per assay in the
test-kits. In addition, the amount of wasted resources is
quite high. We have thoroughly tested the performance
of the Neonatal Total Galactose kit from Perkin Elmer.
We have determined specificity, LOD, LOQ, intra- and
inter-assay variation, recovery, signal stability of the flu-
orescent reaction product, and stability of reagents. Re-
sults were also compared with the Astoria Pacific Spot
Check System. In addition, we had (by chance) the op-
portunity to test 2 kits, which were already expired for
more than 3 years.
Copyright © 2013 SciRes. JASMI